Rahul Kumar Agarwal

LMF-Based Control Algorithm for Single Stage Three-Phase Grid Integrated Solar PV System

This paper proposes the use of a least mean fourth (LMF)-based algorithm for single-stage three-phase grid-integrated solar photovoltaic (SPV) system. It consists of an SPV array, voltage source converter (VSC), three-phase grid, and linear/nonlinear loads. This system has an SPV array coupled with a VSC to provide three-phase active power and also acts as a static compensator for the reactive power compensation. It also conforms to an IEEE-519 standard on harmonics by improving the quality of power in the three-phase distribution network. Therefore, this system serves to provide harmonics alleviation, load balancing, power factor correction and regulating the terminal voltage at the point of common coupling. In order to increase the efficiency and maximum power to be extracted from the SPV array at varying environmental conditions, a single-stage system is used along with perturb and observe method of maximum power point tracking (MPPT) integrated with the LMF-based control technique. The proposed system is modeled and simulated using MATLAB/Simulink with available simpower system toolbox and the behaviour of the system under different loads and environmental conditions are verified experimentally on a developed system in the laboratory.

Application of LMS-Based NN Structure for Power Quality Enhancement in a Distribution Network Under Abnormal Conditions

This paper proposes an application of a least mean-square (LMS)-based neural network (NN) structure for the power quality improvement of a three-phase power distribution network under abnormal conditions. It uses a single-layer neuron structure for the control in a distribution static compensator (DSTATCOM) to attenuate the harmonics such as noise, bias, notches, dc offset, and distortion, injected in the grid current due to connection of several nonlinear loads. This admittance LMS-based NN structure has a simple architecture which reduces the computational complexity and burden which makes it easy to implement. A DSTATCOM is a custom power device which performs various functionalities such as harmonics attenuation, reactive power compensation, load balancing, zero voltage regulation, and power factor correction. Other main contribution of this paper involves operation of the system under abnormal conditions of distribution network which means noise and distortion in voltage and imbalance in three-phase voltages at the point of interconnection. For substantiating and demonstrating the performance of proposed control approach, simulations are carried on MATLAB/Simulink software and corresponding experimental tests are conducted on a developed prototype in the laboratory.

Implementation of LLMF Control Algorithm for Three-Phase Grid-Tied SPV-DSTATCOM System

This paper proposes a three-phase single-stage grid integrated solar photovoltaic distributed static compensator (SPV-DSTATCOM) system using a leaky least mean fourth (LLMF) control algorithm. The prime contributions of this paper include: 1) the SPV generating system, which fulfills the active power requirement of connected loads and supplies the excess power to the grid; 2) the voltage-source converter (VSC) acts as a dc–ac inverter and DSTATCOM, which provides reactive power compensation, harmonics filtering, load balancing, power factor correction, zero voltage regulation, and mitigates several other power quality issues; 3) even when the SPV power is unavailable, the VSC operates as a DSTATCOM, which enhances the utilization factor of devices; and 4) the LLMF-based control approach for fundamental component extraction from load currents for good harmonics compensation as well as to keep the overall system stable and to achieve rapid response at changing conditions. The proposed system is modeled and simulated using MATLAB/Simulink as well as its performance is verified experimentally on a developed prototype.

Improved power quality of three-phase grid connected Solar Energy Conversion System under grid voltages distortion and imbalances

This paper proposes a control technique for improving power quality of a three-phase grid connected SECS (Solar Energy Conversion System) under grid voltage distortion and imbalances. SECS mainly extracts DC power from solar PV (Photovoltaic) array and converts it into AC power via a voltage source converter (VSC) and supplies it to grid and connected loads. This system functions on an incremental conductance (INC) driven MPPT (Maximum Power Point Tracking) algorithm along with unit vectors estimation via positive sequence voltages extraction and a neural network (NN) based least mean sixth (LM-Sixth) current control technique. The system aims to eliminate power quality issues and provides current conditioning while operating in coherence with a weak grid such as Indian grid which has poor power supply quality and voltages distortion and imbalances. The system provides functions of both SECS as well as shunt active power filter (SAPF) depending on the availability of sunlight. For validation of this system, experimental tests are carried out on a developed laboratory prototype and results are recorded for supporting the same.

