JP7792892B2 - Power generation control device, power supply control system, power generation control method, and program - Google Patents

Description

This disclosure relates to a power generation control device, a unit price determination device, a power supply control system, a power generation control method, and a program, particularly in a power system where power generation is liberalized and multiple independent power generation companies each supply their own generated power.

Traditionally, the power system has been operated by essentially one electric utility per region. A local electric utility owns a sufficient number of power plants to meet the region's electricity demand, and adjusts the load allocation of the power plants to meet the region's electricity demand at the lowest fuel cost. However, each of the many power plants has different fuel cost characteristics, and even if the total amount of electricity generated is the same, the total fuel cost depends on the quality of the load allocation to the power plants. It is important for electric utilities to adjust the load allocation to power plants to meet the region's electricity demand at the lowest fuel cost.

If we call the load distribution that minimizes fuel costs optimal load distribution, then the optimal load distribution for a power plant can generally be obtained using the equal incremental fuel cost method. A property widely known in economics as the law of increasing marginal cost applies to power plants as well, which states that the additional cost required to add one unit of power generation, or utility, increases with utility. The equal incremental fuel cost method utilizes this property to determine the optimal load distribution for operating power plants. Therefore, traditionally, electric power companies have decided on the combination of power plants to operate, and then distribute the load according to the equal incremental fuel cost method to save on fuel costs (see, for example, Patent Document 1).

Special Publication No. 63-066144

In recent years, power generation has been liberalized in the electricity system, and each region now receives electricity from power plants operated by both traditional electric utilities and new independent power producers. Traditional electric utilities are also independent power producers, and they share local demand with multiple independent power producers. The electricity system generates electricity in accordance with demand. For power producers, demand is a given, and at the same time, the total amount of electricity generated by all power producers is also a given. Therefore, assuming demand remains constant, for example, if a power producer increases its power generation to improve profits, one of the other power producers will reduce its power generation so that supply and demand are equal. Although it is not often recognized, producers who reduce their power generation to adjust supply and demand are forced to endure a decline in their profits.

When local power plants belonged to a single power generation company, the profits of each power plant were not important, so a single power generation company could simply allocate the load to power plants based on the total amount of power they could generate to meet local demand with minimal fuel costs. However, when multiple power generation companies share local demand, fairness is also required in how that demand is distributed.

In an electricity system where power generation is liberalized, each individual power plant may be a unit of revenue, and it is inevitable that each power plant will act selfishly to improve its own profits. Therefore, technology is needed to harmonize the selfish actions of each power plant so that the overall demand is met without excess or shortage.

The purpose of this disclosure is to provide a power generation control device, unit price determination device, power supply control system, power generation control method, and program that can adjust electrical output according to the unit price and demand of generated power, while preventing unfair bias in the benefits or disadvantages of some power generation companies in a power system in which multiple power generation companies each supply generated power.

According to one aspect of the present disclosure, a power generation control device provided at each of a plurality of power plants includes an optimal value determination unit that determines the optimal value of the power plant's electrical output based on the unit price of generated power supplied to the power grid, and an adjustment unit that adjusts the command value of the electrical output according to the frequency of the power grid, with the optimal value as the upper limit of the electrical output.

According to one aspect of the present disclosure, the unit price determination device includes an aggregate value acquisition unit that acquires, from each of a plurality of power plants, an aggregate value of an optimal value of electrical output corresponding to the unit price of generated power supplied to the power grid, and an aggregate value of an equilibrium point signal, which is the value of electrical output adjusted to bring the deviation between the frequency of the power grid and a reference frequency closer to zero; and a unit price determination unit that determines the unit price based on the aggregate value of the optimal value and the aggregate value of the equilibrium point signal.

According to one aspect of the present disclosure, a power supply control system that controls the power supplied to a power grid includes the power generation control device according to the above aspect and the unit price determination device according to the above aspect.

According to one aspect of the present disclosure, a power generation control method includes the steps of determining an optimal value for the electrical output of a power plant based on the unit price of generated power supplied to a power grid, and adjusting a command value for the electrical output according to the frequency of the power grid, with the optimal value set as the upper limit for the electrical output.

According to one aspect of the present disclosure, the program causes a power generation control device provided at each of a plurality of power plants to execute the steps of determining an optimal value for the power plant's electrical output based on the unit price of generated power supplied to the power grid, and adjusting the command value for the electrical output according to the frequency of the power grid, with the optimal value set as the upper limit for the electrical output.

According to the above aspect, in a power system in which multiple power generation companies each supply generated power, it is possible to adjust electrical output according to the unit price and demand of generated power while preventing unfair bias in the benefits or disadvantages of some power generation companies.

1 is a diagram showing the overall configuration of a power supply control system according to a first embodiment; FIG. 2 is a first block diagram showing the functional configuration of the power generation control device according to the first embodiment. FIG. 2 is a second block diagram showing the functional configuration of the power generation control device according to the first embodiment. 2 is a block diagram showing the functional configuration of a tallying device and a unit price determination device according to the first embodiment; FIG. FIG. 10 is a diagram showing the overall configuration of a power supply control system according to a modified example of the first embodiment. FIG. 10 is a diagram showing the overall configuration of a power supply control system according to a modified example of the second embodiment. FIG. 10 is a block diagram showing the functional configuration of a power generation control device according to a second embodiment. FIG. 10 is a first diagram for explaining the function of a reallocation device according to a second embodiment. FIG. 10 is a second diagram for explaining the function of the reallocation device according to the second embodiment. FIG. 2 illustrates an example of a hardware configuration of an allocation device according to at least one embodiment.

First Embodiment
The first embodiment will be described in detail below with reference to the drawings.

(Overall structure)
FIG. 1 is a diagram showing the overall configuration of a power supply control system according to the first embodiment.
FIG. 1 shows an example of a power system 10 in a certain region. The power system 10 according to this embodiment is a power system in which power generation is deregulated, in which multiple power generation companies each own and operate one or more power plants, and the power generated at each power plant is supplied to the power grid. For example, the multiple power plants 1, 2, ..., n shown in FIG. 1 may each be owned and operated by a different power generation company. Furthermore, the power plants may be, for example, thermal power plants, nuclear power plants, or power generation facilities that use natural energy such as solar power or wind power.

