Grid-connected solar power generating systems with superior power quality controlled using PBT

The dynamic voltage restorer (DVR) combined with a photovoltaic–thermoelectric generator (PV-TEG) system is proposed for voltage disturbance compensation in the three-phase four-wire distribution system. The PV-TEG hybrid energy source is used in the DVR system to improve the system ability for deep and long-period power quality disturbance compensation. In addition, the DVR will save grid energy consumption when the hybrid PV-TEG module generates sufficient power to meet the load demand. An enhanced variable factor adaptive fuzzy logic controller (VFAFLC)-based maximum power point tracking (MPPT) control scheme is proposed to extract the maximum possible power from the PV module. Since the PV and TEG combine a hybrid energy source for generating power, the DVR can work efficiently for the voltage sag/swell, outage compensation, and energy conservation mode with minimum energy storage facilities. The in-phase compensation method and the three-leg voltage source inverter (VSI) circuit are chosen in the present system for better voltage and/or power compensation. To confirm the effectiveness of the proposed hybrid PV-TEG integrated DVR system, a simulation-based investigation is carried out with four different operational modes with MATLAB software. The study results confirm that the proposed DVR system can compensate power quality disturbances of the three-phase load with less total harmonics distortion (THD) and will also work efficiently under energy conservation mode to save grid energy consumption. Moreover, the proposed VFAFLC-based control technique performs better to achieve the maximum power point (MPP) quickly and accurately, thereby improving the efficiency of the hybrid energy module.

This paper presents a single stage, three phase grid connected solar PV (Photovoltaic) system. The MPPT (Maximum Power Point Tracking) based on P&O (Perturb and Observe) technique is used to obtain maximum power of the PV array. An adaptive Laguerre filter based control algorithm is used for the control of VSC (Voltage Source Converter). For sustaining the voltage of DC link with the reference value, a PI (Proportional Integral) controller is used. The behavior of the grid connected solar PV system is studied on a laboratory prototype. The performance of this system is demonstrated under non-ideal conditions where it performs satisfactorily for wide range of variations of load.

This paper proposes a new Firefly optimized Ridge Extreme Learning Machine (RELM-FF) algorithm based maximum power point tracking (MPPT) investigation for stability study of photovoltaic (PV) interactive microgrid dynamics. The proposed MPPT study is effective by managing minimum uncertainty limits, during solar uncertainty conditions (i.e., inconsistent irradiation, partial shading, etc.), compared with conventional techniques. A two stage converter dynamics is considered for the proposed grid interactive PV system. To withstand stability during worst grid operating scenario (both PV side and grid side uncertainty), a robust nonlinear Lyapunov based finite time sliding mode (LFSM) control is proposed for PV-VSC (voltage source converter) system. As the proposed multiple distributed energy resources based microgrid is considered as weak (low short circuit ratio), and PV is considered as an active power source, the Q-V based state variables are used for the dynamic control loop. A small signal stability analysis with the two stage PV converters is presented using the proposed RELM-FF algorithm and LFSM control. The performance evaluation of the microgrid operating with the PV array is demonstrated through various case scenarios, in MATLAB/Script environment. A hardware validation with TMS320C DSK board and embedded MATLAB coder is performed to establish effectiveness of the proposed MPPT algorithm, in real time. The superiority of the proposed MPPT over the conventional techniques is validated by comparing the stability improvement performance in grid interactive PV-VSC microgrid.

This paper deals with a three phase multifunctional grid connected SECS (Solar Energy Conversion system). A two stage power circuit topology is used in this work, in which the first stage is a boost converter, which serves the purpose of MPPT (Maximum Power Point Tracking) and the second stage is a 4-leg VSC (Voltage Source Converter) which serves the purpose of feeding extracted energy along with power quality improvement in the distribution system. The SECS not only feeds solar PV (Photo-Voltaic) energy into the grid but also serves purpose of grid currents balancing, reactive power compensation, harmonics elimination and neutral current mitigation. A feed-forward term for the solar contribution is used to improve the dynamic response for climatic changes. The PV array voltage is continuously adjusted with the help of boost converter to achieve MPPT whereas the DC link voltage of VSC is kept constant with the help of a PI (Proportional-Integral) controller. A SOGI-Q (Second Order Generalized Integrator - Quadrature) based algorithm is proposed for control of four-leg VSC. The system is modeled and simulated on MATLAB based platform. A wide range of simulation results are shown to demonstrate all features of proposed system. The simulation results show the feasibility of the proposed control algorithm. The THD (Total Harmonics Distortion) of grid current has been found well under IEEE-519 standard.

