Reliability of Power Electronics Converters for Solar Photovoltaic Applications by Haque Ahteshamul;Blaabjerg Frede;Wang Huai;Yang Yongheng;Jaffery Zainul Abdin;

Author:Haque, Ahteshamul;Blaabjerg, Frede;Wang, Huai;Yang, Yongheng;Jaffery, Zainul Abdin;
Language: eng
Format: epub
Publisher: Institution of Engineering & Technology
Published: 2021-08-05T16:00:00+00:00

Figure 5.11 Frequency response of the double-loop control (i.e., the DC-link voltage control loop and the d-axis current control loops) with the designed parameters: (a) open loop Bode plots and (b) closed-loop Bode plots, where BW represents bandwidth of the system

With the above parameters, a two-stage three-phase grid-connected solar inverter system is built up in MATLAB®. Then, the designed controller parameters (i.e., (5.36) and (5.37)) are applied to the three-phase grid-connected solar inverter. Simulation results are shown in Figure 5.12, which includes the performance of the grid line-to-line voltages, the grid currents, the DC-link voltage, and the dq-current components. There are two transient operations in the simulations, i.e., one is a step change in the active power from 0 to 8 kW at t = 0.2 s, and the other is a step change of the reactive power from 0 to 6 kVAR at t = 0.4 s. Specifically, when the input power is changed at t = 0.2 s, the d-axis current fast-tracks the change. As shown in Figure 5.12c, the DC-link voltage appears as a 7.5 percent overshoot and recovers to steady-state after one cycle. Moreover, the q-axis current step change occurs at t = 0.4 s, which can be achieved by directly setting the reactive power reference according to the open-loop control in Figure 5.10. That is an effective and simple reactive power control method under an abnormal grid voltage condition (e.g., the low-voltage ride-through). Furthermore, Figure 5.12e indicates that the q-axis current can regulate quickly when there is a disturbance in the q-axis current, i.e., the step change at t = 0.2 s, which verified the effectiveness of the PI controller for the q-axis current.

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