Grid Connected PV System with Partial Shading Effect
- lms editor
- 1 day ago
- 8 min read
Grid Connected PV System with Partial Shading Effect
𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧
Partial shading is one of the major challenges affecting the performance of large-scale solar photovoltaic systems. Unequal irradiation caused by clouds, buildings, trees, dust, or nearby structures reduces PV current and produces multiple operating points.
This MATLAB/Simulink model demonstrates the operation of a 3.048 MW grid-connected PV system under uniform and partial-shading conditions.
Grid Connected PV System with Partial Shading Effect
The model includes:
Two parallel PV strings
Multiple PV array groups
Variable solar irradiation inputs
P&O MPPT control
DC–DC boost converter
700 V DC-link regulation
Three-phase voltage-source inverter
Grid synchronization using a PLL
Grid-side current control
PV, inverter, and grid performance analysis
The model is suitable for understanding how a utility-scale PV system extracts and transfers the available solar power to a three-phase grid during changing environmental conditions.
𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰
The proposed configuration contains two identical PV strings connected in parallel. Each string is designed to generate approximately 1.5 MW, giving a combined rated power of approximately 3.048 MW.
Each PV string contains three array groups. The groups contain different numbers of series-connected PV modules while maintaining a high number of parallel strings.
PV Array Configuration
Parameter | Value |
Total PV rated power | 3.048 MW |
Number of parallel PV strings | 2 |
Approximate power per string | 1.524 MW |
PV array groups per string | 3 |
Parallel strings in each group | 650 |
Series modules in Group 1 | 4 |
Series modules in Group 2 | 4 |
Series modules in Group 3 | 3 |
Total series modules per string | 11 |
PV voltage at maximum power point | Approximately 319 V |
Standard irradiation | 1000 W/m² |
Standard temperature | 25°C |
The two PV strings operate at the same terminal voltage because they are connected in parallel. Their currents combine to supply the total PV power to the boost converter.
𝐌𝐚𝐢𝐧 𝐒𝐲𝐬𝐭𝐞𝐦 𝐂𝐨𝐦𝐩𝐨𝐧𝐞𝐧𝐭𝐬
The complete grid-connected PV system consists of the following sections:
Section | Function |
PV array | Converts solar irradiation into DC electrical power |
Irradiation inputs | Produce uniform and partial-shading conditions |
Temperature inputs | Define the PV operating temperature |
P&O MPPT controller | Tracks the available maximum power point |
Boost converter | Increases the PV voltage from approximately 319 V to 700 V |
DC-link capacitor | Stabilizes the DC-bus voltage |
Voltage-source inverter | Converts DC power into three-phase AC power |
Filter inductors | Reduce switching harmonics in the inverter current |
Three-phase PLL | Calculates the grid phase angle |
Current controller | Regulates active and reactive grid currents |
Grid connection | Receives the generated solar power |
𝐏𝐚𝐫𝐭𝐢𝐚𝐥-𝐒𝐡𝐚𝐝𝐢𝐧𝐠 𝐂𝐨𝐧𝐝𝐢𝐭𝐢𝐨𝐧
Initially, all PV array groups operate under uniform irradiation of 1000 W/m² at a temperature of 25°C.
After one second, different irradiation values are applied to the PV groups to create a partial-shading condition.
Irradiation Test Conditions
Operating period | PV Group Condition | Irradiation |
Before 1 second | All groups | 1000 W/m² |
After 1 second | First pair of groups | 800 W/m² |
After 1 second | Second pair of groups | 600 W/m² |
After 1 second | Third pair of groups | 500 W/m² |
This unequal irradiation reduces the current generated by the shaded PV groups. As a result, the total PV power and grid-injected power decrease.
A second operating condition can also be tested by setting all PV groups to 500 W/m². Under this condition, the available PV power is approximately half of the rated power.
𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
The operation of the model can be explained in the following stages.
1. Solar Power Generation
The PV arrays receive irradiation and temperature inputs.
Each PV group produces DC voltage and current.
The currents of the two parallel strings are combined.
PV voltage, current, and power are continuously measured.
2. Maximum Power Point Tracking
PV voltage and PV current are supplied to the P&O MPPT controller.
The controller calculates the present PV power.
It compares the present voltage and power with their previous values.
Based on the changes, the duty cycle is increased, decreased, or maintained.
The updated duty cycle is limited within the selected minimum and maximum values.
3. Boost-Converter Operation
The MPPT duty cycle is supplied to a PWM generator.
The PWM pulse controls the boost-converter IGBT.
The boost converter increases the PV voltage from approximately 319 V to 700 V.
The DC-link capacitor reduces voltage fluctuations.
4. DC-to-AC Conversion
The 700 V DC-link output is connected to a three-phase voltage-source inverter.
The inverter converts DC power into three-phase AC power.
Filter inductors reduce switching ripple before grid connection.
5. Grid Power Injection
The inverter voltage is synchronized with the grid voltage.