The power supply control system 1 adjusts the electrical output of each power plant in the power system 10. The power supply control system 1 includes a power generation control device 2, a data collection device 3, and a unit price determination device 4.

A power generation control device 2 is provided at each of the multiple power plants 1, 2, ..., n. The power generation control device 2 adjusts the electrical output of the power plant in which it is installed according to the unit price γ of generated power and the demand of the region (power grid).

The aggregation device 3 aggregates various information from each power generation control device 2, which the unit price determination device 4 uses to determine the unit price.

The unit price determination device 4 determines the unit price γ of the generated electricity in the region based on the information collected by the collection device 3.

(Functional configuration of power generation control device)
FIG. 2 is a first block diagram showing the functional configuration of the power generation control device according to the first embodiment.
The functional configuration of the power generation control device 2 will be described with reference to Figure 2. The power generation control device 2 includes an optimal value determination unit 21 and an adjustment unit 22. The optimal value determination unit 21 determines an optimal value u ^* of the power output of the power plant based on the unit price γ of the power generated in the power system. The adjustment unit 22 adjusts the command value u of the power output according to the frequency f of the power system, with the optimal value u ^* of the power output as the upper limit.

The processing of the power generation control device 2 will be explained in detail. The power plant's electrical output (command value) that the power generation control device 2 commands the power plant to output is denoted as u. The power plant's electrical output u [kW] has a lower limit u_ (u underlined; the same applies below) and an upper limit u (u overlined; the same applies below). The power generation cost of the power plant is approximately expressed by the following equation (1). The coefficients {β ₂ , β ₁ , β ₀ } represent the relationship between electrical output and cost, and their values are determined for each power plant.

The additional power generation cost incurred when increasing electrical output by one unit is denoted as marginal cost _mc . Since marginal cost _mc is the cost differentiated by electrical output, it is expressed by the following equation (2).

Generally, the law of increasing marginal cost, known in economics, applies to the cost of generating electricity relative to electrical output. The law of increasing marginal cost states that the additional cost (cost of generating electricity) required to increase utility (electrical output) by one unit gradually increases. This can also be said to mean that the electrical output per unit of cost gradually decreases from the perspective of electrical output. If the cost of generating electricity is approximately expressed as a quadratic equation, as in equation (1), the law of increasing marginal cost is equivalent to equation (3). Equation (3) can also be expressed as β ₂ > 0, 2β ₂ u_ + β ₁ > 0.

In a power system where power generation is liberalized, the operation of power plants is determined by the power generation companies that own the plants. At least during normal times, power generation companies are free to operate or shut down their power plants; for example, other power generation companies do not instruct other power generation companies to operate or shut down. Therefore, the number of power plants operating as a whole is given. If the number of operating power plants is n and the power generation cost of each is expressed by equation (1), the optimal load distribution of the operating power plants, i.e., the optimal electrical output to each power plant, is expressed as equation (4) using marginal cost _mc as a parameter.

Since optimal load dispatching changes only the distribution while maintaining the total power generation output, the value of the marginal cost m _c can be found from equation (5A) using equation (5B).

Substituting the marginal cost _mc calculated in equation (5B) into equation (4) immediately reveals the electrical output that each power plant should contribute to achieve the total current electrical output of the n power plants at the lowest overall cost. This is known as the equal incremental fuel cost method for optimal operation of a group of power plants. However, to reiterate, in a deregulated power system 10, power is generated by power plants owned by different power producers. For example, each power plant may be owned by a different power producer. In this case, each power producer's primary concern would be their own profits. From the perspective of overall efficiency, it would be rational for less efficient power plants to reduce their power output and for more efficient power plants to increase their power output. However, in a deregulated power system, such altruistic behavior cannot be expected. Each power producer will behave in a manner that appears selfish, aiming to maximize its own profits. The power system requires technology that can accept the seemingly selfish behavior of power producers and harmoniously meet the demand for electricity as a whole. This technology is described below.

Let's consider the revenue of a single power plant. If the unit price of the generated electricity is denoted as γ [¥/kWh], the power plant's profit p can be expressed by equation (6).

Since the graph of equation (6) is upwardly convex, the electrical output u ^* at which profit p is maximized can be obtained by solving ∂p/∂u = 0 for u, as shown in equation (7).

While the value of the electricity unit price γ is the same for all power plants, the constants _β1 and _β2 , which represent the cost of power generation, differ from power plant to power plant, resulting in a different value for the electrical output u ^* at which profit p is maximized. It should be noted that in a power system 10 where power generation is deregulated, power plants cannot be operated at the electrical output u ^* given by equation (7). In the past, when each region essentially had one large electric utility, the large regional electric utility balanced the supply and demand of electricity. Therefore, even if independent power producers independently increased their power output according to equation (7) to maximize their profits, the resulting disturbances in the electricity supply and demand balance were offset by the large regional electric utility reducing its power output. However, it is unfair to assign the responsibility of balancing supply and demand to a specific electric utility. A power system would not function if each individual power plant were to arbitrarily increase its output, so technology is needed to ensure that each power producer fairly shares the responsibility of balancing supply and demand.

In this embodiment, the technology for achieving this is the power generation control device 2 shown in Figure 2, which adjusts the electrical output of each power plant. The power generation control device 2 is characterized by increasing or decreasing the output of the power plant according to the demand for electricity. In other words, the power generation control device 2 controls the power plant so that if the demand for electricity increases, the power generation output is increased accordingly, and if the demand for electricity decreases, the power generation control device 2 controls the power plant so that the output is decreased accordingly.

The unit price γ of the generated power is input to the optimum value determination unit 21 of the power generation control device 2. The power generation control device 2 records constants {β ₂ , β ₁ , β ₀ } that represent the costs of the power plant, and the optimum value determination unit 21 determines the optimum value u ^* of the electrical output that maximizes the profit of the power plant according to equation (7).

