Power Management of Solar PV Battery and Supercapacitor in DC Microgrid
Power Management of Solar PV Battery and Supercapacitor in DC Microgrid
𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧
The integration of solar photovoltaic (PV), battery energy storage, and supercapacitor storage provides an effective solution for maintaining reliable power flow in a DC microgrid.
Power Management of Solar PV Battery and Supercapacitor in DC Microgrid
In this MATLAB/Simulink-based system, a 2 kW solar PV array acts as the primary energy source. A battery provides long-duration energy balancing, while a supercapacitor handles fast transient power changes. All three sources are coordinated to maintain the DC bus voltage at 400 V while supplying a 1000 W DC load.
The system demonstrates how intelligent energy sharing can improve DC microgrid stability when solar irradiance changes rapidly.
𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰
The DC microgrid consists of four major sections:
Solar PV system with Incremental Conductance MPPT
Boost converter for PV power conversion
Battery energy storage system with bidirectional DC–DC converter
Supercapacitor storage system with bidirectional DC–DC converter
400 V common DC bus
1000 W DC load
Voltage and current control loops for energy management
PWM-based switching control for power converters
The solar PV system supplies renewable power whenever sufficient irradiation is available. The battery handles the long-term difference between generation and load demand, while the supercapacitor responds quickly during sudden changes.
𝐒𝐨𝐥𝐚𝐫 𝐏𝐕 𝐒𝐲𝐬𝐭𝐞𝐦 𝐏𝐚𝐫𝐚𝐦𝐞𝐭𝐞𝐫𝐬
The PV array has a total rated power of approximately 2000 W.
Parameter | Value |
Total PV array rating | 2000 W |
Single PV panel rating | 250 W |
Open-circuit voltage | 37.3 V |
Voltage at maximum power point | 30.7 V |
Short-circuit current | 8.66 A |
Current at maximum power point | 8.15 A |
DC bus reference voltage | 400 V |
DC load power | 1000 W |
The I–V and P–V characteristics of the PV array change with solar irradiation. As irradiation decreases, the available maximum PV power also decreases.
𝐏𝐕 𝐏𝐨𝐰𝐞𝐫 𝐔𝐧𝐝𝐞𝐫 𝐃𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐭 𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞 𝐋𝐞𝐯𝐞𝐥𝐬
Typical PV characteristics obtained under different irradiation conditions are shown below.
Irradiance | Approximate Maximum PV Power |
1000 W/m² | 2002 W |
800 W/m² | 1599 W |
600 W/m² | 1197 W |
400 W/m² | 791.8 W |
At 1000 W/m², the PV array operates near its rated power, with the maximum-power-point voltage around 245.6 V.
As the irradiation decreases, the PV power reduces significantly. Therefore, an MPPT controller is required to continuously identify and extract the available maximum power.
𝐈𝐧𝐜𝐫𝐞𝐦𝐞𝐧𝐭𝐚𝐥 𝐂𝐨𝐧𝐝𝐮𝐜𝐭𝐚𝐧𝐜𝐞 𝐌𝐏𝐏𝐓
The solar PV system uses an Incremental Conductance Maximum Power Point Tracking (MPPT) algorithm.
The controller receives:
PV voltage
PV current
Based on these measurements, the MPPT algorithm determines the required duty cycle for the PV boost converter.
The generated duty cycle is processed by a PWM generator, which provides switching pulses to the converter.
This arrangement enables the system to:
Track the PV maximum power point
Respond to changing solar irradiation
Extract maximum available solar energy
Transfer PV power to the 400 V DC bus
Improve renewable-energy utilization
𝐏𝐕 𝐁𝐨𝐨𝐬𝐭 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫
The PV array voltage is lower than the required DC-link voltage. Therefore, a DC–DC boost converter interfaces the PV array with the common DC bus.
Its main functions are:
Increase the PV-side voltage
Transfer renewable power to the DC bus
Operate according to the MPPT duty cycle
Maintain efficient PV energy conversion
Support operation under varying irradiance conditions
The common DC bus is regulated at approximately 400 V.
𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐄𝐧𝐞𝐫𝐠𝐲 𝐒𝐭𝐨𝐫𝐚𝐠𝐞 𝐒𝐲𝐬𝐭𝐞𝐦
The battery is connected to the DC microgrid through a bidirectional DC–DC converter.
Battery Parameter | Value |
Nominal battery voltage | 220 V |
Rated capacity | 48 Ah |
Initial state of charge | 50% |
Converter type | Bidirectional DC–DC |
Main function | Charging and discharging |
The bidirectional converter allows power to flow in both directions.
During surplus PV generation, the battery operates in charging mode. When PV generation is insufficient, the battery changes to discharging mode and supplies the missing load power.
This makes the battery the main energy-balancing storage element in the DC microgrid.
𝐒𝐮𝐩𝐞𝐫𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐨𝐫 𝐄𝐧𝐞𝐫𝐠𝐲 𝐒𝐭𝐨𝐫𝐚𝐠𝐞
A supercapacitor is also connected to the common DC bus using a separate bidirectional converter.
Supercapacitor Parameter | Value |
Rated capacitance | 99.5 F |
Rated voltage | 300 V |
Initial voltage | 295 V |
Converter type | Bidirectional DC–DC |
Main role | Fast transient power compensation |
Unlike the battery, the supercapacitor is primarily used for short-duration and high-speed power support.
It responds rapidly when:
Solar irradiation changes suddenly
PV power rises or falls quickly
The load-generation power balance changes
The DC bus experiences a transient disturbance
After the transient condition settles, the supercapacitor power moves back toward zero.
𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐚𝐧𝐝 𝐒𝐮𝐩𝐞𝐫𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐨𝐫 𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲
A double-loop control strategy is used for the battery and supercapacitor converters.
Outer Voltage Control Loop
The measured DC bus voltage is compared with the 400 V reference value.
The resulting voltage error is processed by a PI voltage controller.
This produces the required reference current for energy balancing.
Inner Current Control Loop
The reference current is compared with the actual storage-system current.
A PI current controller then generates the duty-cycle command.
The duty cycle is supplied to the PWM generator, which produces switching pulses for the IGBTs.
The overall controller therefore coordinates:
DC voltage regulation → reference current generation → current control → PWM generation → bidirectional converter operation
This control structure allows the energy-storage systems to respond automatically according to the PV generation and load demand.
𝐏𝐨𝐰𝐞𝐫 𝐌𝐚𝐧𝐚𝐠𝐞𝐦𝐞𝐧𝐭 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲
The main energy-management objective is to maintain the DC bus near 400 V while continuously supplying the 1000 W load.
Operating Condition | PV | Battery | Supercapacitor |
PV power greater than load | Supplies load | Charges | Charges/supports transition |
PV power approximately equal to load | Supplies most load demand | Small support | Near zero |
PV power lower than load | Supplies available power | Discharges | Supports transient |
Sudden irradiance reduction | Power decreases | Increases discharge | Responds rapidly |
Steady low irradiance | Supplies limited power | Supplies deficit | Returns near zero |
This hybrid storage arrangement combines the high-energy capability of the battery with the high-power capability of the supercapacitor.
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞 𝐏𝐫𝐨𝐟𝐢𝐥𝐞
The solar irradiation is varied during the simulation to evaluate the power-management system under changing renewable generation.
Simulation Interval | Irradiance |
0–1 s | 1000 W/m² |
1–2 s | 800 W/m² |
2–3 s | 500 W/m² |
3–4 s | 300 W/m² |
4–5 s | 100 W/m² |
Each irradiation level is maintained for approximately 1 second, creating several step changes in PV power.
These variations allow the performance of the MPPT, battery controller, supercapacitor controller, and DC-link voltage controller to be evaluated.
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬
Several electrical quantities are monitored during the simulation:
PV voltage, current, and power
Battery voltage, current, and power
Supercapacitor voltage, current, and power
DC bus voltage, current, and power
PV Performance
The PV voltage remains approximately within the 245–250 V range, while PV current changes according to solar irradiation.
