2 MW PV Battery Grid System

𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧

The 2 MW PV Battery Grid System in MATLAB/Simulink demonstrates the integration of a large-scale solar photovoltaic source, battery energy storage, utility grid, and AC load through a common power conversion system.

The simulation is designed to study:

• 2 MW solar PV power generation

• Battery charging and discharging

• Grid power import and export

• DC-link power management

• Grid-connected inverter control

• dq-axis current control

• Active power injection

• Harmonic performance

• System response under changing solar irradiance

• Continuous power supply to the connected load

The model is useful for students, researchers, and engineers studying renewable energy integration, battery energy storage, grid-connected converters, and power management using MATLAB/Simulink.

𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰

The complete system contains four major power sections:

• Solar PV array

• Battery energy storage system

• Three-phase utility grid

• Three-phase AC load

The PV source and battery are connected to a common DC link, while a grid-connected inverter transfers power between the DC side and the point of common coupling.

Main System Parameters

𝐒𝐲𝐬𝐭𝐞𝐦 𝐀𝐫𝐜𝐡𝐢𝐭𝐞𝐜𝐭𝐮𝐫𝐞

The power flow structure can be summarized as:

Solar PV → DC Link → Grid Inverter → PCC → Grid and Load

The battery is connected as:

Battery ↔ Bidirectional DC–DC Converter ↔ DC Link

This configuration allows the battery to operate in both directions.

Battery Charging Mode

When sufficient PV power is available:

• PV supplies the load.

• Excess renewable energy can charge the battery.

• Battery current becomes negative according to the adopted charging convention.

• Battery state of charge gradually increases.

Battery Discharging Mode

When PV generation falls:

• Battery supplies additional power to the DC link.

• Battery current becomes positive.

• Stored battery energy supports the connected load.

• The utility grid provides the remaining power whenever required.

𝐒𝐨𝐥𝐚𝐫 𝐏𝐕 𝐀𝐫𝐫𝐚𝐲

The model uses a large PV array designed to produce approximately 2 MW under standard operating conditions.

PV Array Configuration

At high irradiance, the PV array supplies a large portion of the load requirement and can also provide energy for battery charging.

𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐄𝐧𝐞𝐫𝐠𝐲 𝐒𝐭𝐨𝐫𝐚𝐠𝐞

The battery is connected to the common DC link through a bidirectional DC–DC converter.

This converter provides controlled power transfer in both directions.

Main Functions of the Battery

• Store surplus PV energy

• Support the DC link during reduced solar generation

• Reduce sudden grid power demand

• Improve power balance

• Supply additional power during low irradiance

• Support continuous load operation

The battery nominal voltage is approximately 300 V.

For a megawatt-scale system, the required battery current capability is very high. Therefore, practical implementation normally requires multiple battery strings or modules connected in suitable series-parallel combinations.

𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

A controlled reference current is generated for the battery converter.

The battery controller performs the following process:

1. PV operating information is measured.

2. A suitable battery current reference is generated.

3. The reference current is compared with actual battery current.

4. The current error is processed by a PI controller.

5. The controller generates the required duty command.

6. A PWM generator produces switching pulses.

7. The bidirectional converter controls battery charging or discharging.

This approach allows the battery current to automatically change according to renewable power availability.

𝐃𝐂-𝐋𝐢𝐧𝐤 𝐚𝐧𝐝 𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫

The DC link acts as the common energy interface between:

• Solar PV

• Battery system

• Grid-connected inverter

The inverter converts the DC-link power into three-phase AC power suitable for the point of common coupling.

An output filter is included to reduce switching harmonics before the inverter power reaches the grid.

𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲

The grid-side converter uses a synchronous dq-axis control technique.

The major control stages are:

• DC-link/reference voltage processing

• Active current reference generation

• Reactive current reference selection

• Three-phase voltage and current measurement

• Phase-Locked Loop

• abc-to-dq transformation

• dq-axis current control

• Feedforward and decoupling compensation

• dq-to-abc inverse transformation

• PWM pulse generation

𝐏𝐡𝐚𝐬𝐞-𝐋𝐨𝐜𝐤𝐞𝐝 𝐋𝐨𝐨𝐩

A PLL synchronizes the inverter controller with the three-phase utility grid.

The PLL provides the electrical angle required for coordinate transformations.

It supports:

• Accurate grid synchronization

• abc-to-dq transformation

• dq-to-abc transformation

• Stable current control

• Controlled real and reactive power transfer

𝐝𝐪-𝐀𝐱𝐢𝐬 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

The measured three-phase voltage and current signals are transformed into the rotating reference frame.

The controller produces:

• d-axis current

• q-axis current

In this model:

• Id reference is used mainly for real power control.

• Iq reference is maintained at zero.

Therefore, the inverter is primarily commanded to transfer active power, while reactive power injection is kept close to zero under the selected operating strategy.

𝐅𝐞𝐞𝐝𝐟𝐨𝐫𝐰𝐚𝐫𝐝 𝐚𝐧𝐝 𝐃𝐞𝐜𝐨𝐮𝐩𝐥𝐢𝐧𝐠 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

The d-axis and q-axis current errors are processed through PI controllers.

Feedforward and decoupling terms are included to improve:

• Current tracking

• Dynamic response

• d-axis and q-axis independence

• Grid voltage disturbance rejection

• Active power control

The resulting voltage references are converted back into three-phase quantities and sent to the PWM modulator.

𝐏𝐖𝐌 𝐆𝐞𝐧𝐞𝐫𝐚𝐭𝐢𝐨𝐧

The three-phase reference voltage signals are supplied to the PWM stage.

The PWM generator creates switching signals for the grid-side power converter.

