MATLAB Simulation of 30 MW Grid Connected Solar PV System with P&O MPPT
MATLAB Simulation of 30 MW Grid Connected Solar PV System with P&O MPPT
𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧
A large-scale grid-connected solar photovoltaic system requires efficient maximum power extraction, stable DC-link voltage control, proper inverter synchronization, and good grid-current quality.
This MATLAB/Simulink model demonstrates a 30 MW grid-connected solar PV system using a Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) algorithm.
The complete system includes:
30 MW solar PV array
DC–DC boost converter
P&O MPPT controller
DC-link capacitor
Three-phase grid-connected inverter
Voltage and current control loops
Synchronous reference frame control
Three-phase grid interface
Grid-current harmonic analysis
Irradiance variation testing
The simulation shows how the PV system extracts maximum available solar power and transfers it to an 11 kV, 50 Hz utility grid.
𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰
The power flow of the system is:
Solar PV Array → Boost Converter → DC Link → Three-Phase Inverter → Filter → Utility Grid
The boost converter performs maximum power point tracking, while the inverter converts the DC power into three-phase AC power suitable for grid integration.
Main System Parameters
Parameter | Value |
PV system rated power | 30 MW |
PV operating voltage near MPP | Approximately 5000 V |
PV current at full irradiance | Approximately 6000 A |
DC-link reference voltage | Approximately 20 kV |
Grid voltage | 11 kV |
Grid frequency | 50 Hz |
Maximum irradiance | 1000 W/m² |
Reduced irradiance | 100 W/m² |
MPPT technique | P&O MPPT |
Power converter | DC–DC Boost Converter |
Grid converter | Three-Phase Inverter |
𝐌𝐚𝐢𝐧 𝐂𝐨𝐦𝐩𝐨𝐧𝐞𝐧𝐭𝐬
1. Solar PV Array
The PV array acts as the main renewable energy source.
Its output mainly depends on:
Solar irradiance
PV operating voltage
PV operating current
PV array configuration
A PV array has a nonlinear power-voltage characteristic. Therefore, simply connecting the PV array to a converter does not guarantee maximum power extraction.
An MPPT controller is required to continuously identify the operating point where the available PV power is maximum.
2. DC–DC Boost Converter
The PV array is connected to the DC link through a boost converter.
The boost converter provides two important functions:
Controls the operating voltage of the PV array
Supports maximum power extraction using the MPPT duty cycle
Important factors considered while designing a high-power boost converter include:
PV array rated power
PV terminal voltage
Required DC-link voltage
Switching frequency
Permissible inductor-current ripple
Permissible capacitor-voltage ripple
The calculated duty cycle from the P&O MPPT controller is converted into switching pulses for the boost converter.
𝐏&𝐎 𝐌𝐏𝐏𝐓 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
The Perturb and Observe method is one of the commonly used conventional MPPT techniques for photovoltaic systems.
The controller continuously observes changes in:
PV voltage
PV power
It compares the present operating condition with the previous operating condition and decides whether the PV operating voltage should be increased or decreased.
Basic P&O Decision Process
PV Power Change | PV Voltage Change | Required PV Voltage Movement |
Increasing | Increasing | Increase PV voltage |
Decreasing | Decreasing | Increase PV voltage |
Decreasing | Increasing | Decrease PV voltage |
Increasing | Decreasing | Decrease PV voltage |
For a boost converter, the required PV-voltage adjustment is achieved by changing the converter duty cycle.
The MPPT controller therefore keeps moving the operating point toward the maximum power region of the PV array.
𝐏&𝐎 𝐌𝐏𝐏𝐓 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
The MPPT controller performs the following operations continuously:
Measures the instantaneous PV voltage
Measures the instantaneous PV current
Determines the corresponding PV power
Compares present and previous operating conditions
Identifies the direction of maximum power
Adjusts the boost-converter duty cycle
Limits the duty cycle between predefined minimum and maximum values
Updates the previous operating values
Repeats the process during the simulation
Important controller settings include:
Initial duty cycle
Minimum duty cycle
Maximum duty cycle
Small duty-cycle perturbation step
This continuous process allows the PV system to follow the changing maximum power point when solar irradiance changes.
