Circuit achieving power flow control and small current ground fault active compensation arc suppression simultaneously

Abstract

A circuit achieving power flow control and small current ground fault active compensation arc suppression simultaneously is characterized by comprising a three-phase parallel module, a first coupling transformer, a three-phase serial module, a second coupling transformer and a direct current bus voltage stabilizing unit; when power flow control is conducted, the three-phase parallel module and the first coupling transformer are used for providing active power balance for the interior of the circuit and conducting reactive compensation on the circuit through the first coupling transformer, and when active compensation arc suppression is conducted, the three-phase parallel module and the first coupling transformer are used for providing a zero-sequence compensation current for a small current ground fault; when power flow control is conducted, voltage is inserted into a power distribution system circuit through the second coupling transformer to change power flow; the direct current bus voltage stabilizing unit connects the three-phase serial module with the three-phase parallel module and is used for providing stable direct current voltage for the direct current side of the three-phase serial module and the direct current side of the three-phase parallel module. According to the circuit achieving power flow control and small current ground fault active compensation arc suppression simultaneously, by means of the three-phase parallel module, the three-phase serial module and the direct current bus voltage stabilizing unit, the functions of power flow control small current ground fault active compensation can be achieved simultaneously.

Description

technical field [0001] The invention relates to a circuit for simultaneously realizing power flow control and active compensation arc suppression for small current grounding faults, belonging to the field of medium-voltage power distribution systems. Background technique [0002] With the development of science and technology and the progress of society, various distributed power sources are increasing, resulting in the continuous expansion of the distribution network scale and the increasingly complex operation mode. In the early days, there were only serious power flow problems in the power transmission system. In recent years, due to the large number of distributed power sources and micro-grids being put into the power distribution system, the power flow problem of the power distribution system has become more and more serious. At the same time, ground faults often occur in the medium-voltage power distribution system, causing impact on the power distribution system and e...

AI Technical Summary

Problems solved by technology

At the same time, ground faults often occur in the medium-voltage power distribution system, causing impact on the power distribution system and even causing power outages

About 70% of the faults in the ground fault are instantaneous single-phase ground faults. For the low-current grounding system, the system can operate with a single-phase ground fault for two hours. Fault overvoltage, causing multiple accidents, may burn out transformers and switch cabinets, cause large-scale power outages, and cause great economic losses

[0003] For the power flow control problem of the medium-voltage power distribution system, the existing power electronic device UPFC (Unified Power Flow Controller) applied to the power transmission system can be used. UPFC can better solve various problems such as voltage fluctuation, reactive power compensation, and power flow control. function, but cannot handle ground faults

In order to reduce the single-phase ground fault current, the power grid of some voltage levels usually adopts the neutral point non-effective grounding method, including neutral point ungrounded and grounded through the arc suppression coil. When a single-phase ground fault occurs, the fault current is small and can be Let the power grid continue to operate with a fault for a period of time, but a small current grounding fault may cause the arc to be extinguished and re-ignited, which will cause a large system overvoltage and cause a major hazardous accident

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