The grid phase angle is obtained using a three-phase PLL.
The inverter current is controlled in the rotating reference frame.
The generated active power is transferred from the PV system to the grid.
𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲
The model uses separate controllers for the PV boost converter and the grid-connected inverter.
P&O MPPT Controller
The Perturb and Observe MPPT algorithm uses PV voltage and current as its inputs.
Its main functions are:
Calculate instantaneous PV power
Detect changes in PV voltage
Detect changes in PV power
Modify the boost-converter duty cycle
Keep the duty cycle within safe limits
Continuously search for the maximum power operating point
MPPT Parameters
MPPT Parameter | Selected Value |
Initial duty cycle | 0.42 |
Minimum duty cycle | 0.10 |
Maximum duty cycle | 0.90 |
Duty-cycle step size | 0.08 |
MPPT inputs | PV voltage and PV current |
MPPT output | Boost-converter duty cycle |
The previous PV voltage, PV power, and duty-cycle values are stored and updated during each execution step.
𝐁𝐨𝐨𝐬𝐭-𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫 𝐃𝐞𝐬𝐢𝐠𝐧
The boost converter is designed according to the PV rated power, input voltage, output voltage, switching frequency, and permitted ripple values.
Boost-Converter Specifications
Parameter | Value |
Rated PV input power | 3.048 MW |
Nominal input voltage | Approximately 319 V |
Output DC-link voltage | 700 V |
Switching frequency | 10 kHz |
Converter type | DC–DC boost converter |
Switching device | IGBT |
Control method | P&O MPPT with PWM |
The converter inductor and capacitor values are selected to:
Limit the input-current ripple
Reduce DC-link voltage ripple
Maintain stable converter operation
Support maximum-power extraction
Provide the required inverter input voltage
𝐆𝐫𝐢𝐝-𝐂𝐨𝐧𝐧𝐞𝐜𝐭𝐞𝐝 𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
The inverter controller regulates the DC-link voltage and the grid current.
DC-Link Voltage Control
The measured DC-link voltage is filtered using a low-pass filter.
It is compared with the 700 V reference.
The resulting error is processed by a PI controller.
The PI-controller output produces the active-current reference.
Grid-Current Control
Three-phase grid currents are measured.
The measured currents are converted from the ABC frame to the DQ frame.
The grid phase angle is obtained from the PLL.
D-axis and Q-axis currents are compared with their references.
PI current controllers generate the inverter control signals.
The control signals are converted back into three-phase reference voltages.
A two-level PWM generator produces the inverter switching pulses.
Inverter and Grid Parameters
Parameter | Value |
DC-link voltage reference | 700 V |
Grid line-to-line voltage | 400 V |
Grid type | Three-phase AC grid |
Grid synchronization | Three-phase PLL |
Current-control frame | DQ reference frame |
Inverter type | Two-level voltage-source inverter |
Output filter | Three-phase inductive filter |
Power direction | PV system to grid |
𝐏𝐈 𝐂𝐨𝐧𝐭𝐫𝐨𝐥𝐥𝐞𝐫 𝐓𝐮𝐧𝐢𝐧𝐠
The PI-controller gains can be selected using:
Trial-and-error tuning
MATLAB PID Tuner
Analytical controller design
Optimization-based tuning
During manual tuning, small gain values can initially be applied. The gains can then be gradually increased while observing:
PV voltage
PV current
PV power
DC-link voltage
Grid voltage
Grid current
Inverter current
Grid active power
In the demonstrated model, improved performance was observed after increasing the voltage-controller proportional and integral gains to approximately 5.
Controller gains should be verified for stability before applying them to different operating conditions.
𝐑𝐨𝐥𝐞 𝐨𝐟 𝐭𝐡𝐞 𝐑𝐚𝐭𝐞 𝐋𝐢𝐦𝐢𝐭𝐞𝐫
A rate limiter is used with the irradiation input to avoid an unrealistically abrupt change.
Without rate limiting:
Irradiation may change instantaneously.
Large numerical variations may occur.
Converter states may change suddenly.
The simulation may produce numerical or function-related errors.
With rate limiting:
The step change is converted into a fast ramp.
The irradiation reaches its final value smoothly.
Converter variables change in a controlled manner.
Simulation stability is improved.
Rate-Limiter Setting
Parameter | Selected Value |
Rising slew rate | Approximately 10,000 |
Falling slew rate | Approximately −10,000 |
Main purpose | Smooth irradiation transitions |
Response | Fast transition without an ideal discontinuity |
A very low rate-limit value produces a slow irradiation transition, while a high value produces a faster response.
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬
The simulation evaluates the PV system during uniform irradiation, partial shading, and reduced uniform irradiation.
Condition 1: Uniform Irradiation
When all PV groups receive 1000 W/m²:
Output Variable | Approximate Result |
PV terminal voltage | 319–320 V |
PV current | Approximately 9000 A |
PV power | Approximately 3 MW |
DC-link voltage | Approximately 700 V |
Operating condition | Rated solar generation |
The MPPT controller operates the PV array near its maximum-power point, and the generated power is transferred to the grid.
