JPH02174587A - Control device for variable-speed pumped-storage power system - Google Patents

Abstract

PURPOSE:To perform operation continuously within the limiting value of a secondary exciting voltage by resetting a speed command value, when a fault occurrence preview signal in a power transmission area is issued. CONSTITUTION:The secondary side of a variable speed induction machine 1 is directly coupled to a reversible pumpturbine 2, the primary side thereof is connected with an electric power system, and a secondary exciter 3 composed of a frequency converter is connected with the secondary side to supply a secondary winding with power. A rotational speed detected by a speed detector 5 is compared with that of a speed command generator 7, and the deviation thereof is given to a secondary current command setting circuit 14 via a speed control function generator 9 and controlled so that the speed becomes a command value. Similarly, and output voltage is detected by a voltage sensor 10 and the deviation from the output of a voltage command generator 11 is given to the secondary current command setting circuit 14 via a voltage-controlled generator 13. When a preview signal is inputted from a lightning preview information receiver 20, the speed command value is changed by a resetting device 21 and an apparatus can continue operation within the limited range of a secondary exciting voltage even if an abnormality occurs.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention provides a variable speed pumped storage power generation system that can be operated at any rotation speed by a variable speed induction machine with secondary excitation control.
In particular, the present invention relates to an operation control device for a variable speed pumped storage power generation system that improves the security of the entire power system including the variable speed induction machine.

(Prior Art) In recent years, variable speed pumped storage power generation systems have been adopted as one of power generation systems. This variable-speed pumped storage power generation system mechanically connects the secondary side of the variable-speed induction machine directly to the pump turbine, and connects the primary side of the variable-speed induction machine to the power grid. By connecting a secondary excitation device consisting of a frequency converter such as a cycloconverter to the side and supplying excitation power with variable voltage and variable frequency to the secondary winding of the variable speed induction machine, it is possible to operate at any rotational speed. It is composed of Conventionally, secondary excitation control of variable speed pumped storage power generation systems uses a cycloconverter, etc. to maintain the primary terminal voltage and rotational speed (or primary active power) of the variable speed induction machine at certain constant values. This is done by controlling the firing angle of a secondary excitation device consisting of a frequency converter.

By the way, in this type of variable-speed pumped storage power generation system, even if the rotational speed changes, the secondary winding of the variable-speed induction machine is always supplied with an AC excitation current with a slip frequency that corresponds to the rotational speed. It is said that it is always in synchronization with the grid and does not suffer from the so-called stability problems that occur with conventional synchronous machines. Therefore, no proposals regarding operational control for improving stability have been made so far.

However, in order for the variable speed pumped storage power generation system to always operate stably, as mentioned above, the secondary winding of the variable speed induction machine must always be supplied with an AC excitation current with a slip frequency that corresponds to its rotation speed. In addition to the condition that the secondary excitation voltage is limited, it is also necessary that the secondary excitation control is always performed regardless of the limit value of the secondary excitation voltage. In this case, the former condition is fully satisfied, but the latter condition may not be satisfied due to the limit value of the secondary excitation voltage in a transient state during a system fault caused by lightning, etc. It is necessary to take measures against this.

This point will be explained in detail below using FIG. 2.

FIG. 2 is a diagram for explaining the response of the variable speed induction machine in the event of a system accident. In Figure 2, IM is a variable speed induction machine, SG/M is a generator motor, TR1, TR2
is the main transformer, Ll,, L2 is the power transmission line, CH3,...
CB2 is a circuit breaker, and S is a power system. In steady state, when the variable speed induction machine IM is operating to generate electricity, it is operated at the rotation speed that maximizes the efficiency of the turbine according to the head and the turbine output, and when the variable speed induction machine IM is operating for pumping water. is automatic frequency control (hereinafter referred to as A) based on instructions from the central power supply station.
(referred to as FC). A during pumping
To perform FC operation, the pump output is adjusted by changing the rotation speed. In the variable speed induction machine IM, even when the primary side voltage and primary side active power are the same, the required secondary side excitation voltage varies depending on the rotation speed (slip), and at synchronous speed (slip zero), the required secondary side excitation voltage is at least 1. Rotation speed or lower than synchronous speed (positive slip)
Or it becomes larger as it rises (negative slip). For example, in the case of a certain large-capacity machine, when operating at the rated voltage and output, the thickness of the secondary excitation pressure at zero slip is set to 1.
．． 0, the slip is 5% and 34, and the slip is 1.10% and 68.
8. At -5% it becomes 35.2, at -10% it becomes 70.6, and if the slip is doubled, it will roughly double. In this way, the magnitude of the secondary excitation voltage varies greatly depending on the operating rotational speed (slip), so the range of rotational speed (slip) that allows operation, that is, the range that does not exceed the limit value of the secondary excitation voltage, is , is selected taking into consideration the advantages and economics of system operation, and is usually within the permissible slip range (S■ax -8m1n
) is selected to be around 5% to -5%.

