Fed Induction Generator Wind Farms Research Articles

An adaptive distance protection back‐up scheme for transmission lines connected to doubly fed induction generator wind farms based on setting groups procedure

AbstractGenerally, wind speed alters continuously during a day and leads to fluctuating output power of a wind farm (WF). Connecting such a WF to the transmission line of grid causes a malfunction in the performance of the backup zone of the distance relays due to the random nature of generation and the number of connected wind turbines (WF penetration). In this study, a new adaptive setting groups‐based method has been proposed to set the second zone of the distance relay in the grid with a WF equipped with a doubly fed induction generator. In this method, the authors have also taken into account the uncertainty of wind fluctuations and the availability of WT. A Markov model is developed to implement these features. To determine the impedance setting of each of the set groups of the second zone in the distance relays of the remote bus, the obtained impedances are clustered in four clusters by using the combination of K‐means and particle swarm optimization algorithms. Finally, the details of the analysis results of this issue have been compared with other methods available in the literature. The validity and accuracy of the proposed approach also have been assayed and confirmed.

Application and Comparison of a Modified Protection Scheme Utilizing a Proportional–Integral Controller with a Conventional Design to Enhance Doubly Fed Induction Generator Wind Farm Operations during a Balanced Voltage Dip

The doubly fed induction generator (DFIG) is vulnerable to grid faults due to its direct stator connection, causing issues like excess stator current during voltage dips. Consequently, sensitive inverters suffer from increased currents, and the DC-link capacitor undergoes overcharging. This document examines two protection strategies employing a proportional–integral (PI) controller to manage the transient rotor current and mitigate DC-link overcharging, thereby optimizing DFIG behavior during network faults. One option combines a classic crowbar circuit with a DC-chopper, while the other is a modified protection scheme (MPS) that includes an impedance with passive elements and a crowbar. The impedance forms a resistance Rp parallel with an inductance Lp. Both configurations, situated between the rotor coils and the rotor-side converter (RSC), augment the capacity for low-voltage ride-through (LVRT). MATLAB/SIMULINK simulations of the two schemes demonstrate successful rotor current reduction at 2.9 kA and 3.4 kA, and DC-link tension reduction below and at 1.4 KV. In addition, the conventional crowbar and MPS configurations efficiently restrict the RSC current to levels below 0.21 kA and 2.94 kA, while absorbing up to 2.52 kA and 1.52 kA, respectively. The key difference lies in the fact that fine-tuning the parameters in the MPS design prevents rotor disconnection when faced with a balanced fault. This enhancement enhances machine performance and enables full stator power control via the RSC.

Improving dynamic stability of wind integrated system by incorporating magnetic energy storage

AbstractThe need to incorporate renewable energy sources in the present grid due to energy demand and environmental issues has led the power industry to face new challenges and unexpected transformations. This new epitome to build a flexible power system with coordination of increasing intermittent renewable energy resources and delivering power efficiently with reliability demand new technologies. This work investigates the coupling of static synchronous compensator (STATCOM) with the most exclusive superconducting magnetic energy storage (SMES) device designed for the improved functioning of a grid network that is incorporated with a wind farm. The widespread integration of intermittent wind generators in the grid is disturbing its stability and reliability. The SMES is interlinked with the grid system via a power electronic interface and chopper for the energy exchange. This work suggests STATCOM as a power electronic interface and a three‐level chopper configuration with novel control scheme for enhancing the functioning of the test system. This integrated controller (STAT‐SMES) has been analyzed for grid‐connected doubly fed induction generator wind farm under different fault conditions and time durations. The results have been compared without any controller, with STATCOM only, and with the proposed STAT‐SMES controller using MATLAB. The simulation outcomes prove that coupled control scheme is effective and better in handling wind farm integration issues.

