JPS6343582B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for protecting equipment in a pumped storage power plant, and in particular, it protects electrical equipment by preventing an increase in motor current due to a drop in static head or a drop in motor voltage. The present invention relates to a method for protecting pumped storage power plant equipment suitable for protection.

[Technical background of the invention and its problems]

Generally, a pumped storage power plant is configured as shown in Figure 1. During pumped storage operation, the synchronous generator motor 1 is operated as an electric motor using electric power P from the power system, and torque is supplied to the directly connected pump turbine 2. 3
The water is pumped up to the upper pond 8 via a suction pipe 4, a guide vane 5, an inlet valve 6, and a pressure iron pipe 7.

In this case, the inlet valve 6 is fully open or fixed at a constant opening, and the guide vane 5 is controlled to an appropriate opening by the water level difference response device 9. That is, the guide vane control device during pumping operation is called a water level difference responsive device, and this water level difference responsive device 9 calculates the static head difference HST (H ₁ - H ₂ ) from the upper pond water level H ₁ and the lower reservoir water level H ₂ . Calculate the optimal guide vane opening command value that allows pumping operation at the highest efficiency with the static head difference HST at that time. Based on the difference between this and the actual guide vane opening GVA,
A drive pulse is generated to the operating motor to open and close the guide vane 5 via a hydraulic servo system.

Furthermore, as shown in FIG. 2, the pump-turbine 2 has a characteristic that when the static head HST decreases, the motor input P increases. In other words, when the static head HST changes, the maximum efficiency point of pumping operation changes accordingly, so the guide vane opening degree depends on the static head HST.
The opening is controlled to the maximum possible operating efficiency. The characteristics when the electric motor is operated with the guide vane opening are such that as the static head HST decreases, both the electric motor input P and the pumped water flow rate Q increase, as shown in FIG.

On the other hand, the voltage V and current I of the synchronous generator motor 1 are
The relationship shown in FIG. 3 is such that when the voltage V is constant and the motor input P increases, the current I increases, and when the current I is constant and the motor input P increases, the voltage V also increases.

Therefore, as can be seen from Figures 2 and 3, when the static head HST decreases, the motor input P increases,
If motor voltage V is constant, motor current I increases. Further, when the system voltage, that is, the motor voltage V decreases, the motor current I increases if the motor input is constant (the static head is constant).

On the other hand, the permissible value of electrical equipment in a pumped storage power plant is determined by the current capacity, so if the motor current I increases as described above and pumped storage operation continues for a long time with the permissible value exceeded, the transformer , a problem arises in which electrical equipment such as electric motors burns out.

Conventional pumped storage power plants have been constructed and operated in locations where static head HST does not fluctuate much, so the problems described above have not occurred much. Therefore, in the rare case that the static head difference HST becomes small or the motor voltage V decreases, causing a problem of burning out electrical equipment, the pumping operation is stopped or other measures are taken. However, in the future, it will be difficult to secure land for pumped storage power plants, and due to the location and operational conditions of pumped storage power plants, such as the increase in large-capacity nuclear power plants in the power system, pumped storage power plants with large static head fluctuations are becoming increasingly difficult to secure. tend to be built. Therefore, it has become necessary to solve the above problem.

[Purpose of the invention]

In view of this point, the present invention has been developed to reduce the electricity consumption of pumped storage power plants by suppressing the motor current below the permissible value when the static head drops beyond the permissible value or when the motor voltage decreases for some reason during pumped storage operation. The purpose of the present invention is to provide a method for protecting equipment in a pumped storage power plant that can safely protect the equipment.

[Summary of the invention]

In order to achieve this object, the present invention calculates an inlet valve opening value from a static head difference and a motor voltage or a system voltage, and uses this inlet valve opening value as a command value to control an inlet valve determined from the static head difference at that time. It is characterized in that the opening degree is adjusted within a range that does not deviate from the lower limit value of the opening degree.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to the drawings.

