Biased Maximum Power Extraction from a PV during Low Irradiation and a Highly Stiffed Grid Condition
Biased Maximum Power Extraction from a PV during Low Irradiation and a Highly Stiffed Grid Condition
Prasad, P. Arokiya;Sivakumar, P.
2022-03-18 00:00:00
Hindawi International Transactions on Electrical Energy Systems Volume 2022, Article ID 4802473, 19 pages https://doi.org/10.1155/2022/4802473 Research Article Biased Maximum Power Extraction from a PV during Low Irradiation and a Highly Stiffed Grid Condition 1 2 P. Arokiya Prasad and P. Sivakumar Department of EEE, St. Joseph College of Engineering, Anna University, Chennai, TN, India Department of EEE, Rajalakshmi Engineering College, Chennai, TN, India Correspondence should be addressed to P. Sivakumar; sivakumar.p@rajalakshmi.edu.in Received 15 November 2021; Revised 20 January 2022; Accepted 27 January 2022; Published 18 March 2022 Academic Editor: Akshay Kumar Saha Copyright © 2022 P. Arokiya Prasad and P. SivaKumar. )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. Growing electrical demand is to be met dynamically through conventional and nonconventional power sources. PV power generation plays a vital role. Because of low irradiation and overcast weather condition, the installed PV sources are not fully utilized. Many research papers were presented to extract maximum power from PV using various MPPT techniques. )is paper presents a new idea of implementing a biased transformer to extract maximum power during the above condition. )e proposed method uses three winding transformers to give sufficient biased voltage and current. )e biased current and voltage were obtained from the grid that is fed to the primary winding—two of the three winding transformers through the controller. A 10 kW panel is checked for low irradiation and overcast weather condition using the biased MPPT technique. )e proposed method is compared with the conventional incremental conductance method with power, cost, and efficiency analysis. Simulation was carried out in MATLAB/Simulink software and experimentally evaluated through a suitable hardware setup. coupling point. Perturb and observe (P&O) method, in- 1. Introduction cremental conductance method (IC) [7], and constant Rapid usage of energy from nonfossil fuel is increased in the voltage method (CV) are basic MPPT techniques, while modern world. )is photovoltaic (PV) sourced power plays methods of soft computing combining intelligent techniques are tuned to the basic methods [8]. )e constant voltage a significant role. )e PV panel at a specific point delivers maximum power for which a technique has been developed method tracks only the nearby original maximum power to improve the effective utilization of PV called the maxi- point (MPP; within boundary) and not the exact MPP mum power point tracking (MPPT) techniques in [1]. Power position [9], which can lead to energy loss from the PV. )e electronic converters are used for these techniques due to the incremental conductance (IC) method fits MPPT at specific PV panel’s nonlinear characteristics in [2]. Researchers positions but varies due to variable load impedance [10]. )e developed many MPPT techniques as discussed in [3] to algebraic sum of conductance across the terminal of the PV extract maximum power from PV cells. Factors considered array is equal to the conductance of PV (I /V ), and then pv pv by most existing MPPT techniques include the number of maximum power is transferred from the PV to the load [11]. unique sensors used, technology implementation method, )e PV source is connected to the load through single- or speed of operation, utilization method, complexity of al- dual-stage converters for both standalone or grid-connected gorithm, and the cost of controller [4–6]. Many existing modes [12]. Most-grid connected systems consist of a dual MPPT methods concentrate on standalone operations with stage for the MPPT process and for DC-to-AC inversion in single-source PV power utilization systems. Grid-connected [13]; however, the system are tracked to the nearby original PV operations using MPPT methods are comparatively less MPP [14, 15]. Pulse with modulated converters are used to in the market due to constant grid voltage at the common achieve MPPT by varying the PWM conductance value in 2 International Transactions on Electrical Energy Systems [30]. Additionally, the proposed biased MPPT scheme [16]. As the load impedance changes, the actual MPP de- viates from its original value, causing the PV to lose energy helps significantly reduce low voltage problems faced by residential consumers and imbalance in the loading effect supply to the load in relation to the current irradiation [17]. Analysis of MPPT with fixed step size IC based on direct of Indian distribution transformers [31], for which a de- control method was tested in [18] without load variations. IC tailed explanation is given in Section 2. Globally, renewable method with variable