Distributed direct-current power supply system for substation

Abstract

The invention discloses a distributed direct-current power supply system for a substation. The direct-current power supply system is reasonably divided into several direct-current power supply systems in independent operation according to layout planning of the substation and needed capacity of electric equipment, and the direct-current power supply systems are disposed nearby the electric equipment. The distributed direct-current power supply system comprises a substation communication bus, main control systems respectively connected with the substation communication bus and a plurality of direct-current power supply subsystems in independent operation, the direct-current power supply subsystems are divided into a main control room subsystem, a GIS (geographical information system) equipment subsystem, an intelligent terminal subsystem, a merging unit cabinet subsystem and protecting chamber subsystems according to regions, the protecting chamber subsystems are distributed in regions of the substation, each direct-current power supply subsystem comprises a plurality of direct-current bus sections, direct-current buses are connected with a feeder terminal unit, and each two adjacent direct-current bus sections are connected through a switch and provided with a plurality of box-type packaged lithium ion battery packs in parallel, at least one charging unit and at least one monitoring unit.

Description

technical field [0001] The invention relates to a distributed direct current independent power supply system, in particular to a distributed direct current independent power supply system for substations. Background technique [0002] At present, the DC power supply system, especially the smart substation with a voltage level of 220kV and above, adopts the design mode of three charging and two batteries, 220V DC bus segment and connection switch, and the DC power passes through the DC bus in the main control room through the feeder panel and The power distribution screens scattered in each protection cell or the DC power subsystem connected to the DC bus supply power to the electrical equipment, which is a traditional centralized DC power supply system. As a centralized DC power supply system, it is more likely to cause insulation degradation or large-area multiple branch circuits to be grounded at the same time. What is more critical is that when multiple points are grounde...

AI Technical Summary

Problems solved by technology

Distributed capacitance makes the line capacitive when the line is unloaded. If it is too large, it will affect the accuracy of branch circuit insulation detection, cause false alarms for branch circuit grounding, and increase the voltage at the end, causing damage to the insulation of power equipment and affecting the anti-electromagnetic interference of the equipment. ability

More importantly, when the capacitive current generated by the distributed capacitance is too large, when a point is grounded in the secondary circuit, it may also cause the protection equipment to malfunction.

[0007] 2) The selective coordination of the upper and lower protection devices cannot be realized between the systems (gradual coordination)

[0008] The DC power supply system has a lot of power supply equipment, and the feeder branches are widely distributed. There are many branches in the system that need to be protected by circuit breakers or fuses. This distributed DC uninterruptible power supply system connects the subsystems together through the DC bus. Realize the reasonable cooperation between choosing the correct protection scheme and protecting the upper and lower levels

Leading to leapfrog tripping and magnifying the power accident

[0009] 3) The operating condition of the system battery is unclear

[0010] Whether it is a centralized DC power supply system or a distributed DC uninterruptible power supply system, the lithium-ion battery pack is always in a floating charge standby state. If some of the batteries have problems such as insufficient capacity or overcharge, the Periodic internal resistance inspection and checking charge and discharge are used for detection. This detection method has poor real-time performance and cannot make judgments on the working condition of the battery at the first time; Security risks

[0011] 4) The system design is complex and there are many failure points

[0012] The design of this distributed DC uninterruptible power supply system is relatively complicated; the DC bus is divided into multiple sections, and multi-way switches need to be switched on and off when maintaining the bus or charging and discharging lithium-ion batteries, which increases the failure points of the system, and the DC bus network The chemical power supply is easy to cause the crossover between the sections of the DC bus. Once these problems occur, not only will it cause serious damage to the electrical equipment, but it is also difficult for the operating personnel to conduct timely investigations, let alone online maintenance.

[0013] 5) Lack of an effective monitoring system

[0014] Chinese patent application 201110130055.0 is that the communication unit in the subsystem communicates with the host computer in the station through RS485 or CAN bus or Ethernet port. The information processing is cumbersome and lacks overall information processing and monitoring.

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