Renewable energy sources‐based hybrid microgrid system for off‐grid electricity solution for rural communities

Rural electrification is a crucial component of meeting sustainable development goals. In Pakistan, load shedding and power outages are frequent. According to the current data, Pakistan is experiencing a shortfall of power between 6000 and 6500 MW. Microgrid technology has the potential to provide a solution to this problem in an efficient and low‐cost manner. This paper proposes the development of a hybrid microgrid system (HMGS) for rural communities. For that purpose, a technological analysis of the HMGS system for rural electrification is performed. Solar photovoltaic (PV) and wind resource‐based renewable energy systems are considered in this work for the electrification of rural areas of Pakistan. A hybrid PV/wind system is designed using MATLAB software. Simulation results show that a 230‐V sinusoidal output voltage has been produced by the proposed model. The advantage of this model is that it minimizes the impact of transients and provides a sinusoidal output waveform.


| INTRODUCTION
The International Energy Agency estimates that 1.3 billion people reside in developing nations, of whom 17.5% do not have access to electricity.The most important component of social life in our world, including production, transportation, family life, and other areas, is energy.On the other hand, as it is currently the primary source of energy production around the globe, energy production is the biggest challenge facing humans. 1 The concentration on creating sustainable energy sources as fossil fuel replacements has increased due to global warming (GW), energy security, and climate pollution. 2Utilizing fossil fuels has several drawbacks, including future resource depletion, exhaustible sources, cost increases, and so forth.Aside from that, pollution from fossil fuels also contributes to temperature increases and GW. 3 By 2050, the population and economic growth are expected to have more than doubled, which would increase global energy consumption.Therefore, practically all issues with fossil fuels may be resolved by renewable energy (RE).There are many different types of RE, including geothermal, wind, solar, hydropower, hydrogen, and biomass. 4In 2018, 5 energy from RS increased by 14.5%.Pakistan is rewarded with an abundance of coal reserves, but only a small portion of them is utilized.It will be easier for the Islamic Republic of Pakistan to fulfill its goals for sustainable development if electricity generation is switched to the native coal of the nation.The largest coal reserve potential exists in Thar, out of all the Pakistani cities.
Imam et al. 6 presented the effect of solar photovoltaic (PV) technologies cost drop on the economic viability of residential grid-tied solar PV systems in Saudi Arabia.The costs of RE sources have already fallen significantly compared with conventional energy sources, making them economically viable.The advantages of RE include its sustainability, cleanliness, and favorable effects on the environment.RE's fluctuating nature and generally higher initial cost are its drawbacks.Around the world, RE is incredibly beneficial, particularly for rural areas.PV panels can be used to convert solar energy (SE) into power, though wind turbines (WTs) convert the available energy from increased wind outflow into electrical energy using a generator.Solar and wind energies cause tremendous worry. 7

| Literature survey
To reduce the harmful effects of fossil fuels on the environment and to fulfill demand, solar PV energy and wind energy applications have recently risen quickly. 8At the same time, hybrid wind and PV power generating systems emerge as a promising option for power delivery in distant locations, villages, and other places where there is no utility grid power supply accessible. 9Given that a wind/PV-based hybrid system can generate more power than PV or wind used alone, WT development, PV panel research, and applications for wind/PV hybrid systems are all receiving increasing amounts of attention. 10

| Electricity and rural areas
Both rural and urban communities demand energy as a basic necessity of life.This indicates that, in contrast to the slow-moving program we have been implementing to provide them with grid electricity, one-third of our population is destined to lead a primitive and challenging life if we do nothing for them right away.Rural electrification has a great chance of happening because of RE, and SE in particular. 11In the solar age, electrifying all the unconnected homes should not take more than 10 years.International Renewable Energy Agency estimates that just 50% of the nation's rural residents have access to power and that fossil fuel imports are rising as domestic oil and gas production declines.About 30,000 villages out of a total of 125,000 have not yet been electrified. 12This indicates that 30 million people still live without electricity in rural areas.As a result, 4.6 million rural households will receive energy in total.There is no specific program for rural electrification on the distributed local generation lines being introduced in many other parts of the world, though provincial governments have funded rural SE projects. 13

