基于撑网逆变器的交流微电网分布式协调控制

Distributed Coordinated Control of AC Microgrids Based on Grid-supporting Inverters

为了解决分层控制体系中下垂控制存在电压调节性能和功率分配的固有矛盾,以及功率分配受线路阻抗影响的缺点,针对基于电网支撑型逆变器的交流微电网,采用扩散算法,提出了一种不依赖下垂机制的分布式协调控制策略:首先引入权重系数以协调各分布式电源所承担的负荷比例;其次,电压调节器、无功功率调节器和有功功率调节器中采用分布式控制,并基于扩散算法,控制功率分配和电压/频率精准调节。理论分析了扩散算法和一致性算法的收敛性能,并通过仿真对比基于传统下垂机制的分层控制策略,和基于一致性算法的分布式协调控制,结果表明:所提基于扩散算法的分布式协调控制策略在线路阻抗不匹配、负荷突变、通信故障、通信延时、变流器故障等情况下,能够同时实现电压/频率的精准调节和功率的精确分配,具有较高的稳定性。

In a droop-based hierarchical control,the primary control has the inherent compromise between voltage regulation performance and power distribution,and the secondary control is commonly installed to solve these problems in a long-time scale,which significantly affects the system stability.To solve these problems,this paper proposes a distributed cooperative control strategy for grid supporting inverters-based AC microgrid.This strategy is independent of droop mechanism.Firstly,a weight coefficient is introduced to coordinate the load proportion born by each distributed generation.Secondly,distributed control and diffusion algorithm are adopted in voltage regulator,reactive power regulator,and active power regulator,and the power sharing and voltage/frequency regulation are controlled on the basis of the diffusion algorithm.The convergence performance of diffusion algorithm and consensus algorithm is analyzed theoretically.In addition,by comparison with droop-based hierarchical control,the consensus algorithm-based cooperative control strategy is conducted in simulation.The results show that,the proposed strategy has high stability and can realize high-quality voltage/frequency regulation and accurate power sharing can be realized in the case of line impedance mismatch,load mutation,communication link failure,inverter failure and communication delay.