Analysis of Single-Diode PV Model and Optimized MPPT Model for Different Environmental Conditions
Analysis of Single-Diode PV Model and Optimized MPPT Model for Different Environmental Conditions
Senthilkumar, S.;Mohan, V.;Mangaiyarkarasi, S. P.;Karthikeyan, M.
2022-01-31 00:00:00
Hindawi International Transactions on Electrical Energy Systems Volume 2022, Article ID 4980843, 17 pages https://doi.org/10.1155/2022/4980843 Research Article Analysis of Single-Diode PV Model and Optimized MPPT Model for Different Environmental Conditions 1 2 3 4 S. Senthilkumar , V. Mohan , S. P. Mangaiyarkarasi , and M. Karthikeyan Department of Electronics and Communication Engineering, E.G.S. Pillay Engineering College (Autonomous), Nagapattinam, Tamilnadu, India Department of Electrical and Electronics Engineering, E.G.S. Pillay Engineering College (Autonomous), Nagapattinam, Tamilnadu, India Department of Electrical and Electronics Engineering, University College of Engineering, Panruti Campus, Panruti, Tamilnadu, India Department of Electrical and Electronics Engineering, University College of Engineering, Pattukkottai Campus, Pattukkottai, Tamilnadu, India Correspondence should be addressed to S. Senthilkumar; senthil.lanthiri@gmail.com Received 30 September 2021; Revised 4 November 2021; Accepted 23 November 2021; Published 31 January 2022 Academic Editor: Sudhakar babu T Copyright © 2022 S. Senthilkumar et al. &is 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. &e performance of photovoltaic (PV) systems must be predicted through accurate simulation designs before proceeding to a real- time application to avoid errors. However, predicting the cohesive relationship between current and voltage and estimating the parameters of a single diode model become a perplexing task due to insufficient data in the datasheet of PV panels. &is research work presents single-diode solar PV system simulation analysis under different conditions, and the performance is improved by introducing an optimization-based maximum power point tracking (MPPT) strategy. Before simulation, a mathematical model for a single diode and optimization approaches are presented in this research work. Particle swarm optimization (PSO), genetic algorithm (GA), BAT optimization, and grey wolf optimization (GWO) model-based MPPT circuits are designed, and the performances are comparatively analyzed. &e simulation results identify the nonlinear relationship between current and voltage and between power and voltage as characteristic curves for different temperature and irradiance values. For maximum power (P ), the maximum peak point tracking power and efficiency are analyzed to verify the optimization-based MPPTsystem. &e max simulation results demonstrate that the GWO model obtains a maximum tracking efficiency (TE) of 98%, which is much better than that of other optimization techniques. energy at a particular time [2]. But the abundant availability 1. Introduction and seasonal-independent characteristics of solar energy- Among all renewable energy sources, solar-based power based systems make them perform better than wind energy- generation gains more attention due to its inexhaustible and based systems [3]. High-quality ac output with reduced clean energy characteristics. &e conversion of energy, i.e., lower order harmonics and total harmonic distortion can be sunlight to electricity, can be obtained directly using PV cells synthesized from the PV modules using multilevel inverters or a combination of concentrated solar power systems. Solar [4–7]. &e power generated by solar PV systems can be power generation prominently helps to minimize the transferred through grids, which is equal to the power emissions from fossil fuel-based power generation [1]. Wind generated through thermal power plants [8, 9]. &ough the energy-based power generation systems also contribute power generation of solar power systems is better, their better energy and reduce fossil fuel requirements. Wind implementation cost is quite high. So, it is essential to energy is seasonally dependent, and it can produce more measure the reliability and power generation accuracy of the 2 International Transactions on Electrical Energy Systems detailed mathematical formulations are presented for the solar power systems before installation. Simulation envi- ronments are used to measure the performance so that proposed solar PV model and MPPT. In Section 4, exper- imental results and their observations are presented. Finally, errors can be avoided and performance can be improved upon implementing in real time. in Section 5, the conclusion and future scope are presented. In the design procedure of solar PV cells, a thin wafer of semiconductors