In order to ensure that all the connected Equipment in the distribution network operates smoothly, the voltage stability of photovoltaic (PV) integrated distribution systems is very important. Sustaining the voltage profile when integrating PV is a particularly difficult issue. The primary goal of this article is to provide a consistent voltage profile to a sensitive load. A three-phase PV integrated distribution system has been chosen for investigation. An innovative feature of this system is that UPQC DVR and STATCOM systems are powered by Z-source inverters instead of traditional inverters. The ability to actively decouple power is the primary benefit of utilizing a Z-source inverter. The objective of the study effort is to use this new UPQC to synchronize a solar PV system with the distribution system. For the UPQC with battery energy storage system (BESS), the research study examines and develops the most appropriate control approach. A UPQC is a device that is used to integrate solar panels and improve the voltage stability of the distribution system. The prototype model is being developed, and the experimental findings confirm the main objective.

An integrated Z-source inverter for the single-phase single-stage grid-connected photovoltaic system is proposed in this paper. The inverter integrates three functional blocks including maximum-power-point-tracking, step-up/down DC-side voltage and output grid-connected current. According to the non-minimum-phase characteristic presented in DC-side and the functional demands of the system, two constant-frequency sliding-mode controllers with integral compensation are proposed to guarantee the system robustness. By using two controllers, the effects caused by the non-minimum-phase characteristic are mitigated. Under the circumstance of that the input voltage or the grid-connected current changes suddenly, the notches/protrusions following the over-shoot/ under-shoot of the DC-bus voltage are eliminated. The quality of grid-connected current is ensured. Also, a small-signal modelling method is employed to analyze the close-loop system. A 300W prototype is built in the laboratory. A solar-array simulator (SAS) is used to verify the systematic responses in the experiment. The correctness and validity of the inverter and proposed control algorithm are proved by simulation and experimental results.

In order to overcome the shortcoming of large switching losses caused by variable switching frequency appears in the conventional finite control set model predictive control (FCS-MPC) algorithm, a model predictive direct power control (MP-DPC) for an energy storage quasi-Z-source inverter (ES-qZSI) is proposed. Firstly, the power prediction model of the ES-qZSI is established based on the instantaneous power theory. Then the average voltage vector in the ���� coordinate system is optimized by the power cost function. Finally, the average voltage vector is used as the modulation signal, and the corresponding switching signal with fixed frequency is generated by the shoot-through segment space vector pulse width modulation (SVPWM) technology. The simulation results show that the ES-qZSI realizes six shoot-through actions per control cycle and achieves the constant frequency control of the system, which verifies the correctness of the proposed control strategy.