Stand-alone Permanent Magnet Synchronous Generator Research Articles

ANALYSIS OF PERFORMANCE COEFFICIENTS IN MAXIMUM ELECTRICAL POWER EXTRACTION FROM STAND-ALONE WIND ENERGY CONVERSION SYSTEM

Increasing performance and improving efficiency in maximum power extraction from Wind Energy Conversion Systems (WECS) is a quite important research topic. Today, in the large-scale WECS, it is widely aimed to extract the maximum mechanical power from the wind turbine using the Maximum Power Point Tracking (MPPT) unit. Similarly, it can also be targeted to achieve maximum mechanical power in small-scale WECS applications. However, losses occur in structural subsystems and electrical subunits located in WECS. Due to these losses, the overall system efficiency decreases and the characteristic of the system is also affected. The operation of these systems can also be performed via maximum electrical output power extraction, which is one of the most up-to-date ideas. Thus, the overall WECS rather than the wind turbine can be optimally controlled. Eventually, maximum electrical power tracking (MEPT) based designs can provide higher power extraction with higher efficiency than MPPT-based ones. In this paper, considering the system operating concepts with MPPT and MEPT for a stand-alone Permanent Magnet Synchronous Generator (PMSG) based WECS, the changes in performance coefficients at defined focus points in terms of system efficiency are evaluated. Technical and theoretical comparative analyzes are also made for each specific wind speed between 8m/s and 12m/s.

Intelligent approach on sensorless control of permanent magnet synchronous generator

In this paper, a standalone permanent magnet synchronous generator (PMSG) system is designed to generate power at maximum power point (MPP). The variable speed operation of wind energy conversion system consists of PMSG, controlled rectifier and voltage source inverter co to the load. Proportional integral (PI), sliding mode (SM), and feed forward neural network (FFNN) control strategies are applied in field oriented control (FOC) at generator side converter. A comparative study on power generated at maximum power point (MPP) is done with these controllers using simulation. Hill climb search (HCS) method is applied to attain MPP. Load side inverter control strategy involves the PI and SM controllers in order to maintain the unity power factor and to control the active and reactive power for nonlinear load. The control strategies are modelled and simulated with MATLAB/Simulink. The effectiveness of proposed control method is demonstrated using simulation results.

Development and implementation of control of stand‐alone PMSG‐based distributed energy system with variation in input and output parameters

This work develops a combined control for a stand-alone permanent magnet synchronous generator (PMSG) working with variable source and output demand. The power circuit consists of one PMSG, driven by uncontrolled prime mover supplying load through two voltage source converter (VSC) connected through a dc link capacitor. The main objective of the control is to supply load at constant voltage and frequency, even with variation in source speed and power, and also to accommodate the change in load transients. The generator side converter control is developed in rotor flux oriented synchronously rotating reference frame, to keep the dc link voltage, of the back to back VSC, constant. The load side converter control is also developed in the synchronously rotating reference frame to supply load at constant voltage and frequency. The developed combined control strategy is implemented in MATLAB/SIMULINK environment and found to be successful under all considered operating conditions. The theoretical findings are experimentally verified with a real-time prototype.

Adaptive SRF-PLL Based Voltage and Frequency Control of Hybrid Standalone WECS with PMSG-BESS

Abstract The variable-speed Permanent Magnet Synchronous Generator (PMSG) based Wind Energy Conversion System (WECS) attracts the maximum power from wind, but voltage-regulation and frequency-control of the system in standalone operation is a challenging task A modern-control-based-tracking of power from wind for its best utilization is proposed in this paper for standalone PMSG based hybrid-WECS comprising Battery Energy Storage System (BESS). An Adaptive Synchronous Reference Frame Phase-Locked-Loop (SRF-PLL) based control scheme for load side bi-directional voltage source converter (VSC) is presented for the system. MATLAB/Simulink model is developed for simulation study for the proposed system and the effectiveness of the controller for bi-directional-converter is discussed under different operating conditions: like variable wind-velocity, sudden load variation, and load unbalancing. Converter control scheme enhances the power smoothening, supply-load power-matching. Also it is able to regulate the active & reactive power from PMSG-BESS hybrid system with control of fluctuations in voltage & frequency with respect to varying operating conditions. Proposed controller successfully offers reactive-power-compensation, harmonics-reduction, and power-balancing. The proposed scheme is based on proportional & integral (PI) controller. Also system is experimentally validated in the laboratory-environment and results are presented here.

