Single Stage Solar Photovoltaic Research Articles

Design and Development of ANFIS based Controller for Three Phase Grid Connected System

A proposal is presented for a low voltage (LV) grid integrated single-stage solar photovoltaic (SPV) system, accompanied by a hybrid control methodology aimed at optimizing system performance. To address prevailing challenges, the hybrid method incorporates the Adaptive Neuro-Fuzzy Inference System (ANFIS). Anticipated benefits of this initiative include efficient power distribution, load connectivity facilitated by the system, and operational functionalities such as mode zero voltage regulation and power factor adjustment. These functionalities collectively enhance energy quality by mitigating harmonic components, compensating for reactive power, and ensuring load balance. The proposed control strategy for a photovoltaic (PV) system interfaced with the grid is designed to exhibit rapid response times in both static and dynamic conditions. Comparative analyses were conducted between the output of our method and that of several competing approaches. The MATLAB/Simulink platform is employed for the purpose of demonstrating the developed system. The results show the extent to which the proposed controller works with reactive power compensation and load balancing to minimize network harmonics and maximize power consumption while keeping power factor functions at unity.

Performance Assessment of Three-Phase NPC-Based Grid Integrated Single-Stage Solar PV System With Reduced DC Bus Capacitor

This work proposes an effective reduction in the capacitor size of the DC-bus of a conventional three-phase neutral point clamped (NPC) inverter-based grid integrated single-stage solar photovoltaic (PV) system. This has been done by implementing a metallized polypropylene film DC-bus capacitor instead of an electrolytic capacitor. As an outcome, this enhances the system's long-term reliability, reduces cost, and increases the system's life expectancy. The unbalance in capacitor voltage due to a small DC-bus capacitor is also identified. As a solution, a carrier-based modified modulation strategy is implemented to improve the dynamic response of neutral-point voltage. A single-stage solar PV array is utilized in this paper. An optimal power extraction (OPE) scheme is adopted to extract solar PV power. The DC-bus voltage overshoot issue that arises during the change in irradiation is resolved, and minimal oscillations are observed. The implemented scheme allows the feeding of the extracted power to the three-phase grid via the NPC converter, which in turn diminishes the total harmonic distortion (THD) of the grid. The PI controller minimizes the voltage and current error. The system performance is observed using a MATLAB version simulation model and authenticated through the experimental results obtained from the laboratory prototype.

A Single-Stage SPV-Fed Reduced Switching Inverter-Based Sensorless Speed Control of IM for Water Pumping Applications

This article elaborates on a reduced switch count-based inverter for a single-stage solar photovoltaic (SPV) fed induction motor (IM) with sensorless speed control for water pumping applications. The traditional SPV-fed IM for water pumping applications requires a six-switch voltage source inverter (SSVSI) for transforming the DC power from the SPV system into AC power. However, the same performance is achieved using a four-switch voltage source inverter (FSVSI). Here, the entire system requires less number of switches and hence reduces switching losses and cost as compared to the traditional solar water pumping system. Moreover, the sensorless speed control is implemented using a speed estimator to reduce the overall cost further and enhance reliability. The reference voltage ( V d c r ) is achieved using an adapted incremental conductance (AINC), and the control of IM is performed using direct vector control (DVC). The control signals for the proposed system are generated using DSPACE DS-1104 for real-time implementation. The proposed SPV-fed FSVSI-based 1-HP IM operation is performed at different irradiation levels in the MATLAB-Simulink environment and validated experimentally.

SCHEMING OF CONTROLLER FOR SINGLE STAGE SOLAR PV FED BLDC MOTOR-DRIVEN WATER PUMP

To optimize the solar photovoltaic (PV) generated power using a maximum power point tracking (MPPT) technique, a DC-DC conversion stage is usually required in solar PV-fed water pumping which is driven by a brushless DC (BLDC) motor. This power reformation stage leads to an increased cost, size, difficulty, and decreased efficiency. As a unique solution, this work addresses a single-stage solar PV energy conversion system feeding a BLDC motor pump, which eliminates the DC-DC conversion stage. A simple control technique capable of operating the solar PV array at its peak power using a common voltage source inverter (VSI), is proposed for BLDC motor control. The proposed control eliminates the BLDC motor phase current sensors. No supplementary control is associated with the speed control of the motor pump and its soft start. The speed is controlled through the optimum power of the solar PV array. The suitability of the proposed system is exhibited through its performance evaluation using MATLAB/Simulink-based simulated results. keywords: MPPT, solar PV array, BLDC motor, Water pump, Voltage source inverter (VSI)

