Machine Side Research Articles

Six-Phase Machine Conversion System With Three- and Single-Phase Series Converters

This paper presents two conversion systems based on the association of a six-phase machine (SPM) with an electrical grid by means of three- and single-phase converters. The machine is composed of two three-phase groups. One of them provides the power to the three-phase converter, and the other provides the power to the single-phase converters, in an open-end winding connection (see Fig. 2). The first conversion system is composed of bidirectional switches and can be used with induction or permanent-magnet synchronous machines. The second system is partially reversible since the single-phase converters are also composed of diodes and is more indicated for permanent-magnet synchronous machines. Furthermore, the proposed configurations do not use transformers and generate multilevel voltage at the grid-side converter with amplitude higher than that of the machine side, permitting one to reduce the transmission I 2 R losses. The complete analysis of the systems, including the pulsewidth- modulated techniques, is presented. Simulation and experimental results are also presented.

Coordinated controller design of PMSG-based wind turbine using response surface methodology and NSGAII

SUMMARY This paper presents an optimum design procedure for the coordinated tuning of machine side converter (MSC) and grid side converter (GSC) controllers of permanent magnet synchronous generator (PMSG)-based wind energy conversion system (WECS). The MSC and GSC controller parameters are determined by simultaneously optimizing the performance indices. The performance indices considered are maximum peak overshoot (MPOSω) and settling time (Tssω) of the generator speed and the maximum peak overshoot (MPOSVdc), maximum peak undershoot (MPUSVdc) and settling time (TssVdc) of DC-link voltage. The coordinated controller design is carried out in two steps. The first step is to arrive at the analytical expression that relates the performance indices and the controller parameters. This is achieved using response surface methodology. In the second step, the determination of controller parameters is posed as a constrained multi-objective optimization problem. The constrained multi-objective optimization problem is solved using non-dominated sorted genetic algorithm II. The proposed methodology is tested on a sample system with PMSG-based WECS, and results are compared with conventional and genetic algorithm-based design techniques. Simulation results demonstrate the effectiveness of the proposed methodology. Copyright © 2014 John Wiley & Sons, Ltd.

English

This paper presents the simplified control of hybrid system (wind -hydro) system connected to two back-to-back converters in which one is connected to hydro turbine and the other is connected to wind turbine system through squirrel cage induction generators (SCIG) feeding three phase four wire loads in isolated locations. The main objective of this work is to provide a better control algorithm for the VSC and to achieve maximum power tracking (M.P.T) through rotor speed control of the wind turbine driven S.C.I.G under varying speeds at the machine side and to control the magnitude and frequency of the voltage at load side. The system mainly ensures in sending the power generated by SCIGw is supplied to the load through the load-side converter and remaining power is stored in ESBS. And at the same time if the required active power of the load is more than the total power generated by SCIGw and SCIGh. Then the deficit power is supplied by the ESBS. Simulation models of the proposed hybrid system and the simulation results are obtained in MATLAB using Simulink and Sim Power System set toolboxes, with different load condition at different wind conditions

English

This paper presents a three phase four wire local loads connected two squirrel cage induction generators (S.C.I.G) , one driven by a variable wind turbine and another driven by a constant power hydro turbine. The proposed system has a battery at the middle of the two back-to-back connected PWM controlled IGBT based voltage source converters(VSCs).The two VSCs are used to achieve maximum power tracking (M.P.T) at the machine side (Wind power generation side) and to regulate the magnitude and the frequency of the load voltage at load side(Hydro power generation).

Growing Neural Gas Based MPPT for Wind Generator Using DFIG

This paper presents Growing Neural Gas (GNG) based a maximum power point tracking (MPPT) technique for a high performance wind generator using DFIG. It is used in variable speed wind energy conversion system. Here, two back to back converters is used and connected to the stator, correspondingly FOC and VOC is done on machine and supply side converter. Constant voltage over the grid is obtained through dc link voltage. For Variable speed wind energy conversion system the maximum power point tracking (MPPT) is a very important requirement in order to maximize the efficiency. Here Neural Network has been trained to learn the turbine characteristic i.e torque versus wind speed and machine speed. It has been implemented to obtain maximum power point tracking for varying wind speed. And finally comparison has been made with and without growing neural gas.