and a p-n junction diode are used. Electricity 2. Related Works has been generated by converting solar radiation by fabricating the diode into the cell wafers [10]. Characteristics of semi- A vast survey of existing research works on solar PV systems conductors are the key feature of the PV process. &e photons and their feature merits, demerits, and applications is dis- fromsunlight have higher energythan the semiconductor band cussed in detail in this section. Researchers pay more at- gap energy. Due to this, electron-hole pairs are created in the tention to analyze the performance of single-diode solar PV cell. &e pair generation is directly proportional to solar ir- models in various research works. &e parameters are es- radiance, and it is isolated by the p-n junction internal electric timated through characteristic equations, and extracting field. Due to this process, photocurrent is generated and solar relevant optimal parameters from the manufacturer’s radiation acts as the most important part of the energy gen- datasheet is quite complex [23]. Also, it is difficult to obtain eration process. &e dc power generated from solar panels is the parameters of a PV model from the current-voltage converted into ac power as load using novel control strategies characteristics due to its implicit nature. &e power-law [11, 12]. &e characteristics of PV cells such as I-V and P-V are system characterizes the PV module’s I-V properties. Dif- nonlinear due to cell temperature, solar radiation, and other ferent operating incidences are considered to predict the parameters. Typically, solar cells are assembled using silicon, electrical characteristics, which do not require any iterative and due to low conversion efficiency, the generated power will or nonelementary functions. Reduced computational be inadequate [13, 14]. So, it is essential to analyze and improve complexity and cost are the major features of the power-law the conversion efficiency of the PV systems through efficient model [24]. &e parameters such as irradiance and tem- cell modeling. perature are considered, and the parameters of the single- Cell modeling is directly related to accuracy, which diode, double-diode, and triple-diode PV systems are represents the PV system characteristics [15]. To obtain a evaluated for different conditions [25–27]. Combining the desired current and voltage from a solar panel, a series or analytical equations and pattern search algorithm, the I-V parallel combination of cells is generally used. However, the characteristics are analyzed with maximum accuracy, which performance can be affected by temperature, solar radiation, is the feature merit of research work. However, the com- etc.; due to this, simulation of solar panels becomes crucial. putational complexity is quite high due to the long training Generally, a comprehensive investigation is followed to process. measure the performance of solar PV models [16, 17]. &e reduced space search approach efficiently estimates Different parametric models are presented by researchers the parameters of the single-diode model [28]. &e no such as the single-diode model and two-diode model [18]. convex nature of the optimization problem is eliminated Among all, the single-diode model is widely preferred as the through the space search approach. Due to this, the com- performance matches the real-time solar cell performance putational complexity in parameter estimation is reduced [19–21]. &e single-diode model is alternatively called the and high-quality solutions are obtained without user in- five-parameter model, and its design includes a parallel tervention. &e performance of parameter estimation of PV connection of ideal diode and current source with bypassed modules is improved by converting no convex optimization shunt resistance. Single-diode model solar cell parameters problems into convex optimization problems using a can be efficiently analyzed to improve the performance of PV modified barrier function [29]. &e optimal values are ob- systems. &e single-diode model has more benefits in terms tained using an adaptive identification technique, which of parameters such as minimum error I-V and P-V curves, provide a unique solution to improve the precision of and a simple and easy implementation provides better re- electrical parameters. &e relationship between operating sults similar to manufacturer’s results [22]. conditions and electrical parameters utilizes the thermal &e major contributions of this research work are as coefficient of power to evaluate the performance of the PV follows: cell [30]. &e impact of energy production due to changes in (i) A single-diode model is developed for solar PV the operating point and