JPH0360400A - Exciting device for variable speed generating motor - Google Patents

Abstract

PURPOSE:To prevent voltage rise instantaneously at the time of power supply cutoff by judging whether the voltage rise can be suppressed or not from the deviation be tween a voltage instruction value and a voltage detection value and the AVR integral value when a power system has been cutoff. CONSTITUTION:Automatic voltage adjuster(AVR) 16 is equipped with a means 22, which detects the cutoff of a power system 5, a means 21, which judges the polarity of the deviation Vg between an output voltage instruction and a detected value Vg, a means 23, which judges the polarity of the current instruction of current ingredients Id in the direction of magnetic flux, and a means 25, which inverts the polarities of the output voltage instruction and the detected value according to the outputs of the cutoff detection means 22, the polarity judging means 21, and the means 23 for judging the polarity of current instruction in the direction of magnetic flux. And the voltage is automatically controlled based on the inverted deviation. That is, this ts equipped with an AND circuit 24, which seeks the logical product of the outputs of comparators 21-23 by each mean, a switch 25, which changes over the polarity of the voltage deviation Vg by the output of the AND circuit 24, and others. Hereby, the voltage rise of a generator at the time of power system cutoff can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an excitation device for a variable-speed generator-motor that uses a frequency converter to excite a secondary winding with alternating current and performs variable-speed operation. The present invention relates to an excitation device suitable for suppressing a rise in generator voltage that occurs when a power system is shut down.

[Conventional technology]

Conventionally, synchronous machines have generally been used as pumped storage power generators. Since this synchronous machine can only operate at a constant rotation speed, the efficiency of the pump-turbine fluctuates depending on the amount of power generated, the amount of water pumped, and the head, and there are also problems such as difficulty in adjusting the load when pumping water.

Therefore, a variable speed pumped storage power generation system has been proposed that solves the above problem by making the rotational speed of the pump turbine variable. This system uses a method in which the secondary winding is secondarily excited at a slip frequency in a large-capacity winding generator-motor (hereinafter referred to as a variable speed machine), and this exciting current is m
This system realizes power generation and water pumping at variable speeds.

The major differences between such a variable speed machine and the above-mentioned synchronous machine are as follows. In other words, in a synchronous machine,
By changing the internal phase difference angle, a torque commensurate with the load (active power) is generated, and the exciting current does not contribute to the torque. On the other hand, in a variable speed machine, the secondary excitation current is decomposed into a torque component (also called an active power component or q component) and a magnetic flux direction component (also called a reactive power component, voltage component, or d component). active power and reactive power can be controlled independently. (For example, see Japanese Patent Application No. 61-23162).

[Problem to be solved by the invention]

However, due to the characteristics of variable speed machines,
The following problems may occur. A phenomenon may occur in which the power generation Iaffi pressure suddenly increases when the near end or far end of the power system is shut off, or when the load of the variable speed machine is cut off (hereinafter referred to as power system shutoff).

In the case of a synchronous machine, when the load on the system is removed, the internal phase difference angle returns to zero, and in order to suppress the increase in generator voltage ΔV, the DC current (excitation of the synchronous machine is DC excitation) is A constant voltage controller (hereinafter referred to as an automatic voltage regulator AVR) throttles the voltage and maintains the voltage of one generator at a command value.

On the other hand, in a variable speed machine, when the load on the system is removed,
The torque current component Iq also contributes to the voltage increase, resulting in an increase in the output voltage increase ΔV. In other words, the magnetic flux coincides with the magnetic flux direction current component Id immediately before the interruption, but at the same time as the interruption, the magnetic flux is synthesized in the direction and magnitude of the vector combination of the magnetic flux direction component 1d before the interruption and the torque current component I (I). If the amplitude of the excitation current is larger than the magnetic flux direction current component Id before the cutoff, the output voltage will increase by ΔV.This voltage increase ΔV will cause the auxiliary equipment in the power plant connected to one generator to increase. etc., there was a risk of damage.

Furthermore, as already mentioned about the difference between a conventional synchronous machine and a variable speed machine, a synchronous machine uses DC excitation, whereas a variable speed machine uses AC secondary excitation. In other words, when the voltage increases, in a synchronous machine, AVR only reduces the DC amount, but
Variable speed machines use alternating current.

The amplitude and phase of the excitation current must be controlled. The AVR of a synchronous machine is DC excitation and its lower limit value is zero, but AC excitation may have a negative lower limit value smaller than zero.

