JPH0813173B2 - Energy storage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention converts surplus electric power of a train line into kinetic energy and stores the electric energy in a flywheel. The present invention relates to an energy storage device that reconverts the generated kinetic energy into electric energy and emits the electric energy to compensate for the power shortage of the electric power line.

[Prior Art] Conventionally, as an apparatus of this type, there is one described in JP-A-59-194643.

FIG. 3 is a circuit diagram showing a conventional device of this type.

In the figure, 1 is a DC feeding circuit (hereinafter referred to as a power line), 2 is a ground wire, 3 is a switch, 4 is a DC reactor,
Reference numeral 5 is a capacitor, 6 is a main circuit of the power converter (hereinafter, simply referred to as power converter), 7 is a three-phase induction machine, and 8 is a flywheel connected to this induction machine 7. Power converter 6
Is a rectangular wave inverter formed by connecting a semiconductor switching element, in this example, a gate turn-off thyristor (GTO) 12 to 17 in a 6-phase bridge, and diodes 18 to 23 are connected in antiparallel to the GTOs 12 to 17, respectively. 24 is a direct current detector and 25 is a direct current voltage detector, and the outputs of both detectors are led to a multiplier 26. 27 is a stored power reference value setting device, 28 is a discharge power reference value setting device that outputs a signal of a polarity different from that of the stored power reference value setting device 27, and outputs of both setting devices are
Power is supplied to the power controller 31 through the switches 29 and 30, respectively, and the power controller 31 requests the slip frequency Δ of the induction machine 7.
f is generated by calculation. 32 is a speed detector,
A frequency signal f _{0 obtained} by subtracting the slip frequency of the induction machine 7 from the output frequency of the power converter 6 based on the rotation speed of the induction machine 7.
(Hereinafter, referred to as rotation frequency f ₀ ) is detected. Reference numeral 33 is a frequency controller, to which the outputs of the power controller 31 and the speed detector 32 are introduced. Reference numeral 34 denotes an oscillator, which supplies a control signal corresponding to the frequency command signal f _S sent by the frequency controller 33 to the gate pulse generator 35. 26 to 35 form a control circuit of the power converter 6.

 Next, the operation of this device will be described.

When there is a surplus in regenerative electric power from a vehicle that is performing regenerative braking, or when the number of powering vehicles is small and there is leeway in train line power, these surplus power is supplied from the train line 1 to the DC reactor 4 and the capacitor 5. Through the smoothing circuit, the power converter 6 converts the AC power into AC power and supplies the AC power to the induction machine 7 to operate the induction machine 7 (power running operation).

At the time of this energy storage, the switch 29 is closed by a controller (not shown), and the output P ^{* of the} stored power reference value setter 27 and the output P of the multiplier 26 (actual converted power of the power converter 6) The power controller 31 calculates and generates the required slip frequency Δf (here Δf> 0) of the induction machine 7.
Slip frequency Δf and rotation frequency f ₀ required by the frequency controller 33
And are added, and the GTOs 12 to 17 of the power converter 6 are switching-controlled according to the operation frequency f _S that is the addition result to convert the electric power P from the power line 1 into kinetic energy via the induction machine 7 and flywheel 8 Store in.

 FIG. 4 (A) shows an operation waveform during energy storage.

In the figure, (a) is an output waveform of the power converter 6,
(B) is the current of the induction machine 7, (c) is the current flowing through the GTOs 12 to 17, (d) is the current flowing through the diodes 18 to 23, and φ is the phase angle.

On the other hand, when there are many power-running vehicles and a large amount of electric power is required for the train line 1 such as during a rush hour, the kinetic energy stored in the flywheel is released by the induction machine 7 as a generator operation, and the power converter 6 is operated. The DC voltage is converted to DC power and sent to the train line 1 to compensate for the voltage drop on the train line.

At the time of this energy release, the switch 30 is closed by a controller (not shown), and the power controller 31 outputs the output P ^{** of the} release power reference value setter 28 (where | P ^** |> | P ^* ｜
, And the output of the multiplier 26 (actual converted power of the power converter 6) P, the required slip frequency Δf (where Δf> 0) of the induction machine 7 is calculated and generated. The frequency controller 33 determines the rotation frequency f ₀ of the induction machine 7 and the required slip frequency Δf.
In addition to generating the operating frequency f _S, in accordance with the operating frequency f _S, controls the GTO12~17 of the power converter 6. Then, the induction machine 7 is operated as a generator, the kinetic energy stored in the flywheel 8 is exchanged to AC power, and further converted to DC power via the power converter 6 and released to the train line 1.

 FIG. 4 (B) shows an operation waveform when energy is released.

In the figure, (a) is a generated voltage of the induction machine 7, (b) is a generated current of the induction machine 7, (c) is a current flowing through the GTO 12 to 17, and (d) is a current flowing through the diodes 18 to 23. is there.

[Problems to be Solved by the Invention] By the way, the DC voltage E _d of the train line 1 normally fluctuates in the range of 900 to 1800 V in a train line having a nominal DC voltage of 1500 V, for example. On the other hand, the frequency of the AC power supplied to the induction machine 7 needs to be changed according to the rotational speed of the flywheel 8 that changes with absorption or release of kinetic energy of the flywheel 8.