the disconnected array is reduced, systems under different environmental conditions which obtains P for the temperature and irradiance. max Shunt resistance was evaluated from a mathematical (ii) For the achieved single-diode solar PV model, model based on the manufacturer’s datasheet information different optimization techniques are presented for [31]. &e balance between computation time and accuracy is MPPT demonstrated to validate the shunt PV module. Evaluation (iii) Comparative analysis of different optimization of series resistance for a single-diode PV module presents a models is performed to find an appropriate tech- comparative analysis of different techniques [32]. &e sys- nique for MPPT tematic analysis describes the feature merits and demerits of &is research work is structured as follows. In Section 2, series resistance parameter estimation techniques in terms of a review of existing research works is presented. In Section 3, accuracy and reliability. A voltage-dependent temperature International Transactions on Electrical Energy Systems 3 performance for the MPPT methods. &e perturb and ob- coefficient is considered for I-V parameter estimation of a single-diode model [33]. Series resistance is obtained to get serve method utilizes the local irradiance data to determine the offline conditions [44]. &e perturbation step size is improved accuracy for different temperature ranges. Ac- curate estimation of the solar PV parameters for single diode optimized based on the analysis results of the support vector and double diode models depends on solar irradiance, machine model. &is process improves the system perfor- temperature, and values from solar PV datasheet. Improved mance without any complex control circuits. An adaptive precision is obtained for different irradiance and tempera- neurofuzzy inference system and PSO methods are com- tures that increase the voltage range as well as P point bined as a hybrid MPPT model to obtain maximum PV max extraction. power [45]. &e hybrid approach provides maximum TE &e explicit nonlinear model presents a generalized per- with zero oscillations, and it does not require any extra unit-single-diode model for a PV system to extract the I-V sensor arrangements to measure the temperature and ir- radiance parameters. An adaptive fuzzy logic-based MPPT characteristics [34]. &e nonlinear least-square fit technique utilized in this research work extracts the three parameters, model improves the adaptive skills of conventional fuzzy logic-based techniques [46]. &e operating point of existing and it is refined using the per-unit-single-diode model to extract five parameters. After MATLAB programming is methods varies due to temperature and irradiance in real- over and done with, the demonstration is presented to depict time conditions, which introduces slow convergence and the minimum computational cost. A data-driven model poor accuracy in the results. &e adaptive method eliminates includes feature extraction techniques to extract essential such practical limitations and improves accuracy with faster information from a large volume of I-V data [35]. &ree convergence under dynamic conditions. different sources are considered with different data point Recently, various optimization models are introduced densities to generate the single-diode PV module’s I-V for MPPT. Among all, PSO gains more attention, and nu- characteristics, which make the approach suitable for time- merous research works are evolved to enhance the tracking performance of PV systems [47]. However, conventional series performance evaluation. RStudio is used to demon- strate the feature extraction process and power degradation PSO-based MPPT methods’ efficiency decreases because of several peaks in the PV curves that occur due to partially mechanisms in the PV module [36]. Computation of the average cell temperature of PV shaded conditions. Modified PSO is used to eliminate this modules is reported, which discusses the limitations in the limitation and to improve efficiency, which increase the temperature measurement process [37]. Conventional output power under nonuniform irradiation level and partial computational models ignore the sensor temperatures, shading conditions [48, 49]. &e dynamic PSO model which are from the backside of the PV module. However, considers the converter topology and solar panel configu- they will establish a temperature gradient that affects the rations to select the parameters for the PSO model, which provides optimal sampling time for MPPT [50]. parameter evaluation performance. Using standard test conditions and translational formulas, the factors that affect &ough PSO-based MPPT techniques are evolved for efficiency