JPS6051342B2 - Coil excitation power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an energy storage device using a (superconducting) coil, and more particularly to a coil for storing energy.

Conventionally, it was the first energy storage device using a coil.
A configuration as shown in the figure is known.

In the figure, 1 is a coil for storing energy, 2
1 is a thyristor conversion device for inputting and outputting energy to the coil 1, and is composed of thyristor arms 2a to 2f.
3 is a rectifier transformer, 4 is an AC power supply (system), 51, 5
2 is a switch.

The operation of the circuit shown in FIG. 1 will be explained with reference to FIG.

In the figure, (a) Ed is the DC side output voltage of the thyristor converter, (b) Id is the coil current, and (c) P is Ed×
Id) (d) W indicates the stored energy of the coil. Note that FIG. 2 shows a case where the thyristor conversion device is operated so that the output voltage is constant when energy is input and output. As shown in Figure 2, in order to operate with a constant DC voltage Ed, the ignition control angle of the thyristor converter can be kept constant if the overlap angle is ignored. From 2 to 2, the rectifier is operated (control angle α<90 degrees).

The coil current Id increases almost linearly as shown in FIG. During this time, energy is stored in the coil 1 using the power from the AC power supply 4. When the coil current reaches the required value after a certain period of time, the operation of the thyristor converter is stopped and the switch 5
1 and transfer the coil current there. For this purpose, for example, the series arms (2c and 2f, etc.) of the thyristor conversion device 2 may be operated in a bypass pair mode, and then the switch 51 may be closed. Time [Ding. The period from to to is the energy storage period. In order to eliminate energy loss during this time, it is preferable to use 1 as a superconducting coil and 51 as a superconducting switch. After some time, it becomes a period of energy release. At this time, the thyristor converter is operated as an inverter (control angle α>90 degrees). This releases the energy stored in the coil 1 to the AC system 4.
In this method, the control angle is kept almost constant at this time as well, and the DC voltage is kept constant. In this way, energy can be stored in the coil from the power of the AC power supply, and then the energy of the coil can be used to supply power to the AC system.

However, in this case, as shown in FIG. 2c, the DC power P (which is approximately equal to the power of the AC power source) changes significantly over time. That is, when storing energy, the electric power is initially small and gradually increases, and when releasing energy, the electric power is initially large and gradually decreases. Such characteristics are not preferable when the present energy storage is used as a countermeasure against peak loads in electric power systems. This method stores energy in a coil using surplus power at night and releases it during peak loads during the day, but it is preferable because the power input and output changes depending on the operating characteristics of the thyristor converter as shown in Figure 2c. do not have. As described above, this type of device has the disadvantage that power fluctuations are large when energy flows in and out.

As a countermeasure for this, the DC output voltage E of the thyristor converter is
There are things that change d.

However, when the coil current is small, this device operates by reducing the control angle and increasing the DC voltage Ed, so it has the disadvantage that the converter must have a large capacity that corresponds to the DC output voltage. . In addition, as the coil current increases, the control angle of the converter must be increased to decrease the DC output voltage and operate so that the power P remains almost constant. It consumes power and has disadvantages such as a decrease in AC power supply voltage and an increase in power supply voltage waveform distortion. An object of the present invention is to provide an energy storage system that has small fluctuations in power during energy inflow and energy release, does not require a large-capacity converter, and has low reactive power consumption.

The gist of the present invention is to configure a plurality of coils that store energy using the power of an AC power supply, and when the coil current is small in the early energy storage period and the energy release period, the plurality of coils are connected in parallel, and the coils are connected in parallel. By connecting multiple coils in series when the coil current is large in the early stage of discharge, a thyristor converter with excessive capacity is not required, and fluctuations in inflow and discharge power during operation are suppressed to a small level. The present invention will be explained in detail with reference to an embodiment shown in FIG.

In the figure, the same parts as in FIG. 1 are given the same reference numerals.
The features of Fig. 3 compared to Fig. 1 are that the energy storage coil is divided into two, 11 and 12, and the switch 6
8. Incidentally, the size of the coils 11 and 12 may be 1/2 of the size of the coil shown in FIG. Third
The operation of the circuit shown in the figure will be explained with reference to FIG.

In the figure, (a) Ed is the DC side output voltage of the thyristor converter, (b) is the load current, (C) IL is the current of each coil, (d) P is Ed×, and (e) W is the coil current. Indicates stored energy. The first half of the energy accumulation period (t1~
In T2), first close switches 6 and 7,
Switch 8 is open and connects the coils in parallel.

As a result, a load current of 112 flows through the coil. During this period, the coil current is still small. At time T5 when the coil current reaches 1 to 2 of the load current rating, the coil connection is switched from parallel to series. That is, switch 8 is closed and switches 6 and 7 are opened. This switching is done by switch 51.
This can also be done by closing 52 and opening 52 to briefly disconnect the thyristor converter from the coil. In the latter half of the energy storage period T5 to T2, the magnitudes of the load current and coil current become equal because the coils 11 and 12 are connected in series.

When such an operation is performed, the electric power P becomes as shown in FIG. 4d, which is considerably averaged compared to the case shown in FIG. 1, and has favorable characteristics for the power supply system. Next, when energy is to be released, operation will be carried out using the same concept. That is, in the first half T3 to T6 of the energy release period, the coil 1
1 and 12 are connected in series, and in the second half, coil 11
and 12 are connected in parallel and operated. This results in averaging of the emitted power, similar to the energy storage period. As described above, according to the present invention, the electric power when energy flows into and discharges from the coil is averaged, and characteristics favorable to the power supply system can be achieved. Furthermore, according to this system, if the output voltage of the converter is made the same as in FIG. 1, the storage time can be shortened, and if the storage time is the same, the capacity of the converter can be reduced. This point will be further explained using an example. 10,000 as an energy storage system
Let's take up a case where MWH energy is stored in 1011 temples and released after a while in ■ time. In the conventional system shown in Figure 1, the power changes linearly, so the initial power is 2000 MW at the end of 01, and the average power is 1000 MW, which means that energy is stored for an hour or so. Capacity is required. On the other hand, according to the method of the present invention,
Assuming that the capacity of the converter is 2000 MW, which is the same as described above, the current increases at a fourfold slope during the early energy accumulation period t1 to T5, and the current increases again from the load current of 1 hour during the latter period ζ to T2. Therefore, according to the method of the present invention, 10
The energy of 000r14WH is 7. This means that the storage time can be shortened.

Furthermore, if the storage time is set to one cycle, the capacity of the converter can be 75% of that of the conventional system. By increasing the number of coils that store energy, the power can be further averaged, and by keeping the storage time constant, the capacity of the converter can be reduced.

[Brief explanation of drawings]

Fig. 1 is a drawing showing a conventional example, Fig. 2 is a drawing for explaining the operation of Fig. 1, Fig. 3 is a drawing showing an embodiment of the present invention, and Fig. 4 is a drawing for explaining the operation of Fig. 3. This is a drawing for

Claims (1)

[Claims] 1. An energy storage system consisting of an energy storage coil and a thyristor conversion device that inputs and outputs power from an AC power supply to the coil. It is composed of a plurality of energy storage coils and is operated by changing the connection of the coils in series or parallel. A coil excitation power supply characterized in that the plurality of coils are connected in parallel during the first half of energy accumulation and the second half of energy release, and the plurality of coils are connected in series during the second half of energy accumulation and the first half of energy release. Device.