JP2746966B2 - Operation control device of variable speed pumped storage power generation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention is particularly applicable to a variable speed pumped-storage power generation system that can be operated at an arbitrary rotation speed by a variable speed induction machine with secondary excitation control. The present invention relates to an operation control device of a variable-speed pumped-storage power generation system capable of improving security of an entire power system including a transmission induction machine.

(Prior Art) In recent years, a variable speed pumped storage power generation system has been adopted as one of the power generation systems. This variable-speed pumped-storage power generation system is configured such that the secondary side of the variable-speed induction machine is mechanically directly connected to the pump turbine, and the primary side of the variable-speed induction machine is connected to the electric power system. By connecting a secondary excitation device consisting of a frequency converter such as a cycloconverter to the side and supplying excitation power of variable voltage and variable frequency to the secondary winding of the variable speed induction machine, it can be operated at any rotational speed. It is constituted in. Conventionally, the secondary excitation control of the variable speed pumped-storage power generation system uses a cycloconverter or the like to maintain the primary terminal voltage and the rotation speed (or primary active power) of the variable speed induction machine at certain constant values. This is performed by controlling the firing angle of a secondary excitation device including a frequency converter.

By the way, in this type of variable speed pumped-storage power generation system, even if the rotation speed changes, the secondary winding of the variable speed induction machine is always supplied with an AC exciting current having a slip frequency corresponding to the rotation speed, so that It is said that the system is always synchronized with the system, and there is no so-called stability problem which is a problem in the conventional synchronous machine. Therefore, no proposal has been made on operation control for improving stability.

However, in order for the variable-speed pumped-storage power system to always operate stably, as described above, the secondary winding of the variable-speed induction machine is always supplied with the AC exciting current having a slip frequency corresponding to the rotation speed thereof. Besides the condition that
The condition that the secondary excitation control is always performed regardless of the limit value of the secondary excitation voltage is required. In this case, the former condition is sufficiently satisfied, but the latter condition may not be satisfied due to the limit value of the secondary excitation voltage in a transient state at the time of a system failure due to, for example, lightning. It is necessary to take countermeasures.

 Hereinafter, this point will be described in detail with reference to FIG.

FIG. 2 is a diagram for explaining the response of the variable speed induction machine at the time of a system fault. In FIG. 2, IM is a variable speed induction motor, SG / M is a generator motor, TR1 and TR2 are main transformers, L1 and L2.
Is a power transmission line, CB1 and CB2 are circuit breakers, and S is a power system. At regular time, when the variable speed induction machine IM is operating for power generation, it operates at the rotation speed that maximizes the turbine efficiency according to the head and the turbine output, and when the variable speed induction machine IM is performing pumping operation. Is generally operated by automatic frequency control (hereinafter referred to as AFC) based on a command from a central power supply station. To perform AFC operation during pumping, adjust the pump output by changing the rotation speed. In the variable-speed induction machine IM, even when the primary voltage and the primary active power are the same, the required secondary excitation voltage varies depending on the rotation speed (slip), and the minimum excitation speed is the minimum at the synchronous speed (zero slip). It increases as the speed falls (slip positive) or rises (slip negative) from the synchronous speed.
For example, in the case of a large-capacity machine, when operating at the rated voltage and output,
1.0, 34.1 at 5%, 68.8 at 10%, -5%
At 35.2, and -10% at 70.6. If the slip doubles, it will roughly double. As described above, since the magnitude of the secondary excitation voltage greatly varies depending on the operating rotational speed (slip), the range of the rotational speed (slip) at which the operation is permitted, that is, the range that does not reach the limit value of the secondary exciting voltage, is set. It is selected in consideration of the advantages and economics in system operation, and usually the allowable range of slip (Smax to Smin) is selected to be around 5% to -5%.

By the way, when the variable-speed induction machine IM is in the power generating operation, for example, if a system fault occurs in the power transmission line L2, the terminal voltage of the variable-speed induction machine IM decreases and the active power also decreases. The machine IM starts accelerating, but when the circuit breakers CB1 and CB2 at both ends of the power transmission line L2 are opened by a command of the protective relay to eliminate the system fault, the terminal voltage increases and the active power also increases. Then, when the active power becomes larger than the initial value (the value before the accident), the vehicle shifts to deceleration at the time of the boundary. On the other hand, when the variable-speed induction machine IM is performing the pumping operation, conversely, during the system fault, the speed is reduced, and after the system fault is eliminated, the process shifts to acceleration. For example, when the variable speed induction machine IM is operating at the rated output, the severest three-phase accident occurs at the transmission end of the power transmission line L2 (the output becomes almost zero). Assuming that the inertia constant of the variable-speed induction machine IM is 5 seconds, in the case of power generation operation only during the system fault, the rotation speed increases by approximately 2% (1 / 5.0 × 1.0 × 0.1 = 0.02p.
u.) In the case of pumping operation, the rotation speed drops by about 2%. After the removal of the system fault, the acceleration (or deceleration) will be further continued until the active power becomes larger than the initial value. The increase (or decrease) of the rotation speed during this period depends on the system state, but 1% is sufficient.

