Wind Turbine Generator System Research Articles

Optimal Allocation of Inverter-Based WTGS Complying With Their DSTATCOM Functionality and PEV Requirements

Recently, the integration of inverter-based wind turbine generation systems (WTGS) and plug-in electric vehicles (PEV) has remarkably been expanded into distribution systems throughout the world. These distributed resources could have various technical benefits to the grid. However, they are also associated with potential operation problems due to their stochastic nature, such as high power losses and voltage deviations. An optimization-based approach is introduced in this paper to properly allocate multiple WTGS in distribution systems in the presence of PEVs. The proposed approach considers 1) uncertainty models of WTGS, PEV, and loads, 2) DSTATCOM functionality of WTGS, and 3) various system constraints. Besides, the realistic operational requirements of PEVs are addressed, including initial and preset conditions of their state of charge (SOC), arriving and departing times, and various controlled/uncontrolled charging schemes. The WTGS planning paradigm is established as a bi-level optimization problem which guarantees the optimal integration of multiple WTGS, besides optimized PEV charging in a simultaneous manner. For this purpose, a bi-level metaheuristic algorithm is developed for solving the planning model. Intensive simulations and comparisons with various approaches on the 69-bus distribution system interconnected with four PEV charging stations are deeply presented considering annual datasets. The results reveal the effectiveness of the proposed approach.

Modified Deloading Strategy of Wind Turbine Generators for Primary Frequency Regulation in Micro-Grid

In this work, the contribution of wind turbine generator (WTG) to support micro-grid (MG) during depressed frequency condition has been studied with a modified strategy for improving the primary load frequency response of MG. The majority of existing deloading techniques to estimate the reference power are based on the linear relationship. Hence they are not so accurate to mimic the actual speed versus power dynamics of turbine rotor during deloading operation which is inherently nonlinear in nature. In this work, the existing methods have been analyzed in detail with an aim to improve the performance. Based on the analysis a modified deloading method assuming non-linear relation between rotor speed and power of WTG system has been proposed which shows the improved load frequency response in MG. The proposed deloading technique is simulated and validated using real-time digital simulator (OP4510) for the variation in load and generation inside an islanded MG. The results obtained using modified deloading method are compared with existing deloading method and it is found that proposed deloading method handles the non-linearity of the system during deloading operation and also it contributes more power to MG in response to load demand at the cost of slight increase in the speed of turbine rotor.

Recurrent Neural Network Based MPPT Control of Grid Connected DFIG for Wind Turbine

This paper presents a new maximum-power-point-tracking (MPPT) controller in wind power generation using artificial neural networks (ANN) in order for making the wind turbine function in optimum working point and get high efficiency of wind energy conversion at different conditions. The algorithm uses fully connected recurrent neural network and is trained online using real-time recurrent learning (RTRL) algorithm in order to avoid the oscillation problem in wind-turbine generation systems. It generates control command for speed of the rotor side converter using optimal algorithm to enable the control system in order to track the maximum power point. The rotor speed and wind-turbine torque are the inputs of the networks, and the command signal for the rotor speed of wind turbine is the output. Simulation results verify the performance of the proposed algorithm.

Design of Load Frequency Control for a Microgrid Using D-partition Method

AbstractThis paper proposes a load frequency control (LFC) scheme for the distributed generation (DG) system of the microgrid (μ-grid) using the D-partition method (DPM). μ-grid is formed with a combination of renewable and non-renewable sources to supply distribution system loads of smaller capacity. In this research paper, μ-grid comprising of a combination of a wind turbine generator (WTG) and Diesel Generator (DG) are taken for investigation of LFC. For the effective control of real power generation of μ-grid, Proportional-integral (PI) controllers are implemented for WTG and DG system so that the frequency deviation is minimized. The PI controller parameters found by using DPM are compared with the conventional Ziegler-Nichols method (ZNM). The main contribution of this work is to provide a single step /simplistic computing method for calculating the PI controller parameters of a dynamic system such as the microgrid system comprising of the renewable energy sources without any further requirements of retuning. Simulation results demonstrate the robustness of the DPM, which is superior in damping frequency oscillations of μ-grid.

