引用本文: | 任 颉,周鹏鹏.用于光伏逆变器故障穿越的载波交叠调制优化[J].电力系统保护与控制,2024,52(14):167-176.[点击复制] |
REN Jie,ZHOU Pengpeng.Optimization of carrier overlap modulation for fault ride-through of photovoltaic inverters[J].Power System Protection and Control,2024,52(14):167-176[点击复制] |
|
摘要: |
为了解决三电平光伏逆变器故障穿越时的中点电位平衡问题,在已有的脉宽调制和中点电位平衡方法基础上,提出一种新型的深度载波交叠调制法(deep carrier overlapping PWM, DCO-PWM)。该方法通过尽量增加上下层载波的交叠深度,削弱了中矢量对中点电位的影响,实现了在故障冲击和高无功电流工况下保持中点电位平衡和并网电流可控。针对DCO-PWM增加了功率器件开关次数的问题,开发了一种调制策略的分相切换方法,仅在中点电位差超出设定阈值时,将调制波中间相切换到DCO-PWM,其他状态仍然使用常规的载波同相层叠调制法(carrier phase disposition PWM, CPD-PWM),从而降低了并网电流的谐波含量和器件开关损耗。通过实验验证了上述方法在三电平逆变器低电压故障穿越过程中,可有效增强对并网电流和中点电压的控制,从而保证故障状态的安全可靠穿越。 |
关键词: 三电平逆变器 低电压穿越 载波交叠调制 中点电位控制 |
DOI:10.19783/j.cnki.pspc.240769 |
投稿时间:2024-04-19 |
基金项目:国家自然科学基金项目资助(52007143) |
|
Optimization of carrier overlap modulation for fault ride-through of photovoltaic inverters |
REN Jie1,ZHOU Pengpeng2 |
(1. Nokia Shanghai Bell Co., Ltd., Nanjing 210037, China; 2. Xuchang KETOP Testing Research
Institute Co., Ltd., Xuchang 461000, China) |
Abstract: |
To solve the problem of midpoint potential balance in a three-level photovoltaic inverter during fault ride-through, this paper proposes a novel deep carrier overlapping PWM (DCO-PWM) method based on existing pulse-width modulation and midpoint potential balance methods. This method increases the overlap depth of upper and lower carriers, thereby weakening the influence of the middle vector on the midpoint potential and achieving controllable midpoint potential balance and grid-connected current in fault impact and high reactive current conditions. Because of the increase in the switching frequency of power devices by DCO-PWM, a modulation strategy based phase switching method is developed. Only when the midpoint potential difference exceeds the set threshold is the intermediate phase of the modulation wave switched to DCO-PWM, while the conventional carrier phase disposition PWM (CPD-PWM) is still used for other states, thereby reducing the harmonic content of grid-connected current and device switching losses. Experiments have verified that the above method can effectively enhance the control of grid-connected current and midpoint voltage during the low-voltage fault ride-through of a three-level inverter, thereby ensuring the safe and reliable ride-through of the fault state. |
Key words: three-level inverter low voltage ride through carrier overlapping PWM neutral-point potential control |