Research And Design Of 300kVA Dynamic Voltage Restorer

With the gradual depletion of fossil fuels in nature,the conflicts between countries caused by the problem of energy ownership are intensifying,so the development of new energy generation is imminent.Distributed energy,such as wind power generation and photovoltaic power generation,is emerging gradually,but there are a series of problems such as unstable power acquisition,large fluctuation when connected to the power grid system,and power quality is affected.Voltage sag faults damage precision electronic components to a large extent and occur frequently.To ensure the power supply reliability of precision electronic components on the electrical side,voltage compensation equipment is required.Dynamic Voltage Restorer(DVR)can not only effectively solve the Voltage sag problem,but also reduce the influence of Voltage flicker and harmonics on the power grid system.This dissertation takes DVR as the research object and mainly completes the following work:Based on the traditional DVR principle structure,according to its application occasions and corresponding design requirements,in order to reduce the voltage stress IGBT withstand,prolong the service life of power switch tube,A novel Active Neutral-Point-Clamed(ANPC)three-level inverter circuit is proposed,and the main circuit of DVR system is designed and its parameters are calculated.Hall sensor is used to collect current and voltage signals,DSP+FPGA vector generator is used as the main controller of DVR system to achieve the main circuit input and output signal detection and control functions.The single-phase αβ-dq voltage detection algorithm based on instantaneous reactive power theory is studied,and the algorithm is improved with PID control theory to improve the voltage sag detection ability of DVR.This paper studies a comprehensive energy optimal compensation strategy,deduces the relationship between the voltage sag depth and the compensation duration of the traditional compensation strategy,and verifies that the strategy can guarantee the voltage amplitude and offset phase of the DVR compensation sag,reduce the energy loss of the DVR,and improve the compensation efficiency.A new method for measuring the temperature of thermocouple wafer was proposed,and the fifth order Foster thermal resistance model of IGBT was established.The mathematical relationship between the temperature of IGBT wafer and the temperature of thermocouple was deduced under different power conditions.The curve fitting was carried out by Mathcad software to calculate the actual temperature of IGBT wafer.Prevent damage caused by overheating when IGBT works.Finally,a complete DVR prototype was developed and tested by oscilloscope and power analyzer.The experimental test results show that the response time of the whole DVR prototype is short and the voltage compensation error is less than 1%,which meets the design requirements of DVR system and verifies its reliability and effectiveness.