Analysis and Implementation of a Three-Phase Grid-Connected PV/Wind Hybrid System

Abstract

The increasing energy demand and depletion of fossil fuels has risen in awareness of searching for alternative energy source thus the inexhaustible solar and wind energy is becoming an interesting topic which has grabbed the attention of researchers to make it sustainable power. The objective of this paper is to provide sustainable power for rural areas and remote places. This paper gives the architecture of hybrid system. The proposed system consists of solar PV and Doubly Fed Induction Generator (DFIG) based wind turbine. In Solar PV MPPT technique is used to maximize the power. The DFIG has two controllers Rotor side control and Grid side control. Rotor side converter and Grid side Converter have the capability of generating or observing reactive power and to maintain constant rotor speed, and controls the DC-link voltage, inverter AC-DC-AC is implemented using vector control method. This work explains grid connected PV wind system in MATLAB Simulink. simulation of a hybrid PV wind system for three phase grids is explained in this work. The simulation results for varying irradiance conditions and varying wind speed conditions are also explained.

Introduction

I. INTRODUCTION

Over the last decade, it became apparent that the world’s resources of fossil fuels are beginning to come to an end. Estimates of energy resources vary but oil and gas reserves are thought to come to an end in roughly 40 and 60 years respectively and coal reserves could only be able to last another 200 years.

The rapid depletion of fossil fuel resources on a worldwide basis has necessitated an urgent search for alternative energy sources to cater to the present days’ demand. Another key reason to reduce our reliance on fossil fuels is the growing evidence of the global warming phenomena. Since the industrial revolution, by burning these fossil fuels, we have caused a dramatic increase in the release of carbon dioxide into the atmosphere.

The carbon dioxide accumulates in the atmosphere and absorbs the long-wave, infrared radiation emitted by the planet that will otherwise be released into space. By holding this radiation in the Earth's atmosphere, the temperature of the Earth has increased. This global warming effect would have far-reaching effects if it is not reduced as quickly as possible. The natural equilibrium of the planet is very fragile and an increase in temperature of 1 ° C to 2 ° C will break the ice caps that cause extensive floods throughout the world. It is therefore necessary to find alternative sources of energy to offset the continuously rising electricity consumption while minimising harmful environmental impacts. Alternative energy options, such as solar, wind, biomass, ocean, thermal and tidal, have drawn large-scale power generation industries.

Thus, owing to their availability and incentives in local power generations, solar and wind power systems are seen as attractive forms of power generation.

A.  Photovoltaic (PV) Power System

PV power system converts sunlight into electricity. The basic unit of a photovoltaic power system is the PV cell, where cells may be grouped to form panels or modules. The panels then can be grouped to form large photovoltaic array that connected in series or parallel, as shown in Fig.1. Panels connected in parallel increase the current and connected in series provide a greater output voltage.

Small photovoltaic systems can be designed for portable use, on a fixed structure, or permanently mounted. No matter the installation, it is desired to get the maximum amount of power from the panel with minimal cost. As with wind turbine power systems, solar panels use various MPPT approaches depending on the case. One specific device uses an unloaded reference photovoltaic cell from which the MPPT controller determines the optimal power levels. This additional cell makes the discovery of a particular maximal power point that is not subject to electrical noise. However, extra cells can be expensive and require a greater surface area. As a consequence, this MPPT system should be reserved for fixed installations where 10 or more panels are used to collect electricity. When photovoltaic panels or other intermittent energy source are installed, particular attention shall be given to their power output in relation to the appropriate load. They are also installed to improve the power grid, or they themselves are supplemented by secondary batteries or generators. Another installation is based on photovoltaic panels, a rechargeable battery and a non-rechargeable backup battery.

B. Wind Energy Conversion System (WECS)

Wind turbine is an important element in a wind power system to generate electricity. It is categorize into different sizes according to the amount of power generated. A big wind turbine can produce up to two megawatts (MW ) of electricity. A small wind turbine generates less than 100 kW of electricity, which is ideal for use as a backup source. A very small wind turbine produces between 20 and 500 watts of electricity and is usually used for charging batteries.

