微电网中SOFC发电系统控制策略的研究

研究了按主从方式运行的微电网中,以固体氧化物燃料电池(SOFC)发电系统为主控机的控制策略。将该发电系统划分为原动机模块及接口模块两部分,探讨了功率偏差与模块间直流电压的相关性。在考虑电池利用率指标对安全运行影响的前提下,分别为DC/DC变换器以及逆变器设计了多环反馈控制器,使SOFC发电系统通过模式开关切换,在微电网联网模式下输出设定功率;在孤岛模式下作为平衡机组,输出给定电压并为微电网提供频率参考。还引入了直流电压-频率下垂特性,将主控机与负载之间的有功偏差转化为全网的频率偏差,则微电网中的一次调频机组据此调整出力,以达到改善网络暂态响应特性的目的。仿真分析验证了该控制策略的正确性。

Control strategy of SOFC generation system in microgrid

The control strategy of SOFC(Solid Oxide Fuel Cell) generation system is studied,which operates as the master in master-slave mode of microgrid.It is divided into two parts:prime mover model and interface model,and the correlation between the power deviation and the DC voltage connecting models is discussed.With the consideration of the influence of cell utilization on operational safety,the controllers with multiple feedback loops are designed for DC / DC converter and inverter respectively.By mode switching,SOFC generation system outputs the set power in grid-connection mode and acts as a balance unit in islanded mode,outputting fixed voltage and supporting frequency reference.The DC voltage-frequency droop control is also introduced to transform the active power deviation between master output and load into the grid frequency deviation,according to which,the primary frequency regulating units adjust their outputs to improve the transient response characteristic of grid.Simulation verifies the correctness of the proposed control strategy.