Another feature of this embodiment is that the optimal value u ^* is ^set as the upper limit of the electrical output, rather than as the target value of the electrical output. The adjustment unit 22 of the power generation control device 2 determines an equilibrium point signal _uI for the electrical output of the power plant. The adjustment unit 22 varies the equilibrium point signal _uI between the lower limit u_ of the electrical output and the upper limit u ^* of the electrical output in accordance with the imbalance in power supply and demand. It is known that the imbalance in power supply and demand manifests itself in fluctuations in the frequency of AC current. The frequency f of the power system is maintained at a reference frequency _fn . For example, if the reference frequency _fn is 60 Hz, when the supply of power is insufficient compared to the demand, the frequency f of the AC current will be lower than 60 Hz, and when the supply of power exceeds the demand, the frequency f of the AC current will be higher than 60 Hz. Taking advantage of this property, each power plant in the power system adjusts its electrical output in proportion to the difference between the frequency f and the reference frequency _fn , as shown in Equation (8). Here, u _n is the reference electrical output [kW] of the power plant, f _n is the reference frequency [Hz], δ is the speed adjustment rate (rate of increase in frequency relative to reference frequency f _n / rate of decrease in output relative to reference electrical output u _n ), and du is the GF signal (governor-free signal) that adjusts the supply and demand of power. The GF signal du may be calculated using the electrical angular velocity of the rotating shaft of the generator instead of the frequency f as an approximation of equation (8).

The power generation control device 2 adjusts supply and demand in accordance with the GF signal du, centered on the equilibrium point signal _uI of the electrical output. The equilibrium point signal _uI corresponds to the state in which the level of the electrical output of the power plant changes gradually over, for example, several minutes. In contrast, the GF signal du changes in units of seconds. The command value u of the electrical output that the power generation control device 2 commands the power plant is the sum of the equilibrium point signal _uI and the GF signal du, as shown in equation (9).

In the power generation control device 2 of this embodiment, the adjustment unit 22 determines the equilibrium point signal _uI based on the integral of the deviation between the power grid frequency f and the reference frequency _fn . The power grid frequency f may be a value measured at the connection point between the power plant and the power grid for each power plant, or a value measured at a representative point in the region may be used as a common value for all power plants in the region. Since the power grid frequency f is approximately normally distributed around the reference frequency _fn (50 Hz or 60 Hz), the time average value of the GF signal du is generally 0. Therefore, the GF signal du does not affect the amount of power supplied by the power plant.

The integral value of the deviation of the power system frequency f from the reference frequency _fn represents the long-term trend of the deviation of frequency f from the reference frequency _fn . For example, if the supply and demand of electricity are balanced, the frequency f will fluctuate randomly above and below the reference frequency _fn . In this case, the integral value of the deviation will not change.

Also, for example, if the power supply is insufficient, the frequency f is offset to the negative side relative to the reference frequency _fn . This causes the integral value of the deviation to increase over time. In other words, the equilibrium point signal _uI increases over time, and the level of the power plant's electrical output rises. As stated in equation (7), the power plant's profit is maximized at the electrical output u ^* , and if the electrical output exceeds this, profits will actually be reduced. To prevent this, the adjustment unit 22 sets the upper limit of the equilibrium point signal _uI to u ^* .

Conversely, if the power supply is excessive, the frequency f is offset to the positive side relative to the reference frequency _fn , and the integral value of the deviation decreases over time. That is, the equilibrium point signal _uI decreases over time, and the level of the power plant's electrical output decreases.

In this way, the power generation control device 2 autonomously adjusts the electrical output level of each power plant to compensate for imbalances in power supply and demand, allowing supply and demand adjustment for the entire power system to be achieved autonomously and naturally. Furthermore, by having each power plant operate in accordance with the electrical output commands of the power generation control device 2, supply and demand adjustments are not performed by one power generation company increasing its output and other power generation companies reducing their output, as is the case in conventional power systems. In other words, the power generation control device 2 can prevent unfair bias in the benefits or disadvantages of certain power generation companies.

(Functional configuration of power generation control device; modified example)
The power generation control device 2 may also autonomously determine whether to operate or stop the power plant. This technique will be described below with reference to FIG.

FIG. 3 is a second block diagram showing the functional configuration of the power generation control device according to the first embodiment.
3, the power generation control device 2 may further include a minimum value determination unit 23 and a control unit 24. The minimum value determination unit 23 determines the minimum value u _* of electrical output at which the profit of the power plant is zero, based on the unit price γ of generated power. The control unit 24 controls the start or stop of operation of the power plant based on the minimum value u _* of electrical output at which the profit is zero and the equilibrium point signal _uI .

The details of the processing of the power generation control device 2 shown in Figure 3 will now be described. As the level of electrical output decreases, the profit of the power plant also decreases, and at some point the profit will reach zero. For simplicity's sake, we will assume that the power plant stops operating when the profit falls below zero. If the electrical output at which the profit p becomes zero is denoted as u _* , then by solving p = 0, this value can be determined as shown in equation (10A).

As shown in FIG. 3 , the control unit 24 compares the electrical output u _* at which profit becomes zero with the equilibrium point signal _uI of the power plant. For example, when the power plant is shut down, the control unit 24 determines to start operation if _uI ≥ 1.05u _* and outputs an operation command to the power plant. Furthermore, when the power plant is operating, the control unit 24 determines to stop operation if _uI ≤ u _* and outputs a shutdown command to the power plant. Note that "1.05" is just an example, and any value may be set for each power plant depending on the characteristics of the power plant. In equation (10A), _β0 represents fixed costs. There are two types of fixed costs: those that do not occur if operation is shut down, such as lighting in the power plant's control room, and those that occur even if operation is shut down, such as interest on the power plant's construction costs. The fixed cost _β0 in equation (10A) assumes the former, and it is assumed that _β0 = 0 after operation is shut down. If the latter is dominant over the fixed cost β ₀ , the control unit 24 may control the operation to continue even if the profit falls below zero, thereby recovering the fixed cost. The control to stop the operation may be performed by controlling the operation to stop when the profit reaches a predetermined value. The predetermined value may be zero or a negative value. If the operation continues until the profit reaches a predetermined negative value -p _* , u _* is determined by equation (10B). In this embodiment, an example of determining whether to stop the operation based on profit has been described. However, profit is just one example, and the decision to stop the operation may also be made based on sales γ × u, for example.