A multifunctional three-phase grid-connected single-stage SPV system using an intelligent adaptive control technique

In this paper, a multifunctional three-phase grid-connected single-stage solar photovoltaic (SPV) system is presented using an intelligent adaptive control technique. The system configures a SPV array, VSC (Voltage Source Converter), interfacing inductors, ripple filter and three-phase grid connected nonlinear loads. The system is multifunctional as it provides functions of two different modes: 1) It acts as a SPV energy conversion system supplying active power to the loads and grid as well as a DSTATCOM (Distributed Static Compensator), and 2) It acts as a DSTATCOM alone, when SPV generation is unavailable and mitigates several power quality issues such as harmonics attenuation, voltage fluctuations and flickers, reactive power compensation, power factor correction (PFC) and load balancing. It uses a single-stage converter topology with variable step-size least mean fourth (VSS-LMF) derived adaptive control technique for VSC switching incorporating perturb and observe (P&O) method for MPPT (Maximum Power Point Tracking). The performance of the presented system is validated through experimental results obtained on the developed laboratory prototype.

Integration of single-stage SPV generation to grid using admittance based LMS technique

In this paper, an integration of single-stage solar photovoltaic (SPV) generation to three-phase AC grid is proposed using admittance based LMS (Least Mean Square) adaptive control approach. The main focus of the system is to supply active power to the grid as well as loads at PCC and also mitigate several power quality issues like current harmonics distortion, reactive power and load unbalancing. A simple LMS based admittance control with P&O (Perturb and Observe) based MPPT (Maximum Power Point Tracking) is used for achieving efficient system. The proposed control is easy to implement and has a fast response. The performance of the system is simulated in MATLAB environment under variable solar irradiance, balanced and unbalanced load (linear and nonlinear) conditions in both PFC and ZVR modes.

SSI based control for single-stage single-phase PV-grid tied system with self-adjusting capability to voltage fluctuations

In this paper, a SSI (Sinusoidal Signal Integrator) based control technique is proposed for a single-stage single-phase solar photovoltaic (PV) grid tied with self-adjusting capability to voltage fluctuations. This system configures a solar PV array supplying the active power to single-phase grid and connected linear/nonlinear loads. The system aims at improving power quality, eliminating grid current distortions like harmonics, notches, bias etc., providing reactive power compensation while working under UPF (Unity Power Factor) mode. The proposed control technique for the system also provides capability for stable continuous operation during voltage disturbances in a grid such as voltage fluctuations (sag and swell). The control algorithm consists of MPPT (Maximum Power Point Tracking) technique and SSI based control for extraction of the fundamental component of load current. Simulation is done using MATLAB software and behaviour of the system is verified under varying loading and environmental conditions.

Composite observer based control technique for single-phase solar PV-Grid tied system

In this paper, a composite observer based control technique is proposed for a single-stage single-phase solar photovoltaic (PV) grid tied system. The system aims at integrating solar PV power generating station to single-phase distribution grid for supplying active power to linear or nonlinear loads connected at the point of interconnection (PoI). The main contribution of this paper is the use of composite observer driven control technique for a single-stage PV-grid tied system which improves the power quality on the grid side by providing harmonics alleviation, reactive power compensation and power factor correction. For maximum power point tracking, an incremental conductance based approach is implemented to increase the efficacy of the solar PV system. Simulation is done using MATLAB software and experimental tests are carried out on a laboratory prototype for studying the behaviour of the system under varying nonlinear loading and solar insolation conditions.

Grid integration of single stage SPV system using NLMS filtering control technique

This paper pertains to the application of an intelligent control algorithm for the integration of single stage solar photovoltaic (SPV) system with the three-phase grid. The basic attributes of this integration of SPV system with the grid involve active power exchange, reactive power compensation, PFC (Power Factor Correction), zero voltage regulation at the point of common coupling (PCC) and harmonics mitigation conforming to IEEE-519 standard. The topology employed consists of a voltage source converter (VSC) for flexible, reliable and efficient generation of high quality power from SPV array. The control algorithm adopted here involves a single stage topology with a NLMS (Normalized Least Mean Square) based methodology. To extricate maximum power from SPV array, a single stage topology employs MPPT (Maximum Power Point Tracking) methods with P&O (Perturb and Observe) approach. The NLMS based control algorithm is used to regulate the DC link voltage level as well as regulating the AC voltage level during various loading and environmental conditions. Experimental results of the proposed system are presented which are recorded on developed prototype in the laboratory.

Integration of single-stage SPV generation to three-phase distribution grid using a variable step size LMS control technique

In this paper, an integration of single-stage solar photovoltaic (SPV) generation to three-phase distribution grid is proposed using a variable step-size least mean square (VSS-LMS) control technique. The prime focus of the system is to establish a safe, secure and reliable integration which mitigates several power quality issues like voltage fluctuations and flickers, harmonics distortion, DC current injections, reactive power requirement etc. and also provides load balancing, zero voltage regulation (ZVR) and power factor correction (PFC). A single-stage converter topology is used with VSS-LMS control and P&O (Perturb and Observe) based MPPT for achieving efficient system. For the verification of the system operation, a prototype is developed in the laboratory and tests are carried on it when subjected to different conditions like unbalanced nonlinear loads and variable solar insolation.