Three Phase Grid Connected Solar PV and Battery System
Three Phase Grid Connected Solar PV and Battery System
𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧
The Three Phase Grid Connected Solar PV and Battery System is a MATLAB/Simulink-based renewable energy system that combines a solar photovoltaic array, battery energy storage, DC loads, AC loads, and a three-phase utility grid.
The system is designed to demonstrate:
Maximum power extraction from the solar PV array.
Bidirectional power flow between the battery and DC bus.
Grid power import and export.
DC-bus voltage regulation.
Three-phase inverter current control.
Battery charging and discharging under changing solar irradiance.
Incremental Conductance MPPT operation.
Grid-current harmonic performance under different operating conditions.
This model is suitable for students, researchers, and engineers studying grid-connected renewable energy systems, battery storage, power electronics, MPPT, and inverter control.
𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰
The complete system contains five major sections:
Solar PV array
Boost converter
Battery with bidirectional DC–DC converter
Three-phase grid-connected inverter
DC and AC loads
The solar PV array supplies power to the common DC bus through a boost converter. The battery is connected through a bidirectional converter so that it can either absorb excess energy or supply power during a shortage.
The DC bus is then connected to the three-phase grid through a controlled inverter.
Main system specifications
Parameter | Value |
PV module rated power | 250 W |
PV modules in series | 15 |
Parallel strings | 2 |
Total PV modules | 30 |
Approximate PV array rating | 7.5 kW |
Module voltage at maximum power | 30.7 V |
Module current at maximum power | 8.15 A |
PV array operating voltage near MPP | 460.5 V |
DC-bus reference voltage | 700 V |
Grid line-to-line voltage | 400 V |
Grid frequency | 50 Hz |
DC load power | 2.5 kW |
AC load power | 2 kW |
𝐒𝐨𝐥𝐚𝐫 𝐏𝐕 𝐀𝐫𝐫𝐚𝐲
The PV system uses 250 W solar modules arranged as:
15 modules connected in series.
2 parallel strings.
Total installed PV capacity of approximately 7.5 kW.
At standard operating conditions, the complete series string develops an MPP voltage of approximately 460.5 V.
The PV output changes according to solar irradiance, making MPPT control necessary to continuously extract the available maximum power.
PV operating details
Item | Value |
Individual PV module power | 250 W |
Vmpp | 30.7 V |
Impp | 8.15 A |
Series modules | 15 |
Parallel strings | 2 |
Approximate total PV power | 7,500 W |
PV voltage around MPP | 460.5 V |
Under high irradiance, the simulated PV output reaches approximately 7.5 kW.
𝐁𝐨𝐨𝐬𝐭 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫
A boost converter is placed between the PV array and the common DC bus.
Its major functions are:
Increasing the PV-side voltage to the required DC-link level.
Providing an interface for MPPT control.
Transferring maximum available PV power to the DC system.
Supporting the DC load and inverter.
The PV-side voltage is approximately 460.5 V, while the DC bus is maintained at approximately 700 V.
Boost-converter design parameters
Parameter | Value |
Input voltage | 460.5 V |
Rated input power | Approximately 7.5 kW |
Output/DC-bus voltage | 700 V |
Switching frequency | 10 kHz |
Control method | Incremental Conductance MPPT |
Controlled device | IGBT-based boost converter |
The inductance and capacitance are selected based on the required power rating, switching frequency, current ripple, and DC voltage ripple.
𝐖𝐡𝐲 𝐚 𝟕𝟎𝟎 𝐕 𝐃𝐂 𝐁𝐮𝐬?
The three-phase utility grid operates at approximately 400 V line-to-line.
For proper inverter operation, the DC-link voltage must be sufficiently higher than the grid voltage. The selected operating range is approximately 600–800 V, and the midpoint value of:
700 V
is selected as the DC-bus reference.
This provides sufficient voltage margin for the grid-connected inverter while maintaining stable power conversion.
𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐄𝐧𝐞𝐫𝐠𝐲 𝐒𝐭𝐨𝐫𝐚𝐠𝐞
A lithium-based battery bank is connected to the DC bus through a bidirectional DC–DC converter.
The battery can operate in two different modes:
Charging mode – battery absorbs excess power.
Discharging mode – battery supplies power when PV generation is insufficient.
