基于电流保护约束的逆变型分布式电源最大接入容量与接入位置选择

Maximum Access Capacity and Connection Point Choice of Inverter Interfaced DG Based on Current Protection Constraints

逆变型分布式电源接入配电网后,传统配电网采用的三段式电流保护可能会发生不正确动作。为了解决这一问题,提出了基于电流保护约束的逆变型分布式电源最大接入容量和接入位置选择的确定方法。当配电网发生故障时,根据零电压穿越控制的逆变型分布式电源的故障输出特性,分析逆变型分布式电源并网点电压及输出的故障电流随逆变型分布式电源输出功率和接入位置变化而变化的规律。发现逆变型分布式电源的并网点电压及电流随逆变型分布式电源输出功率的增大呈非线性变化、随接入位置远离系统电源而逐渐减小的特征。根据该变化特征,以传统配电网电流保护在不改变原有整定值的情况下能正确动作为条件,确定了逆变型分布式电源的接入容量及接入位置。仿真验证了该方法的有效性。

According to the fault characteristic of the inverter interfaced DG （IIDG） controlled by zero voltage ride through, in this paper, the connection vohage and short-circuit current variation influenced by IIDG＇s capacity and connection point are analyzed when a fault occurs in the distribution sys- tem. It turns out that the connection voltage and current of IIDG vary non-linearly as IIDG＇s output power increases continuo- usly. Meanwhile, it is demonstrated that the connection voltage decreases gradually as the connection point of IIDG stays away from the system sources. According to these characteristics, the current constraints based determination methods for maximum access capacity and best connection point of IIDG are proposed in the premise of ensuring traditional protection effectiveness. The simulation has verified the effectiveness of the proposed method.