As described above, the pump shaft input (motor input P) required by the pump-turbine 1 is determined by the static head HST of the pumped storage power plant. On the other hand, in view of the current capacity of the electric equipment in the power plant, it is necessary to operate the power plant so that the relationship between the motor input P and the motor voltage V satisfies the shaded region of the figure, as shown in FIG. Therefore, from this figure, when the motor voltage V is _V1 , the motor inlet P must be less than _P1 , so from FIG. 2, it is only possible to operate with a static head HST greater than _HST1 . That is, as shown in FIG. 5, when operating the electric equipment within the permissible current capacity, the operable region with the inlet valve fully open is shown by the shaded area, so if the motor voltage V is V ₁ , static head HST
When HST is ₁ , the static head difference of HST _X - HST ₁ , that is, ΔHST ₁ minute, is insufficient. Therefore, if the static head difference HST _is less than or equal to HST _X , it is necessary to somehow make the static head difference HST equal to or exceed HST _X. Also, static head
When HST is HST _{1 ,} if _{the motor} voltage V _is less _than V is equal to HST _Y or HST _Y
We need to do everything we can to exceed this.

On the other hand, the head H of the pump-turbine 1 is the sum of the static head HST and the head loss H _L of the pipeline, that is, H = HST + H _L , so the insufficient head ΔHST ₁ or ΔHST ₂ in Fig. It can be seen that it is possible to compensate for the head loss caused by partially closing the water flow cutoff mechanism, that is, the inlet valve 6 provided between the water turbine 1 and the water turbine 1.

This shortfall of static head difference ΔHST, that is, the inlet valve 6
The inlet valve opening value IV ₀ obtained by subtracting the value for partially closing the inlet valve 6 from the fully open state of the inlet valve 6 is expressed as shown in FIG.
In this figure, the horizontal axis represents the static head HST, the vertical axis represents the inlet valve opening value IV ₀ , and the motor voltage V is expressed as a parameter. Even if the same inlet valve opening value IV ₀ as in the figure is expressed and the static head difference HST is taken as a parameter, the following can be said in the same way. That is, in order to operate within the current limit region regardless of the static head HST or the decrease in the motor voltage V, the inlet valve 6 should be controlled by the function IV ₀ = f
Pumping operation can be performed with the opening determined by (HST, V). For example, if the motor voltage V is V _Y ,
If the static head difference HST is HST ₁ , pumping operation can be performed by setting the valve opening of the inlet valve 6 to IV _2. Furthermore, if the static head difference HST becomes small while the motor voltage V remains at a constant value of V ₂ , the inlet The valve opening value IV ₀ should also be closed along the V ₂ curve. In addition, conversely, static head HST
If the motor voltage V decreases while HST ₁ remains constant, the inlet valve opening value IV ₀ may be closed along the dashed line in the figure. For example, when the motor voltage V is V _1-2 between V ₁ and V ₂ , the inlet valve opening is IV _1-2 = IV ₁ +
V _1-2 −V ₁ /V ₂ −V ₁ (IV ₂ −IV ₁ ) or IV _1-2 = IV ₂ −V ₂ −V _1-2 /V ₂ −V ₁ (IV ₂ −IV ₁ ) Just use the value you found.

By the way, since the inlet valve opening value 6 cannot be closed indefinitely, it is limited by the illustrated curve LL. The lower part of this curve LL is a limit curve for the motor current I. Part A is the inlet valve 6
C is a lower limit curve for preventing the fluttering phenomenon of the inlet valve 6 due to the differential pressure before and after the inlet valve. That is, the limit curves A and C of curve LL are lower limit curves necessary for protecting the inlet valve 3.

Based on the above explanation, FIG. 7 shows a specific control means for controlling the opening degree of the inlet valve 6 according to a decrease in the static head HST or the motor voltage V, and suppressing the motor current I within the allowable limit value. 10 is an inlet valve control device, and 11 is an inlet valve drive mechanism.