Coordinated Controller Design of Grid-connected Variable-speed Wind Energy Conversion System with Model-based Predictive Control Using Response Surface Methodology

This paper presents an optimum design procedure for the coordinated tuning of machine side converter (MSC) and grid side converter (GSC) controllers of grid connected permanent magnet synchronous generator (PMSG). Model based predictive controller (MBPC) is used to control the MSC. MBPC based speed control design consists of two steps. A linearized state space model is employed to predict the future output (rotor speed). An optimal control law is derived by minimizing a quadratic performance index that considers the control effort and the difference between the predicted rotor speed and the reference rotor speed. A proportional-integral (PI) controller is used to control the GSC. The MSC and GSC controller parameters are determined by simultaneously optimizing the controller performance indices. The coordinated controller design is carried out in two steps. The analytical expression that relates the performance indices and the controller parameters is arrived using response surface methodology (RSM). The determination of controller parameters is posed as a constrained multi-objective optimization problem and solved employing NSGA-II (non-dominated sorted genetic algorithm II). The proposed methodology is tested on a sample power system with PMSG based WECS (Wind Energy Conversion System). Simulation results demonstrate the effectiveness of the proposed methodology.

Matrix Converter for PMSG based WECS Using Duty Ratio Based Switching with FOC

This paper presents the direct AC to AC converter for Permanent Magnet Synchronous Generator (PMSG) based wind urbine. The direct AC to AC matrix converter is intended between the PMSG wind turbine and the grid. The power generated by the wind turbine is synchronized with the grid parameters through the converter. A modulation scheme based on duty ratio is proposed. Depending upon the duty ratio the switching of matrix converter is done. Conventional ACDC- AC back to back converter is replaced by direct AC to AC converter. The modulation scheme can be also implemented using Field Programmable Gate Array (FPGA) so that the computational speed can be improved. The machine side control is done by Field Oriented Control (FOC). A three phase to three phase matrix converter is simulated using MATLAB simulink software and the results are shown.

DSP Based Maximum Power Point Tracking (MPPT) for Improving the Performance of DFIG

In the recent years, wind power has been developed rapidly. So most of the research work focus towards the variable speed power generation rather than fixed speed power generation in wind energy conversion system. This paper presents a maximum power point tracking (MPPT) technique for an improved power quality, high energy efficiency and controllability. For the experimental application a Back – to - Back configuration with two voltage source converters has been considered one on the machine side and another on the grid side. Each converter has been controlled with a high performance vector control technique ie FOC & VOC respectively. Two DSPs have been used to control both the inverters. Simulation result shows that the Digital Signal Processor provides effectiveness in controlling under different operating conditions.

PERFORMANCE ANALYSIS OF VARIOUS PARAMETERS BY COMPARISON OF CONVENTIONAL PITCH ANGLE CONTROLLER WITH FUZZY LOGIC CONTROLLER

This paper deals with a variable speed wind turbine coupled with a permanent magnet synchronous generator connected through a two mass drive train. This drive train is connected to synchronous generator and after the conversion process finally connected to grid and the idea of transmission over a long distance makes the use of converter necessary and at the receiving end. The inverter is used to convert it back and the inverter is designed with a proper gate signal to get the best output three phase voltages. The fuzzy logic controller is used to track generator speed with varying wind speed to optimize turbine aerodynamic efficiency in the outer speed loop. Pitch angle control of wind turbine has been used widely to reduce torque and output power variation in high rated wind speed areas .The machine side converter is designed to extract maximum power from the wind. In this work a WECS connected with grid is designed in Matlab and a Fuzzy controller is designed to improve the output and we can see the major difference in DC link voltage and reactive power in transmission line. From the outputs we can also go through the reactive power issue which system is best for inductive load or capacitive load. The simple PI system is good for capacitive load and the fuzzy system is better option for the inductive load. The results of both the system of normal controller and fuzzy controller is compared and analyzed.

