Power Management in PV–Wind–Battery DC Microgrid
- lms editor
- 10 hours ago
- 4 min read
Introduction
DC microgrids integrating solar photovoltaic (PV), wind energy systems, and battery energy storage are gaining importance due to their high efficiency, reduced conversion stages, and suitability for renewable energy integration. However, effective power management is essential to ensure stable DC bus voltage, uninterrupted load supply, and optimal utilization of available renewable resources.
This work presents a PV–Wind–Battery based DC microgrid power management system, where the DC bus voltage is regulated at 400 V, while power sharing among PV, wind, and battery sources is dynamically controlled based on generation and load demand.
Wind Energy Subsystem
The wind energy system is rated at 3 kW and consists of a Permanent Magnet Synchronous Generator (PMSG). The variable AC output of the PMSG is converted into DC using a three-phase diode rectifier. The rectifier output voltage is approximately 250 V, which is boosted to the common DC bus voltage of 400 V using a DC–DC boost converter.
The boost converter is designed using standard inductor and capacitor sizing equations based on:
Wind turbine power rating (3 kW)
Rectifier output voltage (≈ 250 V)
Desired DC bus voltage (400 V)
Switching frequency (5 kHz)
Inductor current ripple percentage
Capacitor voltage ripple percentage
The calculated L and C values ensure continuous conduction mode operation and stable voltage regulation.
To extract maximum power from the wind source, a Perturb and Observe (P&O) MPPT algorithm is implemented. The rectifier voltage and current are measured, and the MPPT logic updates the duty cycle by comparing changes in power and voltage. Duty cycle limits are enforced using predefined minimum and maximum values to ensure safe converter operation.
Solar PV Subsystem
The solar PV system is rated at 2 kW, with an input voltage of approximately 245–250 V under standard irradiance conditions. Similar to the wind system, a boost converter is used to step up the PV voltage to the common 400 V DC bus.
The PV boost converter is designed using:
PV power rating
PV terminal voltage
Required DC bus voltage
Switching frequency
Allowable inductor current ripple
Allowable capacitor voltage ripple
Two MPPT techniques are implemented for PV control:
Perturb and Observe (P&O) MPPT
Incremental Conductance (INC) MPPT
P&O MPPT Operation
The algorithm compares changes in power and voltage to decide whether to increase or decrease the duty cycle. Previous values of voltage, power, and duty cycle are stored and updated every iteration to track the maximum power point.
Incremental Conductance MPPT Operation
The INC algorithm determines the operating point by evaluating the condition:
dIdV=−IV\frac{dI}{dV} = -\frac{I}{V}dVdI=−VI
If this condition is satisfied, the PV system is operating at the maximum power point. Otherwise, the duty cycle is adjusted accordingly. This method offers improved performance during rapidly changing irradiance conditions.
Duty cycle limits are enforced to prevent instability, and previous iteration values are continuously updated to maintain accurate tracking.
Battery Energy Storage System
The battery system is rated at 240 V (2 × 12 V modules) and is connected to the DC bus through a bidirectional DC–DC converter. Although the converter topology resembles a boost converter, the current direction changes depending on system operating conditions.
The bidirectional converter is designed using:
Battery voltage (240 V)
DC bus voltage (400 V)
Switching frequency (10 kHz)
Inductor and capacitor ripple constraints
The converter operates in:
Charging mode when excess power is available from PV and wind
Discharging mode when renewable generation is insufficient to meet the load demand
DC Bus Voltage Control
A voltage control strategy is used to maintain the DC bus voltage at 400 V. The measured DC bus voltage is compared with the reference value and processed through a PI controller. The controller output generates the duty cycle, which is applied through a PWM generator to control the bidirectional converter IGBTs.
This control strategy ensures:
Stable DC bus voltage
Smooth power flow between sources
Reliable operation of DC loads
Load and Power Management Strategy
The DC load is rated at 3 kW and must be supplied continuously. Power management is performed based on real-time availability of PV and wind power.
Simulation scenarios include irradiance changes from:
1000 W/m² → 500 W/m² → 10 W/m²
Observed System Behavior
At 1000 W/m², PV generates approximately 2 kW
At 500 W/m², PV power reduces to 1 kW
At 10 W/m², PV power drops close to zero
When PV power decreases:
The battery transitions from charging to discharging mode
The wind generator contributes up to ~2.8 kW
The battery supplies the remaining power to maintain the 3 kW load
As PV and wind power fluctuate, the battery dynamically switches between charging and discharging modes to balance the power flow.
Simulation Results and Discussion
Simulation results clearly show:
Effective power sharing among PV, wind, and battery
Stable DC bus voltage maintained at 400 V
Constant DC load power despite source variations
Smooth battery charging and discharging transitions
The total system power is managed such that:
PPV+PWind+PBattery=PLoadP_{PV} + P_{Wind} + P_{Battery} = P_{Load}PPV+PWind+PBattery=PLoad
This confirms the robustness of the proposed power management strategy.
Conclusion
This work successfully demonstrates a PV–Wind–Battery based DC microgrid with efficient power management control. By combining MPPT-controlled renewable sources with a voltage-regulated bidirectional battery converter, the system ensures stable operation under varying irradiance and load conditions.
Key achievements include:
Stable DC bus voltage regulation
Optimal renewable energy utilization
Reliable load supply
Intelligent battery energy management
The proposed system is highly suitable for standalone DC microgrids, renewable energy systems, EV charging stations, and remote power applications.
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