换流器型电网的理念与探索

Electric power system with renewable energy in the leading role is evolving with essential change of grid morphology. Electric power is integrated to the grid through converters which increase the proportion of power electronics in power system. Converter-based grid (CBG) will be reached when converter-based power generation replaces synchronous machine to build the grid frequency and voltage. This paper aims to discuss the concept, constitution and operation of CBG. Firstly, the basic characteristics and control strategies are discussed for the elements of CBG such as source, load, energy storage and network configuration. Then, the frequency and voltage formation mechanism of single converter and the coordinated control method of multiple converters are analyzed. Based on the transient behavior of CBG, the fault characteristics and protection strategies are discussed，and the stability problem of CBG are briefly analyzed. Combined with engineering practice, the feasibility of CBG is illustrated by comparing the application in specific grid scenarios. Finally, the key technical issues to be solved in CBG are pointed out, and the future development prospect of power grid is put forward.