International Research Journal of Engineering and Technology (IRJET) Volume: 04 Issue: 02 | Feb -2017
www.irjet.net
e-ISSN: 2395 -0056 p-ISSN: 2395-0072
Modeling of Solar PV system under Partial Shading using Particle Swarm Optimization based MPPT Ujjwala Rai1 1
Assistant Professor, Dept. EED, SGSITS College, MP, INDIA
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Abstract -
This work presents the effects of changing environmental conditions on the solar photovoltaic energy conversion system. Partial shading causes oscillations in output characteristics of the PV (photovoltaic) array and distracts the system to track MPP (maximum power point). In this paper, generalized approximate model of the solar cell is implemented using MATLAB/Simulink software package. In order to track maximum power efficiently from the PV array, evolutionary search technique PSO (particle swarm optimization) algorithm is used. Finally the developed model for PV array is interfaced with DC/DC boost converter using SimPowerSystems tool box to extract stepped up voltage from solar array. The duty cycle of the converter is controlled by the MPPT algorithm and PI (Proportional integral) controller. The PV array model is developed and simulated to produce higher output voltage under partial shading conditions.
Key Words:
Solar photovoltaic systems, Partial shading, Maximum power point tracking (MPPT), Particle swarm optimization (PSO) algorithm, Boost converter.
1. INTRODUCTION Due to the fact that conventional energy resources are in a state of diminution, there is a call for utilizing renewable energy resources to generate electrical energy worldwide. Solar energy is one of the promising natural resource that is used expansively to produce electricity globally using the concept of solar photovoltaic. Solar cell which is made up of P-N junction diode fabricated in a thin layer of semiconductor material is considered as the main fundamental unit for solar photovoltaic energy conversion system [1]. Since, solar cell alone cannot be used for high power generation, hence they are connected in seriesparallel configuration to form modules and further these modules are connected as well to make array to get increased voltage. Solar insolation and temperature are the important factors that affect the output characteristics of the PV cell [2]. However, PV array operations suffer complexity in the output P-V characteristics under partial shading situation caused by the clouding, shadows of trees, obstruction of buildings, bird litters on the array and so forth. The total power in such an array is lower than the sum of the individual rated power of each module. When solar cells are connected in series, all the cells carry the same current. Although, a few cells under shade produce Š 2017, IRJET
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Impact Factor value: 5.181
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less current, these cells are also forced to carry the same current as the other fully illuminated cells. The shaded cells may get reverse biased, acting as loads, draining power from fully illuminated cells [3]. The PV plants are being built in a fixed series-parallel configuration and each module is set with bypass diodes in anti-parallel. This is used to bypass the single module, when it may reduce the current of the whole photovoltaic array. The bypass diode across the group of cells will begin conducting when shading causes a cell to go far enough into reverse bias. The bypass diode allows current from part and limits the effects of shading to the only neighboring group of cells protected by the same bypass diode. This solution is easily adoptable and allowed to improve the energy production from the whole PV array. The characteristics of an array with bypass diodes differ from that of an array without diodes [3], [4]. Authors in [5] proposed a novel algorithm based on several critical observations made out of the PV characteristics and the behavior of the global and local peaks under partially shaded conditions. The proposed algorithm works in conjunction with a DC/DC converter to track the GP (global peak). In order to accelerate the tracking speed, a feed forward control scheme for operating the DC/DC converter is also proposed. Under partial shading, the output P-V characteristic of the array exhibits local multiple peaks with one global peak which leads to a difficult form. Hence, it is necessary to apply MPPT technique as an interface between PV arrays and load so that the PV system always transfers maximum power to the load even in the changing environment. Many methods have been introduced to track the MPP and depend on its implementation complexity, sensed parameters, measurement required, cost, tracking speed, popularity, their application and other factors. Conventional MPPT methods operate very agreeably under uniform irradiance conditions, in which only a single MPP is to be detected. If multiple MPPs exist, these methods can easily be trapped at local maxima. Since the MPP controller detects the local MPP instead of the global MPP, efficiency of the PV system reduced significantly [6][7]. In order to solve this problem, a MPPT algorithm based on Particle Swarm Optimization that is capable of tracking global MPP under partial shaded conditions is implemented in this paper. Reference [8] proposed PSO algorithm with the capability of direct duty cycle is used to track the MPP of a PV system under partially shaded conditions. Simulations are being carried out under various insolations and loading conditions and the performance is compared with the Hill climbing method,
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