JPH0227895B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rescue selection method for a power outage equipment load that performs restoration control of a power outage equipment load due to an equipment fault in an electric power system. Restoration control of power outage equipment loads due to power system equipment failures must be performed to avoid overloading the system equipment after restoration. In other words, there may be cases where the power that can be supplied from the power supply is insufficient for the power required to relieve all the power outage equipment loads, or if all the power outage equipment loads are rescued, even if the power transmission line is optimally configured, the main In the event of an overload on power transmission equipment such as a power outage, a portion of the power outage equipment will be selected and rescued. The following are options for saving this kind of conventional power outage equipment. That is, the first method is a method in which a relief priority is assigned to a load in advance, and this is a method in which the loads are ranked based on their characteristics. As an example, the following can be considered: Rank: Critical loads (loads that require urgent restoration such as hospitals, subways, etc.). Rank: Important load (load that does not belong to ). Rank: Load that can be cut off (load with alternative power source equipment such as in-house power generation). Classify the data and attach the data in advance.
Priority relief is given to loads with higher ranks to the extent that there is no overload. The advantages of this method are that it suits the actual load situation, is fast, and is less likely to make mistakes, making it easy to judge the selection. However, it has the following drawbacks. That is, (a) when it is desired to select loads on a transmission line basis, the above-mentioned various loads coexist on the transmission line, making it difficult to rank them. (b) Even if it is possible to rank loads when selecting loads on a per-transmission line basis, maintenance of the rankings will be required every time system changes or system operation changes occur frequently, which is not easy.
(c) As the system size increases, the power per rank also increases, making it impossible to make fine-grained selections for relieving more loads. The second method is a method that does not give priority. This method selects loads so that the sum of power of relief loads is maximized without prioritizing the loads, and there are the following two methods. In other words, one method is to calculate the sum of power for all combinations of loads, arrange the set of combined power sums smaller than the supplyable power in descending order, check for equipment overload in that order, and check the overload first. The first step is to select a combination of loads that are not available. However, as the number of loads increases, the number of selection processes increases exponentially, and the selection time becomes longer, resulting in impractical drawbacks. Another method is load selection using 0-1 linear programming, which expresses power as I (pu) and selects load X (relief when X=1, non-relief when X=0). The relief (0, 1 variable) is formulated by the following formula. That is, objective function maxF= _n 〓 ^k=1 IkXk ……(1) Constraint condition IijIi＾＾j Iij=1/Zij _o 〓 ^p=1 (Zip−Zjp)・Ip・Xp ……(2) These formulas are For example, it can be solved using the principal effective gradient method, and the solution is, for example, X={0, 1, 1, 0, ...) ...(3). Here, Ik is the power of the selected load k, where m (mn) of the n node currents Ip of the target system
It is. Equation (2) is the conditional expression for no overload of equipment ij.
Ii^j is the rating of the equipment ij, Iij is the equipment ij
(loop flow between nodes i and j).
Furthermore, Zij, Zip, and Zjp are elements of the node impedance matrix. This method is a method of reducing the selection processing time of the above-mentioned one method, and although its effectiveness can be recognized, it has the drawback that the solution is an approximate solution and an optimal solution cannot be guaranteed. The present invention eliminates the drawbacks of the conventional method described above, and its purpose is to automatically determine relief loads based on the operating conditions before the accident, rank them based on these characteristics, and select relief loads. In addition to
When all loads within the same rank cannot be rescued, priority is determined based on the power level of the load and selective relief is made, enabling faster selection, easy data maintenance, and high-performance power outage facility loads. The objective is to provide a relief selection method. EMBODIMENT OF THE INVENTION Below, the relief selection system of the power outage equipment load based on the Example of this invention is demonstrated with reference to drawings. Figure 1 shows an example of a power system to which the load relief selection method for power outage load equipment of the present invention is applied.
This is an electrical wiring diagram showing an example of implementing relief load selection in a restoration system by putting in a bus tie at a substation according to the method of the present invention, in which A to E are substations, a ₁ , a ₂ , b ₁ to b ₄ ,
c ₁ and d ₁ are power transmission lines, and CB1 to CB8 are switches. FIG. 2 shows a system that executes the load relief selection method according to the embodiment of the present invention, in which 1a to 1n are slave stations of a remote monitoring and control device, and state change signals of important points in the power system, such as voltage, current, switch It collects status change signals such as the status of the power system and sends and receives power system control signals. Reference numeral 2 is a master station of the remote monitoring and control device, which receives status change signals from each slave station and transmits control command signals from an arithmetic processing unit 3, which will be described later, to each slave station 1a to 2.
