MATLAB Simulation of PV Wind Battery Based DC Microgrid with PO MPPT

Understanding the Components of the PV-Wind-Battery DC Microgrid

A PV-Wind-Battery DC Microgrid consists of three primary components:

1. Wind Power Generation: This part utilizes a Permanent Magnet Synchronous Generator (PMSG), which is driven by wind turbines to convert kinetic energy into electrical power. The system includes a universal bridge (rectifier) and a boost converter to convert and step up the voltage from AC to DC.

2. Photovoltaic (PV) Power Generation: PV panels are employed to harness solar energy and convert it into electrical power. In the system, eight panels are connected in series, with three parallel strings, generating a total of 6 kW of power. The DC voltage is boosted using a boost converter.

3. Battery Energy Storage System: The energy storage system consists of a 240V, 48Ah battery that stores excess energy and supplies power to the load when needed. It is connected to the DC bus and regulated by a buck-boost converter, which manages the current flow to charge or discharge the battery based on the system's power balance.

PV Wind Battery Based DC Microgrid PO MPPT in MATLAB

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Operation of Wind Power Generation

The wind power generation system uses a Vban model and a PMSG to convert wind energy into electrical power. The system operates by controlling the pitch angle of the wind turbine to stabilize its performance. By setting the pitch angle to zero, the system ensures that there is no variation in wind direction. The generated speed and wind speed are used to calculate the torque, which drives the generator and produces AC power.

However, since the generated power is AC, a universal bridge rectifier is employed to convert it into DC. The resulting voltage is then stepped up from 200-300V to 400V using a boost converter. The boost converter is designed according to the wind generation model’s power rating (6 kW). Additionally, Maximum Power Point Tracking (MPPT) is applied to extract the maximum possible power from the wind system.

Maximum Power Point Tracking (MPPT) in Wind and PV Systems

MPPT is a crucial method for optimizing the power extracted from renewable energy sources like wind and solar. For both wind and PV systems, the MPPT algorithm adjusts the duty cycle of the boost converter to extract the maximum power. This is achieved by continuously monitoring the change in voltage and change in power.

In the wind system, the speed of the wind turbine is adjusted to ensure it operates at the maximum power point. The system monitors changes in power and voltage and adjusts the duty cycle accordingly. Similarly, for the PV system, the voltage and current are monitored, and the duty cycle is adjusted to maximize power extraction.

Photovoltaic (PV) Power Generation System

The PV system consists of eight solar panels connected in series and arranged into three parallel strings. Each panel generates 250W of power, with a maximum power voltage of 30.7V and a current of 8.15A. This results in a total power generation of 6 kW from the system.

To optimize power extraction, the PV system uses a boost converter to step up the output voltage from 245V to 400V. Just like in the wind power generation system, MPPT is applied to control the converter and ensure the system extracts maximum power from the PV panels.

Battery Storage and Power Management

The battery storage system in the microgrid plays a vital role in balancing the power supply and demand. The battery has a rating of 240V and 48Ah and is connected to the DC bus. To ensure that the battery is properly charged or discharged based on the system’s power requirements, a buck-boost converter is used.

The system continuously monitors the DC bus voltage and compares it with a reference voltage of 400V. If the DC bus voltage deviates from this reference, the PI controller adjusts the duty cycle to either charge or discharge the battery as required, maintaining a stable voltage across the bus.

Simulation Results and Performance Analysis

The simulation results reveal how the system responds to variations in wind speed and solar radiation. By adjusting the wind speed every 1.5 seconds and changing the solar radiation levels every second, the system is able to track the maximum power points for both wind and PV systems effectively.

The results also show the behavior of the battery. Initially, the battery is in charging mode, storing excess energy. Once the power from the renewable sources begins to drop, the battery enters discharging mode to supply energy to the load. The system ensures that the DC bus voltage remains stable, and the required power is available for the connected load.

Conclusion: The Future of PV-Wind-Battery DC Microgrids

This simulation model of a PV-Wind-Battery DC Microgrid demonstrates the potential of integrating renewable energy sources with energy storage to create a reliable and efficient off-grid power system. With the application of MPPT for both wind and solar power generation, as well as battery storage management, the system ensures maximum power extraction and continuous energy supply.