improvement, they face difficulties while the performance are identified. Different temperature and irradiation levels are considered to define the high degree of extracting global parameters. Other than PSO, few other optimization models are introduced such as the flower accuracy in the evaluation process. In solar-based power generation, another important pollination algorithm [51], the Lipschitz optimization MPPT factor that must be considered to improve the conversion algorithm [52], artificial bee colony optimization [53], and efficiency and power generation is MPPT. MPPT is used to the perturb and observe algorithm [54] for MPPT. From the track solar irradiance, and various MPPT techniques are literature analysis, it could be observed that the single-diode introduced by researchers in the recent era [38]. &e liter- model is widely used for solar PV modules. &e performance ature analysis presents a detailed analysis of MPPT tech- of the single-diode model is more reliable and accurate than that of other models. For MPPT, the PSO model is widely niques [39]. &e nonuniform solar irradiance condition is considered to analyze hybrid techniques, and online, uni- used. However, it faces issues while extracting global pa- rameters that affect the accuracy. Considering these ob- form irradiance is considered for offline conditions. &e electrical characteristics of the PV system and MPPT esti- servations, this research work presents an analysis of a single-diode model under different conditions and an op- mation process utilize a series of analytical equations under partial and uniform shading conditions [40–42]. Research timization model for MPPT. &e performance of the overall work accurately evaluates the I-V characteristics and im- system is verified under different environmental conditions proves the MPPTefficiency. Similarly, the MPPTestimation for better results. model processes the PV current and voltage characteristics and eliminates oscillations in the power point tracking 3. Proposed Work process [43]. &e estimation loss is reduced and estimation speed is increased for the evaluation procedure of the single- Solar PV cells are made from semiconducting materials. diode model. Different manufacturing processes are followed to design the &e major factor that needs to be considered for MPPT PV cells. &e working of PV cells is based on the PV effect models is their tracking accuracy and tracking speed. It is that generates a potential difference in the junction of p-n in essential to introduce a better tradeoff between cost and response to radiation or visible light. &e basic structure of 4 International Transactions on Electrical Energy Systems silicon-based PV cells includes a thin layer of bulk silicon or R a thin film of Si that is connected to electric terminals. Also, a I I d sh metallic grid is connected to the semiconductor top surface, while a thin semiconductor layer is specially treated to D R I V obtain a p-n junction. Depending on the necessity, a series or pg sh parallel combination of PV models is used. When the module is exposed to light, the charge carriers are generated, while the semiconductor absorbs the photons from the light. Figure 1: Single-diode solar cell equivalent circuit. &e electric field in the p-n junction separates the carriers so that an electric current will start to flow through the external circuit. &e working procedure is similar to the p-n junction Mathematically, the above circuit output current is obtained diode if the PV effect is removed. Based on this, the current from equation (2) as flow of the PV module is obtained from the diode current equation, and it is given as I � I − I − , (5) pg d sh V /nN V d s t I � I e − 1, (1) d o where the diode voltage (V ) is obtained from the sum- where V is the potential difference, I is the reverse mation of actual input voltage (V) and the voltage across the d o saturation current, V is the thermal voltage, and N is the series resistance as V � V + IR . However, the shunt and t s d s number of series-connected cells. &e diode ideality series resistance will introduce an impact on the I-V factor is represented as n. &e thermal voltage is obtained characteristics of the PV device. Series resistance has an from the Boltzmann constant and electron charge as impact on the output voltage, and shunt resistance has an V � kT/q, where k is the Boltzmann constant and q impact on current. So, the above equation is modified to represents the electron charge whose values are obtain a single-diode model, and the current is expressed as − 23 − 19 1.380650 ×10 J/K and 1.602176 ×10 C, respectively, V + IR qV /nkT s and T is the temperature. I � I − I e − 1 − . (6) pg s sh &e characteristics