Solar power-driven permanent magnet synchronous motor coupled with pump load: design, development and control

This paper presents design, development and control of solar photovoltaic (SPV) supply system for permanent magnet synchronous motor (PMSM) driven pump load. The proposed system is very effective in curtailing power demand on existing grid supply on highly dense population areas. An incremental conductance method followed by sliding mode control scheme is used to track SPV array maximum power point (MPP) and vary the speed of the PMSM accordingly under the change in atmospheric conditions. The direct torque control (DTC), voltage source inverter (VSI) is employed to control the PMSM speed and to achieve stable operating point. A prototype of single stage SPV supply-based PMSM coupled with DC machine is developed in laboratory for emulating the centrifugal pump characteristics. Performances under different environmental and operating conditions are obtained on the developed prototype to prove the efficacy of the proposed control.

Independent Active and Reactive Power Control for Single Stage H8 Transformer-less Solar PV Inverter

With the rapid development in power electronics technologies and solar photovoltaic (PV) cells, the interest in solar PV cell-based electric power generation and other applications is increasing more incredibly. For low power grid or direct load applications, single-stage solar PV inverters without transformers are advantageous. Based on this concept solar single-stage eight switch H8 based transformerless solar PV inverter is proposed. The objective of the work is to present a control scheme for the H8 inverter to have better power handling capability and for independent active and reactive power control. For this, the test system is studied using MATLAB/ SIMULINK software under three cases (i) constant active power and varying reactive power, (ii) varying active power and constant reactive power, and (iii) varying both active and reactive power. The proposed inverter is compared with single-stage solar PV with two switches boost and six switches inverter topology. It is found that power flow ripples and surges are lesser for proposed H8 than with single-stage topology.

Implementation of Solar Photovoltaic Grid Interfaced System Using Improved Second Order Generalised Integrator Quadrature (ISOGI-Q) Algorithm

This article deals with a single-stage solar photo voltaic (SPV) array tied toward a three-phase grid by means of an improved second-order generalised integrator quadrature (ISOGI-Q)-based control algorithm to develop the power quality of the grid. The maximum point power tracking (MPPT) is achieved by using a perturb and observe method (P&O). P&O MPPT technique is efficient to extract additional power commencing an SPV array and easy. The SOGI-Q based control serves multi functionalities for example load balancing, power factor correction as well as enhanced solar power penetration addicted to a distribution network. Investigation consequences of the SOGI-Q-based control algorithm are found to be adequate in favour of enhanced power quality in conditions of load balancing, harmonics elimination with very effective power factor correction under different dynamic conditions for instance load unbalancing, variable solar insolation, distorted grid along with imbalanced grid voltage conditions. Distributed static compensator capabilities of a SPV-based system are functional to supply the active power to the load as well as surplus power to the grid.

Power quality monitoring for a solar PV grid controlled system at non-linear induction drives load

This paper unveils the impact of non-linear induction motor drives on operation of transformer-less single-stage solar photovoltaic (SPV) grid tied inverter system. The system is controlled by an indirect type data-based maximum power point tracking (MPPT) technique. A fuzzy-logic controlled (FLC) dynamic voltage restorer (DVR) is operated coordinating two non-linear induction motor drives load: direct torque flux control (DTFC) and field-oriented control (FOC). Importantly, power quality (PQ) analysis for FOC induction motor drive is validated with DTFC induction motor drive. Results reveal mitigation of unbalanced voltage sag and voltage swell among the SPV converter, load and grid during transient conditions produced by fault. The effectiveness of FLC-DVR at FOC drive load is demonstrated over DTFC drive load and linear load for validation. It is worth mentioning that controlling action of FLC-DVR is implemented effectively at non-linear loads. As illustrated by IEEE-519/1547 standard, a reduction in total harmonic distortion (THD) and DC offset current is reported in grid voltage and current for accuracy. The proposed framework illustrates a comparative PQ study to justify satisfactory performance under varying environmental conditions.