Irradiance | Approx. PV Current | Approx. PV Power |
1000 W/m² | 8 A | 2000 W |
800 W/m² | 6.2 A | 1600 W |
500 W/m² | 4 A | 1000 W |
300 W/m² | 2.2 A | 350 W |
100 W/m² | 1 A | 100 W |
The results clearly demonstrate that the MPPT-controlled boost converter adjusts the PV operating condition as the available solar energy changes.
𝐃𝐂 𝐁𝐮𝐬 𝐏𝐞𝐫𝐟𝐨𝐫𝐦𝐚𝐧𝐜𝐞
Despite large changes in solar irradiation, the common DC-link voltage is maintained close to its reference.
DC-Side Parameter | Approximate Value |
DC bus voltage | 400 V |
DC load current | 2.5 A |
DC load power | 1000 W |
Maintaining the DC voltage around 400 V confirms that the battery and supercapacitor controllers compensate for variations between PV generation and load demand.
𝐏𝐨𝐰𝐞𝐫 𝐅𝐥𝐨𝐰 𝐃𝐮𝐫𝐢𝐧𝐠 𝟎–𝟐 𝐒𝐞𝐜𝐨𝐧𝐝𝐬
During the first two seconds, solar irradiation is relatively high.
PV generation is approximately:
Time Period | PV Power | Load Power | Energy Condition |
0–1 s | 2000 W | 1000 W | Large surplus |
1–2 s | 1600 W | 1000 W | Surplus |
Since PV power is higher than the load demand, the excess energy is transferred to the storage systems.
The battery and supercapacitor therefore operate in charging mode.
In the measured waveforms:
Negative battery current indicates charging
Negative battery power indicates energy absorption
Negative supercapacitor current indicates charging/support
Storage voltages gradually increase
𝐏𝐨𝐰𝐞𝐫 𝐅𝐥𝐨𝐰 𝐀𝐫𝐨𝐮𝐧𝐝 𝟐 𝐒𝐞𝐜𝐨𝐧𝐝𝐬
At approximately 2 seconds, the PV output reduces toward the load requirement.
PV generation is approximately 1000 W, which is close to the 1000 W load demand.
Under this condition:
PV supplies nearly all required load power
Battery power requirement becomes relatively small
Supercapacitor current approaches zero after the transient
DC bus voltage remains regulated
This demonstrates smooth transition between charging and discharging operating regions.
𝐏𝐨𝐰𝐞𝐫 𝐅𝐥𝐨𝐰 𝐃𝐮𝐫𝐢𝐧𝐠 𝐋𝐨𝐰 𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐧𝐜𝐞
When solar irradiation decreases further, the PV system can no longer independently supply the 1000 W DC load.
The battery then changes to discharging operation.
For example:
Operating Point | Approx. PV Power | Load Power | Storage Requirement |
Medium irradiance | 1000 W | 1000 W | Small |
Low irradiance | 350 W | 1000 W | Battery supplies deficit |
Very low irradiance | 100 W | 1000 W | Battery supplies major deficit |
The battery therefore acts as the main source of sustained backup power.
𝐒𝐮𝐩𝐞𝐫𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐨𝐫 𝐓𝐫𝐚𝐧𝐬𝐢𝐞𝐧𝐭 𝐑𝐞𝐬𝐩𝐨𝐧𝐬𝐞
One of the most important features of the system is the supercapacitor response during sudden irradiation transitions.
Whenever PV generation changes abruptly:
The supercapacitor immediately exchanges power with the DC bus
Fast transient power demand is compensated
DC bus voltage variations are reduced
Battery stress is reduced
After stabilization, supercapacitor current returns near zero
This division of responsibility is useful because the battery handles relatively slower energy balancing while the supercapacitor responds to rapid fluctuations.
𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
The complete power-management sequence can be understood as follows:
Solar irradiation reaches the PV array.
PV voltage and current are measured.
Incremental Conductance MPPT calculates the required operating duty cycle.
PWM pulses control the PV boost converter.
Maximum available PV power is transferred to the 400 V DC bus.
The DC load continuously consumes approximately 1000 W.
If PV generation exceeds load demand, surplus energy charges the storage systems.
