JP2714287B2 - System stabilizer using flywheel generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter, in which a variable frequency power is applied to a secondary winding of a wound induction machine to perform variable speed control, and power is absorbed and released when a system power fluctuates. The present invention relates to a system stabilizer using a flywheel generator for stabilizing the system.

[0002]

2. Description of the Related Art Generally, flywheel power generation is used when very large energy is required in a short time by utilizing the energy storage effect of a flywheel. That is, the rotational energy (kinetic energy) is converted into electric energy, and the magnitude of the energy to be released is adjusted by controlling the exciting current of the generator as a medium for the conversion.

[0003] Synchronous machines and DC equipment are used as generators, and the generated electric energy is ultimately used in the form of heat energy, electromagnetic energy, or the like.

In recent years, as a variable speed control system using a winding type induction machine has been developed, it has been considered to apply a flywheel power generation system to a power system.

Conventionally, when electric energy is released, the rotation speed of the rotating machine decreases, and when power is generated using a synchronous machine, it has been difficult to match the output frequency of the generator with the frequency of the power system. By performing the variable speed control, power generation and power reception (motor operation) can be performed without restricting the rotation speed of the rotor to the synchronous speed.

[0006] When flywheel power generation is applied to a power system, the following effects can be obtained.

[0007] In order to keep the power system stable, it is necessary to always balance the supply and demand of power. However, if a load fluctuates rapidly, a general power generation system (thermal, hydro, nuclear, etc.) will not respond. Is slow, supply and demand imbalance occurs, and frequency fluctuation occurs in the system.

The flywheel power generation system using the variable speed control can perform the mutual conversion between the rotational energy and the electric energy at a high speed only by controlling the exciting current. Can be followed. Therefore, a short-time imbalance until a general power generation system responds can be filled, and the power system can be stabilized.

FIG. 4 shows the configuration of a conventional variable speed flywheel power generation system.

The generator motor 3 is a winding type induction machine having a secondary winding of AC excitation in a rotor, and the primary winding is connected to the power system 1 via the main transformer 2.

The secondary winding of the generator motor 3 is connected to a converter 6, which is connected to a converter transformer 5.
A flywheel 4 and a speed detector 15 for detecting a rotation speed are attached to a rotating shaft of the generator motor 3.

The converter 6 is a power converter composed of switching elements such as a thyristor, a GTO, and a power transistor. The converter 6 converts a variable frequency current based on a command from the exciting current control device 14 into a secondary winding of the generator motor 3. Output to

An exciting current control device 14 controls a secondary current flowing through a secondary winding of the generator motor 3 and is a current detector 9.
The feedback control of the converter 6 is performed so that the value of the secondary current detected in the step (b) matches the current command signal value from the input / output limiter 13. The excitation current control device 14 also receives the frequency and phase signal of the system voltage from the frequency detector 8 and the speed detector 1.
5, the rotation phase and rotation speed of the rotor are input, and the secondary magnetic field is generated so that the rotating magnetic field generated in the rotor by the secondary current is synchronized with the phase rotation of the power system 1 generated in the primary winding of the generator motor 3. Controls the phase of the current. For example, if the system frequency is ωl and the rotor frequency is ωr, the frequency of the secondary current is ω1−ωr. Controlling the generator motor by performing AC excitation on the rotor that is not synchronized in this way and electrically synchronizing the rotor will be referred to as variable speed control, and the following description will be made.

The load compensator 10 detects a load fluctuation in a specific area of the power system 1 by the load detector 7 and calculates an exciting current required for outputting or taking out power for compensating the fluctuation, that is, a secondary current value. Is what you do. The output becomes a negative value when the load increases and decreases, and becomes a positive value when the load decreases. The load compensator 10 operates only when the load change rate is large, and outputs a signal in proportion to the amount of change.

The frequency compensator 11 detects a frequency variation of the power system 1 by the frequency detector 8 and calculates an exciting current required for outputting or taking out power for compensating the variation, that is, a secondary current value. is there. The output becomes a negative value when the frequency increases and decreases, and becomes a positive value when the frequency decreases.

The input / output limiter 13 limits the magnitude of the secondary current and prevents the generator motor 3 from deviating into an operation range exceeding the capacity.

