JPS6285699A - Variable-speed generator - Google Patents

Abstract

PURPOSE:To improve stability by using a difference between power required for a control spot and an output capable of being made to correspond by other periodic machines as a power command value for a variable speed machine. CONSTITUTION:A command-value computing section 15 outputs an opening command value V for a governor valve 12 for a hydraulic turbine 13 and a speed command value N) on the basis of static head H ad an output command value P0. A phase-angle computing section 16 computes the phase angle DELTAdeltaof a secondary winding for an induction generator 100 on the basis of the output command value P0, effective power P, the speed command value N0 and a speed signal N. An excitation-quantity setting section 17 sets the quantity of the secondary winding excited by the speed signal N, the phase angle DELTAdelta and an output from a voltage regulating section 18. A proportional arithmetic section 60 compensates the output command value P0 on the generation of a grounding accident, outputs a compensated commend value P01, and absorbs the unbalanced energy of a system.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a variable speed power generation device operated at variable speed by an induction motor employing a secondary excitation control method, and in particular to a variable speed power generation device that improves system stability. Regarding power generation equipment.

[Background of the invention]

Conventional pumped storage power generation systems have the disadvantages that the load cannot be adjusted during pumping, and the efficiency of the system changes due to changes in the power required by the grid during power generation and pumping operations, as well as the head during pumping. Ta.

For this reason, research is progressing on how to operate the above system at maximum efficiency regardless of power output or lift. In order to achieve this objective, there is an idea of using an induction machine that employs a secondary excitation control method as a pumped storage power generator instead of a conventional pumped storage power generator configured with a synchronous machine. Since the induction machine that employs the secondary excitation control method is capable of variable speed operation, it is possible to operate at the highest efficiency of the power generation system regardless of the power generation capacity or head.

Regarding the concept of variable-speed operation of large-capacity synchronous motors, even if they are synchronous machines, see "Variable-speed operation characteristics of large-capacity synchronous motors" (Proceedings of the 1981 National Conference of the Institute of Electrical Engineers of Japan, Ejima, Japan).
Ito and two others, Toshiba).

On the other hand, in or near power plants, synchronous machines are used to stabilize the system. This synchronous machine serves as a generator or electric motor to stabilize the system. However, if a large imbalance occurs in the system, the synchronous machine may lose synchronization.

When a variable speed induction machine is used as a generator, this problem occurs: I! It is necessary to prevent the following four phenomena.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a variable speed power generator using an induction motor that can prevent step-out phenomena.

[Summary of the invention]

The present invention focuses on the fact that variable speed induction motors are free from the tax adjustment phenomenon, and attempts to improve the stability of the system by absorbing the unbalanced power of the system using the variable speed induction machine.

That is, the difference between the power required by the control point and the corresponding output of another synchronous machine is set as the power command value of the variable speed machine. By doing this, the variable speed machine bears the amount of power that other synchronous machines cannot handle, so other synchronous machines do not have to bear more than a certain amount of power, improving stability. .

[Embodiments of the invention]

Figure 2 shows the overall configuration of a generator using a variable speed induction machine. The induction machine 100 is a three-phase second-turn vA5Q.

A stator 1 having windings 5b and 5c, and a three-phase secondary winding 6a.

It consists of a rotor 2 having 6b and 6c.

If the rated frequency is f and the slip is S, the speed of rotor 2 is f(1-8), and by exciting the secondary winding of the rotor at a frequency of S, the rotation of rotor 2 is increased. The magnetic field rotates with zero slip (synchronous speed) and is the same as the speed of the rotating magnetic field of the stator 1.

The control unit 5o performs excitation control of the secondary windings 6a, 6b, and 6c. The control unit 50 controls the excitation voltage v according to the command value, ,
V, , v3 and the secondary winding 6a.

Add to 6b and 6c.

Here, E is the voltage value, δ, determined by the operating conditions of the suberi S and variable speed induction machine. is a phase angle determined by the operating state of the variable speed induction machine, and Δδ is a phase angle controlled by an external command.

By adopting a configuration north of this point, the armature windings (rotor 2 windings 6a, 6b
, 6c), a voltage at the grid frequency can be generated. That is, in the example of FIG. 2, the rotating magnetic field of the rotor 2 is: ! <1. -8”)+fS=f...
(2), and regardless of the slip S, a rotating magnetic field of the rated frequency can be obtained.

The above induction machine is used in a generator for a pumped storage power plant.

The aim of the present invention is to improve stability in the event of a system failure during power generation operation using this induction machine.

Figure 3 shows a generator control system diagram at a pumped storage power plant. The induction machine 100 has a function as a generator.

The power generation output is provided to the grid 10. induction machine 10
The rotation shaft of the rotor 2 of 0 is connected to the water wheel 13.
Rotate by.