The electrical angular velocity of the induction machine 7 is ω _m , the slip angular velocity ω
_S (here, ω _S > 0), the angular frequency ω ₀ of the AC power supplied to the induction machine 7 is ω ₀ = ω _m ± ω
_S (however, the + sign is when the flywheel 8 stores kinetic energy, and the − sign is when discharging).

Now, the energy used by this energy storage device is 25kW
Assuming that h is h, the rotating part GD ² of this device is 14300 kg-m ² , and the upper limit rotation speed is 3000 rpm, the change range of the rotation speed is 2100 to 3000 r.
pm. Further, when the number of poles of the induction machine 7 is set to 2 and the slip speed which is several percent or less of the synchronous speed is ignored, the range of the AC input frequency of the induction machine 7 is 35 to 50 Hz. The magnitude of the fundamental wave of the AC voltage supplied from the power converter 6 which is a rectangular wave inverter to the induction machine 7 is √6 × E _d / π when the input DC voltage of the power converter 6 is E _d , It is proportional to the magnitude of the voltage E _d . Therefore, in the case of a device that stores and releases energy from a train line with a nominal voltage of 1500 V DC, the induction machine 7 has an input DC voltage range of the power converter 6 of 900 to 1800.
The V and AC sides must use a structure that produces a specified output over the frequency range of 35 to 50 Hz. For this purpose, it should be a low impedance machine that does not magnetically saturate at 1403V (√6 × 1800 / π), 35Hz, and can obtain a predetermined output even at 701V (√6 × 900 / π), 50Hz field weakening. It is necessary to provide an induction machine with a large volume per unit output, which may lead to unrealistic design specifications.

The present invention has been made to solve the above-mentioned problems in the conventional energy storage device, and copes with a large fluctuation of the input DC voltage even when a general-purpose induction machine is used in combination with a flywheel. It is an object of the present invention to provide an energy storage device that can be manufactured at a low cost as compared with the related art.

[Means for Solving the Problem] In order to achieve the above-mentioned object, the present invention operates a power conversion circuit such that the AC voltage on the output side is always constant even if the DC voltage on the input side fluctuates. It is configured to be performed.

[Operation] In the present invention, even if the DC voltage on the input side fluctuates, the AC voltage on the output side of the power conversion circuit operates so that it is always constant. Therefore, even if the DC voltage on the input side fluctuates significantly, The AC voltage applied to the induction machine is always constant.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an energy storage device according to the present invention.

In the figure, 1 to 35 are the same constituent elements as in FIG. 3 described as a conventional apparatus. A fourth quadrant chopper 100 is inserted between the power converter 6 and the smoothing circuit including the DC reactor 4 and the capacitor 5. The 4-quadrant chopper 100 consists of a GTO 101 and a diode 11 connected in anti-parallel to the GTO 101.
1, GTO102 and diode 112, GTO1 connected in anti-parallel to it
03 and the diode 113 antiparallel connected thereto, GTO104 and the diode 114 antiparallel connected thereto, having a smoothing reactor 200 inserted between the connection point of GTO101 and 102 and the connection point of GTO103 and 104, and GTO101 and The series circuit of 102 is capacitor 5
, And the series circuit of the GTO 103 and 104 is connected between the DC side terminals of the power converter 6. Reference numeral 121 denotes a filter capacitor inserted between the DC side terminals of the power converter 6, and a voltage detector 251 for detecting the DC input voltage V _d of the power converter 6 is connected in parallel with the capacitor 121. 2
_{Reference numeral} 41 denotes a current detector, which detects a direct current I _din (an input current of the power converter 6) flowing through the direct current circuit of the power converter 6. 331 is a voltage reference controller and 341 is a current controller. This current controller 341 generates a current control command signal from the output of the voltage reference controller 331 and the DC current detected by the current detector 24. The voltage reference controller 331 generates the deviation between the reference value (input reference voltage) V _d ^{* of the} voltage applied between the DC side terminals of the power converter 6 and the current control command signal. The voltage controller 351 compares the output of the current controller 341 with the voltage (input voltage) V _d between the DC side terminals of the power converter 6 detected by the voltage detector 251, and the voltage V _d is the input reference voltage V. _A gate control signal is generated so as to match _d ^* and is supplied to the gate controller 361. The gate controller 361 sends out a gate pulse having a pulse width corresponding to the magnitude of the gate control signal. This gate pulse is supplied to the GTOs 101 to 104 designated by the quadrant switch 371.

In this embodiment, the stored / released power reference value is generated by the electric line current reference generator 321 and the multiplier 261. The electric line current reference generator 321 uses the voltage detection value E _d of the voltage detector 25.
The compared to the catenary voltage reference value E _d ^* for generating a current reference value I _d ^*. The current reference value I _d ^* is multiplied by the voltage detection value E _d in the multiplier 261. The output of the multiplier 26E is the stored / released power reference value P ^* and is compared with the converted power P of the power converter 6 which is the output of the multiplier 26 in the power controller 31. 311 is a speed limiting element, which _{corrects the} current reference value I _d ^* so that the rotation frequency f _{0 of the} flywheel 8 does not _{exceed the} limiting frequency f _0MAX .

