Solar PV Battery Integrated UPQC

Solar PV Battery Integrated UPQC

𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧

The Solar PV Battery Integrated UPQC system combines renewable energy generation, battery energy storage, and power-quality improvement in a single MATLAB/Simulink architecture.

Solar PV Battery Integrated UPQC

₹12,000.00₹6,000.00

Buy Now

A Unified Power Quality Conditioner (UPQC) uses two power electronic converters to improve voltage and current quality:

• Series Converter – compensates grid-side voltage disturbances.

• Shunt Converter – compensates load-current harmonics and improves source current.

• Solar PV System – supplies renewable DC power to the common DC link.

• Battery Storage – supports DC-link voltage through charging and discharging.

• MPPT Controller – extracts maximum available power from the PV array.

The complete system demonstrates how renewable energy can be integrated with voltage sag/swell compensation, harmonic mitigation, DC-link regulation, and battery energy management.

𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰

The MATLAB/Simulink model contains the following major sections:

1. Solar PV array

2. Boost converter

3. P&O MPPT controller

4. Battery energy storage system

5. Bidirectional DC–DC converter

6. Common DC link

7. Shunt active converter

8. Series active converter

9. Coupling transformer

10. Nonlinear load

11. Three-phase utility grid

12. Power-quality control system

The arrangement allows the renewable energy source and battery to work together while the UPQC improves both grid-current quality and load-voltage quality.

𝐒𝐨𝐥𝐚𝐫 𝐏𝐕 𝐒𝐲𝐬𝐭𝐞𝐦

The PV system forms the renewable energy source of the proposed UPQC configuration.

PV Array Parameters

Parameter	Value
Series-connected modules per string	18
Parallel-connected strings	28
Power of each PV module	Approx. 213.15 W
Voltage at maximum power point	29 V
Current at maximum power point	7.35 A
Approximate PV array maximum power	107.4 kW
Approximate operating PV voltage	522 V
DC-link reference voltage	700 V

With 18 modules connected in series, the PV operating voltage is approximately 522 V near its maximum power point.

The PV array is connected to the DC link through a DC–DC boost converter.

𝐏𝐕 𝐁𝐨𝐨𝐬𝐭 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫

The boost converter increases the PV-side voltage to the required DC-link level.

Boost Converter Details

Parameter	Approximate Value
PV-side operating voltage	522 V
DC-link voltage	700 V
PV system rating	107.4 kW
Boost inductance	3 mH
Calculated capacitance	Approx. 6600 µF

The converter is controlled using the duty cycle generated by the PV MPPT algorithm.

Its primary functions are:

• Increase the PV voltage to the DC-link voltage.

• Control PV operating conditions.

• Support maximum power extraction.

• Transfer solar energy to the UPQC DC bus.

• Maintain efficient PV-side power conversion.

𝐏&𝐎 𝐌𝐏𝐏𝐓 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

A Perturb and Observe (P&O) MPPT algorithm is used for extracting maximum available solar power.

The MPPT controller continuously receives:

• PV voltage

• PV current

From these measurements, the controller determines the appropriate boost-converter duty cycle.

The duty-cycle command is processed by the PWM generator, which produces the switching pulses for the boost converter.

MPPT Control Flow

PV Voltage + PV Current → P&O MPPT → Duty Cycle → PWM Generator → Boost Converter

When solar irradiance changes, the controller automatically adjusts the converter operating point to obtain the maximum available PV power.

𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐄𝐧𝐞𝐫𝐠𝐲 𝐒𝐭𝐨𝐫𝐚𝐠𝐞

The battery is connected to the common DC bus through a bidirectional DC–DC converter.

Battery Parameters

Parameter	Value
Battery unit voltage	24 V
Series-connected battery units	20
Approximate battery-bank voltage	480 V
Battery capacity	48 Ah
Initial SOC	50%
Converter switching frequency	10 kHz
DC-link reference	700 V

The bidirectional converter allows energy flow in both directions.

Battery Charging Mode

When sufficient PV power is available:

PV Array → DC Link → Bidirectional Converter → Battery

The battery absorbs excess renewable power.

Battery Discharging Mode

When PV generation decreases or additional DC-link support is required:

Battery → Bidirectional Converter → DC Link

The battery therefore helps maintain stable operation even when solar irradiance changes.

𝐃𝐂-𝐋𝐢𝐧𝐤 𝐕𝐨𝐥𝐭𝐚𝐠𝐞 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

A major control objective of the system is maintaining the DC-link voltage at approximately 700 V.