Send to 1n. Reference numeral 3 denotes an arithmetic processing unit consisting of an electronic computer or the like, which executes predetermined arithmetic processing based on the information signal from the master station 2 and transmits a control command signal to the master station 2. That is, the control command signal from the arithmetic processing unit 3 is transmitted from the master station 2 to a predetermined location in the power system via each of the slave stations 1a to 1n. The arithmetic processing unit registers the determination of whether or not full load relief is possible in the power system, ranks loads according to the characteristics of the loads when full load relief is impossible, and when a predetermined ranked load is suddenly cut off, etc. The determination and registration of whether or not a load can be rescued, the selection of load relief within the same rank, and the additional registration of relief loads are executed. FIG. 3 shows a flowchart of an example of processing by the arithmetic processing unit (CPU). In this example, the possibility of full load relief is determined in step ST2. That is, in step ST2,
In a restoration system determined based on a certain well-known restoration control logic after the occurrence of an accident, the power flow distribution of the system is determined assuming that all the loads before the accident are to be relieved, and the power that can be supplied by power sources in addition to power transmission lines and transformers is calculated. For example, if you allow a 20% overload,
The value multiplied by 1.20 is compared with the current obtained, and if there is no overload in a broad sense, it is determined that full load relief is possible. When full load relief is possible, full load relief is registered (step ST3). On the other hand, when it is determined that full load relief is not possible, the loads are ranked in step ST4. In this case, load ranking is performed as a series of load selection processes after the recovery system has been determined due to a system fault, and the ranks are those loads that cannot be switched to other systems via the load line. The rank is a load that cannot be switched to the switching destination for all the loads in route units on the load connection line. The rank load is a load that can switch the entire load of each route to the switching destination using the connection line. After ranking the loads, step ST5
When the load of the rank is finally cut off, it is determined whether all of the load of the rank can be relieved. In other words, in a recovery system determined based on a certain recovery control logic after an accident, the power flow distribution of the system is calculated assuming that the load of the rank is to be cut off and the pre-fault load of the rank is to be relieved, and the power flow distribution of the system is calculated based on that and the equipment rating. Compare and judge whether or not there is an overload. If it is determined that all of the upper rank loads can be relieved, the rank loads are registered for relief (step ST6), and if it is determined that all of the rank loads cannot be relieved, all of the rank loads are determined to be relieved in step ST7 and the same judgment is made as above. . step
If it is determined in ST7 that all rank loads can be salvaged, the rank load is registered for relief in step ST8; if it cannot be determined, step
Proceed to ST9. In step ST9, the same process is performed based on the result of determining that the rank load cannot be relieved at all in step ST7, the load relief registration result of the rank load in step ST6, or the rank load relief registration result of the rank load in step ST8. Selection of load relief within the ranks is performed. Based on this selection result, additional registration of relief loads is performed in step ST10. Now, as for the operational status of the system shown in Figure 1, power is received from transmission line A ₁ (hereinafter expressed in route units) to A bus line BU1 at substation A, and then to substation B via transmission line C ₁ , which is then transferred to substation T. ₁ steps down 275KV to 66KV and connects it to the load P ₂ ~ through the transmission line b ₁ ~ b ₄ through the first bus BU ₃
Suppose that power is being transmitted to each _P5 . If the power transmission system shown by the bold line experiences a power outage due to an accident on transmission line _A1 , the relief load selection will be made when restoring by closing the bus tie switch CB1 of substation A, which was open before the accident. This is done according to the flow shown in Figure 3. The magnitude of the load before the accident was P ₁ = 100MW, P ₂ =
30MW, _P3 = 50MW, _P4 = 40MW, _P5 = 20MW
The supportable power is Ps ₁ = 120MW, Ps ₂ respectively.
= 110MW, Ps ₃ = 50MW, Ps ₄ = 10MW.
