基于三相四线制最优潮流的低压配电网光伏-储能协同控制

大规模户用光伏不平衡接入低压配电网会造成严重的电压越限、网损和三相不平衡。针对当前户用光伏消纳控制技术对三相四线制低压配电网不适用的问题,提出了一种基于三相四线制最优潮流的低压配电网光伏-储能协同控制方法。考虑电压、电流的幅值和相角,采用三相四线制节点导纳矩阵建立了低压配电网的网络拓扑结构;综合考虑网损和三相不平衡度最小,建立了储能元件有功功率和光伏逆变器无功功率的三相四线制线路多时段协同控制模型;通过复数变量拆分和模型凸化以降低三相四线制模型的求解难度,采用CPLEX算法包求出模型全局最优解。仿真结果表明,所提出的基于最优潮流的控制方法在大规模光伏和负荷不对称接入条件下能够有效抑制电压越限,同时达到降低网损、改善电网三相不平衡的目的。

Coordinated Control of Photovoltaic and Energy Storage System in Low-voltage Distribution Networks Based on Three-phase Four-wire Optimal Power Flow

The unbalanced connection of large-scale residential photovoltaic (PV) power integrated into low-voltage distribution network (LVDN) will bring problems such as voltage violations, power losses and three-phase imbalance. In order to solve the problem that the accommodation control technology is not suitable for the three-phase four-wire low-voltage distribution system, a coordinated control method considering PV and energy storage system (ESS) is proposed based on three-phase four-wire optimal power flow (OPF). The network topology of LVDN is established by using three-phase four-wire node admittance, where the amplitudes and phase angles of voltage and current are considered. Multi-period coordinated control model of three-phase four-wire lines for active power of energy storage elements and reactive power of PV inverters is developed considering the minimum of both power loss and three-phase imbalance. The difficulty in solving three-phase four-wire model is reduced through complex variable decomposition and model convexity, and the global optimal solution can be obtained using CPLEX algorithm package. Simulation results show that the proposed OPF based control method can effectively mitigate the voltage violation in conditions of large-scale PV and load unbalanced connection. Meanwhile, the network power loss is reduced and the degree of three-phase imbalance is also optimized.