An increasing growth of non-linear load in the three-phase four-wire distribution system, results in various power quality problems in the distribution system. Custom power devices (CPD) have been evolved to solve the power quality problems in the distribution system. Among the various custom power devices, Distribution Static Compensator (DSTATCOM) is one of the effective solutions for solving the power quality problems. This paper reveals about Distribution static compensator (DSTATCOM) for balancing of source currents, harmonic mitigation and neutral current compensation in three-phase four-wire distribution system. A synchronous reference frame (SRF) theory is projected for the control of DSTATCOM. Four-leg voltage source converter (VSC) with a dc capacitor is used as four-wire DSTATCOM. Here DSTATCOM is operated in load compensation mode. The first three-legs are used for balancing of source current and harmonic mitigation and the fourth leg is used for neutral current compensation. The compensation performance of DSTATCOM using the proposed control strategy is demonstrated using simulation results obtained from MATLAB/SIMULINK.

This paper proposes a robust design for a standalone Distributed Generation (DG) system based on wind, solar photovoltaic (PV), and battery storage to serve isolated or off-grid applications. The system employs an Adaptive Normalized Least Mean Absolute Third (ANLMAT) algorithm to construct an adaptive controller that optimises synchronisation between Renewable Energy Sources (RESs) and the load, enhancing the overall reliability and Power Quality (PQ) of the system. The ANLMAT algorithm with a Voltage Source Converter (VSC) provides support at the Point of Common Coupling (PCC) by balancing loads, reducing harmonics, and improving PQ. The results confirmed the proposed system achieved a Total Harmonic Distortion (THD) of 3.29%, well below the IEEE-519 standard limit of 5%, confirming its capability to maintain PQ standards. The system architecture integrates a battery and a Maximum Power Point Tracking (MPPT)-enabled PV system at the VSC's DC link. The battery storage manages power by absorbing excess energy during periods of low demand and supplying additional power during peak demand. Under dynamic conditions, such as fluctuations in unbalanced loads, solar irradiance, and wind speeds, the ANLMAT-based control shows superior stability, synchronisation, and energy management compared to existing control approaches, including SRF-PLL and LMS algorithms.

Solar Photovoltaic (SPV) offers alternative sources of energy which is in general pollution free, environment friendly, sustainable and unlimited in nature. The concerns of environment due to green house gases and global warming force research communities to develop a smart power system that has capability to integrate Solar Photovoltaic with the power grid. There are many challenges in integrating SPV generation with the grid like efficiency, power quality, stability, cost of the energy conversion, load management, reliability etc. Moreover, power quality problems at distribution level like harmonics, unbalanced supply, unbalanced loads, reactive power, load management etc. affect the operation of grid connected SPV systems. Single stage grid connected PV systems has the advantage of use of a single VSC for MPPT (Maximum Power Point Tracking) and inverter operation. The proposed grid interfaced SPV generating system consists of a SPV array, VSC (Voltage Source Converter), three-phase grid and linear/nonlinear loads. The SPV energy is injected in to the DC bus of VSC during sunshine hours. The DC bus voltage of a three- phase VSC is regulated for MPPT from the PV array. Secondly, this system serves to provide harmonics elimination, load balancing, power factor correction (PFC) and regulating the terminal voltage at the PCC (Point of Common Coupling). In this paper, a SRF (Synchronous Reference Frame) based control of a single stage dual purpose grid connected SPV system is proposed and simulation based on MATLAB and Simpower System Blockset demonstrates the dual purpose of the system.