At step ST2 in Figure 3, the total load power is
While the sum of P ₁ to _{P 5} is 240 MW, the supportable power Ps ₁ is only 120 MW, making it impossible to save the entire load, and proceeding to step ST4. In this case, the transmission capacity of transmission line _A2 made it impossible to rescue the entire load. In addition, in step ST4, b ₁ and b ₂ are ranked as load lines that cannot be switched to other systems, and b ₄ is used as a load connection line that cannot switch the entire load of each route to the switching destination because Ps > Ps ₄ . Since P ₄ < Ps ₃ and P ₁ < Ps ₂ , b ₃ and c _{1 can be ranked as a rank, and b 3 and c 1} can be ranked, respectively, as a communication line that can switch the entire load of each route to the switching destination. Continued step ST5
Then, when the rank loads (b ₃ , c ₁ ) are cut off, the sum of the other loads P ₂ , P ₃ , and P ₅ (100 MW) is smaller than the unsupportable power Ps ₁ =120 MW, so it is determined that all the loads can be rescued. Therefore, in step ST6, the rank loads b ₁ , b ₂ , and b ₄ are registered as relief loads. Then, based on the registration in step ST6, step ST9
In this case, the remaining support power among ranks Ps ₁ −
(P ₂ + P ₃ + P ₅ ) = 20 MW is selected to be salvageable, but in this case, both b ₃ and c ₁ are not salvageable. In the specific example in Figure 1, the supportable power
The following table summarizes the relief load selection for substation A for 120MW.

[Table] As described above, in the equipment load relief selection method, the selection operation can be performed online (in real time) using a computer or the like. next,
A specific example in which the load ranking in the discrimination means (step ST4) is automatically determined by the control computer will be explained with reference to FIG. When determining whether switching to another system is impossible or possible, the other system is considered to be impossible in the following cases (A) or (B),
Other cases are possible. (A) In the case where there is no connection to another system, for example, the power transmission line L ₁ having the load P ₁ of π (pi) draw can be connected to the bus bar B ₀ via the switch CB ₂ . In addition, when there is no system connected to the transmission line L ₁ based on the system equipment information such as that the bus B ₀ can be connected to the transmission line L ₂ via CB ₁ , in other words, in the example in Fig. 4, the switch
This is when CB ₁ and later do not exist. (B) Switch CB ₁ with open connection to other systems
This is when the equipment (switch CB ₁ or bus bar B ₀ ) is unavailable due to work stoppage (or operation stoppage) even if it exists via the bus. Furthermore, among the three ranks mentioned above, the rank determination is explained using the example shown in Figure 4.The transmission line is determined by the transmittable power of the power transmission line _L2 itself, the power supplied by the upper power source, the power transmission bottleneck to that point, etc.
The transmission supply power of L ₂ is P ₀ , and the total load of bus B ₀ is P ₂
If so, the difference will be the power that can be supplied to the load on the transmission line. Compare this with the load P ₁ , and when P ₀ −P ₂ <P _1, the load on the transmission line L ₁ is ranked. Further, when P ₀ −P ₂ ≧P ₁ , the load on the power transmission line L ₁ is assumed to be a rank. In addition to the above 3-rank example, a 4-rank method may be used, for example, if it is not determined whether transmission line L ₂ is subject to overload in Figure 4, priority relief will be given between ranks. You can also do that. FIG. 5 shows an embodiment in which load relief within the same rank is selected in step ST9 of FIG. As shown in Figure 5, step ST9
In the selection of load relief within the same rank, as shown in Fig. 3, if it cannot be determined in step ST7, it is a rank load, and if the rank load relief is registered in step ST6, it is a rank load, and If rank load relief is registered in step ST6, it is a rank load. Therefore, in FIG. 5, B1 is a block for starting, B2 is a block for arranging the loads in descending order of electric power, and B3 is a block for calculating the power flow distribution assuming that the large load is to be relieved. B4 is a block for checking equipment overload, and B5 is a block for registering the load to be relieved when there is no overload, and to be cut off when there is an overload. B
6 is a block for checking all loads. If there is a load that has not been checked, the process returns to block B3; if not, the process proceeds to block B7 (step ST10 in FIG. 3). In the flowchart of FIG. 5, (1) First, in block B2, loads within the same rank are arranged in descending order of power. (2) When calculating the power flow distribution assuming that a large load is to be rescued in block B3, in the first flow, the load that has been rescued up to that point is connected and the power flow distribution is determined from the restoration system by, for example, flow calculation. Furthermore, the power flow distribution related to the largest load is determined and added to the upper air results in a vector manner. In the second flow, if the largest load is relieved in a later flow, it is left as is, and if it is relieved, the power flow distribution related to it is subtracted vectorially from the previous distribution. Furthermore, the power flow distribution component related to the second largest load is determined and added to the above result vectorwise. In the third flow, the same applies to the