| SE consumption in Pakistan and India
Fossil fuels are heavily utilized for energy generation in Asian nations (India and Pakistan).In Pakistan, natural gas accounts for 44% of all electrical production.With a share of 57% in India and 72% in China, respectively, coal serves as the primary energy source to produce electricity.Rare fossil fuels are under extreme strain from shortages due to intensive use.Asian governments are increasingly frequently discussing the use of clean and secure energy sources.By utilizing solar and wind energy, they hope to lessen the financial strain of fossil fuels while simultaneously helping the environment.Chinese SE generation is superior to that of Pakistan and India.China has accomplished much during this time, with its installed energy capacity rising to 131,100 MW.Pakistan and India, on the other hand, lag far behind China in the use of SE.In Table 1, at the end of March 2023, the SE generation between Pakistan and India from 2019 to 2023 is compared. 14

| Modeling of hybrid system
Engin 15 developed a tiny grid-connected PV-wind hybrid system.A 1642 W of silicon PV modules and a 1000-W Permanent Magnet Synchronous Generator (PMSG) WT made up the system.The power converter is made up of two different types of grid-connected inverters: an alternating current (AC)-direct current (DC) converter that transforms the PMSG's AC output into DC and a PV panel converter.The greatest output power from a WT was around 243 W at a wind speed of 8 m/s, and at the radiation of the sun at noon, the PV output power reached about 1.580 kW.The battery bank is used to store the extra energy produced by the hybrid system.In times of low wind speed or gloomy weather, the stored energy is used for emergencies.This paper presents a PV system model and a WT energy conversion system.For dependable rural electrification, Mustafa Kamal and Ashraf 16 offered an assessment of a hybrid power system based on RE and energy storage.For evaluating the suitability of a hybrid RE-based microgrid (MG) system for rural electrification in India, Sweta et al. 17 developed a decision-making approach.The ideal sizing and evaluation of grid-tied hybrid renewable energy systems (RESs) for the electrification of rural areas were described by Shubhangi et al. 18 The ideal size of isolated rural MGs for sustainable electrification using RE sources was suggested by Kamal et al. 19 For the electrification of rural communities, Nishant et al. 20 conducted a technosocio-economic study and tiered assessment of hybrid RES.

| Research gaps
Various researchers have performed modeling and analysis related to rural electrification.Several technologies are utilized by the researchers, such as standalone PV, wind, MGs, and battery energy storage systems.Moreover, for specific areas, modeling and analysis of the RES are also performed, but most of the researchers utilize the HOMER software to perform this analysis where modeling flexibility is limited.Therefore, in this work, hybrid microgrid system (HMGS) modeling performed with the help of MATLAB to get the modeling flexibility as well as the battery energy storage system is not considered to make the system economically viable.

| Novel contribution
This work presented RE resource-based MG and off-grid solutions for rural communities in Pakistan.The novel contribution of the work is as follows: • To model an HMGS and simulate it to analyze the technical viability of the system.• The maximum power from the PV system is extracted by modeling the maximum power point tracking (MPPT) approach.
• The proposed method using voltage control techniques mitigates the impact of transients and provides a sinusoidal output voltage waveform.

| Organization of the manuscript
The organization of the manuscript is as follows: Section 2 discusses the methodology of the work performed.Section 3 discusses the mathematical and MATLAB modeling of the developed HMGS.Section 4 discusses the results obtained from the developed HMGS, followed by the conclusion.

| METHODOLOGY
This section discusses the methodology utilized to perform this research.Figure 1 shows the flowchart of the methodology utilized to perform this research.
F I G U R E 1 Flowchart of performed research methodology.he structure of a solar cell is simple.It is made up of several materials in layers.First of all, the black cover glass surface helps increase photon absorption efficiency, and the glass shields the cell from atmospheric elements.The antireflective coating reduces the loss of photon reproduction to less than 5%.The touch grid shortened the photon's path so that it could reach the semiconductors. 24P and n semiconductors are found in two thin layers that make up the PV device's core.Back contact also produces better outcomes.The sun's beam holds the key to creating a PV effect. 21

| Wind energy
SE has been translated into wind energy.Wind energy is created by the nuclear fusion of hydrogen (H) and helium (He).The hydrogen and helium fusion processes generate heat in both directions.The planet meets practically all of the earth's energy demands despite only partially absorbing solar sunlight. 14Numerous wind power plants are being built in Pakistan, and many of them have already been put into service.The projects that are in operation in Pakistan include the Jhimpir Project, Wind Energy TII, Jhimpir Wind Energy Project, and Three Gorges First Wind Farm.This demonstrates how electricity may be produced anywhere in the nation due to wind pressure.Wind pressure increases in regions close to coasts, which is better for producing power.A recent change in wind pressure in Swat indicated the ability to produce electricity when wind conditions are favorable.The Nukundi, Jhimpir, Noonabad, Thatta, Chagi, and Gharo places are preferred for MG by employing WTs among the off-grid locations that can be operated through it. 25