(Functional configuration of the tallying device and unit price determination device)
FIG. 4 is a block diagram showing the functional configuration of the tallying device and the unit price determination device according to the first embodiment.
The functional configuration of the tallying device 3 and the unit price determining device 4 will be described with reference to FIG.

The collecting device 3 includes a collecting unit 31 that collects the optimal value u ^* of the electrical output corresponding to the unit price γ and the equilibrium point signal _uI from the power generation control devices 2 of the plurality of power plants 1, 2, . . . , n.

The unit price determination device 4 includes a tally value acquisition unit 41 and a unit price determination unit 42. The tally value acquisition unit 41 acquires the tally values of the optimal values u ^* and the tally values of the equilibrium point signals _uI from the tallying device 3. The unit price determination unit 42 determines the unit price γ of the generated power based on the tally values of the optimal values u ^* and the tally values of the equilibrium point signals _uI .

Note that while Figures 1 and 4 show an example in which the tallying device 3 and the unit price determination device 4 are separate devices, this is not limiting. In other embodiments, the tallying device 3 and the unit price determination device 4 may be configured as a single device.

Each power plant has its own upper limit of electrical output, u ^* . If n power plants are operating in a certain region, the maximum power generation in the entire region can be calculated by adding up the u ^* values of the n power plants, Σu ^* . On the other hand, the total actual power generation in the region is calculated by adding up the _uI values of the n power plants, _ΣuI . If Σu ^* is sufficiently large compared to _ΣuI , there is no need to worry about the increase in power supply for the entire region. However, if _ΣuI ≒ Σu ^* , there is no room for increase. In this case, additional power plants must be operated to ensure the increase.

The minimum electrical output at which a power plant can earn a profit p (profit p becomes positive) is u _* , calculated using equation (10). Since the value of ∂u _* /∂γ, obtained by differentiating u _* with respect to γ, is negative, increasing the unit price of generated electricity γ will decrease u _* , and even power plants that are currently shut down will emerge with positive profit p. This increases the margin for increase. In addition, the upper limit of electrical output u ^* , which takes into account the profits of power plants currently in operation, is determined by equation (7), but the value of ∂u ^* /∂γ, obtained by differentiating u ^* with respect to γ, is positive, and additional margin can be obtained from power plants currently in operation. In this way, increasing the unit price of generated electricity γ increases the margin for increase in power supply capacity.

The unit price determination device 4 therefore sets the unit price γ of the generated power lower if the margin is excessive, and higher if the margin is insufficient. The processing of the unit price determination device 4 will be explained in detail with reference to Figure 4.

For example, the appropriate value of the increase _mU can be determined based on the amount of power supply _ΣuI in the region, and calculated using equation (11). _γ0 is the reference value of the unit price, and _Kγ is a positive proportionality coefficient. Note that the equation for calculating the unit price γ is not limited to a linear function; it can also be a general polynomial or exponential function.

Furthermore, when the unit price determination device 4 notifies the power generation control device 2 of each power plant of the unit price γ of the generated electricity, as described above, in the power system 10, each power plant adjusts its electrical output and controls operation/stop, thereby autonomously adjusting supply and demand and ensuring a margin for increase.

(Action, effect)
As described above, the power generation control device 2 according to this embodiment includes an optimal value determination unit 21 that determines an optimal value u ^* of the electrical output of the power plant based on the unit price γ of the generated power supplied to the power grid, and an adjustment unit 22 that adjusts the command value u of the electrical output according to the frequency f of the power grid, with the optimal value u ^* as the upper limit of the electrical output.

In this way, the power generation control device 2 enables each power plant to autonomously adjust supply and demand throughout the entire power system 10. Furthermore, by having each power plant operate in accordance with the electrical output commands of the power generation control device 2, it is possible to prevent supply and demand adjustments made by one power generation company arbitrarily increasing its output and other power generation companies reducing their output, as is the case with conventional power systems. In other words, the power generation control device 2 can prevent unfair bias in the benefits or disadvantages of certain power generation companies.

Furthermore, the adjustment unit 22 of the power generation control device 2 calculates, by integral control, an equilibrium point signal uI, which is the value of the electrical output that brings the deviation between the frequency f of the power grid and the reference frequency _fn closer to zero and has the optimal value u ^* of the electrical output as its upper limit, and adjusts the command value _u of the electrical output based on the equilibrium point signal _uI .

By doing this, the power generation control device 2 allows each power plant to earn a profit from power generation and stabilizes the supply and demand balance in the power grid.

The power generation control device 2 further includes a minimum value determination unit 23 that determines, based on the unit price γ, the minimum value u _* of the electrical output at which the profit of the power plant becomes zero, and a control unit 24 that controls the start or stop of operation of the power plant based on the minimum value u _* of the electrical output and the equilibrium point signal _uI .

In this way, the power generation control device 2 can operate or shut down the power plant so that the power plant can more reliably make a profit or so that profits do not become negative.

The unit price determination device 4 according to this embodiment also includes an aggregate value acquisition unit 41 that acquires, from each of the multiple power plants, an aggregate value of the optimal value u ^* of the electrical output corresponding to the unit price γ of the generated power supplied to the power system, and an aggregate value of the equilibrium point signal _uI , which is an output target value for bringing the frequency f of the power system closer to the reference frequency _fn , and a unit price determination unit 42 that determines the unit price γ based on the aggregate value of the optimal value u ^* and the aggregate value of the equilibrium point signal _uI .

