Research on Two-Stage PV Grid-Tied Inverter With By-Pass Relay

doi:10.11985/2016.12.003

Abstract

Abstract:

An advanced topology is introduced to improve the converting efficiency of the double-stage PV grid-tied inverter, which includes a by-pass relay between PV cell and bus capacitance. The on-off switch of relay and two working modes of the inverter are determined by the output signal of hysteresis comparator of which input signal is the voltage of PV cell. The first-stage boosted circuit stops working and the by-pass relay picks up which the current of main circuit goes through. The second-stage inverter realizes max power point tracking and grid connection, so the dissipation caused by boost inductance and diode disappears. The topology and strategy are not only realized in Matlab, but also verified in a 3kW single-phase double-stage photovoltaic grid-tied inverter.

Key words: Two-stage PV grid-connected inverter, maximum power point tracking (MPPT), by-pass relay, hysteresis comparator

CLC Number:

TM464

Yi Lingzhi,Liu Zhongfan,Chen Caixue,Chen Yu,Wu Jingping. Research on Two-Stage PV Grid-Tied Inverter With By-Pass Relay[J]. Journal of Electrical Engineering, 2016, 11(12): 16-21.

Figures/Tables 11

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类型	参数	数值
仿真模式	离散采样频率/MHz	1
工作频率	升压电路开关频率/kHz	10
工作频率	逆变器开关频率/kHz	30
主电路参数	C₁/μF	1
	C₂/mF	1.5
	L₁/mH	5
	L₂/mH	2
	R_s/Ω	4
母线参考电压	U_{bus_ref}/V	500
光伏电池双闭环控制器 PI调节器系数	比例系数K_p	1
光伏电池双闭环控制器 PI调节器系数	积分系数K_i	0.03
母线稳压双闭环控制器 PI调节器系数	比例系数K_p′	0.1
母线稳压双闭环控制器 PI调节器系数	积分系数K_i′	9
母线稳压双闭环控制器 P调节器系数	比例系数K_p″	11.3
滞环比较器	上限阈值U_{b_up}/V	500
滞环比较器	下限阈值U_{b_dn}/V	420
输出参数	电网电压有效值U_m/V	220
输出参数	电网频率f /Hz	50

参数	初始数值	跳变后数值
光照强度S_b/(W/m²)	1 000	1 000
光伏电池板温度T_b/℃	25	25
开路电压U_oc/V	750	450
短路电流I_sc/A	24	24
最大功率点电压U_m/V	650	320
最大功率点电流I_m/A	21	21

类型	参数	数值
工作频率	升压电路开关频率/kHz	10
工作频率	逆变器开关频率/kHz	30
主电路参数	C₁/pF	470
	C₂/mF	3
	L₁/μH	830
	L₂/μH	550
	R_s/Ω	1.4
母线参考电压	U_{bus_ref}/V	375
光伏电池双闭环控制器 PI调节器系数	比例系数K_p	0.8
光伏电池双闭环控制器 PI调节器系数	积分系数K_i	0.01
母线稳压双闭环控制器 PI调节器系数	比例系数K_p′	0.1
母线稳压双闭环控制器 PI调节器系数	积分系数K_i′	6
母线稳压双闭环控制器 P调节器系数	比例系数K_p″	10.5
滞环比较器	上限阈值U_{b_up}/V	375
滞环比较器	下限阈值U_{b_dn}/V	365
输出参数	电网电压有效值U_m/V	220
输出参数	电网频率f /Hz	50

参数	初始数值	跳变后数值
开路电压U_oc/V	500	310
短路电流I_sc/A	15	15
最大功率点电压U_m/V	440	240
最大功率点电流I_m/A	7	12.5