| Hybrid systems
A hybrid system is one in which we employ many power generation techniques.There are many other hybrid energy system types, but the wind and solar hybrid system is thought to be the cleanest and one that is expanding the fastest. 26A better overall supply pattern is frequently possible by merging two or more sources.The region's wind and solar potential are crucial for the hybrid wind PV system.As a result, it may be used both during the day and at night.During the day, it uses energy from the sun, and at night, when there is no sunlight, it uses potential wind energy or energy from batteries to continue operating.For this reason, wind and solar hybrid systems complement one another nicely. 15he general design depicted in the illustration provides a clear understanding of the suggested model.While a WT converted wind energy into AC electrical power, a PV panel converted sunlight into electricity that was connected to a DC-DC converter.The energy crisis and global climate change are two significant issues, and wind energy can solve both of these issues.Utilizing clean wind energy will result in a reduction in the emissions of CO 2 , SO 2 , NO x , and other hazardous wastes.Additionally, the use of wind energy has the potential to significantly cut costs and reliance on fossil fuels. 27A wind and PV-based hybrid system is illustrated in Figure 2.
F I G U R E 2 Microgrid-based renewable energy resources hybrid system.AC, alternating current; DC, direct current; PMSG, Permanent Magnet Synchronous Generator; PV, photovoltaic.
The lower voltage needed to charge the batteries are created by converting the higher DC output of the solar panels. 28The output of the solar module is continuously examined by MPPT and compared with the battery voltage to determine the best voltage to charge the battery with and the best power to supply to the load connected to the battery. 29The MPPT algorithm makes sure the system is operating at its maximum power point by controlling the voltage we receive from the solar panel. 30The MPPT is connected to the boost and buck/boost converters, and the insulated gate bipolar transistors (IGBTs) in the circuitry are given a duty cycle of 0.5.It switches at a 5000-Hz pulse width modulation (PWM) frequency. 31A highly interesting point on the PV curve is the operating point.At this point, the PV module transmits the most power it can to the load. 32his varies based on variations in the cell's temperature as well as the sun's heat. 33n this work, perturb and observe (P&O) algorithm is utilized for the MPPT of the PV output.

| MODELING OF THE HMGS
In this section, the authors discussed the detailed mathematical and software modeling of the proposed HMGS.

| Mathematical modeling
The largest problem with RE sources is their reliance on the environment, even though they are extremely clean and effective.As a result, the hybrid system is more reliable than a system that uses only RE. 34 Performance and analysis of WTs are largely dependent on the geometrical design of the turbines, which defines the key performance characteristics.The power coefficient C ( ) P presents the efficiency of the wind system.The output power from WT is given as 35 Equation ( 3) can be modified as follows:  ( ) where  U 2 and U w 2 are the upstream and downstream pressure, respectively.The mass flow rate is substituted into Equation (2) to produce the following results: Equations ( 4) and ( 5) can be used to express the wind speed at the rotor plane as the following, where it equals the average of the upstream and downstream wind speeds.
As the friction-related reduction in wind speed, a is unquestionable.Then, Equation ( 7) can be rewritten as Due to continuity, the flow field's diameter must grow as its speed lowers; also, the torque turbine blades rotate as a result of an abrupt drop in pressure on the rotor plane.The thrust times the velocity at the rotor plane equals the rotor output power.If you think back to Equation (4), the output power is stated as follows:  ( ) Equation ( 11) is obtained by substituting Equations ( 8) and ( 9) into Equation ( 10): The ability of WTs to extract electricity determines the amount of power they can produce.The power coefficient C ( ) P is a measurement of this aptitude, so Equations ( 11) and ( 12) are equal, and the resulting power coefficient is It is possible to display the power coefficient.
Equations ( 8) and ( 9) along with Equation ( 5) can be used to express turbine thrust in numerous ways, as seen below.
The turbine torque is expressed as follows: C P is a crucial factor in the performance of the WT.In most cases, the revolutions per minute or radians per second (nearly in rad/s) are used to assess the rotational motion of the WT rotor.Their connection is as follows: Using reference torque, it is possible to determine the reference to DC by determining the rectifier's output voltage.