The controller continuously compares:

• Measured DC-link voltage

• 700 V reference voltage

The resulting voltage error is processed by a PI controller.

For the battery converter, the outer voltage-control loop generates the battery-current reference. The actual battery current is then compared with the required reference and processed through another current controller.

The resulting control signal generates the switching pulses for the bidirectional converter.

This approach enables:

• DC-link voltage stabilization

• Automatic battery charging

• Automatic battery discharging

• Renewable power balancing

• Transient power support

𝐔𝐏𝐐𝐂 𝐂𝐨𝐧𝐟𝐢𝐠𝐮𝐫𝐚𝐭𝐢𝐨𝐧

The UPQC contains two main voltage-source converters.

UPQC Converter	Connection	Main Function
Shunt Converter	Parallel with system	Current harmonic compensation
Series Converter	Series with grid	Voltage disturbance compensation

Both converters share the same 700 V DC link, which is supported by the PV system and battery.

This arrangement provides simultaneous compensation of voltage-related and current-related power-quality disturbances.

𝐒𝐡𝐮𝐧𝐭 𝐀𝐜𝐭𝐢𝐯𝐞 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫

The shunt converter is mainly responsible for improving the source/grid current waveform.

The system contains a nonlinear load that can draw distorted current. Without compensation, these harmonics can propagate toward the utility grid.

The shunt converter injects an appropriate compensation current so that the grid current becomes close to sinusoidal.

Main Objectives

• Compensate nonlinear load-current harmonics.

• Improve source-current waveform.

• Reduce current THD.

• Support reactive-power compensation.

• Assist DC-link voltage regulation.

𝐩–𝐪 𝐓𝐡𝐞𝐨𝐫𝐲 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

The shunt active filter uses the instantaneous p–q theory for determining the required compensation current.

The controller measures:

• Three-phase grid voltage

• Three-phase load current

• DC-link voltage

The three-phase electrical quantities are transformed into stationary components.

From these quantities, the controller determines:

• Instantaneous real power

• Instantaneous reactive power

• Zero-sequence component

• Average real power

• Oscillating power component

A low-pass filter is used to extract the required average power component.

The DC-link controller also calculates the additional power required to maintain the 700 V DC-link voltage.

𝐑𝐞𝐟𝐞𝐫𝐞𝐧𝐜𝐞 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐆𝐞𝐧𝐞𝐫𝐚𝐭𝐢𝐨𝐧

Based on the instantaneous power calculations, the controller generates the required three-phase compensation-current references.

These reference currents are compared with the actual shunt-converter currents.

The current error is then processed using a hysteresis current controller.

Shunt Converter Control Flow

Grid Voltage + Load Current → p–q Theory → Compensation Current → Hysteresis Controller → Gate Pulses → Shunt Converter

Complementary switching signals are produced for the six semiconductor switches of the three-phase converter.

𝐇𝐚𝐫𝐦𝐨𝐧𝐢𝐜 𝐂𝐨𝐦𝐩𝐞𝐧𝐬𝐚𝐭𝐢𝐨𝐧

A nonlinear load produces a distorted load-current waveform containing harmonic components.

The shunt converter generates a compensation current containing the required opposing harmonic components.

As a result:

• Load current may remain distorted.

• Shunt converter supplies the compensation component.

• Grid current becomes much more sinusoidal.

• Current distortion seen by the utility is reduced.

This is one of the most important functions of the UPQC.

𝐒𝐞𝐫𝐢𝐞𝐬 𝐀𝐜𝐭𝐢𝐯𝐞 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫

The series converter is responsible for maintaining the required load voltage when disturbances occur on the grid side.

It is connected to the AC system through a series injection transformer.

The converter can compensate disturbances such as:

• Voltage sag

• Voltage swell

• Voltage imbalance

• Grid-voltage variations

When the utility voltage changes, the series converter generates the required compensating voltage and injects it through the transformer.

𝐒𝐞𝐫𝐢𝐞𝐬 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫 𝐂𝐨𝐧𝐭𝐫𝐨𝐥

The series-converter controller monitors the source and load voltages.

The measured three-phase quantities are processed in the rotating reference frame using abc–dq and dq–abc transformations.

The controller determines the difference between:

• Desired load voltage

• Actual system voltage

The voltage error is processed by PI controllers.

The resulting control voltages are converted back into three-phase quantities and supplied to the PWM generator.