The guide valve 12 of the water turbine 13 is controlled by the valve opening setting device 14, and the secondary winding 22a of the induction machine 100.

Power to 22b and 22c is provided by phase shifters 23a and 23b.

23c.

The above two controls are performed by the following methods.

The command value calculation unit 15 calculates the 2 static head (head) H1 output command value (
Active power command value) Po is taken in, and the opening command value V of the governor valve 12 is calculated in consideration of efficiency, and the speed command value N is calculated.

Calculate. The valve opening setting device 14 receives the opening command value V and adjusts the opening of the valve 12 after a predetermined time delay.

The phase angle calculation unit 16 receives the detected active power P of the active power calculation unit 21 and the active power command value P. Then, the speed command value N0 and the detected speed N are taken in, and the phase angle Aδ of the secondary winding corresponding to N,, P, is calculated. The detected active power P is calculated by the active power detection unit 21 based on the detected current and detected voltage of the current transformer 19 and the voltage transformer 20. The detected speed N is detected by the speed detector 11.

The excitation amount setting unit 17 sets the excitation amount of the secondary winding based on the detected speed N, the phase angle Δδ, and the output of the voltage adjustment unit 18. By this excitation amount setting section 17, the phase shifter 23a
, 23b, 23c, and the phase-shifted excitation amounts v,,v,,v.

The excitation control of the secondary windings (3a, 6b, 6c) is performed by.

Next, FIG. 4 shows an embodiment of the present invention in which an induction machine operated at variable speed using the secondary excitation control method and comprising the above-mentioned control system is used as a q-electric machine for water.

FIG. 4 is an application diagram to an example of a power transmission system having two systems (bus lines) B, , B, and connecting systems I3□ and B by a power transmission line, , L. Strain B. has one synchronous machine G
, and a variable speed induction machine G. are connected in close proximity, and system 8
2 is coupled with one synchronous machine G. Power transmission line■41
In the system B, there is a current transformer 19A and a circuit breaker 2:3 on the side.
, a current transformer 19B and a circuit breaker 24 were provided on the system B2 side. Furthermore, protection relays 25 and 26 are installed.

The variable speed induction machine G1 corresponds to the induction *1-oo in FIG. G
Calculate the active power at 2. The control unit 50A has the same configuration as the control unit 50 in FIGS. 2 and 3, and when an accident occurs, the active power calculation unit 2.1. Modify the output value based on the output of A (11).

The operating end 30 receives an external command lj.

Same 1 (11 aircraft G,, G3, system? Nippa Lance...
It is a device that acts as an electric motor or a generator, and has the role of controlling energy release and absorption.1 Now, with this configuration, if a ground fault occurs at point F, Suppose this occurs. Conventionally, the point! - If a ground fault occurs in
Protection relay 25 through current transformer l, 9A, 1913
．． 26 plows and opens circuit breakers 23 and 24. For this reason, there is a slight imbalance between the input and output of the synchronous machine G2 and (L), and power is not being supplied to the G7 side (G,
When the motor is operated with the electric motor 1 and 2), acceleration out-of-step occurs, and when the electric power is supplied from the G side and m (where Gl is operated as an electric motor and λ overlaps), deceleration out-of-step occurs.

In this embodiment, in order to prevent this explanation, the synchronous machine 6
Current transformer 19 c provided on the 2 side, voltage transformer 20
Based on the detected value of G, the calculation unit 21A constantly monitors the effective output of the 1i11 aircraft G2, and when an accident occurs, the output of the synchronous machine G2 is adjusted to the adjacent synchronous machine G2 so that the output is the same as before the accident. It was decided to control the variable speed induction machine G1. This will help prevent tax adjustments and stabilize the grid. Control of this variable speed induction machine G is performed by a control section 50A.

In addition, the synchronous machines G, ,G, were used for system stabilization, but
Even if the generator is installed as an original generator, this embodiment can be applied. Even if the generator is a synchronous machine, it is possible to absorb the industrial water energy by operating it as an electric motor.

FIG. 5 shows another example of application. This power system is system B,
2 through power transmission line L3. Two synchronous machines Gz, G3
, one variable speed induction machine G is connected, and two variable speed induction machines are connected to system B2.
Two synchronous machines G4. I connected the G5.

This configuration uses the power flow of the interconnection system L3 that is close to the variable speed induction machine G as the control end axis of the variable speed induction machine G.

Assume that the current is now flowing from system B, to B2. If a ground fault occurs at point D, circuit breaker 24A
Due to the operation of , synchronous machine G is disconnected from the system, and the WA flow from B to 132 is reduced to some extent. Therefore, if no control is performed, the synchronous machine (j7°G) will accelerate and step out for the same reason as explained in Fig. 4.
9. Next, the operation of the control section 50A will be explained.