step size method MPPT was imple- energy utilization analysis and installed capacity factual mented in [19], but the variable load was not considered. data were revealed in the Renewables 2019 Global Status Dynamic variation of irradiations was traced by fast varying Report [32]. )e various irradiation data are utilized from step size IC method with output oscillation. )is will be the standard journals [33]. )e efficiency analysis of the proposed system is compared with the existing efficiency suppressed by partial varying step size IC MPPT algorithm introduced in [19] along with the standalone mode with a fixed analysis report [34, 35]. From the inference of the literature survey, there is no and concentrated load. Grid-connected single-stage PV power generation with INC-based MPPT system was used in [20]. biased control attempted to use to track maximum power so far. )is paper presents a novel approach to obtaining MPPT )is may lead to power loss during utilization. One-cycle cost- effective MPPT control for grid-connected PV system was using a biased unit. attempted in [21] with a 4.5% error in peak power performance In this section, a brief introduction of various PV sys- during low irradiation. Fuzzy-based MPPT was established in tems and their MPPT techniques available in the literature [22] with the inputs of duty ratio and chagrin power through are explained. Various methods adopted to attain maximum PIC microcontroller, but on the other hand, dynamic irradi- efficiency and problems faced while connecting the PV ation change was not realized. PV power error and change in system to the grid are discussed. )e merits and demerits given in the reference papers are specified briefly. )e error were fed to the input of fuzzy-based cognitive maps MPPT controller in [23]. )is controller requires historical data concept of the biased MPPT technique and implementation of three winding transformer is introduced. for training. Also, variable load conditions were not considered. )e temperature along the irradiation parameter was the input of the PI fuzzy MPPTmethod simulated in [24] with the change 2. Overture of the Proposed of output load. Visualization of the change of irradiation was System’s Methodology missed. Grid-connected dual-stage PV system with self-orga- nizing fuzzy MPPT was evaluated through software in [25]; DC 2.1. Functional Block Diagram of the Proposed System. In the link voltage of the inverter was not properly regulated; and proposed system, a 1 kW PV panel is connected to the hence, the change of duty ratio and hardware implication could microgrid through the biased MPPT transformer. )e biased 1 2 result in complex work. Real-time optimal power point of the transformer contains two primary winding S and S and pv pv PV array was achieved through historical-data-focused neural one secondary winding S . During irradiation, the biased network controller in [26] with the common power source. transformer adds the voltage and produces the power with High-speed computational digital controllers or PCs’ are re- the help of the feedback power from the grid through the quired for these controller implementations. )e system may inverter. also fail due to drastic changes in weather. )e next level approach of neural network MPPT methods for standalone and grid-connected PV schemes are discussed in [27] with electrical 2.1.1. Description of the Proposed System. Figure 1 shows a and nonelectrical inputs. Implementation and training of these functional block schematic of the proposed biased MPPT controllers require complex hardware with highly knowl- method for PV source power generation. )e photovoltaic edgeable persons are required. Also, the actual MPP works at array is connected to the biased transformer through a the boundary of the original operating point. Further im- reverse blocking diode. )e biased transformer consists of provement of fuzzy-neural with optimization of MPPT two input windings with a center-tap terminal and one schemes was discussed in [27] as this suits MW-level power output winding. One input winding center tap is connected plants with large investment and reduces power utilization to the positive terminal of the PV source, while the other two from PV during low-level irradiation. )is paper proposes the ends are connected through a power electronic switch to the biased MPPT method that allows the user to extract and use negative terminal of the PV source. )e second input power during low irradiation. Most existing MPPT methods for winding center tap point is connected to the positive ter- grid-connected PV systems achieve MPP by adjusting the pulse minal of biased DC that is derived from the grid supply. )e duty ratio of power converts [28]. )e PWM duty ratio can DC negative is connected through power electronics change the input and output conductance of DC/DC power switches to the other two terminals of the second input converters to attain MPPT in a dual-stage grid