Open Fault Characteristics and Simple Diagnosis Scheme in a Back-to-Back Converter for Wind Power Conversion

Switch open fault characteristics and simple diagnosis scheme in a back-to-back converter are presented for a permanent magnet synchronous generator (PMSG) based variable-speed grid-connected wind power conversion. In the back-to-back converter, the failure in switching devices may occur either in a machine side converter (MSC) or in a grid side converter (GSC), which decreases the generator output power and degrades the stability in wind power generation system. To detect such a fault, the second-order harmonic components of the q-axis current are monitored in the MSC as well as in the GSC. To verify the effectiveness of the proposed scheme, the comparative simulation results are presented.

Linear parameter‐varying control of permanent magnet synchronous generators for wind power systems

This study presents an optimal control strategy for the electronic interface of a wind energy conversion system based on a permanent magnet synchronous generator (PMSG). A linear optimal control is used on the grid side of the interface to ensure a proper power transfer and a linear parameter-varying (LPV) control on the machine side to cope with the wide operating conditions demanded by the wind turbine applications. The dynamics of a PMSG working in a variable speed wind turbine is affected by the rotational speed of the wind rotor. The LPV control uses the generator speed as a scheduling variable to adapt itself to different operating conditions. The proposed scheme results in a multi-variable self-scheduled controller with a PI structure similar to classical approaches. Thus, the control ensures performance and stability in all possible operating conditions whereas the implementation and the numerical stability are similar to previous schemes. The proposed control has been implemented in a test bench that includes a fully-rated back-to-back converter. The experimental results show a good performance in different scenarios in which the controller has to adapt itself to highly varying operating conditions.

Dust-free coke discharge on the machine side of coke ovens

Dust-free coke discharge on the machine side of coke ovens

전동기-발전기 실험장치(Motor-Generator Set)를 이용한 조류발전 시스템의 특성 분석

In order to analyze the characteristics of tidal current power generation system, we measured output power in M-G Set (Motor-Generator Set) and MATLAB/Simulink. We installed M-G Set (Motor-Generator Set) and did a simulation using MATLAB/Smulink. The simulation consisted of the tidal current turbine, PMSG, converter, and three-phase PWM inverter. Also, the speed control of the generator was performed using machine side converter. And we measured output voltage, current, power of the generator and the output power of three-phase PWM inverter.

Safety P-Cycle Protection Mechanism for Smart Power Device

Power converter with full closed loop water cooling system, works not only use water cooling characteristics of high efficiency, but also the electricity, and reducing the volume to prevent contamination. In this paper, we proposed a novel p-cycle safety protection approach that can provide rapid cycling radiating, and can restore the status of power device. For power cabinet composition, IGBT power modules and reactors is primarary radiating components, in which IGBT power modules that used for water cooling solution is modeled as the cooled automobile engine cooling system using cycling design principle. Besides, machine side and the network side of the power module is installed in separate cabinet to improve the tightness of the entire cabinet, in order to resist sandstorms.

Direct Drive Permanent Magnet Synchronous Wind Generator Maximum Power Tracking Control

Direct drive permanent magnet synchronous generator have the advantages of direct drive, simple structure, high efficiency and so on, in which make it become one of mainstream models within MW wind turbine presently. Making the direct drive permanent magnet wind power generation system as the main research object, based on the principle of the operating characteristics of direct drive permanent magnet synchronous wind generator ( DDPMG ), establish mathematical model of the whole system including wind velocity, wind turbine, direct drive permanent magnet synchronous generator and machine side converter, Appling the method of stator flux orientation to make the study of vector control strategy, to build the simulation model of direct drive permanent magnet synchronous generator system with Matlab and simulate when wind speed changes by step, the results validate the reasonableness of the model and the correctness and feasibility of the control strategy.

Hybrid Control Strategy for Variable Speed Wind Turbine Power Converters

This article employs a hybrid control strategy for variable speed wind turbine power converters. A voltage-controlled voltage source converter algorithm was used in the machine or rotor side of the variable speed wind turbine system. For the grid or stator side of the variable speed wind turbine, a current-controlled voltage source converter method was used. The effectiveness of the hybrid converter system was compared with those using only voltage or current controlled power converters for the variable speed wind turbine in a standard laboratory power simulation package of the Manitoba Research Centre in Canada (PSCAD/EMTDC). It is palpable and discernable from the results that the hybrid control strategy improves the performance of the variable speed wind turbine stability during transient compared to when only the voltage-controlled algorithm was used for the power converters. However, when the current-controlled method is applied for the variable speed wind turbine power converters, the transient stability of the variable speed wind turbine was slightly improved compared to the hybrid converter system.