The wind turbine absorbs the kinetic energy of the wind in a rotor composed of two or three blades physically connected to an electrical generator and is mounted on a high tower to maximise energy capture. There are actually two types of configuration for the wind turbine, the vertical-axis configuration and the commonly common horizontal-axis configuration. As shown in Fig. 3, a horizontal-axis wind turbine consists of the following basic components.

1. Tower structure
2. Rotor with three blades attached to the hub
3. Shaft with mechanical gear
4. Electrical generator
5. Yaw mechanism

The process of converting wind energy into electricity involves many components. The most noticeable elements are the blades and hubs. They run in a horizontal axis rotor like an airliner or a helicopter propeller, except in reverse. Vertical axis turbines are used less commercially because of their inefficient land use. However, they do not need high wind speeds to start generating electricity, so they are most widely used in suburban areas and at low altitudes. The hub of either the direction of the turbine may be connected to the shaft on the gearbox or straight to the engine. The gearbox is used to adjust the input torque and angular velocity.

Sizes more fitting for the engine. The generator in the wind turbine is a component that transforms rotary kinetic energy into electricity. Electricity produced may be DC, single-phase AC or three-phase AC. Each of them has a particular application which, depending on the application, introduces various difficulties. AC generators output one or two wires with a sine- wave voltage and current. The frequency of this output varies with the speed of angular rotation of the generator. The amplitude of these waves varies with the speed of rotation and the load of the output. One of the most complicated facets of using wind turbines as a source of energy is the interfacing of that power with the power grid or with equipment built to utilise the power grid. This has been done in two ways throughout history. Next, the output power frequency was changed by mechanical means. The internal generator was programmed to spin at a constant rpm, either by altering the gear ratio or by changing the blade pitch. In more advanced systems , electronic circuits are used to convert the amplitude and frequency of the power generated.

The use of power electronics decreases electrical efficiency by producing heat in electrical components, but can have a significant degree of control over the mechanical device. This control helps further energy to be collected at low speeds, decreased wear on the drive train, managed shutdown of the turbine and turbine speed control to increase input from the wind to the mechanical system. Using power from a generator to charge a battery or a battery bank can be challenging. The least complex approach is to use a DC generator that transfers all power directly to the battery. This configuration would not allow the turbine to adjust its speed, because it will not be able to determine the optimum speed of the rotor under increasing wind conditions. In addition, the battery could be overcharged and permanently damaged. In comparison, DC generators are much less physically powerful or stable than AC generators. If a single-phase or three-phase AC generator is corrected using two or six diodes, the resulting system will be more powerful than a DC generator, but still have the same speed and overcharging limits.

II. HYBRID SYSTEM

The dc circuit is set at a steady dc voltage in many small-scale systems and typically consists of a battery bank with energy storage, a controller to prevent the batteries from overcharging, and a load. The load may be dc, or in an ac setup, the inverter may be used. Connecting a wind generator to a constant dc voltage has big issues due to the misalignment of the weak impedance between the generator and the constant dc voltage (battery), which restricts the flow of power to the dc grid. In response to these issues, the researchers investigated the integration of the dc- dc converter in the dc connection. The power conditioning system manages the whole power management of the hybrid system. Fig.4 describes the planned electronic power interface, consisting of a wind side dc / ac converter, PV side dc / dc converter, traditional dc capacitor and grid side inverter

The voltage shift on the dc rectifier adjusts the voltage of the generator terminal and hence provides power over the current flowing out of the generator. As the current is proportional to the torque, the dc-dc converter will control the turbine rpm. The regulation of the dc-dc converter can be accomplished by means of a predetermined relationship between the rotor speed and the rectifier dc voltage to achieve the optimum power point monitoring or by means of a predetermined relationship between the electrical frequency generator and the dc-link voltage. Using these approaches, the PV / WECS hybrid generation system can provide almost good quality electricity. However, these approaches have the downside of needing expensive batteries and the installation of dump load is not an effective way of dissipating fluctuating power. Furthermore, they cannot guarantee the certainty of load requirements at all times, particularly under bad environmental conditions, where there is no power from the PV and WECS systems.