Control Sequence

Voltage Measurement → dq Transformation → Voltage Error → PI Control → dq–abc Transformation → PWM → Series Converter

𝐍𝐨𝐫𝐦𝐚𝐥 𝐆𝐫𝐢𝐝 𝐂𝐨𝐧𝐝𝐢𝐭𝐢𝐨𝐧

When the grid voltage is already at the rated value:

• Voltage error is very small.

• Compensation demand approaches zero.

• Series converter injection is minimal.

• Load receives the required voltage directly from the source.

This avoids unnecessary voltage injection during healthy grid conditions.

𝐕𝐨𝐥𝐭𝐚𝐠𝐞 𝐒𝐚𝐠 𝐎𝐩𝐞𝐫𝐚𝐭𝐢𝐨𝐧

During a voltage sag, the grid voltage drops below its rated level.

The series converter detects the voltage deficiency and generates the required compensation voltage.

The injected voltage is added to the reduced grid voltage so that the load-side voltage remains close to its rated value.

Sag Compensation

Quantity	Behaviour
Grid voltage	Decreases
Series injected voltage	Increases
Load voltage	Maintained near rated value
UPQC response	Supplies missing voltage

𝐕𝐨𝐥𝐭𝐚𝐠𝐞 𝐒𝐰𝐞𝐥𝐥 𝐎𝐩𝐞𝐫𝐚𝐭𝐢𝐨𝐧

During a voltage swell, the grid voltage rises above its rated value.

The series converter produces an opposing compensation voltage.

This injected voltage reduces the effective voltage appearing across the sensitive load.

Swell Compensation

Quantity	Behaviour
Grid voltage	Increases
Series compensation	Opposes excess voltage
Load voltage	Maintained close to rated level
UPQC response	Cancels excess voltage

𝐓𝐞𝐬𝐭 𝐂𝐨𝐧𝐝𝐢𝐭𝐢𝐨𝐧𝐬

The simulation introduces different power-quality disturbances to evaluate the UPQC performance.

Test Parameter	Value / Condition
Three-phase grid voltage	Approx. 450 V
DC-link reference	700 V
Normal voltage	1.0 p.u.
Sag operating level	Approx. 0.8 p.u.
Swell operating level	Approx. 1.2 p.u.
Severe disturbance case	Approx. 0.5 p.u.
Nonlinear load	Diode rectifier with resistive load
Battery initial SOC	50%
Converter switching frequency	10 kHz

Voltage disturbance transitions are introduced at different simulation intervals to examine the dynamic response of the series converter.

𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬

The overall operating process can be summarized as follows:

1. Solar PV GenerationThe PV array converts solar irradiation into DC electrical power.

2. Maximum Power ExtractionP&O MPPT continuously adjusts the boost-converter duty cycle.

3. DC Voltage BoostingThe converter raises the PV voltage toward the 700 V DC bus.

4. Battery Energy ManagementThe bidirectional converter controls charging and discharging.

5. DC-Link RegulationControllers maintain the common DC bus near 700 V.

6. Current Harmonic CompensationThe shunt converter injects compensation current.

7. Voltage Disturbance CompensationThe series converter injects the required compensating voltage.

8. Load Voltage RegulationThe load continues receiving approximately rated voltage during disturbances.

𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲

The complete system combines several control techniques.

System Section	Control Method
Solar PV	P&O MPPT
PV boost converter	PWM control
Battery converter	Cascaded voltage/current control
DC-link regulation	PI control
Shunt converter	Instantaneous p–q theory
Shunt current tracking	Hysteresis current control
Series converter	dq-reference-frame control
Series voltage control	PI control
Converter switching	PWM / switching pulse generation

This coordinated control structure allows the UPQC, PV, and battery systems to operate as one integrated power-quality platform.

𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬

The MATLAB/Simulink results demonstrate the performance of the proposed configuration under several operating conditions.

1. Grid Voltage and Current

The grid voltage contains intentionally created disturbance conditions.

Despite the nonlinear load, the compensated grid current remains close to sinusoidal because the shunt converter supplies the harmonic compensation current.

2. Load Voltage

The load-side voltage remains close to its desired value even when voltage disturbances occur on the grid side.

During sag:

• Grid voltage decreases.

• Series converter supplies additional voltage.

• Load voltage remains regulated.

During swell:

• Grid voltage increases.

• Series converter generates opposing voltage.

• Load voltage remains around the required magnitude.

3. Series Voltage Injection

The series converter only injects substantial voltage when compensation is required.

