MATLAB Implementation of Single stage three Phase Grid connected PV systems
Introduction
Welcome to LMS Solution! In today's session, we'll delve into the detailed implementation of a state-of-the-art grid-connected PV system. Our goal is to design a 100-kilowatt grid-connected PV system, and we'll walk through the process step by step
System Overview
To start, we need a PV array, and for this implementation, we're using a photovoltaic array (PVR). The key specifications for a single panel in our system are a maximum power point voltage of 29 V and a current of 7.35 A. We'll be employing a single-stage connection, where the PV directly connects to the inverter.
Calculating Series and Parallel Connections
The first step is to determine the number of series-connected modules. We do this by dividing the inverter voltage (900 V) by the maximum power point voltage (29 V), resulting in approximately 31 series-connected modules. In our case, the calculated value is 15. This means we need 31 series-connected modules and 15 parallel strings, resulting in a total power output of around 100 kW.
Maximum Power Point Tracking (MPPT) Control
To ensure optimal power generation, we implement a Perturb and Observe (P&O) MPPT control algorithm. This algorithm continuously adjusts the reference voltage for the PV panels to operate them at their maximum power point.
System Components and Control Logic
Our system consists of a PV array, an inverter, and a grid connection. To model these components, we use Simulink blocks and connect them logically. The inverter is equipped with a control logic system that includes a Proportional-Integral (PI) controller for voltage control and a decoupling control block for independent control of direct and quadrature axis currents.
Simulation and Tuning
Simulating the model helps us identify and rectify any issues. We use the PD Tuner app to fine-tune the controller parameters, ensuring stable and efficient operation. Iterative tuning is often necessary to achieve optimal performance.
Results and Analysis
After tuning, we observe the system's response to different irradiation levels. Changing the irradiation from 1000 W/m² to 500 W/m² and back again, we monitor the power output, current, and voltage of the PV system and the grid.
System Performance Metrics
We also analyze Total Harmonic Distortion (THD) in the grid current to ensure the quality of power injected into the grid. Our goal is to maintain THD below 5%, and by tuning the system parameters, we achieve satisfactory results.
Conclusion
In conclusion, the step-by-step implementation of a single-stage grid-connected PV system involves careful design, modeling, and control. Through simulation and iterative tuning, we optimize the system for varying conditions, ensuring efficient power generation and grid connection.
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