MATLAB Simulation of Grid Connected PV System with SEPIC Converter

MATLAB Simulation of Grid Connected PV System with SEPIC Converter

𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧

The MATLAB Simulation of Grid Connected PV System with SEPIC Converter demonstrates how solar photovoltaic energy can be extracted efficiently and supplied to a three-phase utility grid using a SEPIC DC–DC converter, Incremental Conductance MPPT, and a voltage source inverter.

Grid Connected PV System With SEPIC Converter in MATLAB

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The simulated PV array is designed for approximately 100 kW operation. The SEPIC converter regulates the PV-side power conversion, while the grid-side inverter maintains the DC-link voltage and transfers the generated real power to the grid.    Pasted text

This model is useful for understanding:

• PV array modelling

• SEPIC converter operation

• Incremental Conductance MPPT

• DC-link voltage regulation

• Grid synchronization

• dq-axis current control

• Feedforward decoupling control

• Grid power injection under changing solar irradiation

𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰

The complete system consists of the following major sections:

PV Array → SEPIC Converter → DC Link → Voltage Source Inverter → LCL Filter → Three-Phase Grid

The control system includes:

• Incremental Conductance MPPT

• SEPIC converter switching control

• DC-link voltage controller

• abc-to-dq transformation

• Phase-Locked Loop

• d-axis current controller

• q-axis current controller

• Feedforward decoupling control

• Inverse dq-to-abc transformation

• PWM pulse generation

The PV array consists of 10 modules connected in series and 47 parallel strings.    Pasted text

𝐏𝐕 𝐀𝐫𝐫𝐚𝐲 𝐏𝐚𝐫𝐚𝐦𝐞𝐭𝐞𝐫𝐬

Parameter	Value
Single PV Module Power	213.15 W
Open-Circuit Voltage	36.3 V
Voltage at Maximum Power Point	29.9 V
Short-Circuit Current	7.84 A
Current at Maximum Power Point	7.35 A
Series-Connected Modules	10
Parallel Strings	47
Approximate Array Rating	100 kW

The PV module electrical ratings and array configuration are taken directly from the simulated system description.    Pasted text

𝐏𝐕 𝐀𝐫𝐫𝐚𝐲 𝐏𝐞𝐫𝐟𝐨𝐫𝐦𝐚𝐧𝐜𝐞 𝐔𝐧𝐝𝐞𝐫 𝐃𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐭 𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞

The model evaluates the PV array under different solar irradiation conditions.

Irradiance	Maximum PV Power	Operating Voltage
1000 W/m²	100.2 kW	290 V
500 W/m²	50.75 kW	293.3 V
100 W/m²	9.72 kW	280.2 V

These operating points illustrate how solar irradiation directly affects the available PV power while the MPPT controller attempts to maintain operation near the maximum power point.    Pasted text

𝐒𝐄𝐏𝐈𝐂 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫

A SEPIC converter is placed between the PV array and the inverter.

Its main responsibilities are:

• Interface the PV array with the common DC link

• Regulate the PV operating voltage

• Receive switching commands from the MPPT controller

• Support maximum power extraction

• Raise the converter output voltage toward the required DC-link level

The converter is designed around an approximate PV-side input voltage of 290 V and an output voltage of 600 V. Its main passive elements include L1, L2, C1, and C2.    Pasted text

𝐒𝐄𝐏𝐈𝐂 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫 𝐑𝐚𝐭𝐢𝐧𝐠𝐬

Parameter	Value
Approximate Power Rating	100.2 kW
Input Voltage	Around 290 V
Output/DC-Link Voltage	600 V
Main Passive Components	L1, L2, C1, C2
Control Method	Incremental Conductance MPPT

𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬

The overall operating sequence is simple:

1. The PV array generates DC power according to the available irradiation.

2. PV voltage and current are continuously measured.

3. These measurements are supplied to the Incremental Conductance MPPT controller.

4. The MPPT controller determines the required duty-cycle adjustment.

5. The duty cycle is converted into a switching pulse for the SEPIC converter.

6. The SEPIC converter regulates the PV operating point and supplies the DC link.

7. The DC-link voltage is maintained at approximately 600 V.

8. The voltage source inverter converts DC power into three-phase AC power.

9. The inverter output passes through an LCL filter.

10. The filtered AC power is injected into the utility grid.

𝐈𝐧𝐜𝐫𝐞𝐦𝐞𝐧𝐭𝐚𝐥 𝐂𝐨𝐧𝐝𝐮𝐜𝐭𝐚𝐧𝐜𝐞 𝐌𝐏𝐏𝐓

The system uses Incremental Conductance MPPT for extracting maximum available solar power.