integrated PV winding of the biased transformer. )e secondary winding setup [29]. Simultaneously, if the input is maintained for MPP, of this biased transformer is connected to the grid. DC then output conductance changes, and so it is not possible to source voltage is controlled by a bidirectional TRIAC switch. regulate the DC link voltage of the grid integrated inverter. Nonlinear load and grid are integrated at the point of Similarly, if we tuned the output conductance of the power common coupling (PCC). Voltage and current sensors are converter to regulate the DC link voltage, then MPP input interfaced at suitable locations. )ese values are fed into the is lost. However, the proposed system can exactly work in physical controller unit through a signal conditioner and MPP with effective utilization of PV during low irradiation ADC. PWM pulses are connected to the power switch gate International Transactions on Electrical Energy Systems 3 pv Grid pv pv 2 i p () S g pv g pulse generation compute PV (pwm()) pv pv 1 2 *m *m S S comp v , i pv pv pv pv pv *m B (pwm()) 1 2 pv LT S S b b mm v , i b b *m *m b V (pwm()) v , i b b p() compute g sync with () PLL Figure 1: Functional block diagram of the proposed system. terminal through a proper driver isolation circuit. )e entire 2.1.3. Equation of the Biased Transformer Model. Here, R: resistance, L: inductance, M: mutual inductance, P: primary system operation is detailed in Section 4. winding, and S: secondary winding. 2.1.2. Proposed System Methodology. (a) A photovoltaic ar- v � R i + jωL i + M i + M i , (1) p1 p1 p1 p1 p1 p1s s p12 p2 ray’s equivalent model depicted in [3, 33]. PV array with compensations for the photovoltaic light-triggered current source is connected with a parallel diode representing the P–N v � R i + jωL i + M i + M i , (2) p2 p2 p1 p2 p2 p1s s p12 p2 junction of the cell. One resistance is connected in series, and another is connected in parallel. )e relationship between the PV array voltage and current equations is obtained through v � R i + jωL i + M i + M i . (3) s s s s s p1s p1 p2s p2 Kirchhoff’s law given in (1) and (2). )ese equations clearly indicate the nonlinear performance of PV output. PV voltage Solving this equation reveals the following model: and current vary widely with respect to a fall in irradiation and temperature. Hence, the PV delivers peak power at a specific R M M p1 p12 p1s point called maximum power point (MPP); conductance of a ⎡ ⎢ ⎤ ⎥ i ⎢ ⎥ ⎢ ⎥ p1 ⎢ ⎥ i ⎢ ⎥ ⎢ ⎤ ⎥ ⎢ ⎥ ⎡ ⎢ ⎥ ⎢ ⎥ p1 ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ PV array equal to load conductance is connected across the PV ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎡ ⎢ ⎤ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎥ ⎢ ⎥ ⎢ ⎥ ⎥⎢ ⎥ ⎢ ⎢ ⎥⎢ ⎥ ⎢ ⎥ 1 ⎢ ⎢ ⎥ ⎢ ⎥ ⎢ M R M ⎥⎢ ⎥ terminal. Power generated by the PV array is given in the ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ _ ⎥ ⎢ p21 p1 p2s ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ _ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ � jω ⎢ ⎥⎢ i ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ i ⎥ ⎢ ⎥⎢ p2 ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ p2 ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ conventional equation (3). Continuous change of environ- ⎢ ⎥ L L M ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ p1 p2 ⎢ ⎥⎣ ⎦ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎣ ⎦ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ mental conditions solar irradiations and temperature change ⎢ ⎥ ⎢ ⎥ R i s s M M affects the MPP of the PV array, and hence, many algorithms p1s p2s M (4) were developed to track the MPP called maximum power point tracking (MPPT). )e work of MPPT is to create a conductance 1/L p1 p1 ⎡ ⎢ ⎤ ⎥ match between load and source during the change of irradi- ⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎡ ⎢ ⎤ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ation and temperature. DC-to-DC converters (such as trans- ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ + ω⎢ ⎥⎢ v ⎥. ⎢ ⎥⎢ ⎥ ⎢ 1/L ⎥⎢ ⎥ ⎢ ⎥⎢ p2 ⎥ ⎢ p2 ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ formers) are widely used in this application. )is device works ⎢ ⎥⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎢ ⎥ ⎢ ⎥ ⎣ ⎦ perfectly at high irradiation levels but lags at low irradiation 1/M s levels to attain the MPPT due to low load voltage and grid variations in the grid-connected PV generation systems. M � M M M . (5) p1s p2s p12 Hence, we need an MPPT scheme that suits all situations. (b) Biased transformer and the equivalent circuit model of the Here, the biased transformer (BT) has two primary proposed system are depicted in Figure 2. )e given equation is utilized by the biased system. winding and one secondary winding. One primary winding Signal conditioner ADC-PORT LOAD Isolation & driver 4 International Transactions on Electrical Energy Systems p1 R P − P p1 s p pv R ⎡ ⎢ ⎤ ⎥ ⎢ ⎥ ⎢ ⎥ s ⎢ ⎥ ⎣ ⎦ Z � . (13)