JPS6034337B2 - energy storage system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an energy storage system that stores energy in a flywheel and returns it to a power system as electrical energy when necessary.

If energy supply becomes dependent on nuclear energy, the method of delivering that energy to consumers will increasingly be in the form of electrical energy. This means that consumers must install power transmission lines that can continuously transmit energy even when large machines are operated for short periods of time. Therefore, for customers who operate large machines for short periods of time, such as huge civil engineering machines, there is a need for a system that stores energy during idle periods and supplies it all at once when the machine is in use. The flywheel method has long been used as an energy storage method, but most of the methods involved inputting electrical energy and outputting mechanical energy. If this were to be a method for inputting electrical energy and outputting electrical energy, it would have the greatest degree of freedom and could be used widely. The amount of energy stored by the flywheel is proportional to the square of the speed, so the faster the speed, the more advantageous it is. In addition, if an AC motor is used as the rotating machine, it will be possible to connect directly to the current power transmission system. By using an induction motor, it is possible to supply alternating current electrical energy that is always synchronized with the mains frequency. Based on the above, the supersynchronous Servius device is optimal for a flywheel-based energy storage system in terms of reliability, cost, and control performance.

As shown in FIG. 1, the supersynchronous Servius device is constructed by connecting a wound induction motor 1, a cycloconverter 2, and a transformer 3 to a power source.

The cycloconverter is constructed by connecting 18 thyristors 2' and a DC reactor 4 as shown in FIG. The cycloconverter 2 can arbitrarily flow current in the direction of generating driving torque and the direction of generating braking torque with respect to the magnetic flux relative to the secondary conductor of the wound induction motor 1.

When the supersynchronous Servian device is generating driving torque, energy is supplied from the power line and the motor rotor is accelerated; when it is generating braking torque, energy is supplied to the power line and the rotor is decelerated. It will be done.
If the flywheel 41 is connected to this electric motor rotor, a large amount of energy can be input and output. The advantages of applying a supersynchronous Servian device to a flywheel energy storage system are as follows: 01: High rotational speed and large amount of energy storage.

■ It is possible to always synchronize with the power supply, and energy can be supplied in synchronization with the power supply frequency.

{3' The converter capacity may be equivalent to the speed fluctuation of the rotating machine,
The price of the equipment is low.

The present invention connects a flywheel to the drive shaft of an induction motor, and stores and discharges its rotational energy using super-synchronous Serbius control of the induction motor, thereby shortening huge machines with energy supplied by a weak power transmission system. It is an object of the present invention to provide an energy storage system that can be used for hours without affecting the power supply.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a system diagram of the energy compensator of the present invention.
A supersynchronous Servius device 5, a load 6, and a power factor compensation circuit 7 are connected in parallel to the power supply line.

A current and voltage detection circuit is connected to the power source side of these devices 5, 6, and 7. Current signals for each phase are obtained from the current transformer 8, auxiliary current transformer 9, and resistor 101. A voltage signal for each phase is obtained by a transformer 11. Multiplier 1
2 to create voltages and currents for each phase, and an operational amplifier 14 to create the sum of the three phases. 13 and 15 are resistors for calculation, 16
is a capacitor for ripple removal.

When the output signal of the operational amplifier 14 is negative, it indicates that energy is being input from the power supply, and when it is positive, it indicates that energy is being returned to the power supply. FIG. 4 shows an automatic control circuit according to the present invention.

Reference numeral 17 denotes a variable resistor for setting a speed reference, and this speed reference is input to the next-stage control circuit via a contact 18 that closes during driving.

Reference numeral 19 is a contact that closes during braking, and inputs a minimum speed or zero speed reference to the automatic control circuit.

22 is an operational amplifier for speed control, and the speed reference is resistor 2.
0 and speed feedback is input through resistor 21
input through.

