摘要
不对称电网电压下采用传统定义的瞬时有功和无功实现直接功率控制时,会产生较多的电流谐波,导致交流电流波形发生严重的畸变。为此,引入新型无功代替传统无功。对比了分别采用传统无功和新型无功时的区别,并定性分析了采用传统无功产生电流谐波的原因。基于有功和新型无功建立了三电平电压源换流器高压直流输电(high voltage direct current transmission based on voltage source converter,VSC-HVDC)功率模型,提出模型预测直接功率控制策略(model predictive direct power control,MPDPC),实现了不对称电网电压下有功和新型无功波动的有效抑制和直流侧电容电压平衡,并保证了良好的电流波形质量。基于新型无功的MPDPC可以适应对称和不对称电网电压,实现了功率的直接控制,避免了电压、电流的正负序分解和功率补偿策略。在PSCAD/EMTDC中搭建两端三电平VSC-HVDC仿真系统,仿真结果验证了所提策略的正确性和有效性。
When active and reactive powers based on traditional definition are used to achieve direct power control trader unbalanced grid voltages, amount of current harmonics will appear, leading to serious distortion of AC current waveform. To resolve this issue, a novel reactive power was proposed to replace traditional reactive power. Traditional reactive power was compared with the novel reactive power and reason of generation of current harmonics was analyzed qualitatively. A power model based on active power and novel reactive power for three-level VSC-HVDC was established and then a model predictive direct power control （MPDPC） was proposed. Ripple suppression of active power and novel reactive power under unbalanced ＇grid voltages and balanced DC-side capacitor voltage are both achieved when MPDPC based on novel reactive power （N-MPDPC） was adopted, and sinusoidal current waveforms were achieved. N-MPDPC is suitable for balanced and unbalanced grid voltages and able to achieve direct power control, thus avoiding positive- and negative-sequence extraction of voltage and current and power compensation. A two-terminal three-level VSC-HVDC model was set up in PSCAD/EMTDC. Correctness and effectiveness of the proposed control method was validated with simulation results.
出处
《电网技术》
EI
CSCD
北大核心
2017年第8期2455-2461,共7页
Power System Technology
基金
中央高校基本科研业务费资助(2017QJ05)~~
关键词
无功
模型预测控制
直接功率控制
功率波动抑制
reactive power
model predictive control
direct power control
power fluctuation suppression
