6.5 MW grid connected PV system in MATLAB
6.5 MW grid connected PV system in MATLAB
𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧
The 6.5 MW grid connected PV system in MATLAB demonstrates the modeling, sizing, MPPT control, DC-link regulation, and grid integration of a large-scale solar photovoltaic system using MATLAB/Simulink.
The complete model includes:
A large-scale PV array
A DC–DC boost converter
P&O MPPT control
A regulated 20 kV DC link
A three-phase grid-connected inverter
Grid synchronization using a PLL
dq-axis voltage and current control
An inverter-side filter inductor
An 11 kV, 50 Hz utility grid
PV, inverter, grid, power, and DC-link measurements
The simulation also demonstrates how the generated PV power and grid current change when the solar irradiance is varied.
𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰
The overall power conversion path is:
PV Array → Boost Converter → DC Link → Three-Phase Inverter → Filter Inductor → 11 kV Grid
The PV array produces DC power according to the available solar irradiance. The boost converter increases the PV-side voltage and is controlled using the Perturb and Observe MPPT algorithm.
The inverter then converts the DC power into synchronized three-phase AC power and transfers it to the utility grid.
Main System Specifications
Parameter | Value |
PV system rated power | 6.5 MW |
Single PV module power | 360 W |
Module voltage at maximum power | 38.6 V |
Module current at maximum power | 9.33 A |
Series-connected modules | 130 |
Parallel strings | 139 |
Approximate number of modules | 18,070 |
PV array operating voltage | 5018 V |
Standard irradiance | 1000 W/m² |
Standard temperature | 25°C |
Boost converter output / DC link | 20 kV |
Boost switching frequency | 10 kHz |
Grid voltage | 11 kV |
Grid frequency | 50 Hz |
𝐏𝐕 𝐀𝐫𝐫𝐚𝐲 𝐒𝐢𝐳𝐢𝐧𝐠
The solar array is developed using a 360 W PV module.
Each module operates approximately at:
PV Module Parameter | Rating |
Rated power | 360 W |
Maximum-power voltage | 38.6 V |
Maximum-power current | 9.33 A |
Series Module Selection
A total of 130 PV modules are connected in series.
With this configuration, the PV array voltage at its maximum-power operating region is approximately:
5018 V
This relatively high PV voltage is suitable for interfacing the multi-megawatt solar array with the high-voltage DC conversion stage.
Parallel String Selection
For the required 6.5 MW PV capacity, the calculated number of parallel strings is approximately 138.8, and the model uses:
139 parallel strings
Therefore, the array contains approximately 18,070 PV modules.
The complete PV array produces approximately 6.5 MW under standard operating conditions.
𝐃𝐂-𝐋𝐢𝐧𝐤 𝐕𝐨𝐥𝐭𝐚𝐠𝐞 𝐒𝐞𝐥𝐞𝐜𝐭𝐢𝐨𝐧
The PV system is connected to an 11 kV three-phase grid.
For the grid-side converter design:
Quantity | Approximate Value |
Grid line-to-line RMS voltage | 11 kV |
Phase RMS voltage | 6.35 kV |
Phase peak voltage | 8.98 kV |
Selected DC-link voltage | 20 kV |
The required DC-link voltage is selected above the corresponding grid-voltage requirement so that the voltage-source inverter has sufficient voltage margin for proper AC voltage generation and grid power transfer.
The model therefore maintains the DC link at approximately 20 kV.
𝐁𝐨𝐨𝐬𝐭 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫
The DC–DC boost converter connects the PV array to the common DC link.
Its main role is to increase the PV operating voltage of approximately 5.018 kV to the required:
20 kV DC-link voltage
Boost Converter Design Inputs
Design Parameter | Value |
PV power | 6.5 MW |
PV-side voltage | ≈ 5018 V |
DC-link voltage | 20 kV |
Switching frequency | 10 kHz |
The converter inductor and capacitor are selected using the required input voltage, output voltage, rated power, switching frequency, allowable inductor-current ripple, and allowable capacitor-voltage ripple.