of ideal solar PV cells are represented based on current generation. However, the generated cur- &e I-V and P-V characteristics of the single-diode rent gets diverted from its ideal characteristics due to optical model are depicted in Figures 2(a) and 2(b), respectively. and electrical losses. &e ideal model does not consider the To calculate the values of series and shunt resistance, the effects of resistance, and its output is represented as current I from equation (5) is reformulated as follows: pg I � I − I , (2) pg d R + R s sh I � I . (7) pg s sh where I is the current generated by the PV effect and I is pg d the diode current. For ideal analysis, the diode current By substituting the above equation in (6), the shunt equation is represented using the Shockley equation, and it is resistance can be obtained as a function of series resistance as given as follows: V /nV d t I � I e − 1 , (3) I R − V − I R d s s s m m s R � , (8) sh V /nkT I + I e − 1 − I m sat s where V is the potential difference of the diode, I is the d s diode saturation current, and V is the thermal voltage, where V and I are the voltage and current at the max- m m which is given as V � kT/q, and the ideal solar PV final imum power point. From the above equation, the maximum current is given as series resistance value can be obtained by neglecting the qV /nkT denominator terms, and the series resistance is expressed as I � I − I e − 1. (4) pg s nkTln I − I /I − 1 − V s m sat m R � . (9) However, ideal models fail to establish a better and accurate relationship between voltage and current of the cells. &is happens because the analysis does not consider the In the parameter estimation process, the details of solar internal resistance effects. &e practical single-diode PV cell I-V characteristics are analyzed under different tem- model consists of series resistance and shunt resistance to get peratures and irradiation. &e iterative procedure obtains a better relationship among the cell parameters. Single-diode the parameters on every iteration. &e proposed model does models are simple and efficient, but they have constraints for not utilize any optimization techniques and other extraction temperature variations. Figure 1 depicts an illustration of a techniques to obtain the parameters that are the novelty of single-diode PV circuit. this research work. From equation (6), the load current is &e current flow due to metal-semiconductor contact obtained as and resistance due to impurity concentration are observed as V + IR q V+I R /nkT s ( l s) series resistance. &e shunt resistance indicates the leakage � I − I e − 1 − . (10) l pg s sh current across the junction that is parallel to the diode. International Transactions on Electrical Energy Systems 5 9 4.5 sc Maximum Power max 8 4 3.5 6 3 2.5 4 2 3 1.5 1 0.5 V V p oc 0 0.2 0.4 0.6 0 0.2 0.4 0.6 Voltage (V) Voltage (V) (a) (b) Figure 2: Characteristics of the PV cell: (a) I-V characteristics; (b) P-V characteristics. Assume the voltage is fixed at the load side and the zV 1 zI l q V+I R /nkT l ( ) l s � I + I 1 − e − I . (19) derivative of current I with respect to PV current is given as pg s l zR R zI sh sh pg zI qR I zI R zI l s s q V+IR /nkT l s l ( s) � 1 − e − . (11) &e current and voltage points in the curve can be moved zI nkT zI R zI pg pg sh pg vertically using the approximation process, and the change in current and voltage points is given as ΔI (i) and ΔV (i), &e above expression can be expressed finally as l l respectively. However, the nonlinear output voltage and − 1 zI qR I R zI q V+IR /nkT current characteristics are directly proportional to irradi- l s s ( ) s l � 1 + e + . (12) zI nkT R zI ance, load current, and temperature. So, it is essential to pg sh pg introduce an MPPT system for the solar PV module. From &e other parameters are obtained in the same manner, the I-V and P-V characteristics of a PV system, it can be and they are given in the following equations: observed that maximum current is obtained in the absence of shunt and series resistance. By short circuiting the re- zI zI q V+IR /nkT l ( ) l � 1 − e , (13) sistance, the maximum current is obtained as I , whereas the sc zI zI s pg voltage is zero when the PV module is short circuited. If there is a break in the circuit, an open-circuit voltage (V ) oc zI q V + I R zI q V+I R /nkT l l s ( ) l l s will occur and resistance will become high, which reduces � I e , (14) zn zI n kT pg the current. &e knee point where P is obtained is given as max the P point, and the voltage and current at this point are max zI q I I zI given as V and I . In the proposed work, four optimization p p q V+I R /nkT l l ( ) l l l s � − I e + . (15) models are introduced for