Grid Condition	Series Converter Action
Normal	Very low compensation
Voltage Sag	Injects supporting voltage
Voltage Swell	Injects opposing voltage
Voltage imbalance	Generates corrective voltage

This confirms the dynamic response of the series active filter.

4. Nonlinear Load Compensation

The nonlinear diode-rectifier load produces a non-sinusoidal current.

The shunt converter supplies the corresponding harmonic compensation current.

Therefore:

Distorted Load Current + Compensation Current → Improved Grid Current

This prevents a significant portion of the nonlinear load harmonics from flowing into the utility grid.

5. PV Power Response

At high irradiation, the PV system produces high output power and the P&O MPPT operates the array close to its maximum-power region.

When solar irradiation decreases:

• PV current decreases.

• Available PV power decreases.

• MPPT changes the converter duty cycle.

• Battery charging power can decrease.

• Battery support changes according to the system power balance.

6. Battery Charging and Discharging

When PV power is sufficient, the battery can operate in the charging mode.

When renewable generation becomes insufficient or DC-link support is required, the bidirectional converter allows the battery to supply power.

PV Power Condition	Typical Battery Response
High PV generation	Charging
Excess renewable power	Charging
Reduced irradiation	Charging current reduces
Low PV availability	Battery support increases
DC-link power deficit	Discharging

𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬

• 107.4 kW solar PV integration

• 700 V common DC-link operation

• P&O-based maximum power point tracking

• Battery charging and discharging capability

• Bidirectional battery power flow

• Series and shunt UPQC converters

• Voltage sag compensation

• Voltage swell compensation

• Three-phase voltage regulation

• Nonlinear load harmonic compensation

• Improved grid-current waveform

• Instantaneous p–q theory control

• Hysteresis current control

• dq-reference-frame voltage control

• PI-based DC-link regulation

• Dynamic solar irradiation operation

• MATLAB/Simulink-based implementation

𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬

The Solar PV Battery Integrated UPQC configuration is useful for studying and developing:

• Renewable-energy-supported distribution systems

• Power-quality improvement systems

• Smart-grid interfaces

• Industrial power conditioning

• Sensitive-load protection

• Solar PV grid integration

• Battery energy storage integration

• Voltage sag and swell mitigation

• Harmonic compensation

• Distributed renewable generation

• Active power filtering

• Power electronic converter control

• Microgrid power-quality management

𝐖𝐡𝐲 𝐈𝐧𝐭𝐞𝐠𝐫𝐚𝐭𝐞 𝐏𝐕 𝐚𝐧𝐝 𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐰𝐢𝐭𝐡 𝐔𝐏𝐐𝐂?

A conventional UPQC primarily focuses on power-quality compensation.

Integrating solar PV and battery storage extends its functionality.

Conventional UPQC	PV–Battery Integrated UPQC
Power-quality compensation	Power quality + renewable generation
Series voltage compensation	Series voltage compensation
Shunt current compensation	Shunt current compensation
DC-link support required	PV and battery support DC link
No renewable generation	Solar power generation
Limited energy management	Battery charging/discharging
Grid-dependent operation	Improved energy flexibility

The combined configuration therefore provides both energy management and power-quality enhancement.

𝐌𝐚𝐣𝐨𝐫 𝐏𝐨𝐰𝐞𝐫-𝐐𝐮𝐚𝐥𝐢𝐭𝐲 𝐅𝐮𝐧𝐜𝐭𝐢𝐨𝐧𝐬

Power-Quality Issue	Responsible Section
Voltage sag	Series converter
Voltage swell	Series converter
Voltage imbalance	Series converter
Load-current harmonics	Shunt converter
Reactive-current component	Shunt converter
DC-link fluctuation	PV/battery/DC-link controller
Solar-power variation	MPPT + battery
Nonlinear load effects	Shunt active filter

𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧

The Solar PV Battery Integrated UPQC in MATLAB/Simulink provides a complete platform for studying renewable energy integration together with advanced power-quality compensation.

The solar PV system supplies renewable power through a P&O MPPT-controlled boost converter, while the battery system provides bidirectional energy support and assists in maintaining the 700 V DC link.

The shunt converter improves grid-current quality by compensating harmonics generated by the nonlinear load. At the same time, the series converter protects the load against grid-side voltage sag, swell, imbalance, and other voltage variations.

The simulation demonstrates that a coordinated PV–Battery–UPQC architecture can simultaneously provide renewable power utilization, battery energy management, voltage regulation, harmonic compensation, and improved grid-side power quality.