By doing this, the unit price determination device 4 can adjust the electrical output and control operation/shutdown at each power plant by increasing or decreasing the unit price γ, allowing for autonomous supply and demand adjustments and the securing of margins.

<Modification of the First Embodiment>
FIG. 5 is a diagram showing the overall configuration of a power supply control system according to a modified example of the first embodiment.
5, the power supply control system 1 according to this modification may further include a counter-adjustment power totalization device 5. For example, when a power plant generates power in excess of the demand in the power grid, the counter-adjustment power totalization device 5 can totalize the amount of excess power generated (counter-adjustment power).

The counter-regulation power totalizing device 5 includes a first acquiring unit 51 and a counter-regulation power calculating unit 52. The first acquiring unit 51 acquires an equilibrium point signal _uI and an actual measured value y of the power plant's electrical output from the power generation control device 2 of each of the multiple power plants. The counter-regulation power calculating unit 52 calculates the amount of excess power generated q (counter-regulation power) by integrating the difference between the actual measured value y of the electrical output and the equilibrium point signal _uI . The actual measured value y of the electrical output is power [kW] measured at the connection point between the power plant and the power grid.

For the power system 10 to function, supply and demand balancing, i.e., matching the power supplied by a power plant with the demand, is important. In the technology described in the first embodiment, this is achieved by each power plant adjusting its output according to the equilibrium point signal _uI . However, there is a possibility that a power plant may generate more power than the equilibrium point signal _uI in order to increase its profits. As shown in FIG. 5 , the counter-regulation power calculation unit 52 integrates the difference between the actual measured value y of the power output of each power plant and the equilibrium point signal _uI as the amount of power q. If a power plant generates power in excess of the equilibrium point signal _uI , this amount of power q represents the counter-regulation power. Furthermore, the counter-regulation power calculation unit 52 may impose a penalty by reducing the price (sales) for power supply, for example, by subtracting the amount of power (counter-regulation power) generated in excess during a specified settlement period (e.g., one day) from the total amount of power supplied by the power plant to the power grid during the same period.

The counter-regulation power totalizing device 5 can monitor whether each power plant is appropriately adjusting supply and demand by totaling the amount of power generated by the power plant in excess of the equilibrium point signal _uI as counter-regulation power. Monitoring counter-regulation power acts as a deterrent to excessive power generation, contributing to stabilizing the supply and demand balance in the power system. Furthermore, by deducting an amount corresponding to the counter-regulation power from the price of the power generated by the power plant, it is possible to more reliably curb excessive power generation by the power plant.

Second Embodiment
The power supply control system 1 according to the second embodiment improves the profit p of a power generation company when the power generation company owns a plurality of power plants.

FIG. 6 is a diagram showing the overall configuration of a power supply control system according to a modified example of the second embodiment.
In the example of Figure 6, one power generation company owns power plants 1, 2, ..., _nQ among multiple power plants that supply power to a certain region. Power plants 1, 2, ..., _nQ owned by one power generation company are also collectively referred to as a power plant group. The power supply control system 1 further includes a reallocation device 6. The reallocation device 6 reallocates the electrical output of each of the power plants 1, 2, ..., _nQ belonging to the power plant group.

The reallocation device 6 includes a second acquisition unit 61 and a reallocation unit 62. The second acquisition unit 61 acquires, from each of the power plants belonging to the power plant group, an equilibrium point signal _uI , which is an output target value for bringing the frequency of the power grid closer to a reference frequency, and a coefficient β related to the cost required for power generation. The reallocation unit 62 reallocates the electrical output of each of the power plants belonging to the power plant group based on the equilibrium point signal _uI and the coefficient β, so as to minimize the power generation cost of the entire power plant group.

Note that while Figure 6 shows an example in which a redistribution device 6 is added to the power supply control system 1 (Figure 1) according to the first embodiment, this is not limiting. A redistribution device 6 may also be added to a power supply control system 1 (Figure 5) according to a modified example of the first embodiment.

FIG. 7 is a block diagram showing the functional configuration of the power generation control device according to the second embodiment.
In the power generation control device 2 according to this embodiment, the adjustment unit 22 further adjusts the command value u of the electrical output based on the electrical output reallocated by the reallocation device 6 .

If a power generation company owns multiple power plants, the company has the freedom to choose which power plants to use, and will generally select a combination of power plants based on economic efficiency. If the combination of power plants currently in operation by a power generation company is denoted as Q, the total electrical output supplied by that power generation company can be calculated using the following equation (12):

In Figure 6, as a specific example, Q = {1, 2, ..., _nQ } is shown for simplification. The actual Qs are not necessarily consecutive numbers. The total electrical output for a combination Q of power plants is calculated from the equilibrium point signals _uI of each power plant included in the combination. The reason for this is to avoid fluctuations in the total electrical output due to the GF signal, which fluctuates in a short period of time.

In a power system 10 where power generation is deregulated, the total electrical output supplied by a power generation company is determined by the balance between power supply and demand and is a given for the power generation company. Therefore, the power generation company pursues profits by generating the total electrical output _uQ at a lower cost. If the power generation company owns multiple power plants, as described above, the power generation company has the freedom to select the power plants to use. Furthermore, the power generation company can increase profits by increasing the allocation of the total electrical output _uQ to more efficient power plants and shutting down or reducing the allocation of less efficient power plants. Changing the output allocation of power plants while maintaining the total electrical output supplied by the power generation company is generally referred to as "switching," and this embodiment follows this convention. A method of switching will be described using Figures 6 to 9.

FIG. 8 is a first diagram for explaining the function of the reallocation device according to the second embodiment.
Suppose a power generation company operates a group of power plants with a combination Q. When the combination of power plants to be operated is given, optimal switching can be realized using the equal incremental fuel cost method. When switching is performed within combination Q, the equal incremental fuel cost method is expressed as an optimization problem as shown in the following equation (13).