The control unit 50A always operates with high efficiency.
Perform secondary excitation control of the induction machine G, and control the opening of the governor valve 12 of the main river 13. For example, when an instruction is given to reduce the power generation output of the induction machine G, , f Calculate the rotational speed and valve opening degree using a predetermined method. Based on the calculation results of steps 1-2 and 2, the operation υJail is performed to reduce the power generation output as instructed. On the other hand, the deviation of the rotational speed of the induction machine G from the rated value is determined by using the excitation frequency 7 and the slip frequency. By means of two, the rated frequency σ) output can be obtained.

Next, an embodiment of the control section 50A is shown in FIG.

Compared to the control section 50, a comparison calculation section 60 is newly added. , the comparison calculation unit 60 calculates 1 (when an 11 fault occurs).

The output command value P, is corrected to absorb unbalanced energy in the system. The processing contents of the comparison calculation section 60 are shown in FIG. First, it is checked whether the amount of variation in the active power P of the synchronous machine G2 calculated by the active power calculation unit 21A is within a permissible value. If the amount of variation is within the allowable value, the command value Po given from the outside is output as is as the regular command value Pot.

On the other hand, if the amount of variation is greater than the allowable value, the external command value Po
is corrected and a new command value P0. Output. This new command value P. 1 corresponds to the variable output of synchronous machine G2, and if the amount of variation is ΔP, then Pl, 1=P, +Δ
Let it be P.

The phase angle calculation unit 16 calculates Δδ in equation (1).

This Δδ is Aδ= /to□(P-Po1)dt+/k, (N-
N,) to dt-, (p-p, 1) to dt+, (N-No
)-G3). Here, K. 1. 2 is a constant.

The operation of this embodiment under the system shown in FIG. 4 will be explained. Now, with the synchronous machine G2 supplying active power to the 03 side, power is transmitted &! as shown in Figure 4. When an accident occurs at point F of L, current transformer 19A.

19B, the protective relay 25.26 detects the fault, issues a disconnection command to the circuit breaker 23.24, and disconnects the power transmission line L1.
is separated from the lineage. In this case, if the output of the synchronous machine G2 before the accident is pat, then the input of the induction machine as a generator is also operating at a value P2 commensurate with this. However, in the event of an accident, the output as a generator becomes almost zero, so if no control is performed, P2 will be used for acceleration as a generator.

Therefore, in this embodiment, the active power of the synchronous machine G2 is monitored, and it is determined whether the fluctuation in the active power of the synchronous machine G2 is within a permissible value, and if the fluctuation exceeds the permissible value, the induction motor As the command value for □, the difference ΔP= (P, □ - P, ,) between the output P, 1 before the accident of synchronous machine G2 and the output P6 □ after the accident is calculated, and from this difference, 4P, the command value P. Correct. For example, suppose the corrected command value is Pl, 1.

Pa, = Po+AP ・(4
). This new command value P. The calculation unit 16 calculates the formula (3) based on , and the corrected Aδ can be obtained. This Δδ allows the induction machine to absorb power that could not be absorbed into the grid by the synchronous machine G2 due to the accident. This control suppresses a decrease in the output of the generator, thereby suppressing acceleration.

FIG. 7 is a comparison diagram of the effects of this embodiment and the conventional example. This is the phase angle fluctuation curve of synchronous machine G2 at the time of the accident, and curve a
The curves indicate the case according to this embodiment, and the curves indicate the case according to the conventional example. According to this embodiment, fluctuations in one phase angle are reduced.

Note that the correction equation (4) is just an example, and correction can be made depending on the system.

〔Effect of the invention〕

According to the present invention, even when system imbalance occurs in a system having a synchronous machine, energy can be input and output using the variable speed induction machine, and stable system operation has become possible.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the present invention, FIG. 2 is a control system diagram of an induction motor, FIG. 3 is a more detailed control system diagram of the induction motor when used as a water turbine generator, and FIG. FIG. 5 is a system application example diagram, FIG. 6 is a processing flow diagram, and FIG. 7 is a comparison diagram of effects. 100 and G1...variable speed induction machine, G2+G3+G4
rG5...Synchronous machine, 50A...Control unit.

Claims (1)

[Claims] 1. A variable speed induction machine with secondary excitation driven by a water turbine, a synchronous machine connected to an interconnection system adjacent to or in the vicinity of the induction machine, and the synchronous machine from the system a variable speed power generator comprising: means for correcting an output command value for secondary excitation control to the induction machine in accordance with the amount of variation when the variation in active power to the induction machine exceeds a permissible value. 2. The variable speed power generator according to claim 1, wherein the fluctuation in the active power is caused by a ground fault in the grid.