含分布式电源的中低压配电网继电保护研究-电气工程专业论文.docxVIP

华北电力大学硕士学位论文 华北电力大学硕士学位论文 I I 摘 要 分布式电源因其在资源利用和环境保护方面的优势在世界范围内得以快速 发展。作为大电网集中供电的有益补充，成为世界各国电力系统发展的必然趋 势。各类分布式电源的接入，改变了配电网的故障特征，给配电网继电保护带 来多种影响。多端供电改变了配电网故障电流的分布，使部分电流保护灵敏度 降低或失去选择性。光伏、风力等分布式电源出力的波动性、间歇性，高渗透 率下分布式电源的启停，使配电网故障电流大小、方向存在不确定性。经逆变 器并网的分布式电源运行及故障特性与传统发电机有很大不同。这些都使配电 网原有继电保护适应性降低，甚至不能正确地识别、隔离故障。 本文从各类分布式电源的原理及接入电网方式入手，深入研究其故障特性。 通过研究逆变器型分布式电源的控制与特性，得出其在故障暂态下的等效模型， 分析其在配电网故障时的输出特性。 详细分析了分布式电源的数量、容量、接入位置对原有电流保护的影响。 结合中低压配电网运行及接线方式明确了不同类型的分布式电源并网变压器及 接地方式的选取对接地电流保护的影响，指出合理的选择方式。分析了分布式 电源对自动重合闸的影响并提出解决措施。 在分析现有继电保护存在问题的基础上，结合实例提出单个 DG 经专线及 T 接线路并网的保护整定优化方案。进而提出适用于多个 DG 并网的记及 DG 控制特性的三段式自适应电流保护算法。 最后结合某工业园区光伏组合并网实例，提出保护配置设计方案，并通过 仿真分析了多 DG 并网对原有线路保护的影响，验证了自适应保护算法的可行 性。 关键词：分布式电源；配电网；逆变型分布式电源；保护整定；自适应保护 II II Abstract Distributed generation is developing rapidly with its advantages in terms of resource utilization and environmental protection in the world , which, as a useful supplement to the large centralized power grid, has become an inevitable trend in the development of power system around the world. However, the characteristics of the distribution network failure has been changed after DG is connected to the distribution network, which brings about a variety of effects on distribution network protection. First, muti-terminal power change the direction of the fault current,and the part of current protection will be reduced in sensitivity or lose the selectivity. Besides, the uncertainty of fault current may be increased for the volatility and intermittent of photovoltaic, wind and other types of distributed generation as well as the start and stop of it in the integration of high shares of distributed generation. What’s more, the operation and fault characteristics of distributed network, which is connected with DG via an inverter, are very different from the traditional generator. All these contributes to reducing its original adaptive distribution or even its failing to correctly identify and isolate the fault. After that, this essay studies in depth the f