中文摘要：

配电网发生故障时，分布式电源（Distributed Generation，DG）对继电保护有重大影响。为了更好地发挥DG的积极作用．减轻DG对电力系统传统保护的不利影响，基于传统电流保护原理。分析了接有DG的配电网保护配合性．并从保护配合性及供电可靠性角度探讨了DG注入容量问题。DG容量的计算原则是：DG下游故障时，保护不能误动，相邻保护之间的动作时间应留有裕度；上游故障时，保护不能拒动。DG容量不宜太小。还要保证最接近故障点的保护最先动作．保持保护配合性。就DG容量对传统过流保护的影响作了MATLAB仿真，仿真结果表明DG容量应在一定范围之内，否则会引起保护误动或拒动。

英文摘要：

With a fault occurred in the distributed system, DG （Distributed Generation ） will have a significant impact upon protection. To achieve the positive applications and lighten the negative affections of DG, an analysis to the protection for the radial distribution system injected with DG was given, based on the conventional current protection. And according to both the relationship between relays and the reliability of power supply, an exploration to the problem of interconnected DG size was proposed. The calculation criteria of DG size are that the fault current should not bring about false actions for faults downstream, protective devices should not have miss operations and the relay closest to the fault position should be operate first for faults upstream. Finally, the math tool MATLAB was applied to simulate the proposed ideal. The simulation results reveal that the capacity of DG should have some restricts, otherwise the relay may have a false action or miss operation.