Research On Some Protection Problems Of Energy Storage System

The ever rapid development of society and progress of new energy technology increase the importance of intermittent energy sources such as wind power and photovoltaic power generation. But the stochastic and intermittent of intermittent energy bring a new challenge to the power grid safe and stable operation. The energy storage system plays an important role in promoting grid power quality, operation stability and reliability of power system, with its fast and controllable characteristics. Research on the application of the energy storage system has become a hot spot in power system in recent years. However, research on fault diagnosis and protection of energy storage system is poor. Therefore, an in-depth study on fault diagnosis and protection of energy storage system has important significance.This article takes the energy storage system as the research object, conducting relatively strict deduction on the mathematical model of power conducting system, as the theoretical foundation of the energy storage converter design. As well as the control strategy of the energy storage system parallel operation is studied, the implementation of energy storage converter PQ control analyzed. Based on the mathematical model of energy storage converter and grid-connection control strategy, a simulation model for the energy storage system has been set up on the PSCAD/EMTDC simulation platform.In this paper, the most important job is to analyze the converter fault of energy storage system and conduct the simulation research. The converter faults of energy storage system include two parts:the bridge arm IGBT open-circuit fault and short-circuit fault. All kinds of faults have different characteristics. On the basis of the analysis of failure features of open-circuit fault, we can get qualitative description of the change of the electric parameters, choosing the characteristics which can reflect the open-circuit fault as the basis of fault diagnosis and location. We choose some cases for battery energy storage system short circuit fault situations and IGBT converter bridge closure, have a detailed analysis on all possible, draw the fault analysis equivalent circuit of all kinds of cases, and use the method of state variables analysis method or transient circuit three elements method to analyze the equivalent circuit. At last, we conduct a simulation study on the bridge arm IGBT open-circuit fault and short-circuit fault, and put forward a reasonable fault diagnosis and protection suggestions.