The simulation description uses a battery arrangement containing 35 series-connected battery units, with a nominal rating of 48 V per unit.
Battery-side details
Parameter | Description |
Battery technology | Lithium battery |
Series-connected units | 35 |
Nominal unit voltage | 48 V |
Converter | Bidirectional DC–DC converter |
Converter switching frequency | 10 kHz |
DC-bus reference | 700 V |
Main operating modes | Charge and discharge |
𝐁𝐢𝐝𝐢𝐫𝐞𝐜𝐭𝐢𝐨𝐧𝐚𝐥 𝐃𝐂–𝐃𝐂 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫
The bidirectional converter is one of the most important parts of the system because the battery must behave as both an energy source and an energy storage device.
Its power-flow direction depends on:
Available PV power.
DC-load requirement.
Grid power exchange.
Battery state of charge.
DC-bus voltage.
When surplus energy is available, the converter charges the battery.
When renewable generation decreases, the converter reverses its power direction and allows the battery to support the DC bus.
𝐃𝐂-𝐁𝐮𝐬 𝐕𝐨𝐥𝐭𝐚𝐠𝐞 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
The bidirectional converter also plays an important role in maintaining the DC bus at the required voltage.
The control system:
Measures the actual DC-bus voltage.
Compares it with the 700 V reference.
Processes the voltage error through a PI controller.
Generates the required duty cycle.
Produces converter switching pulses through the PWM generator.
As a result, the DC bus remains close to 700 V despite changes in PV power and battery operating mode.
𝐆𝐫𝐢𝐝-𝐂𝐨𝐧𝐧𝐞𝐜𝐭𝐞𝐝 𝐓𝐡𝐫𝐞𝐞-𝐏𝐡𝐚𝐬𝐞 𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫
The common DC bus is connected to the utility grid through a three-phase voltage-source inverter.
The inverter allows power to flow:
From the PV/battery system to the utility grid.
From the utility grid to the DC system.
Toward the connected AC load.
A filter is included between the inverter and grid to improve current and voltage waveform quality.
Inverter and grid parameters
Parameter | Value |
Grid voltage | 400 V line-to-line |
Grid frequency | 50 Hz |
DC-link voltage | 700 V |
Inverter/filter design power | Approximately 8 kW |
Inverter switching frequency used in design | 1.5 kHz |
AC load power | Approximately 2 kW |
Control approach | dq current control |
𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲
The inverter uses a synchronous reference frame current-control approach.
The main control stages include:
Measurement of the three-phase inverter/grid currents.
Measurement of the grid-side voltage.
Grid synchronization using a PLL.
Generation of sine and cosine synchronization signals.
Conversion of three-phase variables into the dq reference frame.
Comparison of measured current with the reference current.
PI-based current regulation.
dq-to-ABC conversion.
PWM pulse generation.
Control of the three-phase inverter switching devices.
The q-axis current reference is maintained at zero, allowing the controller to focus primarily on active-power transfer.
𝐆𝐫𝐢𝐝 𝐈𝐦𝐩𝐨𝐫𝐭 𝐚𝐧𝐝 𝐄𝐱𝐩𝐨𝐫𝐭 𝐋𝐨𝐠𝐢𝐜
Grid power flow is decided using the PV current and battery SOC.
Two important operating conditions are demonstrated.
PV/Battery Condition | Current Reference | Operating Mode |
PV current below approximately 0.5 and SOC below 10% | Around +10 A | Grid supplies power |
PV current above approximately 0.5 and SOC above 10% | Around −3 A | System sends power toward grid |
This simple energy-management logic allows the system to automatically switch between grid import and export.
When battery SOC is healthy
If sufficient PV power is available and the battery SOC is above the minimum threshold:
PV supplies the local loads.
Battery charging may take place.
Surplus power can be transferred toward the grid.
When battery SOC is low
If PV generation becomes very low and battery SOC falls below approximately 10%:
Power is taken from the utility grid.
The grid supports the AC load.
Additional energy is supplied to the DC side.
The battery can be charged.
𝐈𝐧𝐜𝐫𝐞𝐦𝐞𝐧𝐭𝐚𝐥 𝐂𝐨𝐧𝐝𝐮𝐜𝐭𝐚𝐧𝐜𝐞 𝐌𝐏𝐏𝐓
The solar PV boost converter is controlled using an Incremental Conductance MPPT algorithm.