In the inlet valve control device 10, first, an adder A1 calculates the difference between the upper reservoir water level _H1 and the lower reservoir water level _H2 , that is, the static head difference.
Calculate HST. Next, from the static head difference HST and the motor voltage V, the inlet valve opening value IV ₀ is calculated by the function generator A2, as explained with reference to FIG. On the other hand, the function generator A3 calculates the lower limit value _IVLL of the inlet valve opening. With this output IV _LL , a lower limit is applied to IV ₀ to output a final inlet valve opening command IV _OX so that a value less than the lower limit value IV _LL is not output from the lower limit limiter circuit A4. Furthermore, the adder A5 calculates the deviation ΔIV between the final inlet valve opening command IV _OX and the actual inlet valve opening IV _A , and calculates the deviation ΔIV from the inlet valve drive circuit A.
Enter into 6. The inlet valve drive circuit A6 gives a signal to the inlet valve drive mechanism A7 according to the deviation ΔIA, and the inlet valve 6
Open and close.

In this way, static head HST and motor voltage V
If the current decreases below the allowable value, the inlet valve drive mechanism 11 is driven by the corresponding output of the inlet valve control device 10 and the inlet valve 6 is closed, so the motor current I is suppressed within the limit range and the pumped storage power plant electrical equipment remains undamaged and safely protected at all times.

Note that the function generators A2 and A3 and the lower limiter circuit A4 in the inlet valve control device 10 shown in FIG.
It can be realized with one function generator. Also,
It is also possible to detect IV ₀ <IV _LL using the lower limiter circuit A4 or another comparison circuit, and to block only the signal for closing the inlet valve when IV ₀ <IV _LL . Furthermore, instead of the lower limiter circuit A4, a high value priority circuit is used that inputs the lower limit value IV _LL and the inlet valve opening value IV ₀ and outputs the higher one as the final inlet valve opening command IV _OX . You can also do it.

〔Effect of the invention〕

As described above, according to the present invention, even if the static head decreases beyond the permissible range due to a drop in the water level of the upper reservoir or an increase in the water level of the lower reservoir, or even if the motor voltage decreases due to the influence of a system fault, etc. Since the motor current can be suppressed below the allowable value, the electrical equipment of the power plant is always safely protected and safe pumping operation can be performed. In addition, since the actual opening of the inlet valve never falls below the lower limit value, the phenomenon of fluttering of the inlet valve and the phenomenon of partial backflow of water at the inlet valve are prevented, and the inlet valve is also safely protected. .

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a general pumped storage power plant, Figure 2 is a characteristic diagram of a pump-turbine, Figure 3 is a diagram of the relationship between motor voltage and motor current when the motor input is constant, and Figure 4 is a diagram of the relationship between motor voltage and motor current when the motor input is constant. A diagram of the relationship between the motor voltage and the motor input when the current capacity is constant. Figure 5 is an explanatory diagram of the operable range and static head when the inlet valve is fully open when the current capacity is constant, and the insufficient static head due to changes in the motor voltage. , Fig. 6 is a static head difference vs. inlet valve opening value characteristic diagram with motor voltage as a parameter and an explanatory diagram of the inlet valve lower limit value with respect to static head difference, and Fig. 7 shows a specific example for implementing the method of the present invention. FIG. 2 is a configuration diagram of an inlet valve control device. DESCRIPTION OF SYMBOLS 1...Synchronous generator motor, 2...Pump turbine, 3...Lower pond, 4...Suction pipe, 5...Guide vane, 6...Inlet valve, 7...Pressure iron pipe, 8...Upper pond, 9...Water level differential response device, 10...Inlet Valve control device, 11... Inlet valve drive mechanism.

Claims (1)

[Claims] 1. In a method for protecting equipment of a pumped storage power plant from an increase in motor current due to a decrease in the static head difference between an upper reservoir and a lower reservoir or a decrease in motor voltage when operating a pump or a pump-turbine in a pumped storage power plant, the static head An inlet valve opening value that compensates for the head difference that is insufficient to the static head that satisfies the operable region is determined from and the motor voltage, while an inlet valve opening lower limit value is determined from the static head difference, and the inlet valve opening value is determined from the static head difference. A pumped storage power plant characterized in that the inlet valve opening is controlled using the larger of the lower limit value of the inlet valve opening as a final inlet valve opening command, and equipment is protected by limiting an increase in the motor current. equipment protection methods.