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摘要: 随着多馈入直流工程的不断发展,换流站发生谐波扰动的概率大大增加.通过分析换流母线谐波对锁相环和换相过程的影响,研究了高压直流输电系统的控制器在谐波扰动下的运行特性.通过减少电流偏差控制器的输出量以减少定熄弧角控制器在谐波扰动中的稳态误差,提高了直流系统传输容量.最后提出了谐波扰动中系统运行点的计算方法.PSCAD软件的仿真结果证明了分析和计算方法的准确性.Abstract: Possibility of serious harmonic distortion (SHD) increases as multi-infeed direct current (MIDC) transmission develops rapidly in recent years. In this paper, the mechanism of high voltage direct current (HVDC) controller working against SHD is proposed for theoretical derivation of phase locked loop (PLL) output and valve commutation process. To reduce static error of constant extinction angle (CEA) controller and enhance active power transmission, the insertion of current error (CE) controller into CEA is minified. A calculation of inverter operating point is proposed in the end. The correctness of mechanism and algorithm is verified through power systems computer aided design (PSCAD) simulation.
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Key words:
- High voltage direct current (HVDC) /
- converter /
- harmonics /
- serious harmonic distortion (SHD) /
- phase locked loop (PLL) /
- constant extinction angle (CEA)
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Table Ⅰ Simulation and Calculation Result of $\gamma$ Per Cycle ( $^\circ$ )
Com-valve Sim-result without harm Cal-result without harm Sim-result with harm Cal-result with harm 3−1 15.12 15.07 19.58 18.36 4−2 15.12 15.07 16.45 16.36 5−3 15.12 15.07 9.98 10.69 6−4 15.12 15.07 19.58 18.36 1−5 15.12 15.07 16.45 16.36 2−6 15.12 15.07 9.98 10.69 Table Ⅱ Simulation and Calculation Result of Operating Point in SHD
M = 1 M = 0.2 Cal-results of m = 0.2 Voltage (l-g) 125.1 127.4 127.2 Active power (pu) 0.8959 0.9290 0.9298 min γ (°) 16.38 15.25 15.09 Firing order (°) 135.5−139 139−139.4 139.6 -
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