Surrogate-Assisted Cooperation Control of Network-Connected Doubly Fed Induction Generator Wind Farm With Maximized Reactive Power Capacity

This article aims to realize a cooperative active power control of doubly fed induction generator (DFIG)-based wind farm (WF) to maximize the total reactive power capacity while maintaining the active power supply-and-demand balance. Difficulties lie in that the accurate PQ-curve expressions of wind turbines therein are unknown and nonuniform, thereby putting an obstacle to distributed optimization. To address the problem, PQ-curve inaccuracy caused by expression simplification is analyzed through the bridge of rotor current frame, rotor overspeeding control prioritized operation is recommended, and a surrogate-assisted distributed optimization (SADO) scheme is proposed from the WF perspective. The proposed method iteratively uses measured operating data to prompt a surrogate model to fit the accurate model, and then the optimal control action is guaranteed by online exploitation-and-exploration process with demonstrated availability through convergence analysis. Further, coordination with offline pretraining ensures that convergence can be obtained within shortened iteration steps. Case studies on 150-MW DFIG WF demonstrate the effectiveness of the proposed SADO scheme regarding shortening the iteration number, a full extraction on reactive power capacity and the better performance for voltage support.

Voltage and Reactive Power Control in DFIG Wind Farm Load bus by FACT Device – UPFC

This paper deals with the analysis and simulation of the Unified Power Flow Controller (UPFC) for Grid connected DFIG wind farm system mitigation. The purpose of the paper is to derive and analyze a reactive power control strategy of UPFC dedicated for DFIG mitigation. The FACT device Unified Power Flow Controller (UPFC) is connected with load bus. Paper has demonstrated the improvement in voltages, power transferred to grid, active and reactive power control. Matlab/simulink is used for the work. Paper demonstrated the simulation results for with and without UPFC for Grid connected Doubly Fed Induction Generator wind farm system.

Multi-agent energy management and fault tolerant control of the micro-grid powered with doubly fed induction generator wind farm

Multi-agent energy management and fault tolerant control of the micro-grid powered with doubly fed induction generator wind farm

Comprehensive investigation on doubly fed induction generator-Wind farms at fault ride through capabilities: technical difficulties and improvisations

ABSTRACT Renewable wind energy is the fastest-growing energy in the forthcoming green energy era and its generation capabilities has been increasing day by day. Large-penetration of Doubly Fed Induction Generator-Wind Turbine (DFIG-WT) creates severe transient stability issues in the power system. Fault Ride Through (FRT) capabilities are the major concerns in wind generation system in faulty conditions. The purpose of maintaining the FRT capability is that the DFIG-WT system should remain connected to the grid during fault conditions. Therefore, external retrofit solutions, internal control modification schemes, and a few advanced controller approaches are reported to enhance the FRT capabilities. However, improvement of the system transient stability along with LVRT enhancement is a challenging task, in the presence of low inertia contributed by power electronic devices tied wind energy conversion system. So, FRT enchantment with desired inertia is a new field of research interest. Therefore, this survey discusses the most admired external hardware approach and internal modification or advanced controller approaches, which are used to enhance the FRT capabilities in DFIG-WT and also emphasizes the transient stability enhancement aspects.

Robust finite-time controller for damping of subsynchronous resonance in doubly fed induction generator wind farm

To alleviate subsynchronous resonance in doubly fed induction generator–based wind farm, this study devises a robust nonlinear control for a rotor-side converter based on a fractional-order sliding mode controller. The designed fractional-order sliding mode controller is able to realize finite-time control and reduce the control time compared with terminal sliding mode control, which contributes to the faster mitigation of subsynchronous resonance. Impedance-based analysis and transient simulation are carried out to evaluate the performance of the fractional-order sliding mode controller compared with terminal sliding mode control and subsynchronous damping control. Simulation results verify that the fractional-order sliding mode controller is able to damp SSR within shorter time and effectively reduce the fluctuation range of a system’s transient responses under various working conditions of compensation degrees and wind speeds. Furthermore, the fractional-order sliding mode controller enhances the robustness under external disturbance and parametric uncertainty, ensuring safe operation of the practical wind farm.