Alternative energy options, such as solar, wind, biomass and ocean thermal and tidal, have drawn large-scale power generation industries. Solar and wind power systems are perceived to be attractive sources of energy due to their affordability and topological advantages for local power generation. However, the downside, common to wind and solar solutions, is their volatile existence and reliance on weather and climate change, and fluctuations in solar and wind energy may not be compatible with the time distribution of demand. All of these energy systems will have to be oversized to make them fully reliable, resulting in an even higher overall cost.

It is sensible that neither a stand-alone solar energy system nor a wind energy system can provide continuous energy supply due to seasonal and intermittent variations. Fortunately, the difficulties created by the variable existence of these resources can be partly or entirely solved by combining the two resources into a proper mix, using the strengths of one source to overcome the weakness of the other. This is clear from the fact that, in many places, more solar radiation and less wind are possible during the summer months and, equally, more wind and less solar radiation are available during the winter. Hybrid systems that integrate solar and wind power generation units with battery backups will minimise their individual variability and dramatically reduce energy storage needs. With compatible characteristics of solar and wind energy resources at some sites, hybrid solar-wind power generation systems provide us with a highly stable supply of energy. As a result, hybrid solar-wind power generation systems are becoming more and more common for the power supply of small electrical loads at remote locations (telecommunications facilities, alpine huts or data logging stations for environmental criteria and remote villages / locations without grid power). The planet is facing the challenge of solving the oil crisis. The ever-increasing need for traditional energy sources and the need for a stable globe and a better existence for all living beings on this planet are moving society towards research and development of new, environmentally sound energy sources. Renewable energy sources, such as the photovoltaic ( PV ) system and the wind energy conversion (WEC) system, have become two promising potential energy sources, while others, such as fuel cells, are at an early stage of growth. A power generation system that incorporates two or more separate sources of energy is considered a hybrid system. Hybrid power plants have greater stability and lower generation costs than those using only one source of electricity. Wind and photovoltaic are used as primary sources of electricity. The basic control system tracks the maximum power from the wind power source without calculating the speed of the wind or engine, which is very helpful for real small wind turbines. The same regulation theory refers to the monitoring of the highest power point of the photovoltaic device without detecting the level of irradiance and the temperature. Integrating photovoltaic and wind energy sources as a storage system for massive traditional batteries or super-storage condensers, leads to a stable, non-polluting energy supply and lowers overall maintenance costs. The hybrid system shall be fitted with a maximum power point tracking controller, which shall monitor the maximum power from each source and which shall be supplied to the grid. Various MPPT methods have been considered in applications for green energy. Although the demonstration or contrast of MPPT performance with other methods is outside the reach of the current work, for its simplicity and faster tracking response, a voltage- based MPPT for PV and WEC systems has been suggested. The goal of integrating WEC and PV power generation systems is to optimise output energy and reduce output volatility. The proposed hybrid system is connected to the grid by means of an inverter.

 III. METHODOLOGY

Spotless and sustainable power sources like photovoltaic (PV) control is played a significant job in electric power age, and become basic nowadays because of deficiency and natural effects of customary powers. The sunlight-based vitality is straightforwardly changed over into electrical vitality by sun based photovoltaic modules. As a result of nonlinear I-V and PV qualities of PV sources, their yield power is principally relied on the ecological conditions and nature of burden associated. Thus, these conditions will be influenced the general productivity of the PV frameworks [1]. But the productivity of the sun-based PV module is low. Because of the mind-boggling expense of sun-based cells, a most extreme power point tracker is expected to work the PV cluster at its greatest power point. Subsequently the greatest power is extricated from the PV generator depends on three variables: insolation, load profile (load impedance) and cell temperature (surrounding temperature). To get the most extreme power from PV, a greatest power point tracker (MPPT) is utilized [2]. There are so many methods and algorithms for tracking of the MPP of the PV systems. In this paper, comparative investigations of Perturb and observe (P&O) algorithm and artificial neural network (ANN) technique algorithm using dc-dc converter is done in terms of the maximum power transfer capability of these algorithms.

