Distribution network flexible grounding device control system and its parameter design method

Abstract

A power distribution network flexible earthing device control system comprises a first merging comparison module, a SPIR controller, a second merging comparison module and a pulse generating module which are connected one by one, and a proportional amplification module H. An output current i<0> of a flexible earthing device is sampled and input into the first merging comparison module and is compared with an injection current reference value i<ref>, and then a difference value of the i<0> and the i<ref> is output. The SPIR controller is formed by a proportional integral controller (PI) and a proportional resonance controller (PR) connected in series. A filter capacitor current (i<c>) of the flexible earthing device is input into the second merging comparison module, is proportionally amplified, then is merged and compared with an output of the SPIR controller, and finally is output to a single-phase inverter of the flexible earthing device. The system can effectively inhibit the voltage of a neutral point to the ground and achieve three-phase-unbalanced overvoltage inhibition. The system can track the reference current in real time and has good dynamic and steady state performance. When maintaining a relatively large bandwidth, the system can keep stable and has high robustness to power distribution network parameter. Besides, the efficiency of parameter design is high.

Description

technical field [0001] The invention relates to a control system for a flexible grounding device of a power distribution network. The invention also relates to a method for designing parameters of the control system. Background technique [0002] Due to the customary grounding method, line erection method, and asymmetric distribution of voltage transformers and compensation capacitors in the distribution network in my country, the distribution network in China has long-term asymmetry of three-phase-to-ground parameters, which is likely to cause three-phase imbalance. Overvoltage. Three-phase unbalanced overvoltage will bring a series of hazards to the power system and users, including: reducing the output of distribution transformers, endangering the safety and life of transformers; increasing the loss of motors and transmission lines; affecting electrical equipment, especially single The normal operation of the phase load; the asymmetry of the phase voltages will also enda...

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Problems solved by technology

[0002] Due to the customary grounding method of my country's distribution network, the method of line erection and the asymmetric distribution of voltage transformers and compensation capacitors in the line, there has been a long-term asymmetry of three-phase-to-ground parameters in my country's distribution network, which is likely to cause three-phase imbalance. Overvoltage

Three-phase unbalanced overvoltage will bring a series of hazards to the power system and users, including: reducing the output of distribution transformers, endangering the safety and life of transformers; increasing the loss of motors and transmission lines; affecting electrical equipment, especially single The normal operation of the phase load; the asymmetry of the phase voltages will also endanger the insulation of the system, and bring difficulties to fault detection, which will easily lead to misoperation of the protection device

[0004] However, no control system and parameter design method for flexible grounding devices have been found in the prior art

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