换流器型电网的理念与探索

Concept and Practice of Converter-based Grid

新型电力系统的发展将带来电网形态本质性的变化。电源通过换流器接入电网使电力电子设备的比例不断升高。当换流器型电源取代同步机型电源实现电网频率/电压构建时,则形成了换流器型电网(converter-based grid,CBG)。旨在对该电网形态的理念、构成、运行等基本问题进行探讨,首先论述了构成CBG的源、荷、储的基本特征与控制方式,探讨了电网可采用的拓扑方式;分析了换流器的频率/电压形成机制及多换流器协调控制方法;基于CBG的暂态行为,讨论了换流器故障特征及其保护策略,分析了换流器面临的稳定性问题的基本特征;结合工程实例,通过分析典型电网场景的运行特征,探讨了CBG的可行性;最后指出了新型电网形态尚待解决的关键技术问题,并对未来电网发展前景做出展望。

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.