Sensorless Field Oriented SMCC Based Integral Sliding Mode for Solar PV Based Induction Motor Drive for Water Pumping

This article focuses on an efficient and robust speed sensorless control for a solar water pumping system consisting of solar photovoltaic (PV) array fed submersible induction motor drive (SIMD). The speed estimation and sensorless control of SIMD are quite demanding tasks. Additionally, the motor parameter variations lead to deteriorate sensorless control. Therefore, a sensorless control of submersible induction motor (SIM) requires accurate and robust stator current control. The sliding mode based dc link voltage regulator is adopted for regulating the motor power and the speed for single stage solar PV topology. The integral sliding mode observer based speed estimation of SIM and sliding mode current control (SMCC) for decoupling of current provide a robust control against motor parameters variation. The proportional integral controller based speed sensorless control is used, and its performance is verified with a developed sliding mode based control for motor parameter variation. The ISM-based sensorless control with SMCC for submersible motor serves several benefits in water pumping for agricultural purposes in the presence of uncertainities. In addition, it gives fast response during dynamics. The precise estimation of rotor speed is achieved for a wider range of speed under various dynamic conditions. The developed system with a single-stage PV topology and three-phase voltage source inverter fed IMD feeding a pump as a load is designed and implemented in MATLAB/Simulink. The suitability of the system is validated through experimentation in the laboratory.

Design and Performance of Single Stage Three Phase Solar Photo Voltaic using CTF-UPQC

An algorithm is necessary for high performance, reliable and secure control in three phase solar photovoltaic cell. Three phase single stage solar photovoltaic is designed and analysed in this paper by using control triangular function unified power quality conditioner (PV-CTFUPQC) technique. By using PV-CTFUPQC technique, the functioning of three-phase single stage solar photovoltaic can be improved. To produce fundamental output, PV-CTFUPQC maintains Root mean square (RMS) but in the proposed control RMS block is not needed. By using MATLAB/Simulink platform, three phase solar photo voltaic is designed and simulated. The proposed system function is validated on developed laboratory model. The generation of clean energy and enhancement in quality power are provided by proposed system.

Sensorless SynRG Based Variable Speed Wind Generator and Single-Stage Solar PV Array Integrated Grid System With Maximum Power Extraction Capability

This article presents a grid-integrated hybrid renewable energy sources based system comprising a solar photovoltaic (PV) array and a wind energy conversion system (WECS). The WECS uses a position-sensorless synchronous reluctance generator (SynRG) for the electric power generation from the wind turbine (WT), wherein, a sensorless field-oriented control (FOC) is made use of for the maximum power extraction (MPE). A second-order flux estimation (SFE) method along with frequency-locked loop (FLL) is utilized for the accurate flux estimation from the SynRG stator voltages and currents. A set of back-to-back connected three-phase two leg voltage source converter (VSC) topology is selected for the grid integration of WECS. This system has a common dc link where the solar PV array and the machine-side VSC (MSC) of the wind generator, are directly connected. The power output from the solar PV array and WECS, is shared between the grid and the local loads. The maximum power generation from SynRG in the WECS, is achieved by operating the SynRG at the speed estimated by the MPE algorithm. The maximum power is drawn from the solar PV array by adjusting the dc-link voltage, which is decided by the algorithm. For the proper power control and power quality improvement, the grid-side converter (GSC) is adequately controlled by implementing an observer-based control technique. The real-time validation of the system, is carried out using a developed laboratory prototype.