Controlling of Wind Turbine Generator System based on Genetic Fuzzy-PID Controller

Controlling of Wind Turbine Generator System based on Genetic Fuzzy-PID Controller

Modeling and Control Design of an Autonomous Hybrid Wind/Energy Storage Generation Unit

The purpose of the present paper is to investigate a controller design and simulations of autonomous hybrid wind turbine system with variable-speed permanent magnet synchronous generator (PMSG) and a system for storing energy. The proposed system is mainly composed of a wind turbine drives permanent magnet synchronous generator, uncontrolled rectifier, DC/DC converter, DC/AC inverter and static loads. Furthermore, the mathematical model of the studied sub-systems and two control loops are considered. The first one is the controller which needed to preserve the DC-link voltage fixed at its desired value. The second one is the controller which needed to regulate the charge/discharge modes of the storage battery. The suggested hybrid wind/energy storage power generation model is considered and analyzed in case of without controller firstly. Then, the considered hybrid wind/energy storage power generation unit with the proposed controller is examined through a step change in wind speed. Digital simulation results show that the power desired by the linked loads may be successfully supplied and transported by the presented hybrid wind turbine and energy storage power generation system based on proportional-integral-derivative (PID) controller. Also, the emulation results show that there a good foretelling of the electrical variable waveforms and good achievement in case of the presented controller emulated with the case of without controller as maintaining the load voltage fixed at its reference values

공급신뢰도 측면에서의 신재생에너지발전단지와 연계된 BESS의 운용 알고리즘 개발

This paper proposes a probabilistic reliability evaluation model and algorithm for the power system considering wind turbine generator (WTG) and battery energy storage system (BESS) in viewpoint of power system reliability. A large-scale wind turbine generator (WTG) can creates significant power fluctuations and should affect the stability, frequency control and then reliability of the power system. Therefore, wind power should be limited to supply the percentage of load. The output of WTG cannot be predicted accurately and so results in significant fluctuations in power supply balance. Therefore, it is difficult to control the power balance between supply and demand. However, it can be controlled by installing the BESS. The BESS may smooth the fluctuation of the WTG power output. This paper proposes reliability based alternative algorithm in order to simulate the effects of the interaction of multiple WTG and BESS newly. Additionally, this paper presents sample system studies that single BESS as well as multi-BESS are simulated by handwork very clearly. Futhermore, the reliability effects of BESS according to a couple of different BESS operation rules and conditions are demonstrated in sample system case study.

Simulation on power-flow dispatching cases for Microgrid with PVS and battery energy storage system

Modern Microgrid (MG) mainly consists of distributed generators (DGs), energy storage systems (ESSs), different loads, and protection systems. Microgrid plays an important role not only to ensure the power supply reliability but also to improve the power quality in distribution network. Moreover, deployment of distributed generators such as Photovoltaic Generation System (PVS), wind turbine generation system, and energy storage systems diversifies operation and control modes of AC microgrid in order to meet local demand response. This paper studies on power-flow dispatching cases for a MG with PVS and Battery Energy Storage System (BESS), which considers the maximum power consumption generated by the PVS and minimizes the power received from the utility grid. Simulation results validate the effectiveness of BESS for actively dispatching power-flow of MG in case the PVSs cannot partially or fully meet the local demand response in peak hours. By using ETAP software, real data of the PVSs are used to do simulation and power-flow calculation for the MG, which is to evaluate the feasibility of power-flow dispatch solutions proposed in this paper.

Fault Diagnosis Strategy for Wind Turbine Generator Based on the Gaussian Process Metamodel

To facilitate continuous development of the wind power industry, maintaining technological innovation and reducing cost per kilowatt hour of the electricity generated by the wind turbine generator system (WTGS) are effective measures to facilitate the industrial development. Therefore, the improvement of the system availability for wind farms becomes an important issue which can significantly reduce the operational cost. To improve the system availability, it is necessary to diagnose the system fault for the wind turbine generator so as to find the key factors that influence the system performance and further reduce the maintenance cost. In this paper, a wind farm with 200 MW installed capacity in eastern coastal plain in China is chosen as the research object. A prediction model of wind farm’s faults is constructed based on the Gaussian process metamodel. By comparing with actual observation results, the constructed model is proved able to predict failure events of the wind turbine generator accurately. The developed model is further used to analyze the key factors that influence the system failure. These are conducive to increase the running and maintenance efficiency in wind farms, shorten downtime caused by failure, and increase earnings of wind farms.

