Integration of Wind Energy Conversion System with microgrid and utility

Three types of offshore wind power collection topologies are studied for DC power systems in this paper. Permanent Magnet Synchronous Generator (PMSG) based Wind Energy Conversion System (WECS) is considered and the Optimal Power Control (OPC) is used for the Maximum Power Point Track (MPPT) control. The failure of a wind power unit is regarded as the fault condition in this paper. Voltage control strategies are proposed for series and series-parallel power collection topologies when such a fault happens. Input and output voltage references of the Grid-Side Converter (GSC) are modified for series power collection systems on fault conditions. For series-parallel collection systems, power switches are employed between wind power branches and different voltage control effects with different switch options are discussed. Simulation studies are conducted base on PSCAD/EMTDC to validate the proposed control strategies.

Wind energy has established as fastest growing renewable energy technology. During last few decades world has witnessed multidimensional development in this area and made this technology acceptable for efficient production of bulk power. Recent research articles and renewable energy market trends have demonstrated the popularity of permanent magnet synchronous generator (PMSG) based wind energy conversion system (WECS) for such requirements. Objective of present work is to examine the performance of the cylindrical pole PMSG based wind turbine (WT) interfaced to the grid via back-to-back voltage source converter. Present work focuses on generator performance with zero d-axis current control (ZDC) and maximum torque per ampere control (MTPA), it has been observed that cylindrical rotor PMSG displays identical performance with ZDC and MTPA control. In order to analyze the WECS performance, simulation is done in MATLAB/Simulink platform. Excellent performance is observed and is validated with the obtained performance parameters for the system at steady state. The WECS performance is studied in maximum power point tracking (MPPT) range only.

This paper presents a modified space vector pulse width modulation (MSVPWM) technique for nine-level cascaded H-bridge (CHB) inverter. Based on a modular structure and absence of capacitor balancing problems, CHB inverter topology is preferred. Nowadays, space vector PWM (SVPWM) control scheme has achieved higher attention among different PWM techniques. In general, SVPWM method is realized based on disintegrating higher-level hexagons into a number of two-level hexagons. Compared to conventional SVPWM technique, the proposed MSVPWM technique reduces the computational burden and memory requirement involved in the realization of nine-level SVPWM. This is achieved by reducing the number of two-level hexagons without losing the inverter output voltage profile. Also a further modified space vector pulse width modulation technique is presented, which greatly reduces the computation efforts. The proposed SVPWM techniques are applied to a nine-level CHB inverter by using MATLAB/SIMULINK software tool and are compared with carrier-based sinusoidal pulse width modulation (SPWM) technique to validate the proposed techniques. The proposed SVPWM schemes produce lower harmonic distortion and higher DC bus utilization compared to SPWM technique. To verify the practicality of the proposed SVPWM techniques, experimental results are presented on nine-level CHB inverter.

A voltage source inverter with variable frequency and variable voltage is applied for three-phase interior permanent magnet synchronous motor (IPMSM) drive for variable speed application. To obtain the required output voltage in the line side of the inverter a suitable pulse width modulation technique is used. The most prominent PWM techniques are Sinusoidal pulse width modulation (SPWM) and Space vector pulse width modulation (SVPWM). SPWM is simple and easy method to generate pulses for inverter, whereas SVPWM is an accurate method and generate less harmonic distortion compared to SPWM. However there is a lot of complexity involved in calculation of angle and sector as the level increases with SVPWM. To overcome this a similar and easy method known as unified pulse with modulation also know as carrier based space vector pulse width modulation technique(CBSVPWM is described using the concept of effective time. By using this method the inverter output voltage is directly synthesized by the effective times and the voltage modulation task can be greatly simplified. In this paper an IPMSM drive using CBSVPWM is simulated using MATLAB/SIMULINK software and its performance is compared with SPWM by varying modulation index (MI). The simulation study reveals that CBSVPWM simple and easy method which utilizes dc bus voltage more effectively and generates less THD compared to SPWM.

In this paper, a comparative study of shunt active filter (SAPF) with Sinusoidal pulse width modulation (SPWM) and Space vector pulse width modulation (SVPWM) technique to mitigate source current harmonics which are producing by the nonlinear load. In conventional diode clamped multilevel inverter extra diodes and balancing circuit is required. In proposed H-bridge inverter reduction of complexity and cost. The performance of SPWM and SVPWM technique is analysed by using MATLAB/ Simulink software.