In equation (13), Δu _I,i is the electrical output transferred by power plant i, which is an element of Q. Since the electrical output of the entire combination Q must remain unchanged before and after the transfer, the sum of Δu _I,i is 0. With this as a constraint, equation (13) represents an optimization problem of minimizing the sum of the cost c of each power generation cost that makes up combination Q.

The optimization problem of equation (13) can be solved by the Lagrange multiplier method. If the Lagrange multiplier is λ and the Lagrange function L(Δu _I , λ) is as shown in equation (14), the optimal values of Δu _I and λ are Δu _I ∈R ^nQ and λ∈R ¹ , which satisfy the simultaneous equations of equation (15).

Expanding the two equations results in the simultaneous equations of degree n _Q +1 of equation (16).

Expanding the cost c gives us equation (17).

Equation (17) is a linear simultaneous equation for the Lagrange multiplier λ and Δu _I , and the optimal solution is obtained as shown in equations (18) and (19).

As shown in Figures 6 and 8, the reallocation device 6 receives the equilibrium point signal _uI and parameters { _β2 , _β1 , _β0 } representing the power generation cost from each of the power plants in operation, and outputs the electrical output power _ΔuI to be transferred. Figure 7 shows how the electrical output power _ΔuI to be transferred is reflected in the electrical output power u. The electrical output power _ΔuI to be transferred is reflected in the electrical output power u in the same way as the GF adjustment signal. This is unrelated to the equilibrium point signal _uI . This is to strictly ensure that the equilibrium point signal _uI is determined only based on the frequency f. Since the sum of the electrical outputs _ΔuI to be transferred for a combination Q of power plants in operation is zero, whether or not the electrical output power _ΔuI to be transferred is reflected in the equilibrium point signal _uI is unrelated to the function of the de-adjustment power totalization device 5 according to the modified example of the first embodiment (Figure 5), and therefore there is no problem in handling it in this way.

Each power plant has a limit on the rate of change of its electrical output. For example, it is impossible to increase the electrical output from 0% output to 100% output in one second. For this reason, the rate of change of Δu _I may be limited so that the value of the transferred electrical output Δu _I does not change suddenly. For example, the time rate of change of the transferred electrical output may be limited so that even the power plant with the slowest rate of change of electrical output can keep up. When limiting the rate of change of the transferred electrical output of each power plant, Equation (20) may be used as a constraint in determining the rate of change so that the limit on the time rate of change does not affect Equation (12).

The reallocation process (using the equal incremental fuel cost method) involves constantly repeating the calculations of equations (18) and (19), so that the load is transferred continuously over time. This allows optimal load distribution to be achieved in real time.

Power generation companies that own multiple power plants have the freedom to select and use the most efficient power plants among their owned plants, so they should be able to select the most economically optimal power plant. Electricity demand changes over time. For example, during the day, production activity is active, resulting in high demand for electricity, while at night, most production activity is stopped, resulting in low demand for electricity. As demand fluctuates over time, the optimal combination of power plants must also change accordingly. Power generation companies review the combination Q of power plants they operate through a separate combinatorial optimization process. Reviewing the combination Q of power plants they operate involves either (1) shutting down the power plants included in combination Q, (2) adding a new power plant to combination Q, or (3) maintaining combination Q. Of these, the process for (3) is as shown in Figure 8. (2) simply adds a new power plant to Q. The process performed by the electrical output reallocation device after the addition is exactly the same as (3). (1) requires a partial change to the process of the reallocation unit 62 of the reallocation device 6, which is explained below using Figure 9.

FIG. 9 is a second diagram for explaining the function of the reallocation device according to the second embodiment.
Before the revision, suppose that a power generation company is operating a group of power plants with a combination Q, and then shuts down power plant k from combination Q. The remaining power plants are the combination Q with power plant k removed, and are therefore denoted as Q\k. After shutting down power plant k, the total electrical output before shutting down must be taken over by the remaining power plants. This is a constraint, and is expressed by equation (21).

The optimization problem to minimize cost with equation (21) as a constraint is expressed as equation (22).

As mentioned earlier, this problem can also be solved using Lagrange's method of undetermined multipliers. Specifically, equations (23) and (24) are used.

For the power plant k to be shut down, the electrical output must be changed from the current value u _I,k to 0, and the electrical output to be transferred is expressed as equation (25).

If we do so, then equation (12) also holds true for the case of "(1) shutting down power plants included in combination Q." Therefore, the difference between the case of "(1) shutting down power plants included in combination Q" (Figure 9) explained here and the case of "(3) maintaining combination Q" explained earlier (Figure 8) is determined by whether or not there is a power plant, such as power plant k, whose output is specified externally rather than left to the equal incremental fuel cost method. If everything is left to the equal incremental fuel cost method, then the answer is (3), and if not, the answer is (1).

Let us use the symbol k to represent a power plant whose output is externally specified. Since there can be multiple k's, let us denote the set of k's by K. That is, if K = {1, 2, ..., n _K }, k∈K, then Δu _I,k is an externally specified value. In this case, the problem of optimizing the output of power plants that do not belong to K (i.e., belong to the set Q\K) by the equal incremental fuel cost method, while externally specifying the electrical output of power plants that belong to K by r _{I ,k without changing the overall output of power plants Q in operation as in equation (12), is expressed as equation (26). For example, to shut down power plant k, we simply set K = {k}, r I,k} = 0 kW. Furthermore, to shut down power plant k and increase the power of power plant k+1 to 100 MW, we simply set K = {k, k+1}, r _I,k+1 = 100 MW.

In this way, when a power generation company owns multiple power plants, the power supply control system 1 according to this embodiment can increase the profits of the power generation company by reallocating the electrical output of each power plant using the reallocation device 6.

<Hardware configuration>
FIG. 10 is a diagram illustrating an example of a hardware configuration of an allocation device according to at least one embodiment.
An example of the hardware configuration of each device included in the power supply control system 1 will be described below with reference to FIG.

As shown in FIG. 10, the computer 900 includes a processor 901, a main memory device 902, an auxiliary memory device 903, and an interface 904.