Now, when the variable speed induction machine IM is generating electricity, for example, if a system fault occurs in the power transmission line L2, the terminal voltage of the variable speed induction machine IM will drop and the active power will also decrease, so the variable speed induction Does the machine IM start accelerating or the power transmission line L2
When the circuit breakers CBl and CB2 at both ends of the circuit are opened by a command from the protective relay to eliminate the system fault, the terminal voltage rises and the active power also increases. Then, when this active power becomes larger than the initial value (value before the accident), the vehicle shifts to deceleration. On the other hand, when the variable speed induction machine IM is in pumping operation, it decelerates during a system fault and shifts to acceleration after the system fault is removed.

For example, when the variable speed induction machine IM is operating at the rated output, the most severe three-phase fault occurs at the transmission end of the power transmission line L2 (the output becomes almost zero), and the system fault is removed after 0°1 second. If so, the inertia constant of the variable speed induction machine IM is 5
In seconds, if the power generation operation continues during the system fault period, the rotation speed will increase by approximately 2% (], / 5, 0 x
1, 0 x 0, 1- = 0゜02p, u
, ), in the case of pumping operation, the rotational speed decreases by approximately 226 degrees. Even after the grid fault is removed, acceleration (or deceleration) continues until the active power becomes larger than the initial value. The increase (or decrease) in rotation speed during this time varies depending on the system status, but 1% is sufficient.

In this way, if a system accident occurs, there is a risk that the upper limit of the allowable rotational speed may be reached if the system is in power generation operation, or the lower limit of the allowable rotational speed may be reached if the system is in pumping operation. . Then, when the secondary excitation voltage is applied to the limit value,
Not only will the variable speed induction motor IM become unstable and become inoperable, but in some cases, the generator motor SG/M adjacent to the variable speed induction motor IM may be taxed, and the entire power system may collapse. There is a danger of it happening.

(Problem to be solved by the invention) As described above, in the past, for example, in a transient state at the time of a system failure due to an occurrence of lightning, etc., it is not possible to continuously perform operation control depending on the limit value of the secondary excitation voltage. However, as a result, the security of the entire power system including the variable speed induction machine deteriorated.

The purpose of the present invention is to provide two
To provide an operation control device for a variable speed pumped storage power generation system that can continuously control the operation within a limit value of the next excitation voltage and improve the security of the entire power system including the variable speed induction machine. It is in.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention mechanically directly connects the secondary side of the variable speed induction machine to the pump turbine, and A secondary excitation device consisting of a frequency converter is connected to the secondary side of the variable speed induction machine, with the next side being connectable to the electric power system.
The operation control device of a variable speed pumped storage power generation system configured to supply excitation power of variable voltage and variable frequency to the secondary winding of the variable speed induction machine is connected to the rotational speed detection value and speed command value of the variable speed induction machine. speed control means for outputting a speed control command based on the comparison result;
A voltage control means that outputs a voltage control command based on a comparison result between a primary side terminal voltage detection value of the variable speed induction machine and a voltage command value, a speed control command from the speed control means, and voltage control from the voltage control means. Setting the secondary current command value based on the command and the internal induced voltage phase angle detection value of the variable speed induction machine 2
A secondary current command setting means, and a current control means for controlling the firing angle of the secondary excitation device based on the secondary current command value from the secondary current command setting means and the secondary current of the variable speed induction machine. The variable speed induction machine operates while receiving prediction information of an accident in the area including its power transmission line, and sets the speed command value so that the secondary excitation voltage does not exceed the limit value even in the event of a supposed system accident. and preventive control means for changing settings.