AVR command (
Id) moves toward the smaller value, but if a voltage increase ΔV occurs even at Id=O, Id moves to the negative lower limit in the direction of further reduction.Then, as mentioned above, the voltage at cut-off becomes Since it is determined by the amplitude of the vector combination of Id and Iq, moving Id to the negative lower limit increases the amplitude of the vector combination, and as a result, the voltage increase ΔV
It has the disadvantage that it does not suppress it, but on the contrary encourages it and increases it.

SUMMARY OF THE INVENTION An object of the present invention is to provide an excitation device for a variable continuous FFI motor that can suppress a rise in generator voltage when the power system is shut down.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an automatic active power regulator for reducing to zero the deviation between a command value and a detected value of output active power of a wound generator motor connected to a power system. An alternating current that is a vector combination of the current command of the torque current component and the current command of the magnetic flux direction current component obtained by an automatic voltage regulator to zero the deviation between the command value and the detected value of the output voltage of the generator motor. In an excitation device for a variable speed generator motor that excites a secondary winding of the wound generator motor with an excitation current, the automatic voltage regulator includes means for detecting interruption of the t-power system, and an output voltage command and a detected value. means for determining the polarity of the deviation from the magnetic flux direction current component; means for determining the polarity of the current command of the magnetic flux direction current component; The present invention proposes an excitation device for a variable-speed generator-motor that includes means for reversing the polarity of a voltage command and a detected value, and that automatically controls the voltage based on the reversed deviation.

Specifically, the power system disconnection detection means includes a comparator that detects power system disconnection when the detected voltage value reaches a specified value or more, and the means for determining the deviation polarity between the output voltage command value and the detected value. comprises a comparator for determining negative polarity, the current command polarity determining means comprises means for determining negative polarity, and the polarity reversing means comprises a comparator for determining negative polarity.

It includes means for calculating the logical product of the outputs of the detection means and the determination means.

The power system interruption detection means, the deviation polarity determination means between the output voltage command and the detected value, and the magnetic flux direction current command polarity determination means may also exhibit hysteresis characteristics.

The power system interruption detection means, the deviation polarity determination means between the output voltage command and the detected value, and the magnetic flux direction current command polarity determination means each include means for changing the set value of the hysteresis characteristic depending on the operating state. It's okay.

[Effect]

In the present invention, first, when the power system is cut off, the variable speed machine is released from the power system.

The detected active power value becomes zero, the APR increases the torque current component q, and the AVR acts to reduce the excitation direction current component Id to suppress the voltage rise.

The d-axis component Id due to AVH continues to decrease and its polarity becomes negative. Furthermore, the difference ΔV between the voltage command value V r e f and the generated voltage detection value Vg is determined, its polarity is determined, and the polarity of the value of ΔV is inverted only if it is negative polarity, similar to Id. It acts as an input to the AVR.

When one generator voltage is higher than the command value due to this series of operations, the current command Id by the AVR always acts in the direction of Id=O, suppressing the voltage.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 3 of the drawings.

Figure 1 is a block diagram showing an example of the configuration of the main parts of an automatic voltage regulator (AVR) of an excitation device for a variable speed generator motor according to the present invention, and Figure 2 is a variable speed generator using the automatic voltage regulator shown in Figure 1. FIG. 3 is a block diagram showing an example of the overall configuration of a pumped storage power generation system, and FIG. 3 is a time chart illustrating the operation of the automatic voltage regulator shown in FIG.

In FIG. 2 showing an example of the configuration of a variable speed pumped storage power generation system, the primary winding of a variable speed machine 2 connected to a pump turbine 1 receives power via circuit breakers 3A, 3B and a main transformer 4. It is connected to Keiki 5. The secondary winding of the variable speed machine 2 is of a four-wire type having a neutral point, and is supplied with three-phase alternating current excitation current from cycloconverters 6A to 6C as frequency converters. Each cycloconverter 6A to 6C is
It is connected to the primary side of the main transformer 4 via excitation transformers 7A to 7C and a circuit breaker 8. What are the instrument transformer 9, current transformer 10, and power/voltage detector 11?

Active power PQ flowing out from variable speed machine 2 and generator voltage Vg
It is provided to detect. The phase detector 12 and the reference signal calculator 13 detect the phase of the secondary induced voltage of the variable speed machine 2 and generate the d-axis and q-axis reference signals sin sωt, which serve as the reference for calculating the secondary excitation current command I2 tree. and c
Find os sωt.