As described above, when a system fault occurs, there is a risk that the upper limit of the operation allowable circuit speed will be applied when the power generation operation is being performed and the lower limit value of the operation allowable rotation speed will be applied when the pumping operation is being performed. When the secondary excitation voltage reaches the limit value, the variable speed induction machine IM not only becomes unstable due to an unstable phenomenon, but also in some cases, the generation motor SG / M of the generator motor SG / M adjacent to the variable speed induction machine IM. There is a risk of step-out, which could lead to the collapse of the entire power system.

(Problems to be Solved by the Invention) As described above, conventionally, in a transient state at the time of a system failure due to, for example, the occurrence of lightning or the like, it is possible to continuously perform operation control over the limit value of the secondary excitation voltage. As a result, there is a problem that the security of the entire power system including the variable speed induction machine is reduced.

The purpose of the present invention is to provide a
To provide an operation control device of a variable pumped storage power generation system capable of continuously performing operation control within a limit value of a secondary excitation voltage and improving security of an entire power system including a variable speed induction machine. It is in.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, according to the present invention, the secondary side of the variable speed induction machine is mechanically directly connected to the pump turbine, and the variable speed induction machine is connected to the pump turbine. The secondary side is provided so as to be connectable to an electric power system, a secondary excitation device including a frequency converter is connected to the secondary side of the variable speed induction machine, and the variable voltage variable frequency excitation power is connected to the secondary winding of the variable speed induction machine. Speed control means for outputting a speed control command based on a comparison result between a rotation speed detection value of the variable speed induction machine and a speed command value, the operation control device of the variable speed pumped storage power generation system configured to supply Voltage control means for outputting a voltage control command based on a result of comparison between the primary terminal voltage detection value of the variable speed induction machine and the voltage command value, a speed control command from the speed control means, and a voltage control from the voltage control means Command and internal induced voltage level of variable speed induction machine Secondary current command setting means for setting a secondary current command value based on the detected angle value; and a secondary current command value from the secondary current command setting means and a secondary current of the variable speed induction machine based on the secondary current command value. , Current control means for controlling the firing angle of the secondary exciter, and operation while receiving predictive information on the occurrence of an accident in the area including the variable speed induction machine and its power transmission line. The preventive control means also changes the speed command value so that the secondary excitation voltage does not reach the limit value.

(Operation) In the operation control device described above, when the prediction information of the occurrence of the accident in the area including the variable speed induction machine and its power transmission line is issued, the speed command value of the speed control means is changed by the preventive control means. . As a result, the operation is shifted to a region of the rotational speed that does not reach the limit value of the secondary excitation voltage even in the case of an assumed system failure, so that the system failure occurs while the variable speed pumped storage power generation system is performing power generation or pumping operation. It is possible to continuously control the operation within the limit value of the secondary excitation voltage even in the transient state when the error occurs.

Hereinafter, the present invention will be described with reference to an embodiment shown in the drawings.

FIG. 1 shows a configuration example of a variable speed pumped storage power generation system to which an operation control device according to the present invention is applied. In FIG. 1, the secondary side of the variable speed induction machine 1 is mechanically directly connected to the pump turbine 2, and the primary side of the variable speed induction machine 1 is provided so as to be connectable to a power system (not shown). A secondary excitation device 3 including a frequency converter such as a cycloconverter is connected to the secondary side of the machine 1 so as to supply excitation power of a variable voltage and variable frequency to the secondary winding of the variable speed induction machine 1. . The power supply side of the secondary excitation device 3 is connected to the primary side of the variable speed induction machine 1 via the transformer 4.