These components help:
Reduce current ripple
Smooth the converter output
Maintain stable DC-link operation
Support MPPT operation
Provide suitable power to the grid-side inverter
𝐏&𝐎 𝐌𝐏𝐏𝐓 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
The boost converter is controlled using the Perturb and Observe (P&O) Maximum Power Point Tracking algorithm.
The MPPT controller continuously receives:
PV voltage
PV current
The PV power is determined inside the controller and compared with its previous operating condition.
MPPT Controller Parameters
Parameter | Value |
Initial duty cycle | 0.8 |
Maximum duty cycle | 0.9 |
Minimum duty cycle | 0.1 |
Previous voltage initialization | 0 |
Previous power initialization | 0 |
The controller stores the previous:
PV voltage
PV power
Converter duty cycle
These stored values are used during the next control cycle.
𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐨𝐟 𝐏&𝐎 𝐌𝐏𝐏𝐓
The MPPT algorithm continuously checks the change in PV voltage and the corresponding change in PV power.
Depending on the operating position on the PV power-voltage characteristic, the duty cycle of the boost converter is increased or decreased.
When the operating point moves toward the MPP
The controller continues changing the duty cycle in the same beneficial direction.
When the operating point moves away from the MPP
The controller reverses the duty-cycle perturbation.
When there is no meaningful power change
The previous duty-cycle reference is maintained.
The final duty-cycle command is also limited between its predefined minimum and maximum values.
This repeated process enables the PV array to operate near its maximum power point even when solar irradiance changes.
𝐆𝐫𝐢𝐝-𝐒𝐢𝐝𝐞 𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫
A three-phase voltage-source inverter is used to transfer the PV power from the DC link to the utility grid.
The inverter performs two major functions:
Converts DC power into three-phase AC power
Controls the flow of active power into the grid
The inverter output is connected to the grid through an inductive filter.
Grid-Side Parameters
Parameter | Value |
Grid voltage | 11 kV |
Grid frequency | 50 Hz |
DC-link reference | 20 kV |
Reactive-current reference | 0 |
Power flow | PV → Grid |
𝐆𝐫𝐢𝐝 𝐒𝐲𝐧𝐜𝐡𝐫𝐨𝐧𝐢𝐳𝐚𝐭𝐢𝐨𝐧
Correct synchronization between the inverter and the utility grid is essential.
The measured grid voltage is therefore supplied to a Phase-Locked Loop (PLL).
The PLL determines the grid phase angle with respect to time.
This synchronization angle is used for:
abc-to-dq transformation
dq-to-abc transformation
Current regulation
Inverter voltage-reference generation
Synchronization of the inverter output with the grid
Without proper synchronization, stable transfer of several megawatts of PV power to the grid would not be possible.
𝐃𝐂-𝐋𝐢𝐧𝐤 𝐕𝐨𝐥𝐭𝐚𝐠𝐞 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
The measured DC-link voltage is compared with the required 20 kV reference.
The voltage error is processed using a PI controller.
The output of this voltage controller generates the d-axis current reference.
This current reference determines the active-power transfer from the DC link to the AC grid.
Therefore, the outer voltage-control loop helps:
Maintain the DC-link voltage close to 20 kV
Balance PV-side and grid-side power
Generate the active-current reference
Maintain stable power flow during irradiance variation
𝐝𝐪-𝐀𝐱𝐢𝐬 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
The inverter employs a synchronous-reference-frame current-control strategy.
The measured three-phase grid current is first converted into the dq reference frame using Park transformation.
Two current components are controlled:
Current Component | Function |
d-axis current | Controls active-power transfer |
q-axis current | Controls reactive-power transfer |
In this model, the objective is primarily to transfer real power from the PV array to the grid.
Therefore:
q-axis current reference = 0
This allows the inverter to operate approximately at unity power factor while delivering PV-generated real power.
