摘要
真空有载分接开关(on-load tap-changers,OLTC)是换流变压器的重要组件,然而目前我国特高压换流变用OLTC均依赖进口,自主研发仍处于关键阶段,亟需深入开展暂态特性研究。由于换流变用真空OLTC切换电气应力波形十分复杂且影响因素众多,通过模型仿真分析难以进行灵敏度分析和严苛工况的精准筛查,同时OLTC与直流系统联合仿真十分耗时,难以支撑OLTC设计选型和参数选型等工程应用需求。因此,该文提出换流变OLTC切换过程电气应力的解析方法,首先通过对换流变负载电流进行傅里叶分解,分析其谐波特性,定量解析触发角及换相角对谐波含量的影响;其次,提取OLTC切换过程中十余个步骤的物理电路,结合OLTC通流谐波特性和电路分析得到OLTC切换全过程的电压和电流波形解析式;进而,解析得到OLTC真空管的开断电流和恢复电压变化率;最后,在PSCAD中搭建±800kV的LCC-HVDC系统,仿真验证解析方法的正确性。该方法能够为OLTC电气应力影响因素灵敏度分析和严苛工况筛查等研究提供理论依据和计算工具,支撑换流变用真空OLTC的设计选型与试验考核。
Vacuum on-load tap-changer(OLTC) is a crucial component of converter transformers. However, OLTCs for ultra-high voltage converter transformers in China are all imported. Independent research and development are still at a critical stage requiring the study of the transient characteristics of OLTC. The waveforms of the switching electrical stresses of vacuum OLTC in converter transformers are very complex which affected by many factors. At present, simulations are widely used to obtain the waveforms of the switching electrical stresses, but they are not easy to apply to sensitivity analysis and critical operating conditions searching. Meanwhile, the co-simulation analysis of OLTC and DC systems is too time-consuming to support the applications like OLTC design and parameter selection. Therefore, an analysis method of switching electrical stresses of OLTC in converter transformers was proposed in this paper. First, the harmonic characteristics of the load currents of converter transformers were analyzed by Fourier decomposition, and the effects of trigger angle and commutation angle on the harmonics were analyzed quantitatively. Second, each physical circuit of more than ten steps during the OLTC switching process was extracted to derive analytical expressions of voltage and current waveforms with harmonics in the process of OLTC switching.Furthermore, the breaking current and recovery voltage change rates of vacuum interrupters in OLTC were obtained analytically. Finally, a ±800kV LCC-HVDC system was built in PSCAD to validate the analysis method. The analysis method can provide theoretical basis and calculation tool for sensitivity analysis and critical operating conditions searching.It can also support the design, selection, and test of vacuum OLTC in converter transformers.
作者
司马文霞
刘蕙
厉璇
杨鸣
汪可
张和
杨春
SIMA Wenxia;LIU Hui;LI Xuan;YANG Ming;WANG Ke;ZHANG He;YANG Chun(State Key Laboratory of Power Transmission Equipment&System Security and New Technology(Chongqing University),Shapingba District,Chongqing 400044,China;State Grid Economic and Technological Research Institute Co.,Ltd.,Changping District,Beijing 102209,China;China Electric Power Research Institute,Haidian District,Beijing 100192,China;Xi’an XD Transformer Co.,Ltd.,Xi’an 710077,Shaanxi Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2022年第18期6908-6918,共11页
Proceedings of the CSEE
基金
国家电网公司科学技术项目(5500-202056353A-0-0-00,变压器/换流变用分接开关运行环境暂态特性研究)。