Therefore, the load compensator 10 and the frequency compensator 1
1 is calculated by the adder / subtractor 12 as shown in the figure and input to the excitation current limiting device 14 through the input / output limiter 13, when a rapid load change occurs in the power system 1, the fluctuation is compensated. Thus, the generator motor 3 can be controlled.

When the load suddenly increases in the power system 1,
The load compensator 10 and the frequency compensator 11 output a compensation signal, and the exciting current controller 14 increases the current Iq of the q-axis component of the secondary current based on the compensation signal. Then, the electromotive force in the q-axis direction of the primary winding of the generator motor 3 increases, and active power is output to the power system 1. At this time, resistance torque acts on the rotor, and the rotation speed decreases. That is, rotational energy is converted into electric energy and released to the power system 1.

On the other hand, when the load suddenly decreases, the compensation signal becomes negative, and the exciting current limiting device 14 increases the q-axis component of the secondary current in the negative direction. Therefore, the generator motor 3
The generator motor 3 reduces the electromotive force of the primary winding in the q-axis direction.
Current flows into the device and takes in active power. At this time, an acceleration torque acts on the rotor, and the rotation speed increases. That is, electric energy is taken in from the system and converted into rotational energy.

With the above-described operation, it is possible to suppress the fluctuation of the system due to the rapid load fluctuation generated in the system.

[0021]

However, such a flywheel generator control system has the following problems when put into practical use. In other words, the load L of the power system as shown in FIG. 5 when the jumped at time t _0, also varies grid frequency F, and outputs the active power Pf this system operates. On the other hand, the output P of another generator connected to the power system also increases. When the active power Pf is output from this system, a reaction torque acts and the rotational speed R of the flywheel decreases. When the load variation is guaranteed by this operation, the operation stops, and the rotation speed stops decreasing. Therefore, the vehicle stands by at a lower rotational speed RL than before. If the load suddenly increases again in such a state, the same operation as described above is repeated, and the rotational speed R further decreases. Eventually, the vehicle deviates from the speed range in which the variable speed control is possible, and falls into a state where control is impossible.

The same applies to the case where the load suddenly decreases. If the same fluctuation in the decreasing direction occurs repeatedly, the rotation speed increases and deviates from the control range, and control becomes impossible.

Therefore, in the conventional configuration, when the flywheel power generation system is applied for system stabilization, it is difficult to always apply the flywheel power generation system continuously.

The present invention relates to a system stabilization using a flywheel generator which is capable of continuously transmitting and receiving rotational energy of a flywheel to and from an electric power system within a variable speed control range of a rotor. It is intended to provide a device.

[0025]

According to the present invention, a flywheel is connected to a wire-wound induction machine to form a flywheel generator. The primary winding of the wire-wound induction machine is connected to a (power) system,
The secondary winding is connected to a power converter, and an excitation current determined by the rotation speed of the flywheel and the frequency of the system is applied to the secondary winding to perform variable speed control. In a system stabilization device using a flywheel generator to stabilize the system by performing, the rotation speed of the wire-wound induction machine so that the rotation speed of the wire-wound induction machine at the time of system stability becomes a desired standby speed. Standby speed control means for controlling the exciting current of the secondary winding of the wire-wound induction machine so that the deviation becomes 0, compared with the standby speed set value,
At the time of power absorption operation of the flywheel generator due to increase and decrease of system power, the secondary winding of the wound-type induction machine so that the rotation speed of the wound-type induction machine does not exceed a predetermined upper limit speed setting value. Upper limit speed control means for controlling the exciting current of the flywheel generator, and during a power release operation of the flywheel generator due to a decrease in system power, the rotation speed of the wire wound induction machine does not fall below a predetermined lower limit speed set value. And a lower limit speed control means for controlling the exciting current of the secondary winding of the wound induction machine.

[0026]

When the flywheel generator is not performing a power generation operation or a power receiving operation for system stabilization, the standby speed control means controls the rotation speed of the flywheel so that a predetermined standby speed is always maintained during standby. .

When the power generation operation or the power reception operation is being performed for system stabilization, the upper limit speed control means and the lower limit speed control means make the frequency compensator, when the rotation speed comes close to the controllable speed limit point. Alternatively, the output signal of the load compensator is limited to prevent the rotation speed from deviating from the control range.