| PV system modeling
The PV cells are created using semiconductor materials.The PV effect occurs when SE is converted by PV cells into electrical energy. 36The modeling of PV is illustrated in Figure 3.
There is less power dissipation inside the cell because the load resistance must be smaller than the shunt resistance's magnitude and the resistance of the series is significantly lower than the resistance of the load.
The voltage will be equal to zero in a short circuit instance, and photon current and short circuit current will be equal (I ph = I sc ).Consequently, Equation ( 22) can be changed to In the event of an open circuit, the voltage is V = V oc and the current is equal to zero.Therefore, the following formula may be used to get the open-circuit voltage: The PV cell's output power can be determined by PV (25)   The open-circuit output voltage can be calculated using the provided formula.

| Modeling of the wind system
The following presumptions are used in the modeling of wind energy converters.The modeling of wind is presented in Figure 4.
• Let there is no friction.
• There is continual wind.
• Synchronous flow at the rate of 1.22 T kg/m 3 .
• The wind energy converter is surrounded by open air on all sides.
Under the aforementioned circumstances, a theoretical model that is unrelated to the technical design of a wind energy converter can be used to determine the maximum physically possible wind energy conversion.The movement of the air mass possesses a certain amount of energy.Air movement on the earth's surface provides this energy, which is dictated by the velocity and pressure differences.This is the main energy source used in WTs to produce electricity.
The equation yields the theoretical medium power P as a result.
( ) Where A WT can only convert up to 59% of the kinetic energy of the wind into the mechanical energy needed to rotate a rotor, according to German physicist Albert Betz.It is known as the Betz limit.The power coefficient C p is the name given to this limit.
The calculated electrical power is provided by C e is the transformer terminals' total net efficiency coefficient.transistor (MOSFET), and the IGBT.An output voltage waveform with a sinusoidal shape characterizes the ideal inverter.

| Proposed HMGS
In reality, the voltage waveform of an inverter is not sinusoidal and contains some harmonics.A voltage with a square wave or quasi-square wave may be appropriate for low-and medium-power applications.For high-power applications, a sinusoidal waveform that has been somewhat warped is required.The rate at which semiconductor devices are turned on and off by the inverter control circuit determines the inverter output frequency; as a result, the AC output frequency is easily changeable.The harmonic content of the output voltage can be lowered or significantly reduced by the switching approach of variable high-speed power semiconductor devices.This system makes use of a voltage controller, which maintains a constant amount of system voltage.The electronic voltage regulator (VR) maintains the output voltage constant despite changes in the input.The VR is made up of the feedback signal from the output, which is coupled to the reference voltage.For the inverter to adjust the output voltage by the difference, the PWM generator must generate firing pulses.

| RESULTS AND DISCUSSION
MATLAB software is used to simulate the suggested model before optimization.Wind, solar, and other renewable energies have attracted interest and are being developed quickly as environmental protection concerns rise.The proportion of clean energy in rising power demand has increased thanks to advancements in RE technology.Solar and wind power cannot, however, meet all of the world's energy needs.They can be coupled to boost the supply of power.Singleload systems are the major application for off-grid wind-solar hybrid power generation.The BJT is controlled by the VR, which is a discrete PWM generator.DC input voltages are transformed into switched voltages using switching regulators.The power MOSFET, or BJT switch, is then exposed to this voltage.
F I G U R E 6 PV simulation system model.PV, photovoltaic.
Figure 6 shows the MATLAB model of the PV system.In this model the computed open-circuit voltage (V oc ambient ) is 28.5 V, and the time for the PV array to reach V oc ambient which is called saturation time is 0.03 s.

| MPPT technique
The authors used the P&O MPPT method in this work.It is connected to the boost and buck/boost converter, and the IGBTs in the circuitry are given a duty cycle of 0.5.It switches at 5000 Hz PWM frequency.

| WT output
Figure 7 shows the WT model developed in this research.Figure 8 presents the output of the WT utilized in this research.