 Next, the operation of the apparatus of this embodiment will be described.

FIG. 2 shows an example of the operating characteristics of this device. When the electric line voltage E _d is 1500 V or more, the electric lines 1 to 8 are used.
Flywheel 8 by taking in current I _d with a limit of 00A
When the kinetic energy is stored in and drops below 1500V, the current is discharged to the train line with a limit of 2000A.

At the time of energy storage, the power converter 6 converts the DC input (input voltage V _d ) taken in through the four-quadrant chopper 100 into AC power and supplies the AC power to the induction machine 7, and the induction machine 7 is operated in a power running mode. . At the time of this energy storage, the slip frequency Δf required for the induction machine 7 is calculated and generated by the power controller 31 from the output P ^* of the multiplier 261 and the output P of the multiplier 26 (actual converted power of the power converter 6). As in the conventional case, the addition frequency
According to f _S = f ₀ + Δf, the GTOs 12 to 17 of the power converter 6 are switching-controlled, and the flywheel 8 is passed through the induction machine 7.
The kinetic energy corresponding to the electric power P is stored in the train line 1.

Further, when the energy is released, the kinetic energy stored in the flywheel 8 is converted into AC power by the induction machine 7 in the same manner as in the conventional case, and is further converted into DC power by the power converter 6 to be converted into four quadrants. It is sent to the electric line 1 via the chopper 100 to compensate for the voltage drop of the electric line 1.

Next, the operation of the 4-quadrant chopper 100 will be described.

Now, assume that the flywheel 8 is in the energy storage mode in which energy is absorbed from the trolley wire 1. At this time, if E _d ≧ V _d ^* , then the four-quadrant chopper 100 is the GTO 101 chopper-driven and the diode 112 is It becomes a power running step-down chopper that performs a flywheel operation, and steps down the input voltage V _d of the power converter 6 to the input reference voltage V _d ^* . On the contrary, when E _d > V _d ^* , the GTO 101 is turned on, the GTO 104 is driven by the chopper, and the diode 113 becomes the power running boost chopper that performs the series diode operation.

Further, when the flywheel 8 is in the discharge mode in which energy is released to the trolley wire 1, if E _d ≧ V _d ^* , the 4-quadrant chopper 100 turns on the GTO103, drives the GTO102 on the chopper, and drives the diode 111. It is a regenerative boost chopper that operates in series with a diode. Conversely, if E _d <V _d ^* , then GTO10
3 is driven by a chopper, and the diode 114 serves as a regenerative step-down chopper that performs a flywheel operation.

The quadrant switching of the four-quadrant chopper 100, that is, the switching between the power running step-down operation, the power running step-up operation, the regenerative step-down operation, and the regenerative step-up operation, is performed based on the electric line voltage E _d , the input reference voltage V _d ^*, and the operation characteristics shown in FIG. The changer 371 makes a judgment.

As described above, in the present embodiment, the four-quadrant chopper 100 is provided in the preceding stage of the power converter 6 that drives the induction machine 7 when the train line power has a surplus and drives the induction machine 7 when the power is insufficient. Since it is provided, even if the train line voltage E _d fluctuates during power running, or the train line voltage E _d fluctuates during regenerative driving, the voltage between the DC terminals of the power converter 6 becomes the reference voltage value V _d ^* . Can be maintained. For this reason, the magnitude of the fundamental wave of the AC voltage applied from the power converter 6 which is a rectangular wave inverter to the induction machine 7 is always constant, and the induction machine 7 is always constant even if the train line voltage changes. It will be driven with a constant AC voltage.

[Effects of the Invention] As described above, since the AC voltage applied to the induction machine does not change even if the voltage of the DC power supply fluctuates significantly, the induction machine having a special rating and a special structure is used. Since the one having the normal rating and structure can be used without using it, the energy storage device can be realized at a lower cost than the conventional one.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a characteristic curve diagram showing one example of the operating characteristics of the above embodiment, FIG. 3 is a circuit diagram showing a conventional energy storage device, and FIG. The figure is a waveform diagram of each part in the above conventional example. In the figure, 1 ... train line, 6 ... power converter, 7 ...
Induction machine, 8 ... flywheel, 100 ... 4-quadrant chopper. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A power conversion circuit having a direct current side connected to a direct current power source, an induction machine connected to the alternating current side of the power conversion circuit, and a flywheel connected to the induction machine, and the power conversion circuit at the time of energy storage. The DC power is converted into AC power by AC power supply to the induction machine to drive the flywheel by operating the motor to store kinetic energy in the flywheel, and when the energy is released, the flywheel is stored. In the energy storage device that drives the induction machine with the kinetic energy and operates the generator to supply AC power to the power conversion circuit, convert the AC power into DC power, and supply the DC power to the DC power supply, the power conversion circuit Is a four-quadrant chopper that performs a step-up chopper operation and a step-down chopper operation and outputs a constant DC voltage, and the output of the four-quadrant chopper is an alternating current. An energy storage device comprising a rectangular wave inverter for converting into electric power.