采用二次预充电技术的PWM变换器并网控制
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摘要
新能源脉冲宽度调制(PWM)变换器的预充电回路对直流电容充电至额定电压的80%左右,其后进行软并网控制。并网解锁瞬间通常存在较大的冲击电流,特别是在弱电网条件下,并网瞬间容易引起过流。提出一种采用二次预充电的新型并网控制方案。首先通过二极管充电至直流电压的80%左右;此后进行电压开环控制,二次预充电至直流电压额定值左右。在直流额定电压下,进行软并网控制可减小暂态冲击电流。搭建了背靠背型变换器的实验测试平台。测试结果表明,所述方案能够充电至直流额定电压,并减小了并网期间的冲击电流与开关器件损耗。
The pre-charging circuit of new energy PWM converter is used to charge 80% of the rated DC voltage,followed by soft grid-connected controlling. At the moment of grid-connected control unlock,the impact current is very large,especially under the condition of weak power grid,it is easy to cause over current. A new grid-connected control scheme which contains two charge process was proposed. First of all,it was used the diode to charge 80% of the rated DC voltage;since then the open loop control was used to charge the rated DC voltage. Under the rated DC voltage,soft grid-connection control could reduce the transient current. The test platform of back-to-back converter was set up. The test results show that the pre-charging scheme can charge the rated DC voltage,reduce the impact current and the switching devices loss of grid-connected process.
The pre-charging circuit of new energy PWM converter is used to charge 80% of the rated DC voltage,followed by soft grid-connected controlling. At the moment of grid-connected control unlock,the impact current is very large,especially under the condition of weak power grid,it is easy to cause over current. A new grid-connected control scheme which contains two charge process was proposed. First of all,it was used the diode to charge 80% of the rated DC voltage;since then the open loop control was used to charge the rated DC voltage. Under the rated DC voltage,soft grid-connection control could reduce the transient current. The test platform of back-to-back converter was set up. The test results show that the pre-charging scheme can charge the rated DC voltage,reduce the impact current and the switching devices loss of grid-connected process.
引文
[1]顾伟峰,赵新龙,杨志千.直驱风电机组并网变流器预充电电路设计方法优化[J].电气技术,2014,18(6):90-93.
[2]宋平岗,李云丰,王立娜,等.MMC-HVDC电容协同预充电控制策略[J].高电压技术,2014,40(8):2471-2477.
[3]陈坚.电力电子变换和控制技术[M].北京:高等教育出版社,2004.
[4]张馨月.弱电网条件下并网变流器控制策略的研究[D].北京:北京交通大学,2015.
[5]廖勇,庄凯,姚骏.电网电压不平衡时全功率风电并网变流器的控制策略[J].电网技术,2012,36(1):72-78.
[6]王久和,杨微,李华德.功率前馈电压型PWM整流器直接功率解耦控制[J].辽宁工程技术大学学报,2007,26(2):238-241.
[7]郭小强,邬伟扬,漆汉宏.电网电压畸变不平衡情况下三相光伏并网逆变器控制策略[J].中国电机工程学报,2013,33(3):22-28.
[8]张崇巍,张兴.PWM整流器及其控制[M].北京:机械工业出版社,2003.
[2]宋平岗,李云丰,王立娜,等.MMC-HVDC电容协同预充电控制策略[J].高电压技术,2014,40(8):2471-2477.
[3]陈坚.电力电子变换和控制技术[M].北京:高等教育出版社,2004.
[4]张馨月.弱电网条件下并网变流器控制策略的研究[D].北京:北京交通大学,2015.
[5]廖勇,庄凯,姚骏.电网电压不平衡时全功率风电并网变流器的控制策略[J].电网技术,2012,36(1):72-78.
[6]王久和,杨微,李华德.功率前馈电压型PWM整流器直接功率解耦控制[J].辽宁工程技术大学学报,2007,26(2):238-241.
[7]郭小强,邬伟扬,漆汉宏.电网电压畸变不平衡情况下三相光伏并网逆变器控制策略[J].中国电机工程学报,2013,33(3):22-28.
[8]张崇巍,张兴.PWM整流器及其控制[M].北京:机械工业出版社,2003.