Grid Connected Wind Power System Research Articles

Coordinated Control of Wind turbine and Energy storage system for Microgrid Stability

In recent decades, the development of renewable energy has accelerated significantly due to several factors such as changing energy needs, the problem of global warming, and the depletion of fossil fuels. Wind energy is one of the renewable generation sources that can be used to achieve the EU's 2030 targets at a lower cost. However, its intermittent and stochastic nature could significantly impact the reliability and stability of the electricity system. Therefore, there is a clear necessity to mitigate power fluctuations to make the most of wind energy. To fill this gap, this paper presents a centralized control strategy based on a droop controller and a storage-integrated controller for a grid-connected variable speed wind power system (permanent magnet synchronous generator) (PMSG) to manage and stabilize the power output during intermittency periods. The main objective is to provide a stable U/f when a fluctuation event occurs. A grid failure scenario was tested to see how the control system behaves in the event of an unexpected fluctuation and its role in the stability of the power system under varying wind speed and load conditions. The effectiveness of the proposed control method was tested using MATLAB/Simulink on a small power system. The simulation results demonstrate the control system’s performance in the stability of the U/f during grid interruption.

Quantitative Analysis of the Interactive Influence for Harmonic Emission in Wind Farms

In the process of integrating large-scale wind farms into the power system, the harmonic interaction among wind farms causes potential safe and stable operation threats to the power grid. To effectively control the harmonics of the wind power grid-connected system, quantitative analysis of the harmonic interaction is very necessary and meaningful. Therefore, this paper firstly explains the harmonic interaction among wind farms from the perspective of the primary and secondary emission. We use the concept of harmonic impedance to analyze the mechanism of harmonic interaction and proposed a calculation method for quantitative analysis of the harmonic interaction. Using the calculation method, the influence caused by the wind farm self-impedance, the contact impedance, and Static Var Generator to the harmonic interaction are quantitatively analyzed. Finally, taking multiple wind farms in actual operation as a case, the effectiveness of the method is verified by time domain simulation.

DC Bus Voltage Control of Wind Power Inverter Based on First-Order LADRC

The wind power grid-connected inverter system has the characteristics of non-linearity, strong coupling, and susceptibility to grid voltage fluctuations and non-linear loads. To obtain the ideal control effect, the improved linear active disturbance rejection controller (LADRC) controls the voltage outer loop. Firstly, the mathematical model of the wind power grid-connected inverter is analyzed, on this basis, a linear active disturbance rejection control based on the reduced-order linear extended state observer is designed, reduce the phase lag of the observer, improve the system’s disturbance observation accuracy; reference lead correction lag correction method, the observer gain is improved and connected in series to the total disturbance channel to reduce the noise amplification effect of the observer; through frequency domain response characteristic analysis, the results show that the improved LADRC has better disturbance rejection performance. The simulation results of various working conditions show that the improved method has better rapidity and immunity compared with traditional LADRC.

Analysis of Energy Management Controller in Grid-Connected PV Wind Power System Coupled with Battery Using Whale Optimisation Algorithm

Analysis of Energy Management Controller in Grid-Connected PV Wind Power System Coupled with Battery Using Whale Optimisation Algorithm

Storage size determination for grid-connected wind power system based on power spectral density analysis

Energy storage system (ESS) is essential for wind power integration, and it has become more and more important to optimize the wind-energy storage system (WESS) for keeping power grid safe and stable. In this paper, a novel energy storage sizing approach which can improve the performance of WESS is put forward. Firstly, the hinges model is introduced into the power spectral density (PSD) analysis to obtain the low-pass decomposition frequency (LPDF), which is then used for energy storage sizing optimization based on the single-day energy balance. Secondly, a comprehensive evaluation criteria system based on cloud model is proposed to assess various characteristics of WESS. Thirdly, a case study based on a 30 MW wind farm indicates that the power curve of the proposed method meets the conditions for wind power integration, and the size and stability of ESS are optimized. Compared with the traditional filtering algorithms, the WESS performance of the proposed algorithm is improved by 77.55% than wavelet packet decomposition (WPD) and 65.84% than empirical mode decomposition (EMD), and its applicability in different time spans is also verified.

Research on improving transient voltage stability of wind power grid connected system by SFCL and STATCOM

Aiming at the problem of transient voltage instability in the grid-connected wind power system, a combined method of superconducting fault current limiter (SFCL) and static synchronous compensator (STATCOM) was proposed to suppress voltage saps. In this method, a superconducting fault current limiter (SFCL) is connected in series on the transmission line, and a static synchronous compensator (STATCOM) is connected in parallel on the bus of the wind farm. SFCL shows zero impedance when the system is in normal operation, and quickly shows high impedance when the fault occurs, so as to effectively suppress the short-circuit current and provide the bus voltage support. At the same time, STATCOM provides reactive power during the fault period, so that the system voltage can quickly recover. By establishing the corresponding simulation model, SFCL and STATCOM are used to jointly improve the voltage stability of the wind power grid-connected.

10 kW Optimization of grid-connected wind power system and its application in Xiamen

Coastal areas not only have large annual average wind speed, but also have more days of strong winds in a year. Xiamen >8 gale days, 22.4 days a year, so it is very suitable for wind power generation. This design is 10 kW wind grid-connected power generation system, each branch is composed of permanent magnet synchronous motor, rectifier, boost module, inverter and filter, 20 groups are used in parallel to form 10 kW system. Choose a single permanent magnet synchronous wind turbine power of 500 W, need 20. System DC voltage :12 V, when the power is fixed, the proper lifting of DC voltage is helpful to reduce the current, thus preventing the IGBT from causing device damage due to overcurrent. A two-dimensional fuzzy controller is used to select the outer loop error and error differential signal as input variables. In order to verify the correctness of fuzzy adaptive PI control strategy, a system simulation model is built.

Life cycle assessment of wind farms in Ethiopia

The overall aim of this study is to contribute to the creation of LCA database on electricity generation systems in Ethiopia. This study specifically estimates the environmental impacts associated with wind power systems supplying high voltage electricity to the national grid. The study has regional significance as the Ethiopian electric system is already supplying electricity to Sudan and Djibouti and envisioned to supply to other countries in the region. Three different grid-connected wind power systems consisting of four different models of wind turbines with power rates between 1 and 1.67 MW were analyzed for the situation in Ethiopia. The assessment takes into account all the life cycle stages of the total system, cradle to grave, considering all the processes related to the wind farms: raw material acquisition, manufacturing of main components, transporting to the wind farm, construction, operation and maintenance, and the final dismantling and waste treatment. The study has been developed in line with the main principles of the ISO 14040 and