A Study of Dynamic Equivalence Using the Similarity Degree of the Equivalent Power Angle in Doubly Fed Induction Generator Wind Farms

This paper presents a study of dynamic equivalence for doubly fed wind farms (DFWFs) in large power systems. The core idea is to find an attribute representing the critical characteristics of a doubly fed induction generator (DFIG) and use it for clustering in the equivalent modeling process. Using the voltage and flux linkage equations of DFIGs, we derived an electromagnetic power expression. Similar to the power angle concept for synchronous generators, an equivalent power angle (EPA) is proposed and shown to represent the dynamic characteristics of a DFIG in the test system. We introduce the similarity degree of the EPA based on similarity theory and construct a similarity index of the EPA for clustering a DFWF. A practical algorithm was developed for parameter aggregation of the equivalent model. In addition, a simulation of DFWFs in Yunnan, China, was conducted to show the feasibility and high precision of the proposed method.

Robustness and adaptability analysis for equivalent model of doubly fed induction generator wind farm using measured data

As many large wind farms connected to the power grid, it is necessary to develop a robust and adaptable dynamic equivalent model of the wind farm for system analysis and control. In this paper, the trajectory sensitivity of time-varying parameters of the equivalent model is analyzed. Then the non-time- varying parameters of the equivalent model are fixed as aggregated values, while the time-varying parameters are identified using the genetic learning particle swarm optimization based on phasor measurement unit data at the point of interconnection. The robustness and adaptability of the equivalent model under different scenarios are analyzed. The simulation results using the Western Electricity Coordinating Council benchmark test system show that the global searching capability to find the optimal point of the proposed method is higher than canonical particle swarm optimization and genetic algorithm by 2 orders. Further, the biggest mismatch between the identification results of the proposed method and the true values is within 10% for parameters with high sensitivity which is much better than previous work.

Optimal Performance of Doubly Fed Induction Generator Wind Farm Using Multi-Objective Genetic Algorithm

The main purpose of this paper is allowing doubly fed induction generator wind farms (DFIG), which are connected to power system, to effectively participate in feeding electrical loads. The oscillation in power system is one of the challenges of the interconnection of wind farms to the grid. The model of DFIG contains several gains which need to be achieved with optimal values. This aim can be accomplished using an optimization algorithm in order to obtain the best performance. The multi-objective optimization algorithm is used to determine the optimal control system gains under several objectives. In this paper, a multi-objective genetic algorithm is applied to the DFIG model to determine the optimal values of the gains of DFIG control system. In order to point out the contribution of this work; the performance of optimized DFIG model is compared with the non-optimized model of DFIG. The results show that the optimized model of DFIG has better performance over the non-optimized DFIG model.

Robust active disturbance rejection controller design to improve low‐voltage ride‐through capability of doubly fed induction generator wind farms

This study presents the design of a robust active disturbance rejection (ADR) controller in order to improve low-voltage ride-through (LVRT) capability of wind farms connected with doubly fed induction generator (DFIG). The ADR controller is particularly effective in real-time estimation and mitigation of the total effect of various uncertainties against a wide range of parameter variations, model uncertainties and large disturbances. The performance evaluation of the designed controller is performed on an IEEE system under different test cases. The simulation results show that the proposed controller is robust against uncertainties in operating conditions and successfully improves the damping and voltage stability and thus the LVRT capability of DFIGs.

