Abstract—Due to ever increasing powerdemands developing countries like India is facing a major problem of powerdeficit. Due to this demand there is tremendous pressure on conventionalsources for power generation. Hence, the demand for unconventional energyresources has gained rapid pace in the present scenario. Therefore an attempthas been made in this paper to provide an alternative solution for such reallife problems and to meet the customer’s demand during peak load time. In theproposed approach of smart power system for home (SPSH) two different loads asDC and AC load are considered and the results are simulated in MATLABenvironment.
A storage battery and solar panel are synchronized to achievedesired result. The battery back-upaccounts for the power consumption in case of absence of grid supply. Thissolution helps the customer by installing a back up battery system in tandemwith the grid supply and integrating renewable solar energy into a home powersupply system. Keywords—Smart Power System forHome (SPSH),MATLAB Simulation, Solar power, Power Grid, Battery.I.
Introduction Excessive usage ofthe non renewable sources available in nature like coal, petroleum, natural gasis causing its resources to being depleted. Therefore, soon there will be atime when we will face a serious fuel shortage. Hence,it is essential at thisstage for reasonable and effective utilization of resources as an importantpath which can deal with the global energy crisis. Integration of sustainablesources of energy in distribution systems is gaining momentum ever since.
Inderegulation and restructuring of power system, the penetration of distributedresources is usually done at bulk load point but to generate small power likelyfor houses it can be done individually provided that the resources areavailable easily and at economical prices and on regular basis. For renewableresources this is possible in case of solar and wind power generation. It is practicallyimpossible to set up windmills for individual customer for economical reasonsand also wind energy is not always regularly available. Also, wind mills causehuge noise which is unbearable and hence it needs to be installed at far awayfrom the residential areas. Therefore, the solar power is found to be mosteconomical for local generation at a low scale and can be integrated with thegrid system to yield a Smart Home Power Supply to tackle the dependence onrenewable sources and power generation problems.
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But there are certain challenges to integrate the solar panels withexisting grid system and implementing of the smart grid as the output of distributedsystems keep on changing rapidly. But by installing a battery storage inparallel this issue can be resolved and thus power usage can be optimized.While designing solar array a major issue we face is of optimizingoutput power to charge the battery completely. Thus we need to design thissystem using MPPT (maximum power point tracker). An MPPT is a technique usedfor extracting maximum available power from PV panels under certain conditions.It obtains maximum available power from PV module by directing them to functionat the most efficient voltage (maximum power point). It works the best in coldweather cloudy/hazy days and also when battery is deeply discharged.
For designing SPSH, MATLAB Simulink approach has been used. Simulink has been developed by Math Works. It is a graphical programming environment for modelling,simulating and analyzing multi-domain dynamical systems. Its primary interface is a graphical block diagramming tool and a customizable set of block libraries.
It offers tight integration with the rest of the MATLAB environmentand can either drive MATLAB or be scripted from it. Simulink is widely usedin automatic control and digital signal processing for multi-domain simulation and Model-Based Design. It supports system-level design, simulation, automatic codegeneration, and continuous test and verification of embedded systems.
II. Literature survey It is achallenging task to design and implement next generation smart grid asintermittency inherently affects solar energy. This is due to rapid changes inthe output of the distributed system which results in many issues for thedistributor system operator with a large amount of photovoltaic devicesinstalled. Hence usage of battery storage has increased as it is used to helpin integration of solar power with grid. These systems are capable of absorbingand delivering both real and reactive power with sub-second response times anddue to these capabilities, battery energy storage systems can mitigate suchissues with solar power generation as ramp rate, frequency, and voltage issues.It can also focus on system stability and can also integrate energy storagecontrol systems with energy markets thus making the solar resources moreeconomical.
The reference paper 4 provided an overview of challenges facedwhile integrating solar power with electricity distribution system, technicalaspects of battery storage systems and the various modes of battery storagesystems in grid-tied solar applications. Thereference paper 3 has proposed a configuration of a small capacity grid-connected solar powergeneration system by a dual output DC-DC power converter and an inverter. Toconfigure this dual-output DC-DC power converter to convert the output voltageof a solar cell array into two dependent voltage sources with multiplerelationships voltage doubler based topology can be used. The grid-connectedinverter has been configured by a dual-buck power converter and a full-bridgepower converter where a dual-buck power converter is switched at high-frequencypulse-width modulation to generate DC voltage and full-bridge power converteris switched synchronous with the utility voltage, to convert the four-level DCvoltage into AC voltage. The proposed solar power generation system generates asinusoidal output current in phase with the utility voltage.Since past twodecades off-grid solar home systems (SHS) is being used which comprises ofsolar panels, batteries, a charge controller and loads. But there are certainissues with SHS that are cost, reliability, utilization and sustainability. Thereference paper 1 dealt with interconnection of SHS to form a micro grid ofconnected prosumers and consumers that may offer a solution by employing smartmanagement of the power distribution amongst connected households that haspotential to ‘unlock’ latent generation and storage capacity and so improvereliability and security of supply, reduce the system cost per head, andultimately levels the cost of energy supplied.