On the other hand, the operation control device comprises the following. That is, 5 is a speed detector for detecting the rotation speed of the variable speed induction machine 1, 6 is a phase detector for detecting the internal induced voltage phase angle of the variable speed induction machine 1, and 7 is a speed command generation for generating a speed command value. A comparator 8 for comparing the detected value from the speed detector 5 with a speed command value from the speed command generator 7, and 9 a speed control based on a speed deviation which is a comparison result from the comparator 8. It is a speed control function unit that outputs commands functionally. Here, the speed command generator 7 generates a speed command value that maximizes the operating efficiency during steady operation of the variable speed pumped storage power generation system. Reference numeral 10 denotes a voltage detector for detecting a primary terminal voltage of the variable speed induction machine 1, reference numeral 11 denotes a voltage command generator for generating a voltage command value, and reference numeral 12 denotes a voltage detection value from the voltage detector 10 and a voltage command. A comparator 13 for comparing with a voltage command value from the generator 11 is a voltage control function unit that functionally outputs a voltage control command based on a voltage deviation as a comparison result from the comparator 12. Further, a secondary current command value 14 is based on a speed control command from the speed control function unit 9, a voltage control command from the voltage control function unit 13, and an internal induced voltage phase angle detection value from the phase detector 6. This is a secondary current command setting circuit to be set. Further, 15 is a current detector for detecting the secondary current of the variable speed induction machine 1, and 16 is a secondary current command setting circuit 14.
An automatic current control (ACR) circuit for outputting a current control command based on the secondary current command value from the automatic current control circuit 16 and the secondary current detection value from the current detector 15. This is a firing angle setting circuit that sets the firing angle of the secondary excitation device 3 based on a current control command. On the other hand, 20 operates upon receiving lightning occurrence prediction information, which is accident occurrence prediction information transmitted from a weather center (not shown), that is, lightning occurrence prediction information in an area including the variable speed induction machine 1 and its power transmission line, In addition, the lightning occurrence prediction information receiving device 21 that continues its operation during reception of the information, the operation output from the lightning occurrence prediction information receiving device 20, the secondary excitation voltage does not reach the limit value even in the event of a possible system failure As described above, the speed command value setting change device for changing the speed command value of the speed command generator 7 constitutes the preventive control device 22. Here, the speed command value setting change device 21 sets the speed command value to a value lower than the steady state when the variable speed pumped storage power generation system is in the power generation operation state, and sets the speed command value to a value higher than the steady state in the pumped operation state. To change the setting. Also,
Most system accidents are caused by lightning strikes, and lightning occurring in a certain area can be predicted with high probability by catching thunderclouds with weather radar.

In the above, the speed detector 5, speed command generator 7, comparator 8,
The speed control function unit 9 constitutes speed control means, and the voltage detector 10, the voltage command generator 11, the comparator 12, and the voltage control function unit 13 constitute voltage control means, and the current detector 15, the automatic current control circuit 16, the firing angle setting circuit 17 constitutes a current control means.

Next, the operation of the operation control device of the variable speed pumped storage power generation system configured as described above will be described.

First, in a steady state, a speed command value that maximizes the operating efficiency of the variable speed pumped storage power generation system is output from the speed command generator 7. The rotation speed detection value of the variable speed induction machine 1 detected by the speed detector 5 is compared with the speed command value from the speed command generator 7 in the comparator 8 and the speed control function unit 9 determines the speed based on the speed deviation. A control command is output. In addition, one of the variable speed induction machines 1 detected by the voltage detector 10
The secondary terminal voltage is compared with a voltage command value from the voltage command generator 11 in the comparator 12, and a voltage control command is output from the voltage control function unit 13 based on the voltage deviation. on the other hand,
The secondary current command setting circuit 14 controls the speed control command from the speed control function unit 9, the voltage control command from the voltage control function unit 13, and the internal induced voltage phase of the variable speed induction machine 1 detected by the phase detector 6. A secondary current command value is set based on the angle detection value. In the automatic current control circuit 16, a current control command is obtained based on the secondary current command value from the secondary current command setting circuit 14 and the secondary current detection value detected by the current detector 15. A firing angle setting circuit based on this current control command
At 17, the firing angle of the secondary excitation device 3 is set. Then, by controlling the firing angle of the secondary excitation device 3 based on the firing angle, the exciting power of the slip frequency corresponding to the rotation speed of the variable speed induction machine 1 can be controlled by the secondary winding of the variable speed induction machine 1. Line, and the variable speed pumped storage system is always in synchronization with the power system.

On the other hand, when the variable-speed pumped-storage power generation system is in such a state, the lightning-occurrence prediction information receiver 20 now transmits lightning-occurrence prediction information transmitted from a weather center (not shown), that is, the variable-speed induction machine 1 and its power supply. Upon receiving the lightning occurrence prediction information in the area including the transmission line, the lightning occurrence prediction information receiving device 20 operates continuously while receiving the information. Then, the speed command value setting change device 21 uses the operation output from the lightning occurrence prediction information receiving device 20 to control the speed of the speed command generator 7 so that the primary excitation voltage does not reach the limit value even in the case of an assumed system failure. The command value is changed according to the operating state of the variable-speed pumped-storage power generation system, and the operation of the variable-speed pumped-storage power generation system is shifted to a safe rotation speed range. That is, in the state where the variable speed pumped storage power generation system is in the power generation operation, for example, the slip is shifted to a region of (Smax−3)% or less, and in the state where the variable speed pumped storage power generation system is in the pumping operation, the slip is ( Shift to the area of Smin + 3)% or more. Thus, even when a system accident occurs due to lightning or the like, the variable speed pumped-storage power generation system can be stably operated regardless of the limit value of the secondary excitation voltage.

