微电网含非线性与不平衡负荷时的混合储能系统功率分配策略研究

Research on Power Allocation Strategy for Hybrid Energy Storage System in Microgrids under Nonlinear and Unbalanced Loads

混合储能系统HESS(hybrid energy storage system)在微电网中有着广泛的应用,其研究主要集中在能量管理、功率分配和拓扑设计等方面。对于功率分配的研究,大多只涉及到基本的功率分配,而无功功率、负序功率和谐波功率的分配问题却很少被提及。为此,提出了适用于不平衡负载和非线性负载环境的混合储能系统及其协调控制策略。在系统内部,电池功率转换系统工作在下垂模式,提供能量,只输出基本的有功功率;超电容器系统工作在补偿模式,分析总输出功率构成,输出无功、负序和谐波功率。该策略可以在不平衡和非线性负载条件下提供更好的系统性能;此外,该混合储能系统采用双逆变结构,有利于现有设备的升级改造;最后,仿真和实验结果验证了该策略的有效性。

Hybrid energy storage system (HESS) is widely applied in microgrids, and the related researches mainly focus on energy management, power allocation, topology design, etc. For the issue of power allocation, most researches only involve the fundamental power allocation, while the allocation of reactive power, negative-sequence power and harmonic power is rarely studied. To solve the above problem, an HESS under the condition of unbalanced and nonlinear loads is proposed, together with its coordinated control strategy. Inside the HESS, the battery power conversion system works in droop mode, providing energy and only outputting fundamental active power. Meanwhile, the ultracapacitor system works in compensation mode, analyzing the total output power of HESS and providing reactive, negative-sequence and harmonic powers. This strategy can provide better system performance in unbalanced and nonlinear load conditions. Moreover, the HESS adopts a dual-inverter structure, which is conducive for the upgrade of the existing equipment. Finally, the validity of the proposed strategy was verified by simulation and experimental results.