When the device is in the driving state, the resistors include resistors 20 and 21.
The algebraic sum of the signals input through is amplified in relation to the operational impedance 33, and becomes the input to the next stage, that is, the current reference. When the device is in a braking state, the algebraic sum of the signals input through the resistors 20 and 21 becomes the operational impedance 3.
However, if the energy supplied from the supersynchronous Servius device 5 becomes excessive and is returned to the power supply side, it is amplified in relation to 3 and becomes the input of the next stage, that is, the current reference. The final output of the current and voltage detection circuit becomes positive, and this signal is input to the diode 27 in FIG. The output or current reference of operational amplifier 22 is lowered to avoid oversupplying energy. 25 is a current control operational amplifier, a current reference is inputted through a resistor 23, and a current feedback is inputted through a resistor 24.

The algebraic sum of the signals input through the resistors 23 and 24 is amplified in relation to the operational impedance 34, and the output becomes the input to the phase control circuit 26. The phase control circuit 26 controls the thyristor 2 making up the cycloconverter 2. FIG. 5 shows waveforms of various parts when the energy compensator of the present invention is operated.

35 is a signal indicating load operation, 36 is a waveform indicating the regeneration and driving state of the super synchronous Servius device, 37 is a waveform indicating a speed change of the super synchronous Servius device, 38 is a signal indicating the speed of the load, 39 is input to the load It is a signal indicating whether the four-way super-synchronous Cerbius device is in drive operation or control operation.

Next, the operation of the above system will be explained.

Flywheel 4 for storing energy in the motor rotor
The super-synchronized Servius device 5 connected with 1 is accelerated to a constant speed and rotated in advance. If a load operation signal as shown at 35 is issued at time t, the supersynchronous Serbius device 5 enters braking operation as shown at 40 (contact 18 is open and contact 19 is closed in FIG. 4). As a result, the supersynchronous Servius device 5 enters regenerative operation as shown at 36, and its speed decreases as shown at 37. The load speed increases as 38 and the load power also increases as 39. Assuming that the load 6 is decelerated at t2, the supersynchronous Serbius device 5 remains in the braking mode as shown at 40 and enters a no-load operating state as shown at 36. The speed remains constant like 37. The load speed decreases as at 38 and the load power becomes negative as at 39. When the load 6 accelerates again at t3, the state is the same as from t. Further, when the load 6 decelerates at t4, the state becomes the same as from t2. When the load 6 stops at step 5 and a load stop signal is issued as shown at 35,
The super-synchronized Servius device 5 is in the driving operation mode as shown in 40'
(18 closed and 19 open in Figure 4). As a result, the super-synchronous Servius device 5 enters the driving operation as shown in 36.
The speed increases as 37. When the speed reaches the set speed at t6, a no-load operation state occurs as shown in 36, and the speed becomes constant. Energy can be stored and released any number of times in the above cycle, but if more energy is released than the speed change width and the speed drops too much, protective action such as stopping load operation is required. It is.

In the device of the above embodiment, in addition to the current limiting circuit for preventing excessive energy supply to the operational amplifier 22 shown in FIG. It is possible.

In addition, cycloconverter 2 using 18 thyristor elements
Alternatively, a sine wave cycloconverter using three parallel Gretz circuits and a total of three elements may be used. In addition, assuming that the lightning voltage withstand capacity of the thyristor element 2' of the cycloconverter 2 corresponds only to the fluctuation width of the synchronous speed, the energy input, and the output cycle, the induction motor 1 accelerates by starting with the secondary resistance, and reaches an acceleration near the synchronous speed. It is also possible to switch to synchronous Servius operation. Furthermore, when the energy regeneration of the load 6 is large, the supersynchronous Servian device 5 can be switched from regeneration to driving by detecting the energy regeneration of the load 6. Furthermore, as a converter, it is also possible to use a so-called DC type converter type supersynchronous Servius device in which a motor-side Gretz circuit having a forced commutation circuit and a Gretz circuit for supply voltage commutation are coupled on the DC side. In the above embodiment, the super-synchronous Servius device 5 is set in braking mode to release energy in synchronization with a load operation signal, and the super-synchronous Servius device 5 is set in drive mode in synchronization with a load operation stop signal to store energy. The energy storage and release of the flywheel 41 is controlled by the following, but when the grid voltage drops, the super-synchronous Servius device 5 is set in braking mode to release energy, and when the grid voltage rises, it is set to drive mode and energy is stored. The same effect can be obtained.