| Developed HMGS simulation model
Figure 9 shows the MATLAB Simulink model of the developed HMGS.
To maintain a consistent output voltage, a circuit that controls the power switches on and off periods supplied the output voltage as shown in Figure 10.
A transmission line (100 km) connecting threephase sources with a 25 kV voltage is also included in the model.The transmission line's end is connected to the distribution transformer (step-down), which reduces the voltage to 400 V at 50 Hz.
The external voltage and the amount of sunlight the PV cell receives are the two variables that determine its output current.The voltage will be zero and the current will be at its maximum when the cell is shorted (I sc ).The voltage reaches a maximum when the cell is open-circuited.In this instance, the current value is 0. In all scenarios, the power would be zero.Between open and short circuits, the power output exceeds 0. A hybrid-based DC waveform of wind and solar is illustrated in Figure 11.The horizontal axis shows voltages, whereas the vertical axis shows time.From 0 to 220 V, there is no disturbance in the system.After the load is applied to PV and wind, there is a disturbance of 0.2-1 s.
Figure 12 shows the waveform of the PWM generator used to control the VR and produce the pure sinusoidal waveform.
The volatility generated by the proposed HMGS will be transient.The advantage of the proposed system is a reduction in transient adverse effects when it is implemented during load switching.The waveform of the load voltage seen in Figure 13 is entirely sinusoidal for 0.3-0.59s.  model.The advantage of the developed VR-controlled HMGS is that it minimizes the effect of transients on the output voltage and provides a 230 V sinusoidal output waveform.
The main limitation of the proposed work is the unavailability of the hardware implementation of the proposed software analysis.A real-time digital simulator can be utilized to validate the software analysis results.Further, for MPPT, recent adaptive control techniques can be utilized.These techniques make the system complex but can be useful for getting better results.

F I G U R E 3
Equivalent circuit of the photovoltaic cell.

Figure 5
Figure5shows the developed HMGS.A power electronics device known as a DC/AC converter uses the firing pulses produced by a PWM generator to convert a DC supply to an AC supply.It ranges from megawatts to mW (for mobile) and mW (for highvoltage lines).An inverter is a device that is used to convert DC electricity into AC power at the required output voltage and frequency.There are numerous on/ off control devices that can be used for this process.Some examples of these controlling devices include the BJT, the metal oxide semiconductor field-effect

F I G U R E 7
Wind turbine model.PWM, pulse width modulation.

F
I G U R E 8 Wind turbine output (time in seconds at the x-axis and voltage in volt at the y-axis).DC, direct current.F I G U R E 9 Voltage controller-based proposed HMGS simulation model.HMGS, hybrid microgrid system; PV, photovoltaic; PWM, pulse width modulation; RLC, resistor, inductor, and capacitor.This manuscript presents the modeling, simulation, and analysis of a hybrid PV-wind-based MG system.For modeling and simulation, MATLAB software was employed.The DC output from the MG is 230 V DC.The P and O MPPT technique is utilized to get maximum power.The VR control is employed in the proposed model to control the output voltage.The VR is controlled by the PWM generator.The PWM generator for the hybrid PV-wind system creates the firing pulses that are used by the inverter to change the output voltage based on the voltage differences.A 230-V PWM output voltage has been produced by the suggested F I G U R E 10 Simulink model of voltage controller.LC, inductor and capacitor; PWM, pulse width modulation.F I G U R E 11 DC voltage waveform of HMGS (time in seconds at the x-axis and voltage in volts at the y-axis).DC, direct current; HMGS, hybrid microgrid system; PV, photovoltaic.
22lar photovoltaic energySE is abundant in Pakistan and can be used for more than just PV applications; it can also be used to generate thermal energy.Pakistan is fortunate to have 16 h of sunlight each day.Solar-generated electricity powers a large portion of Pakistan's infrastructure.21InBaluchistan,Punjab,Sindh, and Azad Kashmir, Pakistan has solar power plants.The Pakistani private energy industry and the Chinese International Renewable Energy Agency are establishing the scheme.Only locations that are connected to the grid should choose this.Off-grid living is still a challenge that needs to be handled.Pakistan is endowed with abundant SE, and the country's solar irradiation of 5.3 kWh/m 2 /day makes it easier to electrify off-grid areas.22Onemegawatt of energy may illuminate 750 dwellings, according to a fact.To produce free electricity locally, off-grid regions around Pakistan can employ MGs driven by solar panels.Mumniala, Digri, 2.1 | Dittal Khan Lighari, Ghakkar, Khukhera, Manawala, DI Khan, Mianwali, and Narian Khorian are among the affected places (Mirpurkhas district).It can be used to operate in some off-grid places.MGs are found to work best in the Nukundi regions of Katibandar, Jamshoro, Bin Qasim, Gharo, Jhimpir, and Swat.