High-voltage power supply system for compressor energy storage

Abstract

The utility model belongs to the technical field of linkage control, and particularly discloses a high-voltage power supply system for compressor energy storage. According to the invention, through the matched use of fixed-frequency and variable-frequency adjustment of the compressor, the matching degree between the continuously changing pressure of the natural gas storage container (such as rock caves) and the fixedly configured compressor is improved, the starting and stopping times of the compressor are reduced, meanwhile, the bandwidth of the system for maintaining the air pressure is reduced, and the energy-saving property, the safety and the economical efficiency are considered; the main circuit breaker adopts a phase-controlled excitation inrush current suppressor for phase selection connection, so that the impact of excitation inrush current of a compressor transformer on a power grid can be suppressed; a secondary side transformer of a rectifier transformer in the frequency converter is connected with the magnetizing frequency converter, and the actual impact current of the frequency converter is smaller than the rated current through a pre-magnetizing mode, so that the expensive frequency converter is protected. The utility model is suitable for a 300MW compressed air energy storage power station.

Description

Technical Field

[0001] The utility model belongs to the technical field of linkage control and specifically discloses a high-voltage power supply system for compressor energy storage. Background Art

[0002] In order to make the most effective use of power generation resources, when the electricity load of downstream users is less than the economic output of the current power grid, a compressor is used to convert excess electricity into air energy for storage. When the electricity load of downstream users is greater than the economic output of the current power grid, air energy is used to drive the generator to generate electricity to supplement the downstream load gap. Because air energy is a clean energy source, and the energy release time of the compressed air energy storage power station is more than hours, the power level is hundreds of megawatts, and the regulation capacity is minutes, this energy storage application based on the idea of ​​peak shaving and valley filling has been widely promoted. However, since the regulation system of ordinary fixed-frequency compressors is load / unload regulation, for example, loading when the air pressure is 8MPa and unloading when 9MPa, the unloading valve opens when the pressure in the compression main engine cavity reaches 9MPa, and the compressed air is released. Those skilled in the art want to reduce this loss by reducing the bandwidth of the released air pressure. Since the pressure of natural gas storage containers (such as caves) is volatile and has an upper limit requirement, this way of reducing the air pressure bandwidth greatly increases the frequency of loading and unloading, and the frequent startup of the compressor causes an impact on the power grid at each moment. If all compressors use variable frequency regulation system, the number of compressor starts and stops will be greatly reduced. However, high-voltage inverters are expensive and energy-consuming. The inrush current at startup will also cause impact on the inverter (and for the inverter, as long as it is higher than the rated current, it will cause impact on the inverter, and it is difficult to ensure that the inrush current peak is within 2 times the rated current through a general phase-controlled excitation inrush current suppressor), resulting in poor safety and economy.

[0003] Therefore, how to balance energy saving, safety, and economy, and design a power supply system that suppresses the magnetic surge current of a compressed air energy storage power station in combination with the wiring method and operation characteristics of a 300MW compressed air energy storage power station, and reduce the impact of instantaneous surge current on the system and equipment is an urgent problem to be solved by technical personnel in this field. Utility Model Content

[0004] In order to solve the technical problems listed in the background technology, the utility model provides a high-voltage power supply system for compressor energy storage. The specific technical scheme is as follows: it includes a power circuit and a control circuit, the power circuit includes a 220kV compressor power supply branch line, a main circuit breaker, a compressor transformer, and multiple sub-circuit breakers that are electrically connected in sequence; the 220kV compressor power supply branch line is connected to the power grid, and each of the sub-circuit breakers is electrically connected to the compressor through a bypass containing a frequency converter in addition to being electrically connected to the compressor; the control circuit includes a phase-controlled excitation inrush current suppressor electrically connected to the main circuit breaker and a pre-magnetic cabinet electrically connected to the secondary side of the rectifier transformer in the frequency converter.

[0005] The above structure effectively suppresses the impact of the overall load on the power grid and the inverter during the startup process through the phase-controlled excitation inrush current suppressor and the pre-magnetic cabinet electrically connected to the secondary side of the rectifier transformer in the inverter.

[0006] Preferably, the secondary side of the compressor transformer is 10kV, the output end of each branch circuit breaker is electrically connected to the downstream load through the 10kV bus, and branch circuit breakers are provided between the 10kV bus and the downstream load and between the inverter and the compressor.

[0007] This structure allows the electric energy supplied to the compressor to be flexibly adjusted in part by frequency conversion. This "partial" can be achieved in a variety of ways, such as by dividing the time period, pressure range or different compressor types.

[0008] Preferably, the plurality is 4, the compressor is a 4-stage cascade compressor, and each circuit breaker is electrically connected to the motor of each stage of the compressor respectively.

[0009] This connection method allows a single-set compressor to achieve variable frequency operation in stages in different time periods. It uses variable frequency startup when starting. When the compressor reaches the rated speed, the branch circuit breaker between the inverter and the compressor can be disconnected, and the branch circuit breaker between the branch circuit breaker and the downstream compressor can be closed to implement industrial frequency regulation on the motor of this section of the compressor.

