统一潮流控制器用500 kV油浸式串联变压器技术解析

500 kV串联变压器是苏州500 kV统一潮流控制器(UPFC)工程中的关键设备,承担着换流器与线路电压、功率输送调节的任务。由于500 kV串联变压器特殊的联结方式和运行工况,其与常规500 kV变压器存在诸多不同。第一,网侧绕组相对地主绝缘与线路电压等级匹配,而端间纵绝缘则由各项过电压决定,带来了网侧绕组绝缘水平复杂的特点;第二,绝缘试验中雷电全波冲击试验和外施耐压试验也与常规变压器差异较大;第三,串联变压器的特殊工况造成了其对抗短路能力和过励磁能力要求高的特点。在苏州UPFC工程中,针对500 kV油浸式串联变压器开展了大量的技术研究,克服了网侧绕组绝缘复杂、试验技术特殊、抗短路能力和过励磁能力要求高等难题。文中分别从运行工况、技术特点和试验要求等方面对苏州UPFC工程中500 kV串联变压器进行技术解析。

Technical Analysis of 500 kV Oil-immersed Series Transformer for Unified Power Flow Controller

500 kV series transformer is the key equipment in Suzhou 500 kV unified power flow controller (UPFC) project,which undertakes the regulation of voltage and power between the converter and the line.Because of the special connection mode and operating condition of 500 kV series transformers,there are many differences from conventional transformers.First,the main insulation of the net side winding is matched with the line voltage grade,and the longitudinal insulation of the end is determined by the overvoltage,which brings about the complex characteristics of the insulation level of the net side windings.Secondly,the lightning full wave shock test and the external AC withstand voltage test are also different from the conventional transformers in the insulation test.Finally,the special working condition of series transformer has caused the high requirement of resisting short-circuit ability and over excitation capability.In Suzhou UPFC Project,a large number of technical researches have been carried out for 500 kV oil-immersed series transformers,which overcomes the difficult problems of the complex insulation of the windings,the special test technology,the short circuit ability and the high excitation ability.In this paper,the technical analysis of 500 kV series transformers in Suzhou UPFC project is carried out from various aspects,such as operating conditions,technical characteristics and test requirements.