A. Solar Cell And Effect Of Irradiance And Temperature

1. Photovoltaic (PV) System

In this section, model development of a PV module is given in detail. The PV model developed for this study is based on the research work by Caisheng Wang (2006).

Modelling for PV Cell/Module The most commonly used model for a PV cell is the one-diode equivalent circuit as shown in Fig.5. Since the shunt resistance Rsh is large, it normally can be neglected. The five parameters model shown in Fig.5(a) can therefore be simplified into that shown in Fig.5(b). This simplified equivalent circuit model is used in this study.

D. Modes Of Operation

There are two modes of operation of a boost converter. Those are based on the closing and opening of the switch. The first mode is when the switch is closed; this is known as the charging mode of operation. The second mode is when the switch is open; this is known as the discharging mode of operation [12].

1. Charging Mode

In this mode of operation; the switch is closed and the inductor is charged by the source through the switch. The charging current is exponential in nature but for simplicity is assumed to be linearly varying [11]. The diode restricts the flow of current from the source to the load and the demand of the load is met by the discharging of the capacitor.

2. Discharging Mode

In this mode of operation; the switch is open and the diode is forward biased [11]. The inductor now discharges and together with the source charges the capacitor and meets the load demands. The load current variation is very small and in many cases is assumed constant throughout the operation.

E. Stand -Alone Solar Power System

The solar PV system consists of a PV module, the dc/dc boost converter, the maximum power point tracking algorithm and the load. Radiation (R) is incident on the PV module. It generates a voltage (V) and current (I) which will be fed into the load [3]. The voltage power characteristic of a photovoltaic (PV) array is nonlinear and time varying because of the changes caused by the atmospheric conditions. When the solar radiation and temperature varies the output power of the PV module also changes. In order to obtain the maximum efficiency of the PV module, it must operate at the maximum point of the PV characteristic. The most extreme power point relies upon the temperature and irradiance which are non-direct in nature. The greatest power point following control framework is utilized and work viability on the non-straight varieties in the parameters, such as temperature and radiations [4]. A MPPT is used for extracting the maximum power from the solar PV module and transferring that power to the load. A dc/dc converter (boost converter) serves the purpose of transferring maximum power from the solar PV module to the load. A dc/dc converter acts as an interface between the load and the module. The dc/dc converter with maximum power point tracking algorithm and the load is shown in Fig. 11. By changing the duty cycle, the load impedance as seen by the source is varied and matched at the point of the peak power with the source so as to transfer the maximum power. Therefore, MPPT techniques are needed to maintain the PV array’s operating at its MPP [3].

V. FUTURE SCOPE

The proposed hybrid system can be extended to large non-linear loads. This system can be implemented for distorted supply with sinusoidal load and distorted supply with distorted loads. The control techniques can be enhanced to design different control schemes for the microgrid system. The proposed method can be used to regulate the distributed generation (DG) power and managed through DPFC to supply the load at point of common coupling in addition to compensate the power quality problems. The power generated by DG from the renewable energy is fed directly to the high frequency alternating current based micro grid system. In this case, DPFC can be used to enhance quality of power and regulation of power demand.

Conclusion

This work presented the modeling, simulation and Control of a grid connected PV and Wind Hybrid Power System. The system is simulated in MATLAB/Simulink environment. It is observed that the extraction of the maximum power from PV array is obtained using MPPT system. In Wind Energy Conversion system DFIG Doubly-fed induction generator based wind turbine used. The PV output and the wind output is given to the grid.

