Mohan V. Aware

A STATCOM-Control Scheme for Grid Connected Wind Energy System for Power Quality Improvement

Injection of the wind power into an electric grid affects the power quality. The performance of the wind turbine and thereby power quality are determined on the basis of measurements and the norms followed according to the guideline specified in International Electro-technical Commission standard, IEC-61400. The influence of the wind turbine in the grid system concerning the power quality measurements are-the active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operation and these are measured according to national/international guidelines. The paper study demonstrates the power quality problem due to installation of wind turbine with the grid. In this proposed scheme STATic COMpensator (STATCOM) is connected at a point of common coupling with a battery energy storage system (BESS) to mitigate the power quality issues. The battery energy storage is integrated to sustain the real power source under fluctuating wind power. The STATCOM control scheme for the grid connected wind energy generation system for power quality improvement is simulated using MATLAB/SIMULINK in power system block set. The effectiveness of the proposed scheme relives the main supply source from the reactive power demand of the load and the induction generator. The development of the grid co-ordination rule and the scheme for improvement in power quality norms as per IEC-standard on the grid has been presented.

Micro Wind Power Generator With Battery Energy Storage for Critical Load

In the micro-grid network, it is especially difficult to support the critical load without uninterrupted power supply. The proposed micro-wind energy conversion system with battery energy storage is used to exchange the controllable real and reactive power in the grid and to maintain the power quality norms as per International Electro-Technical Commission IEC-61400-21 at the point of common coupling. The generated micro-wind power can be extracted under varying wind speed and can be stored in the batteries at low power demand hours. In this scheme, inverter control is executed with hysteresis current control mode to achieve the faster dynamic switchover for the support of critical load. The combination of battery storage with micro-wind energy generation system (μ WEGS), which will synthesize the output waveform by injecting or absorbing reactive power and enable the real power flow required by the load. The system reduces the burden on the conventional source and utilizes μ WEGS and battery storage power under critical load constraints. The system provides rapid response to support the critical loads. The scheme can also be operated as a stand-alone system in case of grid failure like a uninterrupted power supply. The system is simulated in MATLAB/SIMULINK and results are presented.

Design and Realization of Stand-Alone Digital Fractional Order PID Controller for Buck Converter Fed DC Motor

The aim of paper is to employ digital fractional order proportional integral derivative (FO-PID) controller for speed control of buck converter fed DC motor. Optimal pole-zero approximation method in discrete form is proposed for realization of digital fractional order controller. The stand-alone controller is implemented on embedded platform using digital signal processor TMS320F28027. The five tuning parameters of controller enhance the performance of control scheme. For tuning of the controller parameters, dynamic particle swarm optimization technique is employed. The proposed control scheme is simulated on MATLAB and verified by experimental results. Performance comparison shows better speed control of separately excited DC motor with the realized digital FO-PID controller than that of the integer order PID controller.

Power quality issues &it’s mitigation technique in wind energy generation

Awareness of power quality is highly increased in a sensitive industry, where the standardization and performance is an important aspect. The connection of wind turbine to the grid affectpsilas the electric grid power supply quality. Therefore it is necessary to maintain the power quality norm at the interface of the grid from the disruptive effect caused by wind turbine such as voltage fluctuation, switching operation, voltage dips, and reactive power & harmonics distortion on the grid. These disruptive effected can be minimized by adopting suitable control technique. The paper proposed the control scheme for voltage source inverter (VSI) in a current control mode to inject the compensating current into the power system at point of common coupling. A hysteresis current controller has been implemented to generate the inverter switching signals using the reference from source voltage. This ensures that wind turbine system will inject current through inverter to maintain unity power factor. The wind turbine shall provide active and reactive power support to the load. Thus the power system will operate with stipulated power quality norm at point of common connection. The typical system is simulated in Matlab/Simulink for practical condition in power system and simulated results under varying operating condition are presented.

Improved inverter utilisation using third harmonic injection

In this paper, a comparative analysis of the carrier based pulse width with modified zero space vector modulation or third harmonics injection used in the inverter control is presented. The placement of zero space vector components with in the carrier interval determines the harmonic performance of the modulation strategy. The space vector pulse width modulated inverter gives 15 percent more line to line voltage as compared with the conventional sine pulse width modulated (SPWM) inverter. The optimized zero vector injection controls the blanking time and minimum pulse width of an operating inverter switch. The simulation results are presented for the three phase voltage source inverter to ascertain the effect of this technique. It is also tested on the laboratory prototype inverter to confirm the effectiveness of this modified SVPWM technique.