Condition 2: Partial Shading
When irradiation changes to 800, 600, and 500 W/m² across different PV groups:
PV voltage experiences a small variation.
PV current decreases significantly.
PV power decreases to approximately 2 MW.
Grid current decreases according to the available PV power.
Inverter current also decreases.
Grid and inverter active powers follow the PV power variation.
The MPPT controller continues tracking the available operating point.
Condition 3: All Groups at 500 W/m²
When every PV group operates at 500 W/m²:
Output Variable | Approximate Result |
PV voltage | Close to the operating voltage |
PV current | Approximately 4000 A |
PV power | Approximately 1.5 MW |
Grid current | Reduced |
Grid power | Approximately equal to available PV power |
The simulation confirms that the reduction in solar irradiation mainly reduces the PV current and available active power.
𝐑𝐞𝐬𝐮𝐥𝐭 𝐂𝐨𝐦𝐩𝐚𝐫𝐢𝐬𝐨𝐧
Operating Condition | Irradiation | Approximate PV Power | Observed Effect |
Uniform high irradiation | All groups at 1000 W/m² | 3 MW | Rated PV generation |
Partial shading | Groups at 800, 600, and 500 W/m² | 2 MW | Reduced PV and grid currents |
Uniform low irradiation | All groups at 500 W/m² | 1.5 MW | Nearly half-rated generation |
The results show that the inverter transfers the available solar power to the grid while maintaining synchronized three-phase operation.
𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬
3.048 MW large-scale PV system
Two parallel PV strings
Multiple PV array groups
Uniform and partial-shading analysis
Configurable irradiation and temperature
P&O maximum-power-point tracking
PWM-controlled boost converter
Voltage boosting from 319 V to 700 V
Three-phase voltage-source inverter
DC-link voltage regulation
DQ-frame grid-current control
Three-phase PLL synchronization
Filter-inductor design
Rate-limited irradiation transitions
PV and grid power comparison
Grid voltage and current waveform analysis
Inverter voltage and current monitoring
𝐖𝐡𝐚𝐭 𝐂𝐚𝐧 𝐁𝐞 𝐀𝐧𝐚𝐥𝐲𝐬𝐞𝐝?
The simulation allows users to observe:
PV voltage under different irradiation levels
PV current reduction during shading
PV power variation
MPPT duty-cycle response
Boost-converter operation
DC-link voltage regulation
Three-phase grid voltage
Three-phase grid current
Inverter voltage waveform
Inverter current waveform
Grid active and reactive power
Inverter active and reactive power
Power transfer from the PV system to the grid
𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬
This model can be used for:
Grid-connected solar PV system analysis
Partial-shading performance studies
MPPT algorithm evaluation
Utility-scale PV plant modelling
DC–DC boost-converter analysis
Inverter-controller development
Grid synchronization studies
Solar-power injection analysis
DQ-current-control learning
PV power-quality assessment
Renewable-energy laboratory demonstrations
Controller tuning and waveform analysis
𝐖𝐡𝐨 𝐂𝐚𝐧 𝐔𝐬𝐞 𝐓𝐡𝐢𝐬 𝐌𝐨𝐝𝐞𝐥?
The model is suitable for:
Electrical engineering students
Power-electronics learners
Renewable-energy researchers
MATLAB/Simulink users
Solar-system designers
Grid-integration engineers
Control-system researchers
Academic teaching and laboratory demonstrations
𝐋𝐞𝐚𝐫𝐧𝐢𝐧𝐠 𝐎𝐮𝐭𝐜𝐨𝐦𝐞𝐬
By studying this model, users can understand:
How parallel PV strings are configured
How partial shading is created in Simulink
How irradiation influences PV current and power
How a P&O MPPT algorithm modifies the duty cycle
How a boost converter regulates the PV operating point
Why a 700 V DC link is used for a 400 V three-phase grid
How a PLL synchronizes the inverter with the grid
How ABC and DQ transformations support current control
How active PV power is injected into the utility grid
How grid and inverter waveforms respond to shading
𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧
The MATLAB simulation presents a complete 3.048 MW grid-connected PV system operating under uniform and partial-shading conditions.
The model demonstrates:
Maximum-power extraction using P&O MPPT
Voltage boosting from approximately 319 V to 700 V
Stable DC-link voltage regulation
Three-phase inverter synchronization
Controlled solar-power injection into the grid
Reduction in PV current and grid power during shading
At standard irradiation, the system generates approximately 3 MW. Under unequal irradiation levels of 800, 600, and 500 W/m², the output decreases to approximately 2 MW. When all PV groups operate at 500 W/m², the generated power decreases to approximately 1.5 MW.
This model provides a practical platform for studying PV characteristics, partial-shading effects, MPPT operation, boost conversion, inverter control, and renewable-power integration using MATLAB/Simulink.