If PV generation falls below load demand, the battery supplies the deficit.
The supercapacitor provides rapid power during sudden transitions.
The double-loop controller regulates the DC bus voltage around 400 V.
𝐁𝐚𝐭𝐭𝐞𝐫𝐲 𝐯𝐬. 𝐒𝐮𝐩𝐞𝐫𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐨𝐫 𝐑𝐨𝐥𝐞
Feature | Battery | Supercapacitor |
Main purpose | Energy balancing | Transient power compensation |
Response speed | Moderate | Very fast |
Energy capability | High | Lower |
Short-duration power capability | Moderate | High |
Surplus PV condition | Charging | Charging/transient support |
PV deficit condition | Sustained discharge | Short-term support |
Steady-state operation | Active when needed | Normally near zero |
Contribution to DC bus stability | Long-term | Fast dynamic support |
Using both devices provides better overall performance than relying on only one storage technology.
𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬
2 kW solar PV generation system
Incremental Conductance MPPT control
PV boost converter with PWM switching
400 V regulated DC microgrid
220 V, 48 Ah battery storage
99.5 F, 300 V supercapacitor
Separate bidirectional DC–DC converters
Double-loop voltage and current control
Automatic battery charging and discharging
Fast supercapacitor transient compensation
Dynamic irradiance variation from 1000 to 100 W/m²
Continuous supply to a 1000 W DC load
MATLAB/Simulink-based dynamic performance analysis
𝐀𝐝𝐯𝐚𝐧𝐭𝐚𝐠𝐞𝐬 𝐨𝐟 𝐇𝐲𝐛𝐫𝐢𝐝 𝐁𝐚𝐭𝐭𝐞𝐫𝐲–𝐒𝐮𝐩𝐞𝐫𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐨𝐫 𝐒𝐭𝐨𝐫𝐚𝐠𝐞
The combination of battery and supercapacitor offers several benefits:
Better DC-link voltage regulation
Improved response to rapid solar fluctuations
Reduced sudden battery current changes
Better power balancing between PV and load
Efficient utilization of surplus solar energy
Improved dynamic stability
Faster response during generation disturbances
Better handling of short-duration power peaks
Improved energy-management flexibility
𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬
This type of solar PV–battery–supercapacitor DC microgrid can be studied for applications such as:
Renewable-energy DC microgrids
Solar-powered DC distribution systems
Battery-supercapacitor hybrid energy storage
EV charging infrastructure
Telecom DC power systems
Smart buildings
Renewable-powered industrial DC loads
Standalone energy systems
DC nanogrids
Energy-management research
Power-electronics control studies
Hybrid energy-storage system development
𝐖𝐡𝐲 𝐔𝐬𝐞 𝐚 𝐒𝐮𝐩𝐞𝐫𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐨𝐫 𝐖𝐢𝐭𝐡 𝐚 𝐁𝐚𝐭𝐭𝐞𝐫𝐲?
A battery can store a relatively large amount of energy, but repeatedly forcing it to respond to very fast power fluctuations can increase electrical stress.
A supercapacitor has a much faster power response.
Therefore, combining the two devices provides a practical division of operation:
Battery → sustained energy support
Supercapacitor → fast transient power support
This hybrid approach can improve both the dynamic response and overall power-management performance of a DC microgrid.
𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧
The Power Management of Solar PV Battery and Supercapacitor in DC Microgrid demonstrates coordinated renewable generation and hybrid energy storage using MATLAB/Simulink.
The Incremental Conductance MPPT extracts the available maximum power from the 2 kW solar PV array, while the boost converter connects the PV source to the 400 V DC bus.
When solar generation exceeds the 1000 W load demand, surplus energy is transferred to the battery and supercapacitor. When solar generation decreases, the battery supplies the sustained power deficit. During sudden irradiance changes, the supercapacitor delivers fast transient support and helps stabilize the DC bus.
The simulation therefore provides a clear example of PV power management, hybrid battery-supercapacitor energy storage, bidirectional converter control, MPPT operation, and DC microgrid voltage regulation for students, researchers, and engineers working in renewable energy and power electronics.
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