The controller monitors:

• PV voltage

• PV current

• Change in voltage

• Change in current

• Change in power

• Previous duty cycle

• Present duty cycle

A parameter based on the absolute change in PV power with respect to voltage variation is used as part of the MPP decision process. A threshold value of 0.05 is used in the described controller to identify operation close to the maximum power point.    Pasted text

𝐌𝐏𝐏𝐓 𝐎𝐩𝐞𝐫𝐚𝐭𝐢𝐨𝐧

The controller follows these basic actions:

• If the PV array is already operating close to MPP, the previous duty cycle is maintained.

• If operating conditions move away from MPP, the duty cycle is increased or decreased.

• PV voltage is therefore shifted toward the maximum-power operating region.

• Duty-cycle limits are checked before applying the switching command.

• Updated voltage, current, power, and duty-cycle values are retained for the next control iteration.

The generated duty cycle is compared with a sawtooth waveform to produce the switching pulse for the SEPIC converter IGBT.    Pasted text

𝐆𝐫𝐢𝐝 𝐒𝐢𝐝𝐞 𝐂𝐨𝐧𝐟𝐢𝐠𝐮𝐫𝐚𝐭𝐢𝐨𝐧

The output of the SEPIC converter is connected to a three-phase voltage source inverter.

Grid Parameter	Value
Grid Voltage	Around 400 V
Grid Frequency	50 Hz
DC-Link Reference	600 V
Grid Interface	LCL Filter
Inverter Type	Voltage Source Inverter

The inverter output is connected to the grid through an LCL filter, which helps reduce switching-related current harmonics.    Pasted text

𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲

The grid-side inverter is controlled using dq-axis control with feedforward decoupling.

1. 𝐃𝐂-𝐋𝐢𝐧𝐤 𝐕𝐨𝐥𝐭𝐚𝐠𝐞 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

The actual DC-link voltage is compared with the reference value of:

600 V

The resulting error is processed by a PI controller.

The controller output becomes the d-axis current reference, Id*.    Pasted text

2. 𝐏𝐋𝐋 𝐚𝐧𝐝 𝐝𝐪 𝐓𝐫𝐚𝐧𝐬𝐟𝐨𝐫𝐦𝐚𝐭𝐢𝐨𝐧

The system uses a Phase-Locked Loop to obtain the electrical angle required for coordinate transformation.

The measured three-phase quantities are converted as follows:

• Grid/inverter voltage → Vd and Vq

• Inverter current → Id and Iq

This makes independent control of active and reactive current components easier.    Pasted text

3. 𝐝-𝐀𝐱𝐢𝐬 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

The d-axis current mainly controls the transfer of real power.

• Id reference comes from the DC-link voltage controller.

• Actual Id is compared with the reference.

• The error passes through a PI controller.

• Feedforward decoupling is then applied.

4. 𝐪-𝐀𝐱𝐢𝐬 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

For the simulated operating condition, the system focuses mainly on supplying real power from PV to the grid.

Therefore:

Iq reference = 0

The actual Iq is regulated through another PI controller with q-axis feedforward decoupling.    Pasted text

5. 𝐏𝐖𝐌 𝐆𝐞𝐧𝐞𝐫𝐚𝐭𝐢𝐨𝐧

The controlled d-axis and q-axis voltage commands are converted back into three-phase references using inverse transformation.

These references are then compared with a carrier waveform to generate the inverter PWM signals.    Pasted text

𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞 𝐏𝐫𝐨𝐟𝐢𝐥𝐞

The simulation intentionally changes solar irradiation to test the response of the MPPT controller, converter, inverter, and grid interface.