FIG. 6 shows the automatic control circuit in this case. 45 is a variable resistor for setting a voltage reference, and the voltage reference is inputted to the voltage control operational amplifier 44 through the resistor 43.

The voltage standard should be set slightly lower than the rated power supply voltage. Voltage feedback feeds back the power supply voltage and inputs it to the operational amplifier 44 through the resistor 45. The algebraic sum of the voltage reference and voltage feedback is the operational impedance 4
6, and becomes the input for the next stage, that is, the speed reference. The maximum speed is limited by a block diode 47 or equivalent circuit. 48 is an operational amplifier for speed control;
The speed reference is input through resistor 49.

Velocity feedback is input through resistor 50.
The algebraic sum of the speed reference and the speed feedback is amplified by the relationship of the calculation impedance 51, and becomes the input to the next stage, that is, the current reference. The maximum current is limited by a Zener diode 52 or equivalent circuit. 53 is a current control operational amplifier, and a current reference is inputted through a resistor 54.

Current feedback is input through resistor 55.
The algebraic sum of the current reference and current feedback is amplified by the relationship between the operational impedance 56 and the next stage phase control circuit 5.
7 input. The phase control circuit 57 controls the thyristor 2' making up the cycloconverter 2. FIG. 7 shows the sequence of operation of the energy compensator of this embodiment.

When the load connected to the same power supply line in parallel with this compensator is not operating, the power supply voltage is high and the voltage reference is high, so the output of the operational amplifier 44 in FIG. Synchronous Servius devices have been accelerated to this speed. When load operation is started in Fig. 7 58, if the load drive state is as shown in 59, the line voltage drops as shown in 60,
The voltage feedback in FIG. 6 becomes small, the output of the operational amplifier 44 becomes a negative speed reference, and the supersynchronous Servius device 5 enters the braking mode as shown in FIG. 762.

On the other hand, if the load is in the braking state as shown in FIG. 7 63, the line voltage will rise somewhat as shown in 64, and the supersynchronous Servian device 5 will remain in the driving state as shown in 65. 7th
When the load is stopped in FIG. 66, the line voltage increases, the output of the operational amplifier 44 in FIG. 6 becomes a positive speed reference, and the supersynchronous Servius device 5 enters the drive mode. FIG. 8 shows waveforms of various parts when the compensator of this embodiment is operated.

68 is a signal indicating load operation, 69 is a waveform indicating the regeneration and driving state of the super synchronous Servius device, 20 is a waveform indicating a speed change of the super synchronous Servius device, 71 is a signal indicating the speed of the load, 72 is input to the load This is a waveform showing the power generated.

Next, the operation will be described. The supersynchronous Servius device 5, which is connected to the rotor of the electric motor 1 and the flywheel 41 for storing energy, is accelerated to a constant speed and rotated in advance. t. When the load operation is started as shown in 68, the line voltage decreases, so the output of the operational amplifier 44 in FIG. go. The load speed increases as 71 and the load power increases as 72. When the iron load is braked, the load power becomes negative as shown in 72, the load speed decreases as shown in 71, and the super synchronous Serbius device 5
becomes the drive mode as shown in 69, and the speed increases again as shown in 70. When the load returns to driving operation at t3, the state is the same as from t. L' Trowel load becomes a braking motion additive.
It will be in the same state as before. When the W iron load stops operating as shown in 68, the super-synchronous Servius device 5 is accelerated as shown in 70, and when it reaches the speed equivalent to the output of the operational amplifier 44 in FIG. 6 at t6, it is no longer loaded as shown in FIG. It becomes driving. Energy can be stored and released as many times as necessary through the above cycle, but if the amount of energy released is greater than the speed change width and the speed drops too much, protective actions such as stopping load operation may be taken. is necessary.