Grid Integration of Single-Stage SPV-STATCOM System Using Symmetric Cascaded Five-Level VSC

This work proposes a dual-function single-stage solar photovoltaic (SPV) grid-tied system with STATCOM (static compensator) capabilities using a three-phase five-level cascaded VSC (voltage source converter) operating at low switching frequency with low total harmonic distortion (THD) and low switching losses. The proposed SPV-STATCOM system works in three modes: i.e. Mode-1, in which only an active power is transferred to the grid, Mode-2, in which both active and reactive power are supplied to the grid and Mode-3, in which only reactive power is supplied to the grid, thereby utilizing the full capabilities of the SPV system. An incremental conductance algorithm is used to track power from SPV array which is fed to the grid. To synchronize the VSC to the grid, a decoupled current controller with feed-forward term and double decoupled synchronous reference frame phase-locked loop (DDSRF-PLL) is used. The use of a single-stage five-level cascaded VSC offers the advantages of low switching losses and the operation at high power and high voltage which results in an improvement in quality of power of the system. The simulated results demonstrate the system design and control scheme under varying conditions.

Performance Improvement of Grid-Integrated Solar PV System Using DNLMS Control Algorithm

An integration of renewable sources based distributed generating systems encounters various power quality issues due to uncertain loads at the distribution end. These uncertainties arise due to nonlinearity, disturbances or unbalanced loads. A three-phase grid-integrated solar photovoltaic (PV) system incorporating a control technique based on a modified decorrelation normalized least mean square (DNLMS) algorithm, aiming to enhance its overall performance under adverse conditions, is presented in this work. The three-phase, grid-tied, single-stage solar PV system comprises a solar PV array with a suitable maximum power point tracking method, filters, loads, and a capacitor fed voltage source converter (VSC). The key objective of the solar PV integrated structure with an adaptive law based control algorithm is to attain a unity power factor (UPF) at the grid end ensuring harmonics mitigation from the grid currents. Moreover, this structure effectively transfers active power from the PV array to the local loads and the grid. These aforesaid objectives are achieved through providing controlled switching pulses to the insulated gate bipolar transistor based VSC using the modified DNLMS control algorithm with fast convergence rate. Harmonics-free, sinusoidal reference grid currents, are obtained by using the modified DNLMS algorithm. A simulation model developed in MATLAB/Simulink is used for the validation of the modified DNLMS-based control approach. In the laboratory, an experimental prototype is developed and the proposed algorithm is implemented to verify its performance.

An Adaptive Control Scheme of SPV System Integrated to AC Distribution System

This paper presents a single-stage solar photovoltaic (SPV) system utilizing an adaptive control scheme. The SPV system includes SPV array, voltage source converter (VSC), ripple filter, nonlinear loads, and a distribution network. The proposed SPV system feeds the active power to the distribution system, provides an effective use of SPV array and mitigation of load harmonics currents. The SPV system with an incremental conductance based control scheme is used for obtaining the maximum power from the SPV array and an adaptive control scheme to control the switching pulses of the VSC. In addition, it utilizes a SPV feed-forward loop to improve the dynamic response and reduces the burden on the proportional-integral controller by regulating dc bus voltage. Test results are presented to validate the control, design, and response of SPV system with various states.

Single Stage Solar PV Fed Brushless DC Motor Driven Water Pump

In order to optimize the solar photovoltaic (PV) generated power using a maximum power point tracking technique, a dc–dc conversion stage is usually required in solar PV fed water pumping which is driven by a brushless dc (BLDC) motor. This power conversion stage leads to an increased cost, size, complexity, and reduced efficiency. As a unique solution, this paper addresses a single stage solar PV energy conversion system feeding a BLDC motor-pump, which eliminates the dc–dc conversion stage. A simple control technique capable of operating the solar PV array at its peak power using a common voltage source inverter is proposed for BLDC motor control. The proposed control eliminates the BLDC motor phase current sensors. No supplementary control is associated for the speed control of motor-pump and its soft start. The speed is controlled through the optimum power of solar PV array. The suitability of proposed system is manifested through its performance evaluation using MATLAB/Simulink-based simulated results and experimental validation on a developed prototype, under the practical operating conditions.

