电网换相高压直流(line-commutated-converter based high voltage direct current,LCC-HVDC)输电系统单极闭锁时,由于换流站滤波器延时分组切除,风光水送端系统的新能源场站将承受持续性的过电压冲击。为了使水电机组参与抑制直流单极...电网换相高压直流(line-commutated-converter based high voltage direct current,LCC-HVDC)输电系统单极闭锁时,由于换流站滤波器延时分组切除,风光水送端系统的新能源场站将承受持续性的过电压冲击。为了使水电机组参与抑制直流单极闭锁引起的送端系统过电压,该文首先提出一种以直流换流站交流母线电压为输入信号的附加励磁控制,作为水电机组协调控制策略。直流单极闭锁时,水电机组基于换流站过电压幅值决定进相深度,动态吸收系统盈余无功,从而改善新能源场站的过电压状况。然后,基于励磁系统输出极限和机端电压稳定极限,提出协调控制策略中附加励磁控制器增益上限的整定规则。最后,以青海送端电网为研究背景,基于PSCAD/EMTDC仿真平台验证了协调控制策略的有效性。仿真结果表明:提出的控制策略有效发掘了水电机组参与系统紧急调压的能力,填补了送端系统无功调节功能的短时空缺,可有效抑制系统过电压,具有工程指导意义。展开更多
The frequency domain division theory of dyadic wavelet decomposition and wavelet packet decomposition (WPD) with orthogonal wavelet base frame are presented. The WPD coefficients of signals are treated as the outputs ...The frequency domain division theory of dyadic wavelet decomposition and wavelet packet decomposition (WPD) with orthogonal wavelet base frame are presented. The WPD coefficients of signals are treated as the outputs of equivalent bandwidth filters with different center frequency. The corresponding WPD entropy values of coefficients increase sharply when the discrete spectrum interferences (DSIs), frequency spectrum of which is centered at several frequency points existing in some frequency region. Based on WPD, an entropy threshold method (ETM) is put forward, in which entropy is used to determine whether partial discharge (PD) signals are interfered by DSIs. Simulation and real data processing demonstrate that ETM works with good efficiency, without pre-knowing DSI information. ETM extracts the phase of PD pulses accurately and can calibrate the quantity of single type discharge.展开更多
文摘电网换相高压直流(line-commutated-converter based high voltage direct current,LCC-HVDC)输电系统单极闭锁时,由于换流站滤波器延时分组切除,风光水送端系统的新能源场站将承受持续性的过电压冲击。为了使水电机组参与抑制直流单极闭锁引起的送端系统过电压,该文首先提出一种以直流换流站交流母线电压为输入信号的附加励磁控制,作为水电机组协调控制策略。直流单极闭锁时,水电机组基于换流站过电压幅值决定进相深度,动态吸收系统盈余无功,从而改善新能源场站的过电压状况。然后,基于励磁系统输出极限和机端电压稳定极限,提出协调控制策略中附加励磁控制器增益上限的整定规则。最后,以青海送端电网为研究背景,基于PSCAD/EMTDC仿真平台验证了协调控制策略的有效性。仿真结果表明:提出的控制策略有效发掘了水电机组参与系统紧急调压的能力,填补了送端系统无功调节功能的短时空缺,可有效抑制系统过电压,具有工程指导意义。
基金Funded by the of the Key Teachers Foundation under the State Ministry Education.
文摘The frequency domain division theory of dyadic wavelet decomposition and wavelet packet decomposition (WPD) with orthogonal wavelet base frame are presented. The WPD coefficients of signals are treated as the outputs of equivalent bandwidth filters with different center frequency. The corresponding WPD entropy values of coefficients increase sharply when the discrete spectrum interferences (DSIs), frequency spectrum of which is centered at several frequency points existing in some frequency region. Based on WPD, an entropy threshold method (ETM) is put forward, in which entropy is used to determine whether partial discharge (PD) signals are interfered by DSIs. Simulation and real data processing demonstrate that ETM works with good efficiency, without pre-knowing DSI information. ETM extracts the phase of PD pulses accurately and can calibrate the quantity of single type discharge.