MPPT, and the performances are zR nkT R zI s sh pg compared to obtain a better model. Existing techniques acquire the maximum power point or obtain the diode Similar to the above process, the output voltage pa- rameters are obtained from equation (7) by assuming the model parameters using optimization techniques or the mathematical model. In the case of proposed work, the load current is fixed, and they are expressed as parameters are extracted without any special optimization − 1 zV qR I l sh s q V+IR /nkT ( ) techniques; instead, the optimization model is used to attain � R 1 + e , (16) sh zI nkT pg better performances in terms of tracking efficiency, maxi- mum power, and maximum power point tracking. A short zV zV description of optimization models is presented in the l q V+IR /nkT l ( s) � 1 − e , (17) zI zI following section. s pg zV q V + I R zV l l s q(V+I R )/nkT l l s � I e , 3.1. Particle Swarm Optimization. &e PSO is a stochastic (18) zn zI pg technique that is formulated based on the bird’s flocking Current (A) Power (W) 6 International Transactions on Electrical Energy Systems characteristics when it searches for food. Initially, a random current P. On successive evolution, the optimal solution is population is initiated as particles, and each particle carries obtained in the GA. Objective functions that are stochastic, some information about the search space, which is ex- discontinuous, nonlinear, and nondifferentiable can be ef- changed with other particles in P. &e best solution is ficiently solved by a GA. Genetic algorithm-based MPPT considered the global best, and other particles are starting to identifies the optimal parameter based on the survival of move towards the best particle solution. &e trajectory of fittest principle. &ree basic operators considered in the GA movement will be based on the best solution, and this are selection, crossover, and mutation. In this, the selection process is repeated until it meets the stopping criteria. &e operator defines the selection of materials from the present current and previous velocity values are held by each particle generation that is suitable for the next generation. Generally, so that the next best position can be obtained on every it- the fitness parameter is used to select the materials. &e eration. &e velocity and position vectors of each particle are crossover operator produces new materials by combining updated as follows: two chromosomes, and the mutation operator helps to maintain the genetic diversity of each generation. To get t+1 t t+1 x � x + v , (20) ij ij ij better convergence, the first P is reset into the initial con- dition when there is a variation in irradiance and temper- t th where x is the position vector of the i particle at iteration t ij ature. &e reinitialization is obtained based on the following t+1 th and x is the position vector of the i particle at iteration ij two conditions: t + 1, while the velocity is given as |v(k + 1) − v(k)| < Δv, (25) t+1 t t t t t v � ωv + c r pbest − x + c r gbest − x , (21) ij ij 1 1 ij ij 2 2 ij t+1 th p (k + 1) − p (k) where v is the velocity vector of the i particle at iteration pv pv ij > Δp, (26) t + 1 and c and c are the coefficients. &e random numbers p (k) 1 2 pv that are distributed uniformly in the range [0,1] are rep- resented as r and r . &e best fitness values for the particle 1 2 where v is the output voltage and p is the power of the PV pv are considered pbest, and gbest represents the fitness value system. For each iteration, the initial P and their individuals for all the particles. &e position of each particle has been are applied, and the initial position of P is given as evaluated based on this fitness function, and it is given as P , P , P , P , P � [1.0,0.8,0.6,0.4,0.2]V . (27) 1 2 3 4 5 oc 2 2 t t (22) f � x − v + x − i . ij max ij max &e generated power p (k) at the kth iteration is pv considered the fitness function. &e crossover operator To update the pbest and gbest positions, the fitness function of each particle is compared. If the present position function combines the two chromosomes to obtain a new child, and it is given as is comparatively better than the previous position, then the present position is considered the best value, and the overall c(k) � rp(r) − ((1 − r)p(k + 1)), (28) fitness function is also updated based on that. Mathemati- cally, it is formulated as c(k + 1) � ((r − 1)p(k)) − ((r)p(k + 1)), (29) t t t ⎧ ⎪ x , if fx < pbest , ij ij ij pbest � (23) where c(k) is the next-generation solution and r is the ij ⎪ pbest , otherwise, ij random number. To obtain the relationship between the duty cycle (D) and the output voltage, the ratio of next- t t t t generation solution and