The MPPT controller continuously monitors:
PV voltage.
PV current.
PV power.
Change in PV voltage.
Change in PV current.
Change in PV power.
The controller then decides whether the operating point is:
Below the maximum power point.
At the maximum power point.
Above the maximum power point.
Based on this decision, the boost-converter duty cycle is:
Increased,
Decreased, or
Maintained.
The calculated duty cycle is sent to the PWM generator, which controls the boost-converter IGBT.
𝐌𝐏𝐏𝐓 𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
The Incremental Conductance controller follows this basic sequence:
Measure PV voltage and current.
Calculate present PV power.
Compare present measurements with previous measurements.
Determine the direction of the MPP.
Modify the duty cycle.
Check minimum and maximum duty-cycle limits.
Generate PWM pulses.
Update stored voltage, current, power, and duty-cycle values.
Repeat continuously.
This allows the PV array to respond to rapidly varying solar irradiance.
𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
The complete energy flow can be summarized as follows:
Solar PV → Boost Converter → 700 V DC Bus → Three-Phase Inverter → AC Load/Grid
and
Battery ↔ Bidirectional DC–DC Converter ↔ 700 V DC Bus
During high solar generation
PV operates near maximum power.
DC load is supplied.
AC load receives power through the inverter.
Battery may charge.
Surplus energy can be transferred to the grid.
During reduced solar generation
PV contribution decreases.
Battery starts supporting the DC bus.
Battery discharge current increases as the solar contribution becomes smaller.
During very low solar generation
PV power approaches zero.
Battery supplies energy if sufficient SOC is available.
If battery SOC is below the threshold, grid import is activated.
When solar generation recovers
PV output increases again.
Battery discharge current decreases.
Battery may return to charging operation.
Grid import reduces or the system may switch back to export operation.
𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞 𝐓𝐞𝐬𝐭 𝐏𝐫𝐨𝐟𝐢𝐥𝐞
The simulation tests the system under rapidly changing irradiation.
Stage | Solar Irradiance |
Initial condition | 1000 W/m² |
Second condition | 500 W/m² |
Third condition | 10 W/m² |
Fourth condition | 500 W/m² |
Final condition | 1000 W/m² |
The irradiance is changed at approximately 0.3-second intervals to test the transient response of the MPPT, battery, converters, and grid interface.
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬
The simulation monitors several important signals.
PV measurements
PV voltage
PV current
PV power
At high irradiance, the PV system reaches approximately 7.5 kW.
When irradiance drops:
PV current decreases.
PV power decreases.
The MPPT controller tracks the new operating point.
At very low irradiance, PV power approaches zero.
Battery measurements
The battery response changes automatically according to the available renewable power.
Under the 50% initial SOC case:
Battery initially operates according to available PV surplus.
As PV output falls, battery discharge increases.
When irradiance rises again, discharge decreases.
With sufficient PV power, the battery returns toward charging operation.
This demonstrates successful bidirectional energy flow.
DC-bus performance
The DC-side results show:
Quantity | Approximate Value |
DC-bus voltage | 700 V |
DC load power | 2.5 kW |
DC load operating condition | Nearly constant |
Even during changing solar irradiation, the converter control maintains the DC bus close to its 700 V reference.
AC-side performance
The monitored AC quantities include:
Grid voltage.
Inverter current.
Grid current.
AC-load voltage.
AC-load current.
Grid power.
Inverter power.
AC-load power.
The waveforms remain approximately sinusoidal under the demonstrated operating conditions.
𝐓𝐞𝐬𝐭 𝐂𝐚𝐬𝐞 𝟏 – 𝟓𝟎% 𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐒𝐎𝐂
The first test starts with a battery SOC of approximately 50%.
Since the SOC is above the low-SOC threshold:
The battery can participate normally in charging and discharging.
High PV generation supplies the loads.
Surplus PV energy can be stored or exported.
Reduced PV generation causes the battery to support the DC side.
The inverter operates with an approximately 3 A peak current reference during the demonstrated export condition.
This test confirms proper coordination among the PV source, battery, DC load, AC load, and grid.
𝐓𝐞𝐬𝐭 𝐂𝐚𝐬𝐞 𝟐 – 𝟗% 𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐒𝐎𝐂
The second simulation starts with the battery SOC reduced to approximately 9%.