The proposed work deals with the implementation of a control approach for an active power transfer between solar photovoltaic (PV) array and grid/ load alongwith power quality improvement by eliminating harmonics and compensating reactive power required by the load in the distribution system. The PV array is directly connected across the DC link of a voltage source converter (VSC). The power is transferred to the grid/ load through VSC, which performs the function of distribution static compensator (DSTATCOM) by injecting compensating currents in the proposed system. The PV array is operated at maximum power by employing the usage of perturb and observe (P&O) maximum power point tracking (MPPT) approach in order to extract the available maximum power from the solar PV array. A feed-forward term for the solar PV array power, is incorporated for the enhancement of dynamic response. The prominence of the control algorithm lies in the efficient switching of VSC, by generating reference grid currents, which are obtained through indirect current control technique. The recursive digital filter is utilized for processing the load currents and extracting the active power component of the load currents. Therefore, the active power component of load currents obtained, are used for generating the reference grid currents in the proposed system. A prototype of the system is developed in the laboratory and its performance is studied for varying loads, changing solar insolation, and voltage swell and voltage sag conditions.

<p><span lang="EN-US">This work proposes an adaptive filter based on a new least mean sixth control approach with incremental conductance method of MPP for 3-phase grid-incorporated photovoltaic (PV) system. The proposed system comprises a PV array, 3-phase DC to AC converter, maximum power point tracker (MPPT), three-phase electronic load, and a 3-phase grid. The combination of solar PV array and the voltage source converter (VSC) supplies power to the grid. The 3-phase inverter as a distribution static synchronous compensator (D-STATCOM) improves the quality of the system performance in case of zero solar irradiation. D-STATCOM also reduces total harmonic distortion (THD) in grid currents, improves power factor, and maintainsa constant voltage at the point of common coupling (PCC). The system modelling and simulation is achieved on MATLAB/Simulink. The proposed system performance has been found satisfactory and conform to IEEE-519 standards.</span></p>

This paper presents an algorithm for plug-in electric vehicles (PEVs) charging in the three-phase distribution system for residential houses. It aims to prevent violent voltage level deviation and increasing losses on the three-phase distribution system due to uncontrolled charging and allocate power to each plug-in electric vehicle. The algorithm is comprised of two processes. The first process is power limitation and limited power of load imbalance by if-else rules, while the second process is power allocation to each PEV by the dual cascade scheduling algorithm which is the integration of tasking scheduling algorithms. A 100 kVA distribution transformer and 30 houses are defined in the simulation situation. Also, the available PEVs in single-phase, two-phase, and three-phase systems are assigned for verification of the proposed algorithm. Root-mean-square deviation (RMSD) referred to the satisfaction of PEV owners, total PEVs charged energy, and the average percentage of achieved charging time, as the result indicators. The results show the proposed algorithm can provide good results without rejected PEVs charging. Furthermore, this paper also displays the analysis of voltage level, percentage of voltage unbalance factor, and loss in the distribution system. In the future, coordination with home appliances to gain a high load margin or electric energy cost control will be improved in the proposed algorithm

The solar photovoltaic (PV)‐based microgrid is one of the most ideal renewable energy resources. This paper presents a utility grid intertie multi‐PV‐inverter‐based microgrid (MG) control for the solar rooftop application. The main and ancillary voltage source converters (VSCs) DC links are assimilated with PV arrays of independent maximum power point tracking (MPPT) algorithms for the economical and efficacious single‐stage configuration. At the point of common coupling (PCC), parallel VSCs arrangement increases the MG's power rating with distinctive local loads. In normal circumstances, the current control methodology is employed by the main VSC under the grid‐interactive mode. Conversely, in some grid contingency conditions under the isolated mode, its control transfers to the voltage control, which regulates the frequency and the voltage at PCC and acts like a grid‐forming inverter. The ancillary VSC operation is implemented with the current control algorithm. The main VSC supplies the active power towards the grid and accomplishes the load requirement, whereas the ancillary VSC retains its load demand in a grid‐interactive mode and also regulates the load requirement in an islanded mode of operation. The utilization of feed‐forward components for PV arrays powers in the VSCs current control techniques improves the MG dynamic performance. The seamless mode transfer performance of the main VSC is implemented via a power electronics switch. The MATLAB software is used to model a microgrid and its performance is analysed via RT‐LAB in real time through the OPAL‐RT (OP4510) controller for various scenarios, that is, varying solar insolation, load alterations and unbalanced non‐linear loads. The utilization of the modified Kwong's algorithm‐based current control enhances the power quality such as harmonics current elimination and improvement in the power factor. The voltage profile of PCC voltages is enhanced via using a modified Kwong's algorithm‐based filter in the voltage controller. The modified Kwong's algorithm has fast convergence, reduces misadjustments and gives very good performance compared to the least‐mean‐square (LMS) and Kwong's approaches. The total harmonic distortion (THD) of grid currents and PCC voltages THD in an isolated mode is found according to the limits of the IEEE‐519 standard.

