摘要
变电站内母线电压互感器(TV)的二次侧通常装设有自动投切的阻尼消谐装置以消除投切空载母线引发的铁磁谐振。但受限于小阻值投入利于消谐、大阻值切除利于扰动控制的阻值选择矛盾,此类消谐装置可能因为投入阻值过大而无法消除谐振,或投入阻值过小而在自切除时引发二次谐振。针对上述传统消谐装置的弊端,提出了利用门极可关断晶闸管(GTO)控制小阻值电阻脉冲投入,通过投入占空比逐步减小至零逐步实现阻尼自切除的消谐方案。首先,通过数值仿真拟定了可在较广泛系统参数区间内实现有效消谐的阻值1.5?。然后,对比不同阻尼投入占空比减小方案,设计了不引起二次谐振的占空比减小方案"微步退出策略";谐波平衡分析证明了该方案的可行性,同时亦表明母线对地电容和断路器均压电容过小可能导致占空比减小至零即阻尼设备切除后铁磁谐振的自激。针对上述自激现象,进一步提出了并联二次电容的改善措施。仿真结果证明脉冲阻尼附加二次电容可保证谐振得到有效消除并实现阻尼设备的顺利退出。
Secondary resonance eliminating devices are adopted in substation to eliminate ferroresonance caused by switching no-load bus. However, there is contradiction of the devices＇ resistance setting： launching a device with small resistance benefits to eliminating resonance but if the resistance is too small, cutting off the device will cause secondary resonances; cutting off a device with large resistance benefits to interference control, but if the resistance is too large, the device will fail to eliminate ferroresonance. Hence, we put forward a resonance control strategy which switches on pulsed resistance by gate turn-off thyristor（GTO）, thus the equivalent resistance value could be controlled through duty cycle of switching on. Firstly, a certain resistance of 1.5 ？ for eliminating ferroresonance in a wide range of system parameters was decided through numerical simulation. Then, a micro-step duty cycle decrease strategy for switching on the secondary resonance was designed to avoid ferroresonance being excited once again. It is proved to be feasible by further harmonic balance analysis, which also indicates that this strategy will fail in systems with too small circuit breaker equalizing capacitor or too small bus to ground capacitance. Therefore, we proposed an improvement of adding secondary parallel capacitance with pulsed resistance, which is proved by simulation to be effective in controlling ferroresonance and switching off the pulsed resistance.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2014年第5期1520-1529,共10页
High Voltage Engineering
基金
国家自然科学基金(51177182)
国家重点基础研究发展计划(973计划)(2009CB724504)~~