An Analysis of a Wind Turbine-Generator System in the Presence of Stochasticity and Fokker-Planck Equations

In power systems dynamics and control literature, theoretical and practical aspects of the wind turbine-generator system have received considerable attentions. The evolution equation of the induction machine encompasses a system of three first-order differential equations coupled with two algebraic equations. After accounting for stochasticity in the wind speed, the wind turbine-generator system becomes a stochastic system. That is described by the standard and formal Itô stochastic differential equation. Note that the Itô process is a strong Markov process. The Itô stochasticity of the wind speed is attributed to the Markov modeling of atmospheric turbulence. The article utilizes the Fokker-Planck method, a mathematical stochastic method, to analyse the noise-influenced wind turbine-generator system by doing the following: (i) the authors develop the Fokker-Planck model for the stochastic power system problem considered here; (ii) the Fokker-Planck operator coupled with the Kolmogorov backward operator are exploited to accomplish the noise analysis from the estimation-theoretic viewpoint.

Electro-mechanical Modeling of Wind Turbine and Energy Storage Systems with Enhanced Inertial Response

In this paper, a coordinated control scheme for wind turbine generator (WTG) and supercapacitor energy storage system (ESS) is proposed for temporary frequency supports. Inertial control is designed by using generator torque limit considering the security of WTG system, while ESS releases its energy to compensate the sudden active power deficit during the recovery process of turbine rotor. WTG is modeled using the fatigue, aerodynamic, structure, turbulence (FAST) code, which identifies the mechanical loadings of the turbine and addresses electro-mechanical interactions in the wind energy system. A damping controller is augmented to the inertial control to suppress severe mechanical oscillations in the shaft and tower of the turbine during frequency supports. Furthermore, the result of small-signal stability analysis shows that the WTG-ESS tends to improve the stability of the whole multi-energy power grid. The major contributions of this paper will be validated by utilizing the proposed control method that combines the grid support capability and maintaining the integrity of structural design of the turbine for normal operations.

Model Predictive Control of Floating Offshore Wind Turbine-Generator Systems Based on Preview of Wind Speed and Wave Height

Model Predictive Control of Floating Offshore Wind Turbine-Generator Systems Based on Preview of Wind Speed and Wave Height

Model predictive control of floating offshore wind turbine-generator systems based on preview of wind speed and wave height (Introduction of internal model to predict mechanical loads)

Model predictive control of floating offshore wind turbine-generator systems based on preview of wind speed and wave height (Introduction of internal model to predict mechanical loads)

A novel optimum tip speed ratio control of low speed wind turbine generator based on type-2 fuzzy system

Variable speed control of wind turbine generator systems have been developed to get maximum output power at every wind speed variation, also called Maximum Power Points Tracking (MPPT). Generally, MPPT control system consists of MPPT algorithm to track the controller reference and generator speed controller. In this paper, MPPT control system is proposed for low speed wind turbine generator systems (WTGs) with MPPT algorithms based on optimum tip speed ratio (TSR) and generator speed controller based on field oriented control using type-2 fuzzy system (T2FS). The WTGs are designed using horizontal axis wind turbines to drive permanent magnet synchronous generators (PMSG). The simulation show that the MPPT system based optimum TSR has been able to control the generator output power around the maximum point at all wind speeds.

Coordinated Frequency Stabilization of Wind Turbine Generators and Energy Storage in Microgrids with High Wind Power Penetration

This paper proposes a coordinated control scheme for wind turbine generators (WTGs) and energy storage in microgrids with high wind power penetration. The proposed scheme aimed to reduce the system frequency deviation caused by variations in wind power and loads. To stabilize the frequency, the WTG and energy storage system (ESS) are used for kinetic energy generation and electrical energy storage, respectively. When the WTG contributes excessively to frequency stabilization in the microgrid with a high wind power penetration, the system frequency may fluctuate considerably. Thus, it is necessary to adjust the contribution of a WTG and to share it with other sources. To achieve our objective, we proposed a coordinated control scheme between the WTG and ESS that shares their releasable and absorbable energies. The coordinated control consistently calculated the releasable and absorbable energies of the WTG and ESS and determined weight factors related to the energy ratios. Accordingly, the weight factors improved the ability of providing supporting frequency stabilization of the WTG and ESS by increasing the stored energy utilization. The performance of the scheme was investigated using MATLAB Simulink Electrical. The results show that the proposed coordinated control successfully stabilized the system frequency by calculating the appropriate contributions required from the WTG and ESS.