As described above, in the operation control device of the variable speed pumped storage power generation system according to the present embodiment, while receiving the lightning occurrence prediction information which is the accident occurrence prediction information in the area including the variable speed induction machine 1 and its power transmission line. A lightning occurrence prediction information receiving device 20 that operates and a speed command generator 7 that operates while the lightning generation prediction information receiving device 20 is operating so that the secondary excitation voltage does not reach the limit value even in the event of a possible system failure. A speed command value setting change device for setting and changing the speed command value of the variable speed induction machine 1 and its power supply line. It is assumed that the variable speed pumped-storage power generation system changes the speed command value to a value lower than the steady state in the power generation operation state, and changes the speed command value to a higher value than the steady state in the pumped operation state. You can shift the operation to the rotational speed of the region which can not overlap the limits of the secondary excitation voltage during integration accident. Therefore, even in a transient state at the time of a system failure due to lightning or the like, the operation control can be continuously performed within the limit value of the secondary excitation voltage, so that the stability of the variable speed induction machine 1 becomes abnormal and Thus, the security of the entire power system can be improved.

In the above embodiment, the case of lightning, which is one of the weather information, was described as an example of a transmission line accident occurrence factor.
The present invention is not limited to this, and the present invention can be similarly implemented by using weather information (heavy snow, typhoon, etc.) or disaster information (wildfire, etc.) as accident occurrence prediction information as other accident occurrence factors. is there.

[Effects of the Invention] As described above, according to the present invention, the speed command value is set and changed when the prediction information of the accident occurrence in the area including the variable speed induction machine and its power transmission line is issued. In the event of a system failure, the operation is shifted to a rotation speed range that does not affect the limit value of the secondary excitation voltage. Therefore, even in the transient state at the time of a system failure, the operation continues within the limit value of the secondary excitation voltage. The present invention provides an operation control device for a variable speed pumped storage power generation system capable of controlling the operation of a variable speed induction motor and improving the security of the entire power system including the variable speed induction machine.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a variable speed pumped storage power generation system to which an operation control device according to the present invention is applied, and FIG. 2 is a diagram for explaining the response of a variable speed induction machine at the time of a system fault. DESCRIPTION OF SYMBOLS 1 ... Variable speed induction machine, 2 ... Pump turbine, 3 ... Secondary excitation device, 4 ... Transformer, 5 ... Speed detector, 6 ... Phase detector, 7 ... Speed command generator, 8 ... Comparator, 9 ...
Speed control function device, 10: voltage detector, 11: voltage command generator, 12: comparator, 13: voltage control function device, 14: 2
Next current command setting circuit, 15 current detector, 16 automatic current control circuit, 17 firing angle setting circuit, 20 lightning occurrence prediction information receiving device, 21 speed command value setting change device, twenty two……
Preventive control device.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Komukai 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant (56) References JP-A-2-146996 (JP, A) JP-A-1 JP-A-318766 (JP, A) JP-A-1-318595 (JP, A) JP-A-1-318594 (JP, A) JP-A-62-126899 (JP, A)

Claims (1)

(57) [Claims] A secondary side of the variable speed induction machine is mechanically directly connected to a pump turbine, and a primary side of the variable speed induction machine is provided so as to be connectable to an electric power system. A variable-speed pumped-storage power generation system configured to connect a secondary excitation device including a frequency converter to the secondary winding of the variable-speed induction machine and to supply excitation power of a variable voltage and variable frequency to the secondary winding of the variable-speed induction machine. Speed control means for outputting a speed control command based on a result of comparison between the rotation speed detection value of the induction machine and the speed command value; and a comparison result between the primary terminal voltage detection value of the variable speed induction machine and the power command value Voltage control means for outputting a voltage control command based on the following: a speed control command from the speed control means, a voltage control command from the voltage control means, and a detected value of an internal induced voltage phase angle of the variable speed induction machine. Secondary to set secondary current command value Current command setting means, and current control for controlling a firing angle of the secondary excitation device based on a secondary current command value from the secondary current command setting means and a secondary current of the variable speed induction machine. Means for operating while receiving prediction information of the occurrence of an accident in an area including the variable speed induction machine and its power transmission line, so that the secondary excitation voltage does not reach the limit value even in an assumed system accident. An operation control device for a variable-speed pumped-storage power generation system, comprising: a preventive control means for setting and changing a speed command value.