These factors help to improvethe overall sustainability, efficiency and flexibility of SHS technology. Thispaper thus represents the functionality of a Smart Power Management (SPM) thatseeks to distribute power across prosumers/consumers connected to a micro-gridof interconnected SHS. By simulation of the SPM significant improvements inreliability of supply within the micro-grid can be demonstrated. The powermanagement methodology utilizes algorithms applied to manage power flowsbetween customers. III.
Methodology Fig. 3.1 shows the block diagram of theproposed smart power system for home (SPSH), in this paper. Three different powersources are synchronized in order to meet the load demand at customers end.
Thevarious sources are solar panel, batteries and the grid supply. The solar powerand the battery output are interfaced and the resultant power canal so be fedto the DC loads. Since the grid power is AC therefore, inverter circuit is usedto convert DC into AC of required voltage level at grid frequency.
Staticswitches are used to change the input supply to AC load as per the availability.In day time, the solar power is fed to the load and in night the main power isswitched to the grid supply. However, the battery is always plugged to chargethrough battery charger as shown in Fig.(I). Constant charging of the storagebattery allows the utilization of solar power in peak load hours. Interfaceallows the connection between solar output and the battery such that power canflow in one direction only. However, battery charger is a converter circuitused to converter back ac in to dc for charging at desired level of voltage.2 Figure 3.
1 The electricalperformance of solar system is demonstrated by their current-voltage (1-V) characteristics.For solar system I-V characteristics represents theinfinite operating points under different operating condition of solarradiation and the temperature. In mathematical formulations the commonly developedterminologies are described as under:a. Open circuit voltage (Voc)b.
Short circuit current (Isc)c. Maximum power point (P mp)d. Maximum power voltage (V mp)e. Maximum power current (Imp)(i) Open circuitvoltage (Voe): This is the maximum DC voltage developed across the outputterminals when no load is connected in the system. It is independent of the areaof the solar cell and is the indicator of the maximum voltage limit for solarpanel.(ii) Short circuitcurrent (Ise): This is the maximum current that can flow through the solarpanel when load terminals are short circuited. In practice, it is directlyproportional to the solar irradiance. But, solar cells are inherently currentlimited therefore; care is to be taken if they are shorted for testing purposewith appropriate shortingdevice.
(iii) Maximum powerpoint (P mp): Under particular operating conditions of solar radiation and thetemperature,the maximum value of the product of currentand voltage, in I-V characteristics,indicate the maximumpossible power that can be drawn from solar system.Thecorresponding point in I-V curve is known as themaximum power point.(iv) Maximum powervoltage (V mp): The value of voltagecorresponding to maximum power point istermed as the maximum power voltage.(v)Maximum power current (Imp): The value of currentcorresponding to maximum powerpoint is termed as themaximum power current. Alternatively, it can becalculatedas the ratio of the maximum power (Pmp) to the maximum power voltage (V mp).Inpractice, specific equipment is used to determine thepoint on the I-V curve.The load on solar cell can bea battery or AC load connected through inverter circuitry.
Therefore,the operating point on I-V curve is found to be loaddependent. Also, theMaximum Power Point Tracking (MPTT) circuits are integral to the chargecontrollers and interactive inverters.Formathematical formulations of the above parameters the following assumptions aremade,ISC1=rated short-circuitcurrent (in ampere) at irradiance El.ISC2 = short-circuit current(in ampere) at new irradiance E2 .E1 = rated solar irradiance(W/m2)E2 = new solar irradiance(W/m2)PmPl = rated maximum power(watts) at irradiance E1.Pmp2 = new maximum power(watts) at new irradiance E2 .ImPl = original maximum powercurrent (ampere) at irradiance E1Imp2 = new maximum powercurrent (ampere) at new irradiance E2Asolar cells, modules or arrays produce DC power.
Thecurrent-voltage (T-V)characteristic represents the electricalperformance of solar system. At a givensolar irradiance andtemperature an T-V curve represents an infinite numberofoperating point for current and voltage pairs. .