This controls:

• Inverter output voltage

• Grid current

• Active power transfer

• DC-link energy transfer

𝐌𝐞𝐚𝐬𝐮𝐫𝐞𝐝 𝐏𝐚𝐫𝐚𝐦𝐞𝐭𝐞𝐫𝐬

The MATLAB/Simulink model continuously monitors important electrical parameters.

PV Measurements

• Solar irradiance

• PV voltage

• PV current

• PV power

Battery Measurements

• Battery voltage

• Battery current

• Battery power

• Battery State of Charge

Load Measurements

• Three-phase voltage

• Three-phase current

• Active power

• Current THD

Grid Measurements

• Three-phase grid voltage

• Three-phase grid current

• Grid active power

• Current THD

𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬

The system is tested under different solar irradiance levels to evaluate PV generation, battery operating mode, and grid contribution.

Case 1 — Irradiance of 1000 W/m²

At standard solar irradiance:

The negative battery power indicates charging under the adopted sign convention.

The available PV generation is sufficient to supply the major load demand while also supporting battery charging.

Case 2 — Irradiance of 500 W/m²

When irradiance is reduced to approximately 500 W/m², PV generation decreases significantly.

In this condition:

• PV generation is insufficient to meet the complete load.

• Battery changes from charging to discharging mode.

• The utility grid supplies the remaining load requirement.

• The AC load continues receiving approximately its rated power.

Case 3 — Very Low Solar Irradiance

The system is also examined under very low solar availability.

Under this operating condition:

• PV output becomes very low.

• Battery supplies part of the required energy.

• Grid import increases considerably.

• The load remains continuously supplied.

This demonstrates coordinated operation between PV, battery, and utility grid.

𝐎𝐩𝐞𝐫𝐚𝐭𝐢𝐧𝐠 𝐌𝐨𝐝𝐞 𝐂𝐨𝐦𝐩𝐚𝐫𝐢𝐬𝐨𝐧

The system automatically redistributes power according to available solar generation.

𝐏𝐨𝐰𝐞𝐫 𝐁𝐚𝐥𝐚𝐧𝐜𝐞 𝐁𝐞𝐡𝐚𝐯𝐢𝐨𝐮𝐫

One of the main objectives of the model is maintaining power balance at the point of common coupling.

When PV generation changes:

• Battery power automatically changes.

• Grid contribution adjusts.

• Load demand remains approximately constant.

• DC-side and AC-side power flows remain coordinated.

This makes the model useful for understanding renewable-energy power management under changing environmental conditions.

𝐇𝐚𝐫𝐦𝐨𝐧𝐢𝐜 𝐏𝐞𝐫𝐟𝐨𝐫𝐦𝐚𝐧𝐜𝐞

THD measurement blocks are included for monitoring current quality.

The simulation shows:

• Three-phase grid current with near-sinusoidal behaviour

• Three-phase grid voltage with balanced sinusoidal waveform

• Filtered inverter output

• Load-current harmonic monitoring

• Grid-current harmonic monitoring

The exact THD value depends on simulation settings, converter switching conditions, measurement window, and FFT configuration.

𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬

• 2 MW grid-connected solar PV system

• Large-scale battery energy storage integration

• 154 MW, 34.5 kV utility grid

• 34.5 kV to 400 V transformer

• Approximately 1.5 MW AC load

• Bidirectional battery converter

• Battery charging and discharging control

• Common DC-link architecture

• Three-phase grid inverter

• PLL-based grid synchronization

• abc-to-dq transformation

• dq-to-abc transformation

• PI current control

• Feedforward and decoupling compensation

• Zero reactive-current reference operation

• PWM-based inverter switching

• Harmonic filtering

• Grid-current THD monitoring

• Load-current THD monitoring

• Variable irradiance testing

• PV, battery, grid, and load power monitoring

𝐖𝐡𝐚𝐭 𝐂𝐚𝐧 𝐁𝐞 𝐋𝐞𝐚𝐫𝐧𝐞𝐝 𝐅𝐫𝐨𝐦 𝐓𝐡𝐢𝐬 𝐌𝐨𝐝𝐞𝐥?

This MATLAB/Simulink model provides a clear understanding of:

• Large-scale PV array design

• Battery-grid coordination

• Renewable power fluctuations

• Grid power import and export

• Battery charging and discharging

• DC-link energy management

• Three-phase inverter operation

• PLL synchronization

• Reference-frame transformations

• Active and reactive current control

• Grid-side PWM control

• Harmonic monitoring

• Power balance under changing irradiance

𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬

The concepts demonstrated in this simulation are applicable to:

• Grid-connected solar power plants

• Battery Energy Storage Systems

• Solar-plus-storage systems

• Industrial renewable energy systems

• Smart grids

• Microgrids

• Distributed generation systems

• Utility-scale PV integration

• Energy management studies

• Grid-connected converter research

• Renewable power-quality analysis

𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧

The 2 MW PV Battery Grid System in MATLAB/Simulink demonstrates coordinated operation of solar PV generation, battery storage, a utility grid, and a large AC load.

The simulation clearly shows that:

• At high irradiance, PV generation reaches approximately 2 MW, allowing the battery to charge.

• At medium irradiance, PV output decreases and the battery begins discharging while the grid supplies the remaining power.

• At very low irradiance, the grid becomes the major source while the battery provides additional support.

• The connected load continues receiving power despite substantial changes in solar generation.

• The dq-based inverter controller enables controlled real-power exchange with the utility grid.

Overall, the model provides a practical MATLAB/Simulink platform for studying large-scale solar PV integration, battery energy management, grid-connected inverter control, power balance, and renewable energy system performance.