The power generation control device 2, aggregation device 3, unit price determination device 4, counter-adjustment power aggregation device 5, and reallocation device 6 described in each of the above-mentioned embodiments are each implemented in a computer 900. The operation of each of the above-mentioned processing units is stored in the auxiliary storage device 903 in the form of a program. The processor 901 reads the program from the auxiliary storage device 903, loads it into the main storage device 902, and executes the above-mentioned processing in accordance with the program. The processor 901 also allocates storage areas in the main storage device 902 to be used for various processes in accordance with the program. The processor 901 also allocates storage areas in the auxiliary storage device 903 to store data being processed in accordance with the program.

The program may be for realizing some of the functions to be performed by the computer 900. For example, the program may be a program that performs functions in combination with other programs already stored in the auxiliary storage device 903 or in combination with other programs implemented in other devices. In other embodiments, the computer 900 may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor 901 may be realized by the integrated circuit.

Examples of the auxiliary storage device 903 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read-only memory (CD-ROM), a digital versatile disc read-only memory (DVD-ROM), and semiconductor memory. The auxiliary storage device 903 may be internal media directly connected to the bus of the computer 900, or an external storage device 910 connected to the computer 900 via the interface 904 or a communication line. Furthermore, if this program is distributed to the computer 900 via a communication line, the computer 900 that receives the program may load the program into the main storage device 902 and execute the above-described processing. In at least one embodiment, the auxiliary storage device 903 and the external storage device 910 are non-transitory tangible storage media.

As described above, several embodiments of the present invention have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as the invention and its equivalents as set forth in the claims.

<Additional Notes>
The power generation control device, the unit price determination device, the power supply control system, the power generation control method, and the program described in the above-described embodiments can be understood, for example, as follows.

(1) According to a first aspect of the present disclosure, a power generation control device 2 provided in each of a plurality of power plants includes an optimal value determination unit 21 that determines an optimal value u ^* of an electrical output of the power plant based on the unit price γ of generated electrical power supplied to an electrical grid, and an adjustment unit 22 that adjusts a command value u of the electrical output according to the frequency f of the electrical grid, with the optimal value u ^* as an upper limit of the electrical output.

In this way, the power generation control device 2 enables each power plant to autonomously adjust supply and demand throughout the entire power system 10. Furthermore, by having each power plant operate in accordance with the electrical output commands of the power generation control device 2, supply and demand adjustments are not performed by one power generation company increasing its output and other power generation companies reducing their output, as is the case with conventional power systems. In other words, the power generation control device 2 can prevent unfair bias in the benefits or disadvantages of certain power generation companies.

(2) According to a second aspect of the present disclosure, in the power generation control device 2 according to the first aspect, the adjustment unit 22 calculates, by integral control, an equilibrium point signal uI, which is an electric output value adjusted so as to bring the deviation between the frequency f of the power grid and the reference frequency _fn closer to zero and has an upper limit equal to the optimal value u ^* , and adjusts the electric output command value u based on the equilibrium point signal _{uI .}

By doing this, the power generation control device 2 allows each power plant to earn a profit from power generation and stabilizes the supply and demand balance in the power grid.

(3) According to a third aspect of the present disclosure, the power generation control device 2 according to the second aspect further includes a minimum value determination unit 23 that determines, based on the unit price γ, a minimum value u _* of the electrical output at which the profit p of the power plant becomes a predetermined value, and a control unit 24 that controls the start or stop of operation of the power plant based on the minimum value u _* and the equilibrium point signal _uI .

In this way, the power generation control device 2 can operate or shut down the power plant so that the power plant can more reliably make a profit or so that profits do not become negative.

(4) According to a fourth aspect of the present disclosure, the unit price determination device 4 includes an aggregate value acquisition unit 41 that acquires an aggregate value of an optimal value u ^* of an electrical output corresponding to the unit price γ of generated power supplied to the power grid from each of a plurality of power plants and an aggregate value of an equilibrium point signal _uI, which is the value of the electrical output adjusted so that the deviation between the frequency f of the power grid and the reference frequency _fn approaches zero, and a unit price determination unit 42 that determines the unit price γ based on the aggregate value of the optimal value u ^* and the aggregate value of the equilibrium point signal _uI .

By doing this, the unit price determination device 4 can adjust the electrical output and control operation/shutdown at each power plant by increasing or decreasing the unit price γ, allowing for autonomous supply and demand adjustments and the securing of margins.

(5) According to a fifth aspect of the present disclosure, a power supply control system 1 that controls power supplied to a power grid includes a power generation control device 2 described in any one of the first to third aspects and a unit price determination device 4 described in the fourth aspect.

(6) According to a sixth aspect of the present disclosure, the power supply control system 1 according to the fifth aspect further includes a counter-regulation power aggregation device 5 that aggregates counter-regulation power of each of a plurality of power plants. The counter-regulation power aggregation device 5 includes a first acquisition unit 51 that acquires, from each of the plurality of power plants, an equilibrium point signal _{u_I} that is an electrical output value adjusted so as to bring the deviation between the power grid frequency f and a reference frequency _{f_n} closer to zero, and an actual measured value y of the electrical output of the power plant, and a counter-regulation power calculation unit 52 that calculates the amount of excess power generated as counter-regulation power q by integrating the difference between the actual measured value y of the electrical output and the equilibrium point signal _{u_I} .

In this way, the power supply control system 1 can monitor whether each power plant is appropriately balancing supply and demand by aggregating deregulation power using the deregulation power aggregation device 5. Monitoring deregulation power acts as a deterrent to excessive power generation, contributing to stabilizing the supply and demand balance in the power system. Furthermore, by deducting an amount corresponding to the deregulation power from the price paid for the power generated by the power plant, it is possible to more reliably curb excessive power generation by the power plant.