[0028]

FIG. 1 shows an embodiment of the present invention, and its structure will be described. Reference numerals 1 to 15 are the same as those in the conventional example of FIG. 4, and a standby speed limiter 16, an upper limit speed limiter 17, and a lower limit speed control unit 18 are added in the present invention. The output signal of the speed detector 15 is input to the standby speed control unit 16, the upper limit speed control unit 17, and the lower limit speed control unit 18. The output of the standby speed control unit 16 is output to the adder / subtractor 12, the output of the upper limit speed control unit 17 is output. The output of the lower limit speed control means 18 is input to the input / output limiter 13.

The input / output limiter 13 has a conventional function.
It has a selection function of selecting and outputting an input signal from the upper limit speed control means 17 and the lower limit speed control means 18 and a signal from the adder / subtractor 12.

The standby speed control means 16 has a standby speed set value therein, and outputs a signal proportional to the deviation so that the speed becomes equal to the set value compared with the input speed signal.

The upper limit speed control means 17 has an upper limit speed set value therein, and compares it with the input speed signal. When the speed signal becomes larger than the value of the upper limit speed setter, the speed becomes equal to the set value. Output a signal proportional to the deviation.

The lower limit speed control means 18 internally has a lower limit speed set value, compares it with an input speed signal, and when the speed signal becomes smaller than the set value, sets a deviation so that the speed becomes equal to the set value. Outputs a proportional signal.

First, it is assumed that the rotational speed of the flywheel is at a certain speed. If the speed does not coincide with the standby speed set value, the standby speed control means 16 operates and a signal proportional to the deviation is output to the adder / subtractor 12 to give a secondary current command value, whereby the converter 6 By controlling the current, torque is applied to the rotor in a direction in which the speed approaches the standby speed set value, and the rotor speed is feedback-controlled to the standby speed.

Therefore, normally, the vehicle is made to stand by at the speed of the speed set value provided in the standby speed control means 16.

In this control, electric power is transmitted and received from the electric power system 1. However, the electric power is of course not large enough to cause fluctuations in the electric power system 1 but sufficiently small. Speed is moderately controlled.

[0036] Now, there rotational speed of the flywheel is in the standby speed, and rapid change occurred in the power system 1 at time t ₀ as shown in FIG. In this case, the load compensator 10 or the frequency compensator 11 described above operates, and the rotational speed of the flywheel greatly fluctuates in a short time with the standby speed as the initial speed. Here, F is the power system frequency, L is the power system load, R represents flywheel speed, P _f is the flywheel generator output, P is other generator output, R _w is waiting speed.

Then, the rotation speed of the flywheel drops to R _w0 (time t ₁ ), and the standby speed control means 16 receives power from another generator connected to the power system 1 and recovers to the standby speed. Is controlled by

Next, when the fluctuation of the power system 1 is very large, or after the first fluctuation occurs, a second power fluctuation in the same direction occurs before the rotation speed of the rotor returns to the standby speed. In such a case, the rotation speed may exceed the limit of the controllable speed of the exciting current control device 14 in some cases.

FIG. 3 shows such a case.
Here, the upper limit speed control means 17 and the lower limit speed control means 18
Are set slightly before the speed limit point that can be controlled by the exciting current control device 14. Now
Load variation at time t ₀ 1 time occurs, the second load change at the time t ₂ has occurred. Time t at the second load change
_{If the} flywheel rotation speed exceeds this set value at time ₃ (time point t3), a signal for returning the rotation speed proportional to the deviation is output from the lower limit speed control means 18 to the input / output limiter 13, and the input / output limiter 13 is set. The adder / subtractor 12 outputs the speed signal to the adder / subtractor 12.
To be selected in preference to the signal. As a result, the control of the excitation current control device 14 is switched from the power fluctuation suppression control to the speed control, and the control is performed so that the speed of the rotor remains at the lower limit value, so that the speed does not exceed the controllable limit point.

When the fluctuation of the power system 1 is eliminated, the rotation speed is gently controlled from the lower limit speed to the standby speed by the operation of the standby speed control means 16 described above (time point t ₄ ).

Although FIG. 3 illustrates the case of the lower limit speed, the same applies to the case of the upper limit speed.