(Function) In the above-mentioned operation control device, when predictive information of an accident occurring in an 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, even in the event of a hypothetical grid fault, operation is shifted to a rotation speed range that does not exceed the limit value of the secondary excitation voltage. Even in a transient state when this occurs, it is possible to continue operating control within the limit value of the secondary excitation voltage.

(Example) The present invention will be described below with reference to an example 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 is mechanically directly connected to the pump turbine 2, and the primary side of the variable speed induction machine is connected to a power system (not shown), and further A secondary excitation device 3 consisting of a frequency converter such as a cycloconverter is connected to the secondary side of the variable speed induction machine,
Excitation power of variable voltage and variable frequency is supplied to the secondary winding of the variable speed induction machine 1. In addition, the secondary excitation device 3
The power supply side of the variable speed induction machine 1 is connected to the primary side of the variable speed induction machine 1 via a transformer 4.

On the other hand, the operation control device consists of the following: That is, 5 is a speed detector that detects the rotational speed of the variable speed induction machine 1, 6 is a phase detector that detects the internal induced voltage phase angle of the variable speed induction machine 1, and 7 is a speed command generator that generates a speed command value. 8 is a comparator that compares the detected value from the speed detector 5 and the speed command value from the speed command generator 7; 9 is a speed control based on the speed deviation which is the comparison result from the comparator 8. This is a speed control function device that outputs commands functionally.

Here, the speed command generator 7 generates a speed command value that maximizes the operating efficiency of the variable speed pumped storage power generation system during steady operation. Also, ]0 is 1 of variable speed induction machine 1
A voltage detector that detects the next terminal voltage i(:t, 11 a voltage command generator that generates a voltage command value, 12 a voltage detector 1
Voltage detection value from 0.

A comparator 13 that compares the voltage command value from the voltage command generator 11 is a voltage control function generator that functionally outputs a voltage control command based on the voltage deviation that is the comparison result from the comparator 12. Furthermore, 14 calculates a secondary current command value based on 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 angle detection value from the phase detector 6. This is a secondary current command setting circuit. Furthermore, 15 is 2 of the variable speed induction machine 1.
a current detector for detecting the next-side current; 16 is a secondary current command setting circuit; and a secondary current command value from 4;

Based on the secondary current detection value from [current detector] 5,
automatic current control (ACR) circuit that outputs current control commands;
]7 is a firing angle setting circuit that sets the firing angle of the secondary excitation device 3 based on the current control command from the automatic current control circuit]6. On the other hand, 20 operates upon receiving lightning occurrence prediction information that 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.

The lightning occurrence prediction information receiving device 21, which continues its operation while receiving the information, uses the operational output from the lightning occurrence prediction information receiving device 20 to continue operating even in the event of an assumed system accident.
This is a speed command value setting change device that changes the speed command value of the speed command generator 7 so that the next excitation voltage does not exceed the limit value, and these devices constitute 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 generating operation state, and sets the speed command value to a higher value than the steady state when the variable speed pumped storage power generation system is in the pumping storage operating state. This is to change the settings. Additionally, most system accidents are caused by lightning strikes, and lightning that will occur in a certain area can be predicted with high probability by detecting thunderclouds using weather radar.

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

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

First, during steady state, the speed command generator 7 outputs a speed command value that maximizes the operating efficiency of the variable speed pumped storage power generation system. The rotational 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 based on this speed deviation, the speed is output from the speed control function generator 9. A control command is output.

Further, the primary side terminal voltage of the variable speed induction machine detected by the voltage detector 10 is determined by the voltage command generator 11 in the comparator 12.
The voltage control function unit 3 outputs a voltage control command based on this voltage deviation. On the other hand, in the secondary current command setting circuit] 4, the speed control function unit 9
The secondary current command value is set based on the speed control command from the voltage control function unit 13, the voltage control command from the voltage control function unit 13, and the internal induced voltage phase angle detection value of the variable speed induction machine 1 detected by the 1-phase detector 6. Ru. The automatic current control circuit 16 also obtains a current control command based on the secondary current command value from the secondary current command setting circuit 4 and the secondary current detection value detected by the current detector 5. Further, based on this current control command, the firing angle of the secondary excitation device 3 is set by the firing angle setting circuit]7. Then, by controlling the firing angle of the secondary excitation device 3 based on this firing angle, the excitation power with a slip frequency corresponding to the rotational speed of the variable speed induction machine 1 is applied to the secondary winding of the variable speed induction machine 1. The variable speed pumped storage system is always synchronized with the power grid.