Transient stability of power system integrated with doubly fed induction generator wind farms

A new quantitative assessment of transient stability for power systems integrated with doubly fed induction generator (DFIG) wind farms is proposed by evaluating the transient energy margin (TEM) through the formulation of the transient energy function (TEF) for multimachine systems. To achieve an accurate TEM, the TEF is modified to account for the separation of the critical machines from the system and an unstable equilibrium point is calculated on the basis of post-fault trajectory reaching the potential energy boundary surface. Simulation results show that such power systems integrated with DFIG wind farms are more sensitive to transient events of higher voltage sag, longer fault clearing time, lower load operation and higher wind power penetration level. It is also observed that machines located far from the fault are also exposed to inferior transient stability because of fault with geographical dispersion of wind farms. As a result, advanced switchgear, faster isolators, more efficient power reserve systems and advanced reactive power compensating devices must be equipped to ensure reliable operation of power systems integrated with the DFIG wind farms during transient events.

Improvement of Stable Operation Ability for Large-Scale Wind Power System Based on VSC-HVDC Technology

Rigorous transmission technology is important when large-scale wind farm is connected to the power grid. Hence, a power transmission topological framework based on VSC-HVDC is proposed. The mathematical model is built in the dq synchronous frame, and the related direct current control strategy of VSC converters are designed. The doubly fed induction generator wind farm with VSC-HVDC system are modelled in DIgSILENT/PowerFactory. Ultimately, the conditions of the short-circuit fault at the receiving-end VSC AC bus is simulated. The control scheme is proved to be effective.

Voltage sag ride through using Improved Adaptive Internal Model Controller for doubly fed induction generator wind farms

This paper presents the effect of a single pulse dither signal injection in adaptive internal model controller for a doubly fed induction generator (DFIG)-based wind farm. Rotor current controller using adaptive internal model controller is designed with different Adjustment Mechanisms like Lyapunov theory, fuzzy and ANFIS to improve the voltage sag ride through. During voltage sag period the dither signal is injected in the controller to improve the performance of the controller. Simulation results are presented to demonstrate the proposed control strategy during variations in fixed and variable gain Adjustment Mechanism.

Direct model reference adaptive internal model controller for better voltage sag ride through in doubly fed induction generator wind farms

This paper presents the function of a direct model reference adaptive internal model controller (DMRAIMC) with variable gain adjustment mechanism for a doubly fed induction generator (DFIG) in a wind farm. Rotor current is controlled using the above controller with variable gain adjustment mechanism achieved using fuzzy sets and ANFIS to improve the voltage sag ride. Performance of the variable gain and linearly variable gain adjustment mechanisms are compared and their improvements are explored. Simulation results are used to demonstrate the effectiveness and robustness of the proposed control strategy, during variations in the variable gain adjustment mechanism.

Novel Coordinated Converter Control (3C) Strategy for Enhancement of Fault Ride-through Capability of Doubly Fed Induction Generator Wind Farms

A novel coordinated converter control strategy is proposed in this article for enhancement of the fault ride-through capability of doubly fed induction generator based wind farms. The proposed coordinated converter control strategy is activated only during the instance of fault clearance in order to achieve rapid restoration of terminal voltage and thereby enhance the post-fault performance capability of wind generators connected to the distribution network. An extensive simulation study is carried out employing PSCAD/EMTDC software (Manitoba, Canada). The simulation results demonstrate the laudable performance of the doubly fed induction generator achieved by employing the coordinated converter control strategy.

Modeling, Analysis, and Control for the Rectifier of Hybrid HVdc Systems for DFIG-Based Wind Farms

In order to improve the dynamic performance of the hybrid HVdc system for doubly fed induction generator wind farms, this paper presents the modeling, analysis, and control methods for its line-commutated rectifier. First, the state variable model of the rectifier subsystem on the reference frame is derived considering different control modes of the current source inverter subsystem. Then, the ac current dynamic of the rectifier subsystem is quantitatively analyzed based on the eigenvalue analysis method. According to the analysis results, a double loop control scheme is designed: the inner loop utilizes the inverse system control technique plus a switchable phase-lead compensator, and the outer loop implements an ordinary propotional-integral controller. Finally, the validity of the quantitative analysis method and the superiority of the proposed control scheme are verified by Simulink/SimPowerSystems simulations.