Here, S represents Suberi.

The excitation current controller 14 is an automatic active power regulator (APR).
Torque current component Iq command from 15 and automatic voltage regulator (
Secondary excitation current command I, * (=
Id-sinsωt+Iq-coss (1) t
), an Ec calculator 18 and an automatic pulse phase shifter 19 for controlling the current to be constant.

The automatic active power regulator (APR) 15 receives the active power command P.
0 and the detected value PQ, and the automatic voltage II regulator (AVR) 16 adjusts the voltage according to the deviation ΔV between the voltage command v0 and the detected value Vg. Perform constant control calculations.

Next, the configuration of the automatic voltage regulator (AVR) 16 according to the present invention will be described in detail with reference to FIG.

The automatic voltage regulator (AVR) 16 includes a subtracter 20 that has a hysteresis characteristic and calculates the deviation ΔVg between the voltage command value V0 and the voltage detection value Vg, and a subtracter 20 that has a hysteresis characteristic and calculates the deviation ΔVg between the voltage command value V0 and the voltage detection value Vg.
A comparator 21 that detects the polarity of the output ΔVg of 0, a comparator 22 that has hysteresis characteristics and detects an increase in the voltage detection value Vg, and a comparator 23 that has hysteresis characteristics and determines the polarity of the voltage control calculation result. and the comparators 21, 22 .
AND circuit 24 for calculating the logical product of the outputs of 23;
A switch 25 that switches the polarity of the voltage deviation ΔVg based on the output of the circuit 24, a calculator 26 that proportionally calculates the output of the switch 25, an integrator 27 that integrates the output of the switch 25, and the proportional calculator 26 and the integrator. The adder 28 adds the outputs of the adder 27 to obtain the magnetic flux direction component current 1d.

Referring to the time chart in Figure 3,
The operation of the embodiment shown in the figure will be explained. The time chart in FIG. 3 is an example of load shedding when the circuit breaker 3B is turned off at time t1 during steady operation.

When the generator voltage Vg suddenly increases at the same time as the load is cut off at time t1, the voltage deviation ΔV g ”V o V g <△
V g l < O, and the output of the comparator 21 becomes H level. Further, although the output of the AVR integrator 27 begins to decrease, it does not reach the level of the comparator 23 at the initial stage, and the execution conditions of the present invention are not satisfied. The proportional+integral calculation result Id of the entire automatic voltage regulator (AVR) 16 becomes a negative value.

At time t2, the AVR integral value has negative polarity (comparator 2
3), and the output of the comparator 23 becomes H level, but since the generator voltage does not reach the overvoltage level Vg, steady state control is executed. At this time, as already mentioned, since the deviation ΔVg is negative, the result of AVR integration is in the negative direction, increasing the amplitude of the excitation current.

The voltage continues to rise.

When the generator voltage Vg reaches the overvoltage level Vg at time t, the outputs of the comparators 22 and 23 go to the H level, so the output of the AND circuit 24 goes to the H level, and the deviation ΔV
Activate the polarity changeover switch 25 of g. At this time, the calculation result Id of the entire automatic voltage regulator (AVR) 16 is changed by changing the polarity of the voltage deviation ΔVg, so that Id=(AVR
The calculation result is the integral calculation value I) - (AVR proportional calculation value P), which decreases. The output of the AVR integrator 27 is at time t.

, it starts increasing from a negative value towards zero, and as a result Id
The value of is brought closer to zero, and the rise in the voltage of one generator is suppressed.

In addition, in FIG. 3, the broken line shows the characteristics when the present invention is not applied. In this case, since the AVR integral value decreases to the negative limit value, the AVR calculation result Id also becomes the negative maximum value, increasing the amplitude of the excitation current and increasing the voltage rise. Also.

The reason why the generator voltage is saturated is due to the saturation characteristics of the generator itself.

When the AVR integral increases to the specified value 2 at time t4, the voltage rise suppression mode of the present invention is ended and control returns to normal operation.

In this embodiment, the voltage rise suppression mode is ended when the AVR integral value reaches the specified value, but since the voltage deviation ΔVg has actually become small, the I
The change in d is small and does not pose a problem.