References

[1] Md. Wazedur Rahman; Karthikeyan Velmurugan; Md. Sultan Mahmud; Abdullah Al Mamun; Prasanth Ravindran “Modeling of a stand-alone Wind-PV Hybrid Generation System Using (MATLAB/SIMULINK)” IEEE 2021 International Conference on Computing, Communication, and Intelligent Systems (ICCCIS), 10.1109/ICCCIS51004.2021.9397194. [2] Hayat Elaissaoui; Mohammed Zerouali; Abdelghani El Ougli; Belkassem Tidhaf “MPPT Algorithm Based on Fuzzy Logic and Artificial Neural Network (ANN) for a Hybrid Solar/Wind Power Generation System” IEEE 2020 Fourth International Conference On Intelligent Computing in Data Sciences (ICDS), 10.1109/ICDS50568.2020.9268747. [3] Divyanshi Srivastava; Rahul Kumar Rai; S.K. Srivastava “Performance Analysis of Single MPPT Technique using RBFN for PV and Wind Hybrid System” IEEE 2019 2nd International Conference on Power Energy, Environment and Intelligent Control (PEEIC), 10.1109/PEEIC47157.2019.8976692. [4] Aquib Jahangir; Sukumar Mishra “Autonomous Battery Storage Energy System Control of PV-Wind Based DC Microgrid” IEEE 2018 2nd International Conference on Power, Energy and Environment: Towards Smart Technology (ICEPE), 10.1109/EPETSG.2018.8658550. [5] R. Alik and A. Jusoh, “Modified perturb and observe (p&o) with checking algorithm under various solar irradiation,” Solar Energy, vol. 148, pp. 128–139, 2017. [6] O. Khan and W. Xiao, “Integration of start–stop mechanism to improve maximum power point tracking performance in steady state,” IEEE Transactions on Industrial Electronics, vol. 63, no. 10, pp. 6126–6135, 2016. [7] G. J. G. Jothi and N. Geetha, “An enhanced mppt technique for high gain dc-dc converter for photovoltaic applications,” in Circuit, Power and Computing Technologies (ICCPCT), 2016 International Conference on. IEEE, 2016, pp. 1–9. [8] G. Cipriani, V. D. Dio, F. Genduso, R. Miceli and D. L. Cascia, \"A new modified Inc-Cond MPPT technique and its testing in a whole PV simulator under PSC,\" in Proc. of the 2015 IEEE Applied Power Electronics Conference and Exposition (APEC), Charlotte, NC, pp. 3060- 3066. [9] S. K. Ji, H. Y. Kim, S. S. Hong, Y. W. Kim and S. K. Han, \"Nonoscillation Maximum Power Point Tracking algorithm for Photovoltaic applications,\" in Proc. of the 2014 Power Electronics and ECCE Asia (ICPE & ECCE), Jeju, pp. 380-385. [10] Yi-Hsun Chiu, Yu-Shan Cheng, Yi-Hua Liu, Shun-Chung Wang and ZongZhen Yang, \"A novel asymmetrical FLC-based MPPT technique for photovoltaic generation system,\" in Proc. of the 2014 International Power Electronics Conference (IPEC-Hiroshima 2014 - ECCE ASIA), Hiroshima,pp. 3778-3783. [11] S. Dwari, L. Arnedo, S. Oggianu and V. Blasko, \"An advanced high performance maximum power point tracking technique for photovoltaic systems,\" in Proc. of the 2013 IEEE Applied Power Electronics Conference and Exposition (APEC), Long Beach, CA, 2013, pp. 3011- 3015. [12] N. Mendis, K. M. Muttaqi, S. Sayeef and S. Perera, \"Standalone Operation of Wind Turbine-Based Variable Speed Generators With Maximum Power Extraction Capability,\" IEEE Transactions on Energy Conversion, vol. 27, no. 4, pp. 822-834, Dec. 2012. [13] S. Poshtkouhi and O. Trescases, \"Multi-input single-inductor dc-dc converter for MPPT in parallel-connected photovoltaic applications,\" in Proc. of the 2011 IEEE Applied Power Electronics Conference and Exposition (APEC), Fort Worth, TX, pp. 41-47. [14] I. Colak, E. Kabalci and G. Bal, \"Parallel DC-AC conversion system based on separate solar farms with MPPT control,\" in Proc. of the 2011 Power Electronics and ECCE Asia (ICPE & ECCE), Jeju, pp. 1469-1475. [15] G. Gamboa, J. Elmes, C. Hamilton, J. Baker, M. Pepper