𝐈𝐧𝐧𝐞𝐫 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐋𝐨𝐨𝐩
The measured d-axis and q-axis currents are compared with their respective references.
The resulting current errors are supplied to PI controllers.
The controllers generate:
d-axis control voltage
q-axis control voltage
These control voltages are then converted back to three-phase form using the inverse Park transformation.
The resulting three-phase reference signals are supplied to the inverter modulation stage to generate the switching pulses.
𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫 𝐅𝐢𝐥𝐭𝐞𝐫
An inductive filter is placed between the voltage-source inverter and the utility grid.
Its value is selected based on system parameters including:
PV rated power
DC-link voltage
Grid voltage
Switching frequency
Modulation requirements
Permissible inverter-current ripple
The filter helps suppress the high-frequency switching components generated by the inverter and improves the quality of the current injected into the grid.
𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
The complete operation of the 6.5 MW grid connected PV system can be summarized as follows:
Solar irradiance is applied to the PV array.
The PV array generates DC voltage and current.
PV voltage and current are measured.
The P&O MPPT algorithm determines the required boost-converter duty cycle.
The boost converter extracts maximum available PV power.
The PV voltage is boosted to the 20 kV DC link.
The DC-link controller generates the required active-current reference.
Grid voltage is measured and synchronized using the PLL.
Three-phase grid currents are transformed into dq quantities.
d-axis and q-axis current controllers generate the inverter voltage commands.
The control voltages are transformed back to three-phase references.
Switching pulses control the three-phase inverter.
The filter reduces inverter switching ripple.
The generated solar power is transferred to the 11 kV grid.
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬
Under high solar irradiance, the PV array operates close to its rated condition.
Rated Operating Condition
Measured Quantity | Approximate Result |
PV voltage | ≈ 5 kV |
PV current | ≈ 1.3 kA |
PV power | ≈ 6.5 MW |
DC-link voltage | ≈ 20 kV |
Grid frequency | 50 Hz |
Grid voltage | 11 kV |
The results demonstrate successful conversion of the PV power through the boost converter and inverter before it is supplied to the grid.
𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞 𝐕𝐚𝐫𝐢𝐚𝐭𝐢𝐨𝐧 𝐀𝐧𝐚𝐥𝐲𝐬𝐢𝐬
An important part of the simulation is testing the system under different solar irradiance conditions.
Observed PV Power
Solar Irradiance | PV Power |
1000 W/m² | Approximately 6.5 MW |
800 W/m² | Approximately 5.2 MW |
Lower irradiance test | Approximately 3.27 MW |
At 800 W/m², the PV output reduces to approximately 5.2 MW.
The simulation result closely follows the expected reduction in available solar power.
During the further reduction in irradiance, the PV output decreases to approximately 3.27 MW.
The exact irradiance value for this final test is not clearly stated in the supplied transcript, so it is not assumed here.
𝐄𝐟𝐟𝐞𝐜𝐭 𝐨𝐟 𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞 𝐨𝐧 𝐆𝐫𝐢𝐝 𝐂𝐮𝐫𝐫𝐞𝐧𝐭
One of the important observations from the simulation is the variation in grid-current amplitude.
When solar irradiance decreases:
PV power decreases → inverter power decreases → grid-current amplitude decreases
The grid voltage remains determined by the utility system, while the current injected by the PV inverter changes according to the available solar power.
Therefore:
Higher solar irradiance produces higher grid current.
Lower solar irradiance produces lower grid current.
The current remains synchronized with the grid voltage.
The inverter transfers the available PV power to the grid.
𝐏𝐨𝐰𝐞𝐫 𝐅𝐥𝐨𝐰 𝐎𝐛𝐬𝐞𝐫𝐯𝐚𝐭𝐢𝐨𝐧
The simulation measures power at different locations to verify energy transfer.
PV Power → Boost Converter → DC Link → Inverter Power → Grid Power
The inverter power and grid power follow the available power produced by the PV array.
When the PV generation changes because of irradiance variation, the grid-side power also changes accordingly.
