MATLAB Implementation of Grid and Islanded Mode of PV Wind Battery System

LMS RS
12 hours ago
2 min read

Overview of the Simulation Model

This MATLAB model simulates the dynamic behavior of a hybrid PV-wind-battery system under different environmental and load scenarios. The system is capable of functioning both in standalone and grid-connected modes.

Case 1: Base Condition (Standard Operation)

Wind Speed: 12 m/s
Solar Irradiation: 1000 W/m²
PV Output: 2000 W
Wind Power: 2400 W
AC Load: 1000 W
Battery Output: 3300 W

The total power generation in this scenario is 4400 W, while the total load is approximately 4300 W, accounting for 100 W in system losses. This represents a balanced and efficient system under optimal renewable energy conditions.

Case 2: Reduced Irradiation

In this scenario, the solar irradiation drops from 1000 W/m² to 500 W/m².

PV Output: Reduces to 1000 W
Wind Power: Maintains at 2400 W
Battery Output: Adjusts to 2300 W due to reduced PV input
AC Load: 1000 W

Total generation becomes 3400 W with a load of 3300 W. The decrease in solar power results in a more significant load on the battery to compensate, which also affects the battery current, increasing the depth of discharge.

Case 3: Reduced Wind Speed

This test reduces the wind speed from 12 m/s to 11 m/s while keeping the irradiation constant at 1000 W/m².

PV Output: 2000 W
Wind Power: Drops to 1600 W
Wind Current: Drops from 6 A to around 4 A
Battery Output: Increases to 2300 W to meet load
AC Load: 1000 W

Total system generation is 3600 W versus a load of 3300 W. This scenario demonstrates how the system dynamically compensates for reduced wind power using battery reserves.

Case 4: Increased Load

The load is increased from 1000 W to 1500 W at the 0.5-second mark while maintaining wind speed and irradiation.

PV Output: 2000 W
Wind Power: 2400 W
Battery Output: Around 2800 W
AC Load: Increases to 1500 W

The total power generation reaches 4400 W with a new total load of 4000 W. This scenario showcases the system's ability to adapt to changes in load demand without altering renewable generation conditions.

Grid vs. Standalone Mode

The simulation supports toggling between two operating modes:

Standalone Mode: Grid is disconnected. PV, wind, and battery are solely responsible for supplying power to the load. If renewable input exceeds load, the battery is charged. When there's a shortage, the battery discharges.
Grid-Connected Mode: Grid supplies or absorbs power based on system requirements.

Grid Power Sharing Logic

The system intelligently decides power flow to/from the grid based on:

Battery SOC (State of Charge)
- If SOC < 10% and PV current < 0.5 A → power is drawn from the grid.
- If SOC > 10% and PV current > 0.5 A → power is sent to the grid.

This logic ensures stable operation and efficient energy management across all scenarios.

Conclusion

This MATLAB simulation illustrates the flexible and adaptive behavior of a PV-wind-battery hybrid energy system. Through various test cases, it becomes evident how such systems can effectively manage power generation, storage, and distribution both with and without grid support. These insights are valuable for designing more reliable and intelligent hybrid renewable energy systems.