Optimal power extraction control schemes for five-phase PMSG based wind generation systems

Multilevel inverters have gained significant attention in recent years due to their ability to achieve higher voltage and lower harmonic distortion compared to conventional two-level inverters. Pulse width modulation (PWM) techniques play a crucial role in controlling multilevel inverters by generating the required switching signals for their power electronic devices. This paper presents a comprehensive comparative analysis of various PWM techniques employed in multilevel inverters, including sinusoidal pulse width modulation (SPWM), space vector pulse width modulation (SVPWM), carrier-based pulse width modulation (CBPWM), and selective harmonic elimination (SHEPWM). Each PWM technique's advantages, limitations, and suitability for different multilevel inverter topologies are discussed. Furthermore, recent advancements and hybrid PWM techniques are also examined to explore potential improvements in performance and efficiency. This paper aims to provide researchers, engineers, and practitioners with valuable insights into selecting the most appropriate PWM technique for their specific multilevel inverter applications, considering factors such as performance requirements, cost constraints, and ease of implementation.

This study compares Field-Oriented Control (FOC) and trapezoidal control techniques for Permanent Magnet Synchronous Motors (PMSMs) in modern industrial variable-speed applications. Traditionally, variable-speed applications have relied on DC machines, which have inherent drawbacks such as increased maintenance, spark losses, higher inertia, and overall higher costs. This FOC has emerged as a sophisticated method that enables independent control of torque and magnetization flux in AC motors, allowing for precise regulation of torque and speed tailored to the motor's electromagnetic state. FOC leverages Sinusoidal Pulse-Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM) techniques to enhance DC voltage utilization and minimize switching and harmonic losses. In contrast, the paper presents a detailed model of a PMSM drive system based on electronic components rather than standard mathematical blocks, leading to more realistic simulation results. All simulation modules, including the inverter and PWM generator, were custom-built, allowing for performance comparison under varying speed and torque conditions. Brushless DC (BLDC) motors, which are typically categorized as PMSMs with trapezoidal back-EMF waveforms, have gained traction due to their simplicity and cost-effectiveness. The trapezoidal control technique, also known as six-step commutation, simplifies the control process by aligning motor phase switching with the rotor position, resulting in a quasi-square-wave current. However, this method introduces torque ripple and presents control challenges, particularly in low-speed applications. Given the rising economic constraints and stringent governmental standards, there is an increasing demand for efficient, low-interference, and adaptable electrical systems. This study demonstrates that FOC provides a more robust and efficient solution for high-performance applications than the trapezoidal control technique in PMSMs.

The paper presents simulation research on a variable structure control scheme of a small variable-speed fixed-pitch wind energy conversion system (WECS) with a three-phase permanent magnet synchronous generator (PMSG) in variable wind conditions. The WECS is connected to a power grid through two back-to-back voltage source converters (VSCs) with a DC link. The presented control algorithm is based on feedforward compensation of the wind turbine aerodynamic torque estimated using a linear disturbance observer (DOB). The torque estimate is employed to determine the effective wind speed, required for setting the reference angular speed, using numerical zero search of a nonlinear function. The simulation model, built in the Matlab/Simulink environment using the Simscape Electrical toolbox, includes the field-oriented control of the PMSG via the machine VSC, performed by cascaded angular velocity and current/torque PI controllers, as well as synchronization with the grid and the reactive power control via the grid VSC. The presented results are focused on the performance of the proposed control in the maximum power point tracking (MPPT) operating region of the WECS for various wind speed profiles.

This paper addresses the design and analysis of the control system for a Wind Energy Conversion System (WECS) with a Permanent Magnet Synchronous Generator (PMSG) and its application for isolated green hydrogen production. The designed control maximizes the wind turbine (WT) power generation by regulating the electrolyzer current consumption, where the electrolyzer operates as a controlled load, ensuring power balance in the system and enabling the generation of maximum power from the WECS without the use of any energy storage system. The system involves directly integrating a WECS with an alkaline electrolyzer (AEL), and its configuration includes a WT with a PMSG, an AC/DC voltage source converter (VSC) acting as the generator side converter (GSC), and a DC/DC converter acting as the electrolyzer side converter (ESC) with Maximum Power Point Tracking (MPPT) control for the WT. The proposed control system has been fully modeled and tested through simulations in Matlab/Simulink, demonstrating its reliable performance under variable wind speeds. Simulation results illustrate how, over rated wind speeds, the pitch control limits the rotational speed and power to their maximum values, and at under rated wind speeds, the ESC control regulates the AEL current following the MPPT of the WT, while the GSC control maintains the DC bus voltage at its designated nominal value. Overall, the proposed control system shows robust and effective performance across the entire range of possible operational points, ensuring no wind generation power losses by following the maximum power point.