(7) According to a seventh aspect of the present disclosure, the power supply control system 1 according to the fifth or sixth aspect further includes a reallocation device 6 that reallocates the electrical output of each of the power plants belonging to a power plant group consisting of two or more of the multiple power plants. The reallocation device 6 includes a second acquisition unit 61 that acquires, from each of the power plants belonging to the power plant group, an equilibrium point signal _uI that is the value of the electrical output adjusted so as to bring the deviation between the power grid frequency f and the reference frequency _fn closer to zero, and a coefficient β related to the cost required for power generation, and a reallocation unit 62 that reallocates the electrical output of each of the power plants belonging to the power plant group based on the equilibrium point signal _uI and the coefficient β so as to minimize the power generation cost of the entire power plant group.

In this way, the power supply control system 1 can reallocate the electrical output of each power plant belonging to a power plant group, thereby increasing the profits of the entire power plant group. A power plant group may consist of multiple power plants owned by a single power generation company, for example. The power generation company can generate the electricity that its own power plant group should supply at minimal cost, thereby increasing the power generation company's profits accordingly.

(8) According to an eighth aspect of the present disclosure, in the power supply control system 1 according to the seventh aspect, the adjustment unit 22 of the power generation control device 2 further adjusts the command value u of the electrical output based on the electrical output reallocated by the reallocation device 6.

By doing this, the power supply control system 1 can autonomously and efficiently operate the power plants belonging to the power plant group at the lowest power generation costs.

(9) According to a ninth aspect of the present disclosure, a power generation control method includes the steps of: determining an optimal value u ^* of an electric output of a power plant based on a unit price γ of generated electric power supplied to an electric power grid; and adjusting a command value u of the electric output according to a frequency f of the electric power grid, with the optimal value u ^* set as an upper limit of the electric output.

(10) According to a tenth aspect of the present disclosure, the program causes the power generation control device 2 provided in each of the plurality of power plants to execute the steps of determining an optimal value u ^* of the power plant's electrical output based on the unit price γ of generated electrical power supplied to the power grid, and adjusting the command value u of the electrical output according to the frequency f of the power grid, with the optimal value u ^* as an upper limit of the electrical output.

REFERENCE SIGNS LIST 1 Power supply control system 10 Power system 2 Power generation control device 21 Optimum value determination unit 22 Adjustment unit 23 Minimum value determination unit 24 Control unit 3 Aggregation device 31 Aggregation unit 4 Unit price determination device 41 Aggregation value acquisition unit 42 Unit price determination unit 5 Counter-adjusted power aggregation device 51 First acquisition unit 52 Counter-adjusted power calculation unit 6 Redistribution device 61 Second acquisition unit 62 Redistribution unit 900 Computer 901 Processor 902 Main memory device 903 Auxiliary memory device 904 Interface 910 External memory device

Claims (9)

A power generation control device provided in each of a plurality of power plants,
an optimal value determination unit that determines an optimal value of the power plant's electrical output based on the unit price of generated power supplied to the power grid;
an adjusting unit that adjusts a command value of the electrical output according to the frequency of the power grid, with the optimum value as an upper limit of the electrical output;
A power generation control device comprising: the adjusting unit calculates an equilibrium point signal by integral control, which is an electric output value adjusted so as to bring the deviation between the frequency of the power grid and a reference frequency closer to zero and has the optimum value as an upper limit, and adjusts the electric output command value based on the equilibrium point signal.
The power generation control device according to claim 1 . a minimum value determination unit that determines a minimum value of the electrical output at which the profit of the power plant becomes a predetermined value based on the unit price;
a control unit that controls the start or stop of operation of the power plant based on the minimum value and the equilibrium point signal;
The power generation control device of claim 2 further comprising: A power supply control system that controls power supplied to a power grid,
The power generation control device according to any one of claims 1 to 3;
a unit price determination device ;
Equipped with
The unit price determination device
an aggregate value acquisition unit that acquires, from each of a plurality of power plants, an aggregate value of an optimal value of an electric output corresponding to the unit price of generated electric power supplied to the electric power grid, and an aggregate value of an equilibrium point signal that is an electric output value adjusted so that the deviation between the frequency of the electric power grid and a reference frequency approaches zero;
a unit price determination unit that determines the unit price based on the aggregated value of the optimal values and the aggregated value of the equilibrium point signals;
Equipped with
Power supply control system. The power generation system further includes a counter-regulation power aggregation device that aggregates counter-regulation power of each of the plurality of power plants,
The counter-regulation power aggregation device
a first acquisition unit that acquires, from each of a plurality of power plants, an equilibrium point signal that is an electrical output value adjusted so as to bring the deviation between the frequency of the power grid and a reference frequency closer to zero, and an actual measured value of the electrical output of the power plant;
a counter-regulation power calculation unit that calculates the amount of excess power generated as counter-regulation power by integrating the difference between the actual measured value of the electrical output and the equilibrium point signal;
The power supply control system according to claim 4 , further comprising: In a power plant group consisting of two or more power plants among the plurality of power plants, a reallocation device is further provided that reallocates the electrical output of each of the power plants belonging to the power plant group,
The reallocation device
a second acquisition unit that acquires, from each of the power plants belonging to the group of power plants, an equilibrium point signal that is an electrical output value adjusted so as to bring the deviation between the frequency of the power grid and a reference frequency closer to zero, and a coefficient related to the cost required for power generation;
a reallocation unit that reallocates the electrical output of each of the power plants belonging to the power plant group based on the equilibrium point signal and the coefficient so as to minimize the power generation cost of the entire power plant group;
The power supply control system according to claim 4 , further comprising: an adjustment unit of the power generation control device further adjusts a command value of the electrical output based on the electrical output reallocated by the reallocation device;
The power supply control system according to claim 6 . determining an optimal value of the electrical output of the power plant based on the unit price of the generated power supplied to the power grid;
adjusting a command value of the electrical output according to the frequency of the power grid, with the optimum value set as an upper limit of the electrical output;
A power generation control method comprising: A power generation control device provided in each of a plurality of power plants,
determining an optimal value of the electrical output of the power plant based on the unit price of the generated power supplied to the power grid;
adjusting a command value of the electrical output according to the frequency of the power grid, with the optimum value set as an upper limit of the electrical output;
A program that executes the following.