Research On Fault Analysis And Suppression Measures Of Resonance Overvoltage In Distribution Network

The characteristics of high frequency and long duration of resonance overvoltage in distribution network and its characteristics of over voltage and over current have brought a huge threat to the safe and reliable operation of distribution network. This paper studies the development mechanism of linear resonance overvoltage, ferromagnetic resonance overvoltage and disconnection resonance overvoltage in distribution network, and puts forward the necessary conditions for the excitation of resonance overvoltage. According to the mechanism of resonance overvoltage in distribution network, firstly the influence of voltage limiting resistor to linear resonance is described, then the phenomena of sub-frequency resonance, the fundamental resonance and high frequency resonance of ferromagnetic resonance overvoltage are presented, and finally the influence of the transmission line parameters and device parameters to the disconnection resonance overvoltage is analyzed.Based on the statistics of the resonance overvoltage fault of distribution network, the main causes, the electrical characteristics and protection action signal in the development process of resonance overvoltage is summarized and then the corresponding mechanism of each causes are described in detail. According to different causes of resonance fault, the corresponding suppression measures taken in the current project are proposed.In order to reveal the variation law of the energy oscillation in grid networks, as well as the transient process of voltage and current when the resonance fault of distribution network happens, a 35kV transformer substation in Yancheng is taken as an example to establish resonance overvoltage simulation models of distribution network which is based on ATP-EMTP simulation platform. By the simulation analysis, the correctness of resonance overvoltage mechanism in the distribution network is verified. Aiming at the existing problems of the arc suppression coil and the shortages of the existing suppression measures of the ferromagnetic resonance and disconnection resonance, a new parallel arc suppression coil automatic compensation device in transformer type, and a novel power distribution network controllable harmonic elimination device based on current value characteristic and over current relay are designed, and measures like increasing phase-to-phase capacity in appropriate site and installing loads near the no-load distribution transformer are proposed. Simulation results verified the effectiveness of the devices and the proposed methods in terms of suppression of the resonant overvoltage in the distribution network.Finally, the concept of distribution network resonance overvoltage vulnerability is defined based on mechanism and phenomena of resonance overvoltage in the distribution network. And the indexes of linear resonance overvoltage structure vulnerability, ferromagnetic resonance overvoltage structure vulnerability and disconnection resonance overvoltage structure vulnerability which are used to estimate the overvoltage vulnerability of distribution network are given from the perspective of the grid topology, line parameters and device characteristics. In this paper, the original IEEE-34 node system and the IEEE-34 node system after adding suppression measures are calculated and simulated. The results showed that the proposed method to estimate the overvoltage vulnerability of distribution network is reasonable and effective.