𝐓𝐡𝐫𝐞𝐞-𝐏𝐡𝐚𝐬𝐞 𝐆𝐫𝐢𝐝-𝐂𝐨𝐧𝐧𝐞𝐜𝐭𝐞𝐝 𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫
The DC power obtained from the PV and boost converter cannot be directly supplied to the AC grid.
A three-phase voltage source inverter converts the DC power into AC power.
The inverter control system performs two major functions:
DC-link voltage regulation
Grid-current control
The generated AC power is transferred to the 11 kV utility grid through the grid-side interface and filter inductance.
𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲
DC-Link Voltage Control
The DC-link voltage is maintained at approximately 20 kV.
The measured DC-link voltage is compared with its reference value.
The resulting control signal is processed by a controller to generate the required d-axis current reference.
This outer voltage-control loop helps maintain a stable DC bus even when the PV-generated power changes.
Grid Current Control
The measured three-phase grid currents are transformed into synchronous rotating reference-frame components.
The controller mainly works with:
d-axis current
q-axis current
The d-axis component is primarily associated with active-power transfer.
The q-axis reference is maintained around zero because the simulation focuses mainly on transferring real power from the PV system to the grid.
The controlled signals are then transformed back into three-phase quantities and used to generate the switching commands for the inverter.
𝐒𝐲𝐧𝐜𝐡𝐫𝐨𝐧𝐨𝐮𝐬 𝐑𝐞𝐟𝐞𝐫𝐞𝐧𝐜𝐞 𝐅𝐫𝐚𝐦𝐞 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
The grid-current controller uses a synchronous reference frame approach.
The control process consists of:
Measuring three-phase grid current
Converting three-phase quantities into rotating-frame quantities
Comparing actual currents with reference currents
Processing the current errors through controllers
Generating inverter voltage-control references
Converting them back into three-phase signals
Generating six switching pulses for the inverter
This control structure allows independent regulation of active and reactive current components.
𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞 𝐕𝐚𝐫𝐢𝐚𝐭𝐢𝐨𝐧 𝐓𝐞𝐬𝐭
The system is tested under a large change in solar irradiance.
Irradiance Test Conditions
Operating Condition | Irradiance |
High solar condition | 1000 W/m² |
Low solar condition | 100 W/m² |
High irradiance restored | 1000 W/m² |
The irradiance is changed during the simulation to observe the dynamic performance of:
PV voltage
PV current
PV power
DC-link voltage
Grid current
Inverter current
Grid power
Inverter power
This test demonstrates whether the MPPT and grid controller can respond correctly to rapid solar-power variations.
𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
At 1000 W/m²
Under high irradiance:
PV voltage remains close to 5000 V
PV current reaches approximately 6000 A
PV output power reaches approximately 30 MW
Grid and inverter currents remain sinusoidal
The generated PV power is delivered to the utility grid
DC-link voltage remains close to its reference value
When Irradiance Drops to 100 W/m²
When solar irradiance decreases:
PV current decreases significantly
PV output power decreases
Grid current decreases
Inverter current decreases
Grid active power decreases
Inverter active power decreases
MPPT continues adjusting the PV operating point
DC-link voltage regulation remains active
The reduction in current is expected because PV current is strongly influenced by solar irradiance.
When Irradiance Returns to 1000 W/m²
When the irradiance increases again:
PV current rises
PV power returns toward its rated operating region
Grid current increases
Inverter current increases
Grid power increases
Inverter power increases
PV voltage returns close to the maximum-power operating voltage
The P&O MPPT controller automatically tracks the changed maximum power point.
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬
The simulation monitors several important signals.
PV-Side Measurements
Solar irradiance
PV voltage
PV current
PV output power
At full irradiance, the system produces approximately:
Quantity | Approximate Result |
Irradiance | 1000 W/m² |
PV voltage | 5000 V |
PV current | 6000 A |
PV power | 30 MW |
Grid and Inverter Measurements
The simulation also monitors:
Three-phase grid voltage
Three-phase grid current
Inverter voltage
Inverter current
Grid active power
Inverter active power
The current waveforms remain approximately sinusoidal during both high- and low-irradiance operating conditions.
DC-Link Performance
The DC-link voltage is regulated close to:
20 kV
Small variations can occur during rapid irradiance transitions because the available PV power changes suddenly.