The rated TVparameters arethe basis for sizing and designing thephoto voltaic source and output circuits,and for comparingwith field measurements on PV arrays. Fig.(II) shows the equivalent circuit diagram of the solar cell.Figure 3.2 Equivalent Circuit ofSolar Cell Thegeneralized characteristic equation of a solar cell, whichrelates solar cellparameters to the output current and voltage,can be written as: (1) Here,I = current following through loadterminals,IL = photo-generated current,Io = reverse saturatedcurrent,V = load terminal voltage,Rs= series resistance,Rsh = shunt resistance,n = diode ideality factor, which is ‘1’for an ideal diode,q = elementary chargek = Boltzmann’s constantT = absolute temperatureA solar cellproduces voltage and current output that varies with solar irradiance andtemperature.
Therefore, the various parameters such as short-circuit current(Isc), maximum power current (Imp), and maximum power (P mp) can be translatedat another level of irradiance and they are obtained as under, (2) (3) (4) Figure 3.3 Circuit Diagram ofGrid Tied Inverter (Part A) Figure 3.4 Circuit Diagram ofGrid Tied Inverter (Part B)Fig. 3 and 4 shows the equivalentcircuit diagram of the gridtied inverter. For grid-tied inverter the DC inputis the power generated by the solar system or the battery. As long as solarsupply is available it is used at its maximum level and the battery is madestandby.
Two stage inverter circuit is used for stepping up the level ofvoltage at desired value. IV. Result The design ofthe proposed SPSH model will be simulated in MATLAB 2017 environment. Under allconditions, three sources namely; grid power , solar panel and battery will be synchronized at load terminalto yield optimum power generation. The battery of voltage level equal to thesolar panel can be selected so that in every working condition, maximum powercan be derived from the solar panel and any other load requirement can be metby the batteries.
This will keep the voltage demand of load in balance. Component description Specification Solar Energy System Temp :35-40o C Irradiance :0.5-1Kwh/m2/day Battery NickelMetal Hydride (NiMH) Charge Discharge Efficiency : 60-90% Grid Supply 250V(peak),50Hz AC load DC load nominal :100V,400W AC load nominal voltage : 250V,305W,50Hz Table 4.1: Component specificationAs real timevariables cannot be accounted for in simulation environment softwares we cannotobtain accurate readings.
But ideal condition readings can be observed andafterhand we can try to account for the variable irradiance and temperaturefactors affecting power generation of solar panels.Hence first weobserve the ideal condition working of PV modules in MATLAB as shown in figure4.a below.With batteryassumed to be in fully charged conditions and grid supply is connected afterthe DC-AC inverter circuit ,the result of these connections made in Figure 3.3can be explained by Figure 4.
2 which shows current obtained from solar panel inthe synchronization process. Figure 4.1: Solar Panel V-I characteristicsFigure 4.2: Current of solar panel during synchronizationFigure 4.3: DC load current during synchronizationThe simulationsof AC and DC loads during synchronization and inverter currents are not yetperformed and these were few of theexpected results. V.
Conclusion The work donein this paper for Smart Power Systems will be simulated in MATLAB environment.This will help the consumers to meet their load demand by local powergeneration. The SPSH will increase the efficiency of the system when the powerdemand becomes more than generation capacity and the synchronization of DCpower from the solar cell and the battery will be achieved, and the grid poweris managed separately. Optimization of the power usage from solar panel,battery and the grid supply needs to be considered in future works.
Theefficiency of solar PV array can be improved for optimum better results. VI. Application andFuture Scope i.Cost reductionii.They improve the adeptness oftransmission linesiii.Intelligent Appliances: Intelligentappliances have capable of deciding when to consume energy based on customerpre-set preferences. This can lead to going away along toward reducing peakloads which have an impact on electricity generation costs. For example, smartsensors, like temperature sensor which is used in thermal stations to controlthe boiler temperature based on predefined temperature levels.
iv.Smart Power Meters: The smart meters provide two-waycommunication between power providers and the end user consumers to automatebilling data collections, detect device failures and dispatch repair crews tothe exact location much faster.v.Smart Substations: Substations are included monitoring andcontrol non-critical and critical operational data such as power status, powerfactor performance, breaker, security, transformer status, etc. substations areused to transform voltage at several times in many locations, that providingsafe and reliable delivery of energy. Smart substations are also necessary forsplitting the path of electricity flow into many directions.
Substations requirelarge and very expensive equipment to operate, including transformers,switches, capacitor banks, circuit breakers, a network protected relays andseveral others.vi.Super Conducting Cables: Theseare used to provide long distance power transmission, and automated monitoringand analysis tools capable of detecting faults itself or even predicting cableand failures based on real-time data weather, and the outage history. VII. References 1 BartoszSoltowski, ScottStrachan, Olimpo Anaya-Lara,DamienFrame,Michael Dolan,”Using smart power management control tomaximize energy utilization and reliability within a microgrid ofinterconnected solar home systems”,Global HumanitarianTechnology Conference (GHTC), 2017 IEEE2 Pawan Kumar, Iqbal Ali, M.S.
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