Energy storage to strengthen the wind generator in integrated power system

The wind energy generation, utilization and its grid penetration in electrical grid is increasing world wide. The wind generated power is always fluctuating due to its time varying nature and causing stability problem. This weak interconnection of wind generating source in the electrical network affect the power quality and reliability. The localized energy storages shall compensate the fluctuating power and support to strengthen the wind generator in the power system. In this paper, it is proposed to control the voltage source inverter (VSI) in current control mode with energy storage, that is, batteries across the dc bus. The generated wind power can be extracted under varying wind speed and stored in the batteries. This energy storage maintains the stiff voltage across the dc bus of the voltage source inverter. The propose scheme enhances the stability and reliability and maintain unity power factor as well as operated in stand alone mode in the power system. The power exchange across the wind generation and the load under dynamic situation is feasible while maintaining the power quality norms at the common point of coupling, strengthen the weak grid in the power system. This control strategy is evaluated on the test system under dynamic condition by using simulation.

Photovoltaic system emulator

The PV system design and its performance evaluation test before installation could be more costly and time consuming. This could be performed with accuracy in the laboratory without having PV array by using the emulator. This paper presents the PV emulator using real-time algorithm execution of the PV array mathematical model and generating the scaled output power from the AC-DC power supply. The generic PV model is simulated in LabVIEW and interfaced to the real world through a data-acquisition system. The GUI interfaced template allows the commercial PV arrays details to be configured. The actual field conditions i.e. varying temperature and irradiations are emulated by the corresponding sensor equivalent voltages. This laboratory prototype is tested with real-time execution of PV model for the steady state and dynamic operating conditions. The performance of MPPT based Golden Section Search algorithm is evaluated using the proposed emulator.

Energy Storage to Stabilize the Weak Wind Generating Grid

The wind energy generation, utilization and its grid penetration in electrical grid is increasing world wide. The wind generated power is always fluctuating due to its time varying nature and causing stability problem. This weak interconnection of wind generating source in the electrical network affect the power quality and reliability. The localized energy storages shall compensate the fluctuating power and support to stabilize the weak grid. In this paper, it is proposed to control the voltage source inverter (VSI) in current control mode with energy storage, that is, batteries across the DC bus. The DC bus voltage control is obtained by using bi-directional DC/DC converter. The generated wind power can be extracted under varying wind speed and stored in the batteries. This energy storage maintains the stiff voltage across the DC bus of the voltage source inverter. The propose scheme enhances the stability and reliability of the power system. The power exchange across the wind generation and the load under dynamic situation is feasible while maintaining the power quality norms at the common point of coupling. This control strategy is evaluated on the test system under dynamic condition by using simulation.

Torque ripple reduction in five-phase direct torque controlled induction motor

This paper presents the torque ripple reduction in the direct torque controlled (DTC) five phase induction motor (IM). The ripples are directly related to the hysteresis band of the controller in torque and flux loops within the operating switching frequency limits. It is proposed to increase the switching frequency by dither signal injection into the torque and flux control loops. A conventional DTC control of five phase model is modified by superimposing a high frequency and small amplitude triangular waveform into torque and flux error. The operation of five phase induction motor within the operating speed range indicates the reduction in the torque ripple and improves its performance in the low speed region. It is observed that the torque ripple is reduced by 30% and improvement in the total harmonic distortions (THD) of current. The overall dynamic performance improvement is indicated through MATLAB/SIMULINK simulation.

Golden section search (GSS) algorithm for Maximum Power Point Tracking in photovoltaic system

This paper presents a new Maximum Power Point Tracking (MPPT) algorithm based on golden section search technique for tracking maximum power point in photovoltaic (PV) systems. This method is robust and also has a fast response as compared to the conventional MPPT algorithms. This algorithm has guaranteed convergence under continuous variable atmospheric conditions. The search variable voltage is used to control the DC-DC converter. This algorithm is executed in real time using NI-Elvis hardware platform along with the PV emulator. The PV emulator eliminates the need of photovoltaic panels required for testing the energy conversion system. The performance of this algorithm is tested for different temperature and irradiation level. The dynamics under different operating conditions of PV array is tested on 300W DC-DC converter to confirm its performance.