The voltage controller acts to restore and maintain the required DC-link operating level.
𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐓𝐇𝐃 𝐀𝐧𝐚𝐥𝐲𝐬𝐢𝐬
Grid-current quality is an important consideration in grid-connected power converters.
FFT analysis is performed at different simulation instants.
Measured THD Values
Analysis Time | Current THD |
0.5 s | 0.81% |
1.2 s | 0.86% |
1.8 s | 0.47% |
Similar harmonic performance is observed for the inverter current.
These values remain well below the 5% level considered in the simulation assessment, indicating low current waveform distortion during the tested operating conditions.
𝐌𝐏𝐏𝐓 𝐑𝐞𝐬𝐩𝐨𝐧𝐬𝐞 𝐔𝐧𝐝𝐞𝐫 𝐕𝐚𝐫𝐲𝐢𝐧𝐠 𝐒𝐨𝐥𝐚𝐫 𝐂𝐨𝐧𝐝𝐢𝐭𝐢𝐨𝐧𝐬
One of the important observations from the simulation is the relationship between irradiance and PV power.
When irradiance decreases:
Irradiance ↓ → PV Current ↓ → PV Power ↓ → Grid Power ↓
When irradiance increases:
Irradiance ↑ → PV Current ↑ → PV Power ↑ → Grid Power ↑
Throughout these variations, the P&O controller continuously adjusts the boost-converter switching duty cycle to keep the PV array close to its maximum available power point.
𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬
30 MW utility-scale solar PV system
P&O MPPT for maximum power extraction
High-power DC–DC boost converter
Approximately 20 kV DC-link
Three-phase voltage source inverter
11 kV, 50 Hz grid connection
DC-link voltage regulation
d-q current control
Active-power transfer to the utility grid
Zero reactive-current reference operation
Dynamic irradiance variation
PV voltage, current and power monitoring
Grid voltage and current monitoring
Inverter voltage and current monitoring
Grid and inverter power measurement
FFT-based current THD analysis
Low current harmonic distortion during the simulated conditions
𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬
This MATLAB/Simulink model is useful for studying:
Utility-scale solar PV generation
Grid-connected renewable energy systems
Solar power conversion
Maximum power point tracking
P&O MPPT operation
High-power DC–DC converters
Three-phase grid-connected inverters
DC-link voltage control
Synchronous reference frame control
Active and reactive current control
Solar irradiance variation
Power-quality analysis
Grid-current harmonic analysis
Renewable-energy integration
It is suitable for students, researchers and power-electronics engineers who want to understand the complete operation of a large-scale grid-connected PV system.
𝐖𝐡𝐚𝐭 𝐘𝐨𝐮 𝐂𝐚𝐧 𝐋𝐞𝐚𝐫𝐧 𝐟𝐫𝐨𝐦 𝐓𝐡𝐢𝐬 𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧
After studying this model, you can understand:
Why MPPT is necessary for a PV array
How the P&O algorithm tracks maximum PV power
How a boost converter controls the PV operating point
How DC power is converted into three-phase AC power
How the DC-link voltage is regulated
How d-q current control is applied to a grid-connected inverter
How solar irradiance affects PV current and power
How generated PV power is transferred to the grid
How grid-current THD can be analyzed using FFT tools
How a large-scale PV plant responds to changing environmental conditions
𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧
The MATLAB Simulation of 30 MW Grid Connected Solar PV System with P&O MPPT demonstrates the complete power conversion and control process from solar generation to utility-grid integration.
The P&O MPPT controller continuously adjusts the PV operating point to extract the available maximum power. The boost converter interfaces the PV array with the DC link, while the three-phase inverter transfers the generated active power to the 11 kV grid.
Under changing irradiance conditions, the simulation shows corresponding changes in PV current, PV power, inverter current and grid power while maintaining DC-link regulation. The measured current THD values of approximately 0.47% to 0.86% during the analyzed intervals indicate low harmonic distortion in the simulated current waveforms.
Overall, the model provides a clear platform for understanding large-scale solar PV generation, P&O MPPT, DC–DC conversion, grid-connected inverter control and power-quality analysis in MATLAB/Simulink.
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