Simulation Interval	Irradiance
0 to 0.4 s	1000 W/m²
Around 0.5 to 0.8 s	800 W/m²
Around 0.9 to 1.2 s	500 W/m²
Around 1.3 to 1.6 s	300 W/m²

The irradiation changes are used to demonstrate how the PV power and grid current adjust dynamically with available solar energy.    Pasted text

𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬

The simulation demonstrates a clear relationship between irradiation and PV power.

𝐀𝐭 1000 𝐖/𝐦²

• PV power is approximately 100 kW.

• Grid voltage remains sinusoidal.

• Grid current is also sinusoidal after the initial transient.

• Maximum power is transferred toward the grid.

𝐀𝐭 800 𝐖/𝐦²

• PV output falls to approximately 80 kW.

• A small transient occurs during the irradiation change.

• Grid current magnitude reduces accordingly.

𝐀𝐭 500 𝐖/𝐦²

• PV output reduces to approximately 50 kW.

• The grid current amplitude reduces further.

• The inverter continues transferring available PV energy.

The source transcript also describes the final 300 W/m² interval as producing a lower PV power and reduced grid current. One spoken numerical value in that section appears inconsistent with the surrounding trend, so it is safer to describe the final result qualitatively rather than reproduce that number as a verified value.    Pasted text

𝐑𝐞𝐬𝐮𝐥𝐭 𝐒𝐮𝐦𝐦𝐚𝐫𝐲

Irradiance Condition	Approximate PV Power	Grid Response
1000 W/m²	100 kW	Highest grid-current magnitude
800 W/m²	80 kW	Current decreases
500 W/m²	50 kW	Further reduction in grid current
300 W/m²	Lower than 500 W/m² case	Lowest current among tested levels

The results show that the injected grid current follows the available PV power while the grid voltage remains controlled by the utility source.

𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬

• Approximately 100 kW grid-connected PV system

• SEPIC DC–DC converter

• Incremental Conductance MPPT

• Variable irradiation testing

• 600 V DC-link regulation

• Three-phase voltage source inverter

• 400 V, 50 Hz grid connection

• LCL output filter

• PLL-based synchronization

• abc-to-dq transformation

• dq current control

• PI-based voltage and current regulation

• Feedforward decoupling

• Zero q-axis current reference for real-power-oriented operation

• PWM inverter control

• PV power and grid power monitoring

𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐨𝐧𝐬

This MATLAB/Simulink model can support learning and research in:

• Grid-connected solar PV systems

• Renewable energy conversion

• SEPIC converter control

• MPPT algorithm development

• Three-phase inverter control

• Grid synchronization studies

• DC-link voltage regulation

• dq-axis current control

• Solar power variation analysis

• Power-electronics education

• Renewable energy laboratory studies

• Advanced converter and inverter control research

𝐖𝐡𝐚𝐭 𝐂𝐚𝐧 𝐁𝐞 𝐋𝐞𝐚𝐫𝐧𝐞𝐝 𝐟𝐫𝐨𝐦 𝐭𝐡𝐞 𝐌𝐨𝐝𝐞𝐥?

Students, researchers, and engineers can understand:

• How a large PV array is configured in MATLAB/Simulink

• How PV output changes with irradiation

• How Incremental Conductance MPPT tracks maximum power

• How a SEPIC converter interfaces the PV array with the DC link

• How a DC-link voltage controller generates active-current demand

• How PLL synchronization is implemented

• How three-phase variables are converted into dq quantities

• How Id and Iq are independently controlled

• How an inverter injects available PV power into the grid

• How grid current changes when PV generation decreases

𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧

The MATLAB Simulation of Grid Connected PV System with SEPIC Converter provides a complete example of solar power conversion from the PV array to the utility grid.

The model combines Incremental Conductance MPPT, a SEPIC converter, 600 V DC-link regulation, dq-axis inverter control, PLL synchronization, feedforward decoupling, and an LCL grid interface.

Simulation under changing irradiation demonstrates that the controller adjusts the PV operating point and grid current according to the available solar energy. This makes the model useful for studying practical concepts in solar PV systems, MPPT, DC–DC converters, inverter control, and grid integration.