摘要
为提升光伏并网逆变设备的利用率和并网电能质量主动补偿能力、减少装置成本,结合有源滤波技术和光伏并网技术,提出了一种三相四开关并网逆变方案。该方案依据实际光伏发电情况和电网谐波污染程度,设计了可工作在并网发电模式、有源滤波模式以及兼容模式下的三相四开关并网逆变器,并推导得到各模式下其指令电流的计算方法;并利用电流直接跟踪技术,有效地实现各模式间的自适应切换;针对方案中三相四开关拓扑的直流中点电位偏移问题,给出了直流母线电容电压差值前馈的补偿方法。实验结果表明,在准确跟踪接入点电网变化的条件下,该方案可有效抑制因电容参数差异及内部交流负载电流变化引起的输出不平衡现象;而所提出的基于周期积分的单相软件锁相方法以周期累加的方法取代2次谐波低通滤波,实现了对电网变化的准确跟踪。
In order to promote the utilization of grid-connected photovoltaic inverter, to enhance the device＇s ability of power quality active compensation, and to reduce its cost, we put forward a three-phase four-switch grid-connected scheme integrating the active filtering and the photovoltaic technologies. According to the practical condition of photovoltaic output and harmonic pollution, we designed a three-phase four-switch grid-connected inverter which could work in grid-connected mode, active power filter mode, or compatible mode. The methods of calculating the inverter＇s current reference in each mode were deduced, and the self-adaptive switching among the modes was realized through current＇s direct tracking. To cope with the neutral voltage offset of the three-phase four-switch inverter under DC condition, we presented a feed-forward compensation method of the DC-bus capacitance-voltage difference. Experimental results show that the proposed method can effectively inhibit the output unbalance caused by the differences between capacitor parameters and the current variation of inner AC load, on condition that the variation of access point grid is tracked accurately. In addition, the proposed cycle-based integration single-phase phase-locking method substitutes the periodic accumulation for second harmonics low-pass filters, and hence it can track the variations of power grid precisely.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2014年第11期3590-3596,共7页
High Voltage Engineering
基金
国家自然科学基金(51107068)
河南省高等学校控制工程重点学科开放实验室开放课题(KG2014-14)~~
关键词
光伏并网
三相四开关
有源滤波
前馈补偿
周期积分锁相法
逆变器
photovoltaic grid-connected inverter
three-phase four-switch
active power filter
feedforward compensation
periodic integral-based phase-locking method
inverter
