分布式能源接入交流微网的单相逆变器功率智能分配策略设计

Design of Intelligent Single-Phase Inverter Power Allocation Strategy for Distributed Energy Access to AC Microgrids

逆变器并联并网系统往往通过两个逆变器通信分别控制进行并联并网,存在通信延迟、不稳定、传输效率低等问题,为此提出了一种分布式能源接入交流微网的单相逆变器功率智能分配策略设计。首先,建立了单相逆变器及并联系统的数学模型,并推导了其相关参数之间的函数关系,分析了并联系统中的环流现象,提出采用电势差均流方法来减小环流影响,在并联设计中,采用电压电流环循环控制实现逆变器组按任意比例分配电流;其次,采用SOGI-PLL进行锁相,使用电流环开闭环交替控制方式实现全桥逆变器组在无通信条件下功率智能分配;再次,设计仿真电路初步验证了所提出的SOGI控制实现锁相的正确性和快速性;最后,搭建了实验样机以验证方案可行性,实验结果表明,在输入50 V直流电压时,该系统可实现输出50 Hz、24 V交流电压,且输出交流电压总谐波畸变率(THD)不大于2%,逆变器1的效率η高达92%,I_(o)在0~2 A变化时,负载调整率S_(I1)≤0.2%,在并网状态下可实现逆变器之间功率按任意比例智能分配。

The parallel grid-connected inverter system is usually controlled by two inverters communication respectively,which usually has the problems of communication delay,instability and low transmission efficiency.In this paper,a distributed energy access to the AC microgrid single phase inverter power intelligent allocation strategy design is proposed.Firstly,the mathematical model of single phase inverter and parallel system were established and the functional relationship between its relevant parameters was derived.The circulating current phenomenon in the parallel system was analyzed,and a solution was proposed to mitigate its impact by implementing the potential difference equalization method.Additionally,the voltage current loop cyclic control was employed to achieve the current distribution of the inverter group in the parallel design according to an arbitrary ratio.Secondly,the SOGI PLL was used for phase locking,and the current loop was controlled alternately in open and closed loops to achieve intelligent power allocation of the full-bridge inverter group without communication.Then,simulation circuits were designed to preliminarily validate the correctness and rapidity of the phase locking achieved by the proposed SOGI control.Finally,experimental prototypes were constructed to verify the feasibility of the scheme,and the experimental results show that,whena 50 V DC voltage was inputted,the present system can achieve an output of 50 Hz,24 V AC voltage.The total harmonic distortion rate(THD)of the output AC voltage was not more than 2%,and the efficiency of inverter 1 wasηas high as 92%.What's more,the load adjustment rate S_(I1)is≤0.2%when I_(o)varies from 0~2 A,and the power can be intelligently distributed among the inverters in any proportion under the grid-connected condition.