open-circuit voltage is considered. gbest � min pbest , pbest , . . . , pbest . (24) ij j j+1 s Due to the sequential aspect of chromosomes, the dynamic To update the position and velocity of all the particles, response and mutation impact on convergence are con- the above equations are used and the same procedure is sidered in the genetic model. c(k) and the random number r implemented to obtain the MPPT process. &e position of are selected in the range [0,1], and the position values are the panel is adjusted for every iteration, and the best position taken in the range [0.2,1.0]. is updated so that P can be tracked during the power max generation process. In the proposed work, the values of c 3.3. BAT Optimization. BAT optimization is a nature-in- and c are considered 2 and 1.5, respectively. &e weight spired optimization algorithm that is formulated based on factor ω is taken as 1.2, and the values of r and r are taken 1 2 the echolocation features of bats’ food-searching process. in the range of [0,1]. Using echolocation, the insects are identified by bats so that the food sources are identified. &e intensity of the return 3.2. Genetic Algorithm Optimization. &e GA was intro- signal and its direction are the major factors to locate the duced to solve constrained and unconstrained optimization prey in the optimization model. &e ultrasonic pulses are issues. Based on natural selection and biological evolution, emitted at a certain amplitude and rate, and a bat receives its the problems are solved in the GA. &e individual solutions own signal as feedback in between the pulse trains to in- in the GA are modified continuously, and next generations terpret the prey location. Depending on the feedback in- are produced by selecting a random individual from the tensity, the distance is measured. If the intensity is high, the International Transactions on Electrical Energy Systems 7 prey is near the bat and it moves towards the prey by in- optimization model, the search agents are limited, and the tensifying the pulse amount to capture the prey. &e flying encircling behavior is formulated as characteristics of bats are random with velocity (v ), and its → → → → (36) D � C x (t) − x (t) , p sg position and loudness are given as x and l . &e emission i i rate of bats is considered in the range [0,1] depending on the → → → → target proximity. &e velocity and position of the bat at each x (t + 1) � x (t) − A . D , (37) sg p step are formulated as → → where A and C are the coefficients that balance the ex- t+1 t t+1 (30) x � x + v , i i i ploitation and exploration factors and are given as A � → → → → (2 a ∗ r ) − (a) and C � 2 r , in which the factors r and 1 2 1 t+1 t t ∗ v � v + x − x f , (31) ij i i i r are random numbers whose range is [0,1]. &e range of coefficient (a) gradually decreased from 2 to 0 for every where f is the randomly assigned frequency that is given as iteration, which indicates the wolves approach the prey. &e position of best search agents is used to update the position f � f + f − f φ, (32) i min max min of all agents for every iteration, and it is given as where φ is the random vector for uniform distribution that is → → → → ∗ D � c x − x , (38) in the range [0,1] and x is the global best position that is α 1 α sg obtained by comparing all the solutions at each iteration. In → → → the position update process, the pulse emission rate is (39) D � c x − x , β 2 β sg considered. If the random vector is greater than the emis- sion, then the exploitation stage is selected. &e current → → → → (40) x � x − A ∗ D , 1 α 1 α position is replaced based on the solution obtained in the local search process, and it is given as → → → → (41) x � x − A ∗ D , ∗ t 2 β 1 β (33) x � x + l , → → where the random number is obtained from Gaussian x + x → 1 2 (42) x (t + 1) � . sg distribution or uniform distribution in the range [− 1,1] and l is the average loudness at this timestamp. &e fitness &e hunting process is stopped if the prey has stopped its function is further improved if the generated random movement and the search agents have finished the attacking number is smaller than loudness. A new solution is obtained process. &e position update and attacking procedure of grey during the exploration process, and the parameters such as wolves are depicted in Figure 3. emission rates and loudness are updated. Mathematically, &e proposed optimization model is used to maximize the parameter update is formulated as the output power of PV array considering its D as the de- t+1 t l � ρl , (34) cision variable. In the initialization process, the population is i i limited in the range of 0.1 to 0.9 of D, and it is expressed as t+1 (− αt) (35) r � r 1 − e , i i d � randn ,1