An adaptive nonlinear control strategy for a stand-alone permanent magnet synchronous generator driven by a variable speed wind turbine

This paper presents a simple control structure using rotor flux oriented vector technique for a stand-alone permanent magnet synchronous generator (PMSG) associated to PWM rectifier, PWM DC–DC converter and PWM inverter. The DC–DC converter feeding an electronic load is controlled to maintain the dc-bus voltage at a desired constant value. The isolated PMSG is assumed to be driven by a variable speed wind turbine. A sliding mode control strategy has been developed to regulate the direct axis current, ensure maximum power tracking issue as well dc-bus voltage regulation. The online estimation of the rotor flux using sliding mode concept is provided. The control and estimator stability analysis is based on Lyapunov theory. Simulation results, carried out in Matlab/Simulink software, are presented to demonstrate the effectiveness of the proposed control method when the control system operates under load variations and parameters uncertainties. The proposed adaptive control can be used in remote area where wind speed is low.

A Downsizing Strategy for Combinatorial PMSG Based Wind Turbine and Micro-SMES System Applied in Standalone DC Microgrid

This paper presents a combinatorial standalone permanent magnet synchronous generator (PMSG) based variable speed wind turbine (VSWT) and small-size superconducting magnetic energy storage (SMES) system into the DC microgrid system. The principal purpose of SMES system is to preserve power balance by absorbing power during peak wind generation and to release it during low power generation. This work accomplished by describing the optimized design of the SMES solenoid coil, ensuring the desired energy storage capacity based on the simulated annealing (SA) algorithm. More importantly, the new control technique is developed for bi-directional DC-DC converter to level output power of the wind turbine depending on the demand thereby reducing the capacity of the DC-DC converter system. Detailed simulation studies implemented in PSCAD/EMTDC corroborate the superior robustness and balancing performance of the proposed micro-SMES controller with an optimal coil size under various situations including variable wind speed. This combination will result in “scaling-factors” knowledge through downsizing strategy which will lead to the most efficient system from cost cutting, energy savings, and downsizing viewpoints.

Permanent Magnet Synchronous Generator-Based Standalone Wind Energy Supply System

In this paper, a novel algorithm, based on dc link voltage, is proposed for effective energy management of a standalone permanent magnet synchronous generator (PMSG)-based variable speed wind energy conversion system consisting of battery, fuel cell, and dump load (i.e., electrolyzer). Moreover, by maintaining the dc link voltage at its reference value, the output ac voltage of the inverter can be kept constant irrespective of variations in the wind speed and load. An effective control technique for the inverter, based on the pulsewidth modulation (PWM) scheme, has been developed to make the line voltages at the point of common coupling (PCC) balanced when the load is unbalanced. Similarly, a proper control of battery current through dc-dc converter has been carried out to reduce the electrical torque pulsation of the PMSG under an unbalanced load scenario. Based on extensive simulation results using MATLAB/SIMULINK, it has been established that the performance of the controllers both in transient as well as in steady state is quite satisfactory and it can also maintain maximum power point tracking.

Analysis of a stand-alone permanent-magnet synchronous generator using a time-stepping coupled field-circuit method

The performance analysis of a stand-alone permanent-magnet synchronous generator with inset rotor using a coupled-circuit, time-stepping, two-dimensional finite-element method is described. The direct-coupled field-circuit method enables the instantaneous values of the field and circuit variables to be solved simultaneously, without having to evaluate the synchronous reactances and the load angle. Magnetic saturation is accounted for by considering the flux densities in the elements of the field solution region. Besides the load characteristics, the coupled field-circuit solution also yields other useful machine information including the flux plots, components of the air-gap flux density, and the waveforms of voltages and currents. The flux plots obtained clearly demonstrate the effect of armature current on the interpolar flux that helps to improve the voltage regulation. Good agreement between the computed and experimental results has been obtained on a 2.5 kVA prototype generator.

Modelling and controller design of an isolated diesel engine permanent magnet synchronous generator

A method to analyze the steady-state performance of a stand-alone permanent magnet synchronous generator driven by a diesel engine is presented. The proposed method is based on equivalent d-q circuits and the phasor diagram of such a generator under steady-state conditions. A fixed capacitor-thyristor controlled reactor scheme is used to regulate the generator terminal voltage by controlling the thyristor ignition angle. Furthermore the overall system dynamics are modelled in terms of state variables and control inputs. Based on a reduced order linearized model, digital optimal state and output feedback controllers are designed by minimising a quadratic performance index using the dynamic programming technique. The objective of the controller is to maintain the load voltage and frequency constant under varying load conditions. The controller's effectiveness is assessed by examining the closed-loop system response to sudden load changes.