[0010] Compared with the prior art, the utility model has the following advantages:

[0011] The utility model provides a high-voltage power supply system for compressor energy storage, which improves the matching degree between the pressure of a natural gas storage container (such as a cave) and a fixed-configuration compressor by using a combination of fixed-frequency and variable-frequency regulation of the compressor, reduces the number of starts and stops of the compressor, and reduces the bandwidth of the system to maintain the air pressure, taking into account energy saving, safety, and economy; the main circuit breaker adopts a phase-controlled excitation surge current suppressor to select phase connection, which can suppress the compressor transformer excitation surge current and reduce the overall impact of the compressor load on the power grid; the secondary side transformer of the rectifier transformer in the inverter is connected to the magnetizing inverter, and the actual impact current of the inverter is made less than the rated current by pre-magnetizing, thereby protecting the expensive inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The figure is a schematic diagram of the structure of a high voltage power supply system for compressor energy storage in an embodiment of the utility model. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on this embodiment, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0014] like Figure 1 As shown, an embodiment of the utility model provides a high-voltage power supply system for compressor energy storage, including a power circuit and a control circuit. The power circuit includes a 220KV compressor power supply branch line, a main circuit breaker, a compressor transformer, and four branch circuit breakers electrically connected in sequence; the 220KV compressor power supply branch line is connected to the power grid, one branch circuit breaker is electrically connected to the compressor via a frequency converter, and the remaining branch circuit breakers are electrically connected to the compressor without a frequency converter; the control circuit includes a phase-controlled excitation surge current suppressor electrically connected to the main circuit breaker and a pre-magnetic cabinet electrically connected to the secondary side of the rectifier transformer in the frequency converter.

[0015] The secondary voltage of the compressor transformer is 10kV. The output end of each sub-circuit breaker is electrically connected to the downstream load through the 10kV busbar (the downstream load includes 4-stage cascade compressors and inverters. The 10kV busbar can also supply power to other loads in the station). Branch circuit breakers are installed between the 10kV busbar and the downstream loads, and between the inverter and the compressor. Each sub-circuit breaker is connected to the motor of each compressor through the 10kV busbar and the branch circuit breaker. A 10kV variable frequency busbar is also connected between the inverter and the branch circuit breaker, which is used for variable frequency starting of the motors of the first to third compressors and switching of the variable frequency operation process of the fourth compressor.

[0016] When the system is running, the motor speed of the first-stage compressor is gradually increased to the industrial frequency speed through the frequency converter, the branch circuit breaker downstream of the frequency converter is disconnected, and the branch circuit breaker between the compressor and the 10kV bus is closed, and the compressor motor starts to operate at the industrial frequency; then the second to third-stage compressor motors are operated in the same way step by step; the fourth-stage compressor motor is operated at variable frequency and can be switched to industrial frequency operation when the frequency converter fails.

[0017] According to the starting sequence of the compressor motor, first close the main circuit breaker, and then close the sub-circuit breaker connected to the inverter.

[0018] A phase-controlled excitation inrush current suppressor is electrically connected to the main circuit breaker, and its current suppression principle is as follows:

[0019] The reason for the transformer excitation inrush current is that the magnetic flux of the inductor coil cannot change suddenly. When there is no residual magnetic flux inside the transformer, closing the switch at the voltage peak and when the magnetic flux is 0 will effectively avoid the generation of inrush current; when there is residual magnetic flux inside the transformer, if the polarity and value of the residual magnetism can be known, closing the switch at the moment when the expected magnetic flux is equal to the residual magnetic flux based on the voltage integral will also effectively avoid the generation of inrush current. For compressor transformers powered by 220kV, combined with existing technologies and products on the market, this solution based on phase control technology can be used to limit the excitation inrush current to within 2 times the rated current.

[0020] Since the capacity of the rectifier transformer configured in the inverter device can be as high as 35000kVA, if the excitation surge current suppression measures are not adopted during the closing process of the low-voltage side circuit breaker of the compressor transformer, the instantaneous surge current will cause impact on the system, equipment damage, protection malfunction and other consequences. The compressor inverter is a core component of the compression process, and the compressor startup and variable frequency operation both require the use of inverters. The investment of compressor inverters in compressed air energy storage power stations accounts for a large proportion, up to tens of millions of yuan. As an electronic product, the compressor inverter has more stringent requirements for impact current. The pre-magnetization principle is to use the method of pre-magnetizing the rectifier transformer to limit the instantaneous surge current, and the pre-magnetization transformer is powered by an auxiliary power supply. The selection of this technical solution based on the pre-magnetization principle can limit the excitation surge current to within the rated current, thereby ensuring that the inverter is not damaged.

[0021] The utility model combines the wiring mode and operation characteristics of a 300MW compressed air energy storage power station to propose a magnetic surge current suppression configuration for a compressed air energy storage power station to reduce the impact of instantaneous surge current on the system and equipment.

[0022] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high voltage power supply system for compressor energy storage, characterized in that It includes a power circuit and a control circuit. The power circuit includes a 220kV compressor power supply branch line, a main circuit breaker, a compressor transformer, and multiple sub-circuit breakers that are electrically connected in sequence. The 220kV compressor power supply branch line is connected to the power grid. In addition to being electrically connected to the compressor respectively, each of the sub-circuit breakers is also electrically connected to the compressor through a bypass containing a frequency converter. The control circuit includes a phase-controlled excitation surge current suppressor electrically connected to the main circuit breaker and a pre-magnetic cabinet electrically connected to the secondary side of the rectifier transformer in the frequency converter.

2. A high voltage power supply system for compressor energy storage according to claim 1, characterized in that: The secondary side of the compressor transformer is 10kV. The output end of each branch circuit breaker is electrically connected to the downstream load through the 10kV bus. Branch circuit breakers are provided between the 10kV bus and the downstream load and between the inverter and the compressor.

3. A high voltage power supply system for compressor energy storage according to claim 2, characterized in that: The plurality is four, the compressor is a four-stage cascade compressor, and each circuit breaker is electrically connected to the motor of each stage of the compressor.

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