微电网群频率调整的分层协调控制策略

针对分属于不同经营主体的微电网组成的微电网群，各微电网的经营目标、调频资源或调频能力等存在差异。为了使微电网群的频率调整达到调频任务的有序分担、调频费用的有序分摊以及调频经济性的有序达成等要求，分析了孤岛微电网群调频备用容量配备应遵循的规则，提出了微电网群频率调整的双层协调控制策略。第一层，各微电网中央控制器MGCC在微电网内部实施基于联络线功率偏差TBC的经济性调频控制，承担微电网自身有功变化所引发的调频任务，恢复系统频率和消除联络线交换功率偏差。当受扰微电网调频能力不足时，向上层微电网群中央控制器MGGCC申请微电网群互济频率调整辅助服务。第二层，MGGCC在微电网群层面实施基于恒频FFC的经济性调频控制，恢复系统频率。该策略可实现分属于不同经营主体的微电网群的频率调整控制的有序性和经济性。在频率分层调整过程中，各微电网承担自身扰动所引发的频率调整所产生的费用，包括自我调整和互济调整费用。算例结果验证了所提控制策略的有效性。该策略思想可为微电网群的设计、组网、运行与控制等工作提供参考借鉴。

Hierarchical coordinated control strategy for frequency adjustment of microgrid groups

In a micro-grid group consisting of Microgrid (MGs) owned by different separate entities, there are differences in the operating goals, frequency modulation resources or capabilities of each MG. There is a requirement for the orderly sharing of frequency modulation tasks and cost fee, and for the orderly achievement of frequency modulation economic efficiency. The reserve capacity allocation rules for an islanded micro-grid group are analyzed and a strategy of hierarchical coordination control for frequency adjustment of the micro-grid group is proposed in this paper. In the first layer, the Micro-Grid Central Controller (MGCC) conducts economical frequency modulation based on Tie-line Load Frequency Bias Control (TBC), undertaking the frequency modulation tasks caused by the power change of the MG itself, to restore the system frequency, and eliminate the tie-line exchange power errors. In the case of an inadequacy of the frequency adjustment of the MG, a frequency adjustment auxiliary service is delivered to the upper Micro-Grid Group Central Controller (MGGCC). In the second layer, the MGGCC conducts an economical frequency modulation based on constant-frequency control FFC in the micro-grid group to restore the system frequency. This strategy can achieve the orderliness and economic efficiency of the frequency adjustment of the micro-grid group owned by separate entities. In the process of frequency layered adjustment, each MG undertakes the frequency modulation costs caused by the power change of the MG itself, including self-adjustment and mutual adjustment costs. Numerical results show the effectiveness of the control strategy. This strategy can provide a reference for the design, networking, operation and control of a micro-grid group. This work is supported by National Natural Science Foundation of China (No. 51607105) and Natural Science Foundation of Hubei Province (No. 2016CFA097).