As described above, according to this embodiment, a simple comparator, logic circuit, and changeover switch are combined into an automatic voltage regulator (AVR).
), stable automatic voltage control operation can be performed intermittently without using a power system interruption detection means.

In addition, as shown in Fig. 1, the overvoltage detection level of the generator voltage Vg is VgtVgz, the voltage deviation polarity detection level is ΔV g x *ΔV g z, and the polarity detection level of the AVR integral calculation result is Vg, 2, by providing hysteresis characteristics.

This eliminates so-called flapping, where the voltage rise suppression mode is switched more frequently than necessary due to fluctuations in each value, and the voltage rise suppression mode can be switched smoothly.

Furthermore, when the present invention is implemented using a microcomputer, if a setting table is provided in which the settings of each specified value of the hysteresis characteristic are changed depending on operating conditions such as active power and reactive power, the waiting time until the specified value is reached can be shortened. , speeding up of voltage suppression is possible.

〔Effect of the invention〕

According to the present invention, when the power grid is cut off.

Based on the overvoltage level of the generator voltage, the deviation between the voltage command value and the voltage detection value, and the AVR integral value, it is determined whether the voltage rise can be suppressed with automatic voltage control during steady state, and the system is shut off. This provides an interlock that instantaneously suppresses voltage rises during normal operation and prevents unnecessary operations during normal operation, thereby realizing a highly reliable excitation device for a variable-speed generator-motor.

[Brief explanation of drawings]

The first engineering drawing is a block diagram of an automatic voltage regulator (AVR) according to the present invention, FIG. FIG. 2 is a time chart illustrating the operation of the device. 1... Pump water turbine, 2... Variable speed machine, 3... Circuit breaker, 4... Main transformer, 5... Power system system, 6... Frequency converter (cycloconverter), 7...Transformer,
8... Circuit breaker, 9... Instrument transformer, 10... Instrument current transformer, 11... Power/voltage detector, 12...
Phase detector, 13... Reference signal calculator, 14... Excitation current controller. 15... Automatic active power regulator (APR), 16...
Automatic voltage regulator (AVR), 17... Engineering 2 computing unit, 1
8... Ec calculator, 19... Pulse phase shifter, 20...
...Subtractor. 21.22, 23... Comparator, 24... AND circuit, 25... Changeover switch, 26... Proportional calculator,
27... Integrator, 28... Adder.

Claims (1)

[Claims] 1. Torque current component determined by an automatic active power regulator to zero the deviation between the command value and the detected value of the output active power of the wound generator-motor connected to the power system. and the current command of the current component in the magnetic flux direction obtained by the automatic voltage regulator to zero the deviation between the command value and the detected value of the output voltage of the generator motor. , in the excitation device for a variable speed generator motor that excites a secondary winding of the wound generator motor, the automatic voltage regulator includes means for detecting a cutoff of the power system, and a means for detecting a cutoff of the power system, and a means for detecting a cutoff of the power system, according to the outputs of the means for determining the polarity of the deviation, the means for determining the polarity of the current command of the magnetic flux direction current component, the cutoff detection means, the deviation polarity determination means, and the magnetic flux direction current command polarity determination means. An excitation device for a variable speed generator motor, comprising means for reversing the polarity of the output voltage command and the detected value, and automatically controlling the voltage based on the reversed deviation. 2. The excitation device for a variable speed generator motor according to claim 1, wherein the power system interruption detection means includes a comparator that detects interruption of the power system when the detected voltage value reaches a specified value or more. , the deviation polarity determining means between the output voltage command value and the detected value comprises a comparator for determining negative polarity, the current command polarity determining means comprises means for determining negative polarity, and the polarity reversing means comprises a comparator for determining negative polarity; An excitation device for a variable speed generator motor, comprising means for calculating the logical product of the outputs of the detection means and the determination means. 3. The excitation device for a variable speed generator motor according to claim 2, wherein the power system interruption detection means, the deviation polarity determination means between the output voltage command and the detected value, and the magnetic flux direction current command polarity determination means. An excitation device for a variable speed generator motor, characterized by having hysteresis characteristics. 4. The excitation device for a variable speed generator motor according to claim 3, wherein the power system interruption detection means, the deviation polarity determination means between the output voltage command and the detected value, and the magnetic flux direction current command polarity determination means. An excitation device for a variable-speed generator-motor, characterized in that each of the excitation devices is provided with means for changing the set value of the hysteresis characteristic depending on the operating state.