This is below the 10% control threshold.
When PV current also becomes very low:
The energy-management logic detects insufficient PV generation.
Grid-import mode is activated.
The inverter current reference increases to approximately 10 A.
Grid energy supplies the AC load.
Additional power is transferred toward the DC side.
The battery receives charging support.
This test clearly demonstrates the grid-to-system power-flow mode.
𝐏𝐨𝐰𝐞𝐫 𝐅𝐥𝐨𝐰 𝐌𝐨𝐝𝐞𝐬
Mode | PV Condition | Battery Condition | Grid Role |
High PV generation | High | Charging/support | Possible export |
Moderate PV generation | Reduced | May discharge | Balancing role |
Very low PV, normal SOC | Very low | Discharging | Support if required |
Very low PV, SOC below 10% | Very low | Charging required | Imports power |
PV recovery | Increasing | Discharge reduces / charging begins | Import reduces |
𝐇𝐚𝐫𝐦𝐨𝐧𝐢𝐜 𝐀𝐧𝐚𝐥𝐲𝐬𝐢𝐬
The inverter-current THD is evaluated for both grid-import and grid-export operating conditions.
Operating Condition | Current THD |
Power taken from grid | Approximately 1.98% |
Power sent toward grid | Approximately 0.29% |
Both reported values are below 5%, demonstrating good inverter-current waveform quality in the simulated operating cases.
𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬
7.5 kW-class solar PV array
Incremental Conductance MPPT
700 V regulated DC bus
Battery charging and discharging
Bidirectional DC–DC converter
Grid import and grid export
Three-phase inverter control
dq-axis current regulation
PLL-based grid synchronization
PWM switching control
Variable solar irradiance testing
Battery SOC-based power management
DC and AC load integration
Grid-current THD analysis
MATLAB/Simulink implementation
𝐖𝐡𝐲 𝐓𝐡𝐢𝐬 𝐒𝐲𝐬𝐭𝐞𝐦 𝐈𝐬 𝐔𝐬𝐞𝐟𝐮𝐥
The model gives a clear understanding of how multiple energy sources and loads interact within a grid-connected renewable power system.
It helps users study:
Solar PV power conversion.
Maximum power point tracking.
DC-link regulation.
Battery energy storage.
Bidirectional converter control.
Grid-connected inverter operation.
Active-power management.
Battery SOC management.
Variable irradiance response.
Grid synchronization.
Power-quality analysis.
𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬
This system concept is relevant to:
Grid-connected solar energy systems.
Solar-plus-storage systems.
Smart-grid energy management.
Commercial solar installations.
Battery-supported renewable energy systems.
Microgrid research.
Distributed energy resources.
Residential and commercial energy storage.
Renewable-energy power-flow studies.
Power-electronics controller development.
MPPT algorithm evaluation.
Grid-interactive inverter studies.
𝐌𝐚𝐢𝐧 𝐒𝐢𝐠𝐧𝐚𝐥𝐬 𝐌𝐨𝐧𝐢𝐭𝐨𝐫𝐞𝐝
System Section | Measured Signals |
Solar PV | Voltage, current, power |
Battery | Voltage, current, SOC |
DC bus | Voltage |
DC load | Current, power |
Grid | Three-phase voltage and current |
Inverter | Three-phase current |
AC load | Voltage and current |
Power flow | Grid, inverter, and load power |
These measurements make it easier to understand how energy moves through the complete system during different operating conditions.
𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧
The Three Phase Grid Connected Solar PV and Battery System demonstrates coordinated operation of solar generation, battery storage, DC loads, AC loads, and the utility grid.
The MATLAB/Simulink model successfully illustrates:
Maximum power extraction using Incremental Conductance MPPT.
Boost conversion from the PV side to a 700 V DC bus.
Bidirectional battery charging and discharging.
Grid power import during low PV and low battery SOC.
Grid export when renewable power and battery conditions permit.
Stable DC-bus voltage regulation.
Three-phase inverter current control.
Low inverter-current harmonic distortion.
With approximately 7.5 kW of PV generation, a 2.5 kW DC load, a 2 kW AC load, variable irradiance, and two different battery SOC operating cases, the simulation provides a useful platform for understanding modern solar PV–battery–grid energy management and power-electronic control.
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