Real‐time implementation of three‐phase single‐stage SPV grid‐tied system using TL‐VSC

This work deals with real-time implementation of a three-phase single-stage solar photovoltaic (SPV) grid-tied system using a three-level voltage source converter (TL-VSC) working at lower switching frequency of 900 Hz under varying solar intensity levels for large power applications. The proposed system consists of SPV array, TL-VSC, interfacing inductors, and three-phase AC grid. The decoupled current controller with the capacitor voltage balancing control and an incremental conductance maximum power point tracking (IC-MPPT)-based algorithms are used to control the TL-VSC to track and transfer maximum active power to AC grid at unity power factor from SPV array. Owing to low switching frequency and single-stage topology, the efficacy of the system is increased. The performance of SPV grid integrated system using TL-VSC is validated under varying solar intensity levels in the laboratory at different switching frequencies and interfacing inductors in accordance to IEEE 519 standard.

Single‐phase solar grid‐interfaced system with active filtering using adaptive linear combiner filter‐based control scheme

This study deals with a control scheme for single-stage solar photovoltaic (SPV) grid-interfaced system. The voltage-source inverter (VSI) is a power electronic interface between SPV array and the grid. The VSI provides power quality features, i.e. harmonics mitigation, power factor correction and perturb and observe maximum power point tracking for single-stage SPV grid-interfaced system. The SPV array supplies active power to the non-linear load and grid through VSI, during daytime only or when SPV generation is more than the load power. To increase the utilisation of VSI, it is used as an active power filter at night, to mitigate harmonics and to provide active power to the load from the utility grid. The proposed adaptive linear combiner filter has the capability to extract harmonics and enhances the power quality in SPV grid-interfaced system. It has also satisfied an IEEE-519 standard of harmonics by improving the quality of power of SPV grid-integrated system. Simulation results of the SPV system are presented, which are simulated using MATLAB and response of system under non-linear load and varying environmental condition are also studied experimentally on a developed prototype in the laboratory.

Adaptive neuron detection‐based control of single‐phase SPV grid integrated system with active filtering

This study deals with an adaptive neuron detection-based control technique for single-phase, single-stage solar photovoltaic (SPV) array grid integrated system using a voltage-source converter (VSC). The VSC also provides power quality features such as harmonics mitigation, power factor correction and perturb and observation-based maximum power point tracking for an SPV grid-interfaced system. With this approach, the VSC has the active power flow from the SPV array to the grid and it also performs the non-linear load current harmonic compensation by keeping the grid current almost sinusoidal. On the other hand, in the night mode, if the SPV power is not available, the VSC works as an active power filter for the harmonics elimination and reactive power compensation. This increases the effective utilisation of the VSC. The adaptive neuron detection technique has lesser noise and oscillation in extraction of fundamental component in comparison of conventional adaptive control algorithm. It has also satisfied an IEEE-519 standard of harmonics by improving the quality of power of SPV grid integrated system. The proposed system is modelled and simulated using MATLAB/Simulink and the response of the system under non-linear loads and varying environmental conditions are evaluated experimentally on a prototype developed in the laboratory.

Linear coefficient function based control approach for single stage SPV system integrated to three phase distribution system

This study proposes a single stage solar photovoltaic (SPV) system utilising a linear coefficient function (LCF) based control approach. The main aim is to develop a cost effective, reliable and efficient SPV system. For estimation of peak power from the SPV array, an adaptive perturb & observe based approach is utilised. Whereas, to control the gating signals of the voltage source converter, a linear coefficient function based approach is used. The proposed system injects the estimated power from the SPV array to the grid. Moreover, it is also used for mitigation of harmonics of the load current, unity power factor operation and load balancing. The proposed SPV system has used a SPV feed forward term to reduce the burden on the proportional integral controller and improves the dynamic response under atmospheric changes. The SPV system is modelled and experimentally verified the control under different operating conditions.

Grid Integration of Single Stage Solar PV System using Three-level Voltage Source Converter

Abstract This paper presents a single stage solar PV (photovoltaic) grid integrated power generating system using a three level voltage source converter (VSC) operating at low switching frequency of 900 Hz with robust synchronizing phase locked loop (RS-PLL) based control algorithm. To track the maximum power from solar PV array, an incremental conductance algorithm is used and this maximum power is fed to the grid via three-level VSC. The use of single stage system with three level VSC offers the advantage of low switching losses and the operation at high voltages and high power which results in enhancement of power quality in the proposed system. Simulated results validate the design and control algorithm under steady state and dynamic conditions.