Stability Assessment of Renewable Energy Integrated Power System

This paper investigates the small-signal stability of grid integrated Doubly Fed Induction Generator (DFIG) based Wind Turbine Generator (WTG) and Photovoltaic (PV) system. The short-circuit study is conducted for the New England 39-bus system using DIgSILENT PowerFactory software. The short-circuit study and dynamic simulation are performed for the study system with distributed generators. Furthermore, the eigenvalues are computed for the various damping level of synchronous generators. The influence of negative damping of synchronous machine with PV generator, DFIG based WTG in the study system is investigated. The eigenvalue analysis results shows that due to negative damping of synchronous generator the system become unstable even with PV generator and DFIG based WTG in the system. The time domain simulation results show that real power generation of the synchronous generator is decreased due to negative damping and its reactive power generation is increased.

Modeling and Investigation of Self-Excited Reluctance Generators for Wind Applications

In the last few years, wind energy conversion systems have been increasingly installed worldwide. The self-excited reluctance generators (SERGs) are found to be potential candidates as isolated wind turbine generators, especially for low- and medium-power applications. This article focuses on the characteristics of SERG for wind turbine generation system. A simplified dynamic model of the generation system is developed, discretized by backward Euler formula, and simulated. With this model, the process of self-excitation and operation characteristic of SERG are investigated. Considering the varying generated voltage at different speeds, variable capacitances allow suitable regulation of the voltage. The variation of capacitance with speed is obtained by the active and reactive power (PQ) balances method. Combining the power speed characteristics of wind turbine and SERG, the PQ balances method is also used to determine the “optimal capacitor and resistor combination” that achieves the highest usage of wind power. This article exhibits the performance of SERG for wind applications, and most importantly, makes the prediction of the highest energy conversion efficiency of the system.

Hybrid methodology to analyse reliability and techno‐economic evaluation of microgrid configurations

Concerns related to environmental pollution, growing population, fossil fuel depletion, ever-increasing load demands etc. lead power utilities to rely on renewable energy resources (RERs). The objective of the research is to evaluate the reliability of the microgrid by focussing on the economic and environmental benefits of RERs. Reliability assessment of power network plays an important role to achieve high demands of reliable power supply globally. Reliability assessment helps power utilities in reducing the frequency and the duration of power outages to their customers. In this work, the impact of a stochastic characteristic of photovoltaic system, wind turbine generator system, and battery storage on the overall reliability of the power system are analysed in both the scenarios, i.e. grid-connected and isolated mode of operation of the microgrid. Various configurations of microgrid based on redundancy levels are considered for reliability evaluation, including common cause outages and miscoordination of protection devices. The effect of addition and removal of different distributed generation units on the overall reliability of the system is analysed using Markov approach. Also, techno-economic analysis of different reliable configurations is performed to finalise the best possible reliable and economic configuration of the microgrid.

Symbiotic organisms search algorithm‐based optimal control strategy for efficient operation of variable‐speed wind generators

The penetration rate of grid-tied wind turbine generator systems (WTGSs) into the existing electricity networks is rapidly increasing worldwide. Huge efforts are exerted for improving the characteristics of variable-speed wind energy conversion systems. This study exhibits a novel symbiotic organisms search algorithm (SOSA)-based optimal control strategy for achieving efficient operation of a grid-connected WTGS. The optimal control strategy relies on proportional–integral (PI) controllers, which are properly fine-tuned using the SOSA. The simulation-based optimisation method is considered in the optimisation process, where the integration of the square error criterion is selected as a fitness function. To obtain realistic performances, practical wind speed data extracted from the Zaafarana power plant in Egypt are used in the analyses. The efficacy of the SOSA-based optimal PI control strategy is compared with that realized using the grey wolf optimiser algorithm (GWOA)-based PI control scheme, considering network disturbances. The feasibility of the proposed control strategy is validated using the simulation studies, which are implemented using MATLAB/Simulink software. Notably, the proposed SOSA-based optimal control strategy is considered to be a precise means of improving the behaviour of grid-tied WTGSs.

Fault-Tolerant Control of Doubly-Fed Wind Turbine Generation Systems under Sensor Fault Conditions

This paper studies the fault-tolerant control problem of uncertain doubly-fed wind turbine generation systems with sensor faults. Considering the uncertainty of the system, a fault-tolerant control strategy based on a T-S fuzzy observer is proposed. The fuzzy observer is established based on the T-S fuzzy model of the uncertain nonlinear system. According to the comparison and analysis of residual between the state estimation of the fuzzy observer output and the measured value of the real sensor, a fault detection and isolation (FDI) based on T-S fuzzy observer is designed. Then by using a Parallel Distributed Compensation (PDC) method we design the robust fuzzy controller. Finally, the necessary and sufficient conditions for the stability of the closed-loop system are proved by quoting Lyapunov stability theory. The simulation results verify the effectiveness of the proposed control method.