second and third large loads. Further, flow processing is performed in the same manner below. Note that this calculation method uses the principle of superposition, but it will not change even if you recalculate each time. (3) Equipment overload check is determined by comparing the power flow obtained in the same way as above with the equipment rating. When (rating of equipment ij) > (Iij^), it is overloaded. Note that Ii^j is the trend of equipment ij. In addition, in FIG. 5, the relief selection is performed in the order of the loads with the highest power, but it is also possible to arrange the relief in the order of the loads with the lowest power. For example, in the above rank, all loads can be rescued from other systems, so if applied here, a larger number of loads can be selected and automatically restored, reducing the number of remaining manual restoration operations. Become. As is clear from the above explanation, in the present invention, the characteristics of the loads are automatically determined from the operating conditions immediately before the accident, the characteristics of the loads are ranked, and the rescue loads are selected. Rather than using a method in which humans determine the operational status immediately before an accident, the system automatically determines the status of the system's connections and power flow, and classifies the load characteristics based on the possibility of relief from other systems. Furthermore, when all the loads within the same rank cannot be relieved, priority is determined based on the power level of the loads and selective relief is performed. Relief is prioritized in descending order of load power, and the possibility of relief is sequentially checked down to the smallest load power, and relief is performed if possible.
It is also possible to combine each of the above. Therefore, according to the present invention, the following various excellent effects can be obtained. (A) Loads can be ranked automatically and maintenance can be performed regardless of operational changes. Furthermore, in the case of expanding system equipment, generally used system equipment information is used, so data maintenance becomes unnecessary. (B) Since it does not depend on the quality of demand, the classification of the load characteristics becomes clear, and the classification can be clearly determined without depending on changes in demand or changes in the operational system, based only on the connection relationship of the supply system and the power flow before the accident. Can be done. (C) In addition to selecting relief by rank, it is possible to select relief within rank, and as a result, more power outage loads can be rescued. Since fine adjustments can be made with small loads, more power outage loads can be relieved as a result. (D) When the selected relief load is automatically operated and the interrupted load is manually rescued, more automatic relief is possible by performing relief within the same rank in the order of the load with the lowest power consumption. It is. (E) It is possible to speed up selection, for example, find the sum of power for all combinations of loads, arrange the set of combination sums smaller than the supplyable power in descending order, and check for equipment overload in that order. Compared to the conventional method that selects a combination of loads that do not cause overload at the beginning, according to the method of the present invention, the number of loads within the same rank is reduced, e.g.
When the number is 10, the selection time is reduced to 1/100, and when the number is 15, the selection time is reduced to about 1/2500.

[Brief explanation of drawings]

Fig. 1 is an electrical wiring diagram showing an example of selection of a relief load in a restoration system using the method of the present invention, Fig. 2 is a block diagram of a system that executes the load relief selection method according to an embodiment of the present invention, and Fig. 3 is a diagram of the present invention. FIG. 4 is a flowchart showing a relief selection method for a power outage equipment load according to an embodiment of the invention; FIG. FIG. 5 is a flowchart showing an embodiment in which load relief within the same rank is selected by the method of the present invention. 1a to 1n... slave station, 2... master station, 3... arithmetic processing unit (CPU).

Claims (1)

[Claims] 1. In a recovery control method for controlling the recovery of power outage equipment loads due to equipment failures in the electric power system, there is a means for determining the possibility of full load relief for the equipment, and a means for determining the possibility of full load relief for the equipment, and a means for determining the possibility of full load relief for the equipment, and when full load relief is not possible, a means for determining the possibility of full load relief for the equipment A means for ranking loads, a means for determining whether or not it is possible to relieve loads of other cranks when a load of a predetermined ranked rank is interrupted, and selection of load relief within the same rank. It consists of a means for carrying out the
The characteristics of the load are automatically determined from the operational status immediately before the accident, and the characteristics are ranked and relief loads are selected in accordance with the priority order. A relief selection method for power outage facility loads characterized by determining priority and selective relief based on the magnitude of electric power.