As described above, the generator motor 3 can make the rotation of the flywheel stand by at the speed set by the standby speed control means 16 during the normal standby. Therefore, when the electric power system 1 fluctuates, immediately after the rotational energy of the flywheel is released to the electric power system 1 as electric power or is taken out and stored as rotational energy, the rotational speed largely deviates from the standby speed. When there is no longer, the rotation speed is controlled to the standby speed at a constant speed change rate by the operation of the standby speed control means 16. Therefore, even when the power system 1 fluctuates next, the rotation speed does not exceed the control range of the control device.

On the other hand, when the fluctuation of the power system 1 is very large, or when the fluctuation is repeated in a short time and the next power fluctuation occurs before returning to the standby speed, the rotation speed is reduced by the excitation current control device 14. It is possible to reach the speed control limit point. In this case, however, the system is controlled not to exceed the limit speed by the operation of the upper limit speed control means 17 or the lower limit speed control means 18, so that the control range is not exceeded and the system is stopped. You won't.

Here, the upper limit speed control means 17 and the lower limit speed control means 18 are composed of an upper limit speed over detector and a lower limit speed over detector. By setting the output of 13 to zero, the same effect as described above can be obtained.

That is, when the speed exceeds the upper and lower limit speeds, the secondary current Iq is set to zero, so that the torque by the exciting current applied to the rotor becomes zero, and the rotor does not accelerate or decelerate, and stays at the upper or lower limit speed. The reset is performed by detecting that the fluctuation of the power system 1 has stopped. That is, the load compensator 1
It is also possible to provide a detector for detecting that the output of the frequency compensator 11 becomes zero and zero, and use the output of the adder / subtractor 12 with the signal.

[0046]

As described above, according to the present invention, the flywheel power generation performs the stabilizing operation in response to the fluctuation of the electric power system. As a result, the flywheel rotation speed largely deviates from the standby speed. After that, it automatically returns to the original standby speed and can prepare for the next fluctuation. Further, even when the power fluctuation is large or when the power fluctuation occurs continuously for a short time, the flywheel power generation system can be continuously operated without deviating from the controllable speed range.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a characteristic diagram of the present invention when a power load change occurs once.

FIG. 3 is a characteristic diagram of the present invention when power load fluctuation occurs twice.

FIG. 4 is a configuration diagram showing a conventional example.

FIG. 5 is a characteristic diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power system 2 Main transformer 3 Generator motor (winding type induction motor) 4 Flywheel 5 Transformer for converter 6 Converter 7 Load detector 8 Frequency detector 9 Current detector 10 Load compensator 11 Frequency compensator 12 Adder / subtractor 13 I / O limiter 14 Excitation current controller 15 Speed detector 16 Standby speed control means 17 Upper limit speed control means 18 Lower limit speed control means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinobu Takeda 1 Toshiba-cho, Fuchu-shi, Tokyo Tokyo Inside the Toshiba Fuchu Plant (72) Inventor Hideyuki Nakano 1-Toshiba-cho, Fuchu-shi, Tokyo Toshiba Fuchu Plant (72) Inventor Yoichi Tone 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu Plant, Toshiba Corporation (56) References JP-A-58-24921 (JP, A) JP-A-61-128800 (JP, A)

Claims (1)

(57) [Claims] 1. A flywheel generator is formed by connecting a flywheel to a winding induction machine, wherein a primary winding of the winding type induction machine is connected to a (power) system, and a secondary winding is connected to a power converter. The variable speed control is performed by giving an exciting current determined by the rotation speed of the flywheel and the frequency of the system to the secondary winding,
Stabilizes the system by performing power absorption / release operations when the system power fluctuates
In a system stabilizing device using a flywheel generator , the rotation speed of the wound-type induction machine during system stabilization is desired.
The standby speed for controlling the exciting current of the secondary winding of the wound-type induction machine so that the rotational speed of the wound-type induction machine is compared with the standby-speed set value so that the standby speed becomes zero. Speed control means, and said flywheel power generation due to increase and decrease of grid power
During the power absorption operation of the machine, the winding type winding machine so that the rotation speed of the winding type induction machine does not exceed a predetermined upper limit speed set value .
An upper limit speed control means for controlling an exciting current of a secondary winding of the induction machine, and the flywheel power generation by reducing system power.
During the power discharge operation of the machine, the winding speed is controlled so that the rotational speed of the wound-type induction machine does not fall below a predetermined lower limit speed setting value .
Flywheel power generation having a lower limit speed control means for controlling an exciting current of a secondary winding of a linear induction machine.
System stabilization device using a machine .