and I. Batarseh, \"A unity power factor, maximum power point tracking battery charger for low power wind turbines,\" in Proc. of the 2010 IEEE Applied Power Electronics Conference and Exposition (APEC), Palm Springs, CA, pp. 143-148. [16] M. E. Haque, M. Negnevitsky and K. M. Muttaqi , “ A novel control strategy for a variable-speed wind turbine with a permanent magnet synchronous generator”. IEEE Transactions on industry application, vol. 46, no. 1, pp. 331-339, jan/feb 2010. [17] M. Kiani, D. Torregrossa, M. Simoes, F. Peyraut and A. Miraoui, \"A novel maximum peak power tracking controller for wind energy systems powered by induction generators,\" in Proc. of the 2009 IEEE Electrical Power & Energy Conference (EPEC), Montreal, QC, pp. 1-3. [18] M. Shirazi, A. H. Viki and O. Babayi, \"A comparative study of maximum power extraction strategies in PMSG wind turbine system,\" in Proc. of the 2009 IEEE Electrical Power & Energy Conference (EPEC), Montreal, QC, pp. 1-6. [19] H. Patel and V. Agarwal, \"Maximum Power Point Tracking Scheme for PV Systems Operating Under Partially Shaded Conditions,\" IEEE Transactions on Industrial Electronics, vol. 55, no. 4, pp. 1689-1698, April 2008. [20] M. E. Haque, K. M. Muttaqi and M. Negnevitsky, “Control of a Stand alone variable speed wind turbine with a permanent magnet synchronous generator”, Proceeding of IEEE power and energy society general meeting , pp. 20-24 july 2008. [21] T. Esram and P. L. Chapman, \"Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques,\" IEEE Transactions on Energy Conversion, vol. 22, no. 2, June 2007, pp. 439-449. [22] [12] T. F. Chan, L. L. Lai, “permanent magnet machines for distributed generation: a review” , Proc. 2007 IEEE power engineering annul meeting , pp. 1-6. [23] M. Fatu, L.Tutelea, I. Boldea , R. Teodorescu, “ Novel motion sensorless control of stand alone permanent magnet synchronous generator (PMSG) : harmonics and negative sequence voltage compensation under nonlinear load ” , 2007 European conference on Power Electronic and Application, 2-5 Sept. 2007. [24] D.Sera, R.Teodorescu, and P.Rodriguez, “PV panel model based on datasheet values” ,IEEE International Symposium on Industrial Electronics,ISIE,PP.2392-2396,2007. [25] H. Polinder, F.F.A van der Pijl, G.J.de Vilder , P.J.Tavner, “Comparison of direct- drive and geared generator concept for wind turbine ” , IEEE Transactions on Energy Conversion , vol., 21, no. 3, pp725-733, Sept. 2006. [26] Seul Ki Kim, Eung Sang Kim, Jong Bo Ahn, “Modeling and control of a Grid connected Wind/PV Hybrid Generation System”, 2005/2006 IEEE PES Transmission and Distribution Conference and Exhibition,21-24 May 2006,pp.1202-1207. [27] Fernando Valencaga, Pablo F. Puleston and Pedro E. Battaiotto, “Power Control of a Solar/Wind Generation System Without Wind Measurement: A Passivity/Sliding Mode Approach”, IEEE Trans. Energy Conversion, Vol. 18, No. 4, pp. 501-507, December 2003. [28] N. Mohan, T. M. Undeland and W. P.Robbins, “ Power Electronic: Converters, Application, and Design” , Wiley, 2002. [29] Francois Giraud and Zyiad M. Salameh, “Steady-State Performance of a GridConnected Rooftop Hybrid Wind-Photovoltaic Power System with Battery Storage”, IEEE Trans. Energy Conversion, Vol. 16, No. 1, pp. 1-7, March 2001. [30] RiadChedid and SaifurRahman, “Unit Sizing and Control of Hybrid Wind-Solar Power Systems”, IEEE Trans. Energy Conversion, Vol. 12, No. 1, pp. 79-85, March 1997.

Copyright

Copyright © 2023 Anju Mishra, Dr. D.K. Agrawal, Mrs. Vandana Sinsodiya. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.