This paper deals with the adaptive estimation of frequency observation (AEFO) based technique for compensating the harmonics component of two-stage grid-connected solar photovoltaic (PV) system. The maximum PV power is extracted using maximum power point tracking (MPPT) algorithm. Moreover, the input DC voltage of the voltage source converter (VSC) is maintained at desired level using a proportional integral (PI) controller. The AEFO control injects the required reactive component, which shapes the balanced grid currents. Moreover, the active power is injected in to the grid, which eliminates the harmonics in the grid currents. Using this controller, the fundamental reference currents are estimated using nonlinear load currents. This system maintains the grid current total harmonic distortion (THD) in accordance to the IEEE 519 standard. The dynamic response is improved by adding the PV feed-forward term with the estimated magnitude of i eα and i eβ current quantities. This control improves the dynamic response when insolation is changed and also provided a good response when switched from PV array to DSTATCOM and vice versa. Moreover, the power quality issues such as load unbalancing, power factor correction and reduced the grid side currents harmonics. Test results has shown the reactive power compensation of balanced and unbalanced nonlinear loads and the steady-state and dynamic performances of the system and PV array to DSTATCOM and vice-versa.

This paper discusses the design of a low tip-speed ratio, drag type vertical axis wind turbine which is incorporated with permanent magnet synchronous generator with maximum power point tracking (MPPT) strategy of control system to acquire the optimal performance. By using two dimensional large eddy simulations (LES) method as fluid dynamic model, the calculated power coefficient for this multi-blade vertical axis wind turbine may reach 0.34 at tip speed ratio (TSR) ranging from 0.8 to 1.0. Also, with the aids of simulation results, a direct coupled permanent magnet synchronous generator with 64-poles is designed and fabricated to generate 1.5 kW rated power at 90 rpm in 12 m/s wind speed. By changing the shape of magnet and applying approximate-skew method as stepped magnet configuration, the cogging torque and noise level of generator can be minimized. Moreover, MPPT control system with low current harmonic distortion level is designed to transfer energy into power grid with estimated 92% of power efficiency. Consequently, by eliminating gearbox system, low start-up wind speed, low current harmonic distortion and low cogging torque, the proposed of low acoustic/noise level wind turbine generator system can be applied for urban-environmental usage.

This research work explains the practical realization of hybrid solar wind-based standalone power system with maximum power point tracker (MPPT) to produce electrical power in rural places (residential applications). The wind inspired Ant Colony Optimization (ACO)-based MPPT algorithm is employed for the purpose of fast and accurate tracking power from wind energy system. Fuzzy Logic Control (FLC) inverter controlling strategy is adopted in this presented work compared to classical proportional-integral (PI) control. Moreover, single Cuk converter is operated as impedance power adapter to execute MPPT functioning. Here, ACO-based MPPT has been implemented with no voltage and current extra circuit requirement compared to existing evolutionary algorithms single cuk converter is employed to improve conversion efficiency of converter by maximizing power stages. DC-link voltage can be regulated by placing Cuk converter Permanent Magnet Synchronous Generator (PMSG) linked rectifier and inverter. The proposed MPPT method is responsible for rapid battery charging and gives power dispersion of battery for hybrid PV-Wind system. ACO-based MPPT provides seven times faster convergence compared to the particle swarm optimization (PSO) algorithm for achievement of maximum power point (MPP) and tracking efficiency. Satisfactory practical results have been realized using the dSPACE (DS1104) platform that justify the superiority of proposed algorithms designed under various operating situations.

A hybrid maximum power point tracking for partially shaded photovoltaic systems in the tropics