A New Approach for Controlling Direct-Driven PMSG Wind Turbines

This paper presents control of wind energy conversion system (WECS) with permanent magnet synchronous generator (PMSG). With the modern power electronic technology, direct-driven PMSG have been increasingly used in wind turbine manufactures. In PMSG wind turbine with two back-to-back voltage source converter (VSC) are used like a commercial passive rectifier followed by an insulated gate bipolar transistor (IGBT) inverter. This paper investigates the new approach for controlling the direct-driven PMSG wind turbines; it has two side-by-side voltage source pulse width modulation (PWM) converters. The paper investigates new approach based on direct current vector control method and also investigates the conventional vector control. Thisnew approach has to control both the machine side converter (MSC) and grid side converter (GSC). The control strategy is developed for integrated control of PMSG for maximum power extraction, dc-link voltage control and grid voltage support control. The WECS have been developed using Matlab Simulink software to compare the conventional vector control method with proposed approach under steady state and gusty wind conditions.

Wind energy conversion system with full-scale power converter and squirrel cage induction generator

This paper describes a modeling and control of a variable speed squirrel-cage induction generator with back to back power electronics converters used in variable speed wind energy conversion system. The power electronics is composed of the generator side converter (GSC) coupling to the grid connected converter (GCC) together via DC bus capacitor. The generator side converter (GSC) is controlled by direct torque control (DTC).The control objectives of the generator side converter (GSC) are to optimize the energy capture from the wind turbine and supply the magnetic flux to the squirrel cage induction generator (SCIG). The GCC converter delivering the energy from the machine side to the utility grid regulated the DC link voltage and the power flows to the grid. The basic idea of P-Q control method used is based on voltage vector oriented control and decoupling in the d-q axis reference frame. The complete control system has been developed; analyzed and validated by Matlab simulation. The two operating modes of GCC converter and the performance under active and reactive power variations are also presented. The low voltage ride-through (LVRT) performances of the variable speed wind turbine (VSWT) is tested, when the grid voltage has dropped to a very low value. Simulation results confirmed the effectiveness of the proposed control strategies and their capability under different case study. Key words: Variable speed wind turbine, converter control, power quality, back to back converters, vector oriented control.

A rotor speed estimation algorithm in variable speed permanent magnet synchronous generator wind energy conversion system

SUMMARYA rotor speed estimation algorithm in a direct vector controlled permanent magnet synchronous generator wind energy conversion system is proposed. The proposed method is based on a simple equation obtained from the flux model of the machine and contains only stator flux and current. Constant gain recursive least squares estimator is used for implementing the speed estimation algorithm. Rotor position information used for coordinate transformation is computed using the estimated speed. Stator flux information required by the speed estimator is obtained using the stator voltage equation by implementing a programmable low pass filter. The estimated speed is used as the feedback signal for the speed control loop of the vector controlled machine side converter control system whose command speed is obtained from a wind speed sensorless maximum power point tracking controller, thus, we obtain a complete rotor speed and wind speed sensorless permanent magnet synchronous generator wind energy conversion system. Simulation is carried out to validate the performance of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.

Controlling PMSG-based wind generation by a locally available signal to damp power system inter-area oscillations

SUMMARY The work reported in this paper adds damping to the inter-area mode of oscillation in a power system with relatively high penetration of wind power, by modulating active power output of the permanent magnet synchronous generator wind turbines (PMSG-WTs) using local information. The dc-link voltage of the voltage source converter is used as a local signal for controller input. This input signal is processed through phase compensator blocks, and the output of the controller is used to vary the active power reference signal of the machine side converter controller. The results are compared to the cases of the same supplementary controller loop with a global signal as its input, added to the both PMSG-WTs and doubly fed induction generator wind turbines. An optimization-based approach is proposed to adjust and coordinate various control loops of the grid-connected PMSG-WTs. The performance of the supplementary damping control loop is evaluated, employing modal analysis and time domain simulations of a power system test case. Copyright © 2012 John Wiley & Sons, Ltd.