This provides a clear demonstration of dynamic power transfer in a utility-scale grid-connected solar PV system.
𝐌𝐨𝐧𝐢𝐭𝐨𝐫𝐞𝐝 𝐒𝐢𝐠𝐧𝐚𝐥𝐬
The Simulink model monitors several important quantities.
PV Side
PV voltage
PV current
PV power
DC Side
Boost-converter operation
DC-link voltage
Inverter Side
Three-phase inverter voltage
Three-phase inverter current
Inverter active power
Grid Side
Three-phase grid voltage
Three-phase grid current
Grid active power
These signals make it easier to analyze the performance of each stage of the system.
𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲
The complete control architecture contains several coordinated control loops.
Control Stage | Purpose |
P&O MPPT | Extract maximum available PV power |
Boost converter control | Regulate PV operating point |
DC-link voltage controller | Maintain approximately 20 kV |
PLL | Determine grid synchronization angle |
abc–dq transformation | Convert measured AC currents into dq quantities |
d-axis controller | Control active current and power |
q-axis controller | Control reactive-current component |
Inverse dq–abc transformation | Generate three-phase control references |
Inverter modulation | Generate six inverter switching pulses |
The combination of these controllers allows the system to maintain stable grid-connected operation even when PV generation changes.
𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬
6.5 MW utility-scale PV array
360 W PV module-based configuration
130 series modules
139 parallel strings
Approximately 5018 V PV operating voltage
P&O MPPT algorithm
High-power DC–DC boost converter
10 kHz boost switching frequency
Regulated 20 kV DC link
Three-phase voltage-source inverter
11 kV, 50 Hz grid
PLL-based grid synchronization
dq-axis current control
Active-power control through the d-axis
Zero reactive-current reference
Grid-side filter inductor
Variable irradiance testing
Measurement of PV, inverter, DC-link, and grid quantities
𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬
This MATLAB/Simulink model is useful for studying:
Large-scale photovoltaic power plants
Utility-scale solar-grid integration
Maximum power point tracking
High-power DC–DC converters
DC-link voltage regulation
Three-phase grid-connected converters
dq-axis inverter control
PLL-based grid synchronization
Renewable-energy power conversion
Solar irradiance variation
Active-power control
Grid-current analysis
Multi-megawatt power-electronic systems
𝐖𝐡𝐚𝐭 𝐂𝐚𝐧 𝐁𝐞 𝐋𝐞𝐚𝐫𝐧𝐞𝐝 𝐟𝐫𝐨𝐦 𝐓𝐡𝐢𝐬 𝐌𝐨𝐝𝐞𝐥?
Students, researchers, and engineers can use this model to understand the complete flow from individual PV module specifications to multi-megawatt grid integration.
The model clearly demonstrates:
How PV modules are arranged in series and parallel
How a 6.5 MW PV array is configured
How MPPT extracts the available solar power
How a boost converter interfaces the PV array with a high-voltage DC link
How the DC-link voltage is regulated
How the PLL synchronizes the inverter with the grid
How dq-axis current control is implemented
How active power is transferred to the utility network
How irradiance affects PV power and grid current
𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧
The 6.5 MW grid connected PV system in MATLAB provides a complete simulation of a large-scale photovoltaic generation system connected to an 11 kV, 50 Hz grid.
The model combines a 6.5 MW PV array, P&O MPPT-controlled boost converter, 20 kV DC link, three-phase grid inverter, PLL synchronization, and dq-axis current control.
Simulation results show that the PV system can extract the available solar power and transfer it successfully to the grid. At approximately 1000 W/m², the PV system generates close to 6.5 MW, while the power reduces to approximately 5.2 MW at 800 W/m². A further irradiance reduction produces approximately 3.27 MW, demonstrating the expected relationship between solar availability and grid power injection.
The model therefore provides a clear and practical platform for understanding large-scale PV modeling, MPPT, converter design, inverter control, grid synchronization, and renewable-energy grid integration in MATLAB/Simulink.
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