In this embodiment, a supersynchronous Servius device using a sinusoidal cycloconverter capable of obtaining a sinusoidal current as a converter can be used.

It is also possible to use a so-called DC type converter-type super synchronous Serbius device in which a motor-side Gretsch circuit having a forced commutation circuit and a Gretsch circuit for supply voltage commutation are coupled on the DC side as a converter. Further, a circuit that limits not only the maximum speed but also the minimum speed can be added to the Jenner diode 47 shown in FIG. In addition, the voltage withstand capacity of the thyristor element 21 of the cycloconverter 2 can be adjusted above and below the synchronous speed.
Assuming that this corresponds only to the fluctuation width of the energy input and output cycles, the induction motor can accelerate with secondary resistance starting and switch to supersynchronous Servian operation near the synchronous speed. According to the present invention described above, an effective energy storage system can be provided when a huge machine is used for a short time while being supplied with energy by a weak power transmission system.

Furthermore, if connected to the general power transmission system, surplus power will be accumulated and
It can be released when needed.

[Brief explanation of the drawing]

Figure 1 is a single-line system diagram of the super-synchronous Serbius device, Figure 2 is a detailed diagram of the cycloconverter of the super-synchronous Serbius device,
Fig. 3 is a system diagram of an energy compensator according to an embodiment of the present invention, Fig. 4 is an automatic control circuit diagram of the energy compensator showing the control circuit of the embodiment, and Fig. 5 shows various parts when the embodiment is operated. Waveform diagram, Fig. 6 is an energy compensator automatic control circuit diagram showing the control circuit of another embodiment, and Figs. 7 and 8 are the energy compensator operation sequence of this embodiment and waveforms of various parts when the device is operated. It is a diagram. 1. ．． ．． ．． ．． ．． Wound induction motor, 2...Cycloconverter, 3...Transformer, 5...Supersynchronous Servius device, 6...Load, 7...・
Power factor compensation circuit, 8...Current transformer, 9...
Auxiliary current transformer, 11...Transformer, I2...
- Multiplier, 14... Operational amplifier, 41...
Flywheel. Figure 1 Figure 4 Figure 7 Figure 3 Figure 6 Figure 2 Figure 5 Figure 8

Claims (1)

[Scope of Claims] 1. A flywheel is coupled to the drive shaft of the induction motor, and a supersynchronous Servius control device generates a driving torque direction and a braking torque with respect to the magnetic flux relative to the secondary conductor of the induction motor. In an energy storage system in which the flywheel is subjected to super-synchronous Servius control so that the current can flow in any direction, and the rotational energy of the flywheel is stored and released via the super-synchronous Servius control device, the drive signal of the load is When the power supply voltage drops synchronously or when the power supply voltage drops, the super synchronous Servius control device is set in braking mode to release energy, and when the power supply voltage rises or in synchronization with the operation stop signal of the load, the An energy storage system that stores energy using a synchronous Servius control device as the drive mode. 2. A flywheel is coupled to the drive shaft of the induction motor, and a supersynchronous Servius controller is used to arbitrarily apply current in the direction of generating driving torque and the direction of generating braking torque with respect to the magnetic flux relative to the secondary conductor of the induction motor. In the energy storage system, the super-synchronous Servian control device performs super-synchronous Servian control so that the flywheel can flow, and the storage and release of rotational energy of the flywheel is performed via the super-synchronous Servian controller. An energy storage system that checks energy regeneration on the power source side so as not to release more energy than the power source, and uses the signal to lower the current limit value of the supersynchronous Cerbius control device.