On the other hand, when the variable speed pumped storage power generation system is in such a state, the lightning occurrence prediction information receiving device 20 receives the lightning occurrence prediction information transmitted from the weather center (not shown), that is, the variable speed induction machine 1 and its power source. When receiving prediction information of lightning occurrence in an area including power transmission lines, the lightning occurrence prediction information receiving device 20 continues to operate 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 adjust the speed of the speed command generator 7 so that the secondary excitation voltage does not reach the limit value even in the event of a supposed system fault. 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 rotational speed range. That is, when the variable speed pumped storage power generation system is in power generation operation, the slip is moved to a region of (Smax-3)% or less, and when the variable speed pumped storage power generation system is in pumping operation, the slip is set to (Smax-3)% or less. S min+3)% or more. As a result, even when a system failure occurs due to lightning or the like, the variable speed pumped storage power generation system can continue to operate stably despite 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, The lightning occurrence prediction information receiving device 20 is in operation, and while the lightning occurrence prediction information receiving device 20 is operating, the speed command generator 7 is configured to prevent the secondary excitation voltage from reaching the limit value even in the event of an assumed system fault. Equipped with a preventive control device 22 consisting of a speed command value setting change device that changes the speed command value setting, when predictive information of lightning occurrence in an area including the variable speed induction machine 1 and its power transmission line is issued, When the variable speed pumped storage power generation system is in power generation mode, the speed command value is set to a lower value than in steady state, and in pumped storage mode, the speed command value is set to a higher value than in steady state, so that the expected system Even in the event of an accident, operation can be shifted to a rotational speed range that does not exceed the limit value of the secondary excitation voltage. Therefore, even in a transient state during a system fault caused by lightning, etc., operation control can be continued within the limit value of the secondary excitation voltage, so the stability of the variable speed induction machine is maintained. , it becomes possible to improve the security of the entire power system.

In the above embodiment, lightning, which is one of the meteorological information, is used as an example of a cause of an accident on a power transmission line. ), or disaster information (wildfire, etc.) as the accident occurrence prediction information, the present invention can be implemented in the same way.

[Effects of the Invention] As explained above, according to the present invention, when prediction information of an accident occurring in an area including a variable speed induction machine and its power transmission line is issued, the setting of the speed command value is changed and the expected speed command value is changed. Even in the event of a grid fault, the operation is shifted to a rotational speed range that does not exceed the secondary excitation voltage limit value, so even in the transient state at the time of a grid fault, the system continues to operate within the secondary excitation voltage limit value. Therefore, it is possible to provide an operation control device for a variable speed pumped storage power generation system, which can control the operation of a variable speed pumped storage power generation system and improve the security of the entire power system including the variable speed induction machine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an 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 the variable speed induction machine in the event of a system fault. ]...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 unit, 10... Voltage detector, 11... Voltage command generator, 12... Comparator,
13... Voltage control function unit, 14... Secondary 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, 22.
・Preventive control device.

Claims (1)

[Claims] The secondary side of the variable speed induction machine is mechanically directly connected to the pump turbine,
A primary side of the variable speed induction machine is provided so as to be connectable to an electric power system, and a frequency converter is provided on the secondary side of the variable speed induction machine.
In a variable speed pumped storage power generation system configured to connect a secondary excitation device and supply variable voltage variable frequency excitation power to a secondary winding of the variable speed induction machine, a detected rotational speed value of the variable speed induction machine. and a speed control means for outputting a speed control command based on a comparison result between the voltage value and a speed command value; A secondary current command value is set based on a voltage control means to output, 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. a secondary current command setting means 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; and a current control means that operates while receiving prediction information of an accident occurrence 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 the event of an assumed system accident. An operation control device for a variable speed pumped storage power generation system, comprising: preventive control means for changing the setting of the speed command value as follows.