A novel converter configuration is proposed in this paper for mega-watt wind energy conversion system (WECS) using permanent magnet synchronous generator (PMSG). The converter consists of a diode rectifier, a buck converter and a pulse-width-modulated (PWM) current source inverter (CSI). Two DC current requirements in the system are analyzed and compared: one from the generator and diode rectifier for maximum power point tracking (MPPT), and the other from the grid and PWM CSI to obtain desired grid power factor. The theoretical analysis concludes the necessity of a buck converter for achieving all the control objectives in the full wind turbine operating range. Moreover, control scheme is developed for MPPT and grid reactive power compensation. The DC current is controlled at the minimum required level for system loss reduction. Simulation results on a 2MW WECS demonstrate the desired performance of the proposed system over a wide range.

Today wind energy has emerged as an alternative energy source for power generation. This paper investigates about standalone Permanent Magnet Synchronous Generator (PMSG) based wind energy conversion system (WECS) with Maximum Power Point Tracking (MPPT). The proposed system comprises of Wind turbine (WT), PMSG, boost converter, uncontrolled diode rectifier, battery bank, bidirectional buck boost converter and dc load. Multi pole PMSG is best suited for low speed, wide range variable speed wind energy applications. Wind flow varies with time; as a result power produced also varies. As maximum power has to be tracked for varying wind speeds, perturbation & Observation (P&O) algorithm is implemented for MPPT. Battery storage system is essential to supply the load during low wind speed condition. In this paper, a simulation study of the proposed standalone system is done using SIMULINK in MATLAB.

Conventional wind energy conversion systems (WECS) typically employ rotor side synchronous frame current control strategies to regulate the active/reactive power supplied by the WECS generator. Such strategies require accurate information regarding the rotor position and speed in order to set the dq frame reference currents and to perform the necessary frame transformations. This information can be obtained using a rotor speed sensor (i.e. a shaft encoder) or via a sensor-less strategy in which a dynamic machine model and stator current measurements are used to estimate the true rotor position. This paper now presents an alternative approach to control the active/reactive power supplied by the WECS permanent magnet synchronous generator (PMSG). The proposed strategy uses the three phase converter modulation commands to identify the phase and frequency of the PMSG stator terminal voltages. This enables the direct regulation of the real and reactive power extracted at the PMSG terminal voltages using a stationary frame Proportional + Resonant (PR) stator current regulation strategy, without requiring precise knowledge of the rotor position. Maximum power point tracking (MPPT) functions are realized using the measured PMSG terminal voltage frequency to form an estimate of the rotor speed. The result is a simple robust WECS control strategy that rapidly and accurately tracks rotor speed changes caused by wind speed variations. Detailed simulation and experimental results obtained for a scaled laboratory prototype system are presented to validate the proposed strategy.

This paper proposes a novel application of a runner-root (RR) algorithm for maximum power point tracking (MPPT) of a wind energy conversion system (WECS) direct-driven by a permanent magnet synchronous generator (PMSG). The WECS is required to operate at the MPP under varying wind conditions. The RR algorithm is the meta-heuristic algorithm, inspired by the function of runners and roots of some plants in nature. The plants are propagated through runners. They look for water resources and minerals by developing runners and roots. The RR algorithm is proposed to define maximum power points (MPP) corresponding to the optimal output voltage of the DC/DC boost converter of the PMSG-based WECS. The numerical results show that the RR algorithm based MPPT approach efficiently defines and tracks the MPPs of the PMSG-based WECS. A comparison with the hill-climb search (HCS) and particle swarm optimization (PSO) algorithms demonstrates the superiority of the RR algorithm and confirms its potential in the MPPT strategy of the PMSG-based WECS.

This paper develops a framework of maximum power point tracking (MPPT) of doubly-fed induction generator (DFIG) based and permanent magnet synchronous generator (PMSG) based wind energy systems. The principles of MPPT in various wind generators are firstly investigated and feedback control schemes to realize MPPT with/without wind speed measurements are presented. Stability analysis of the wind energy conversion system with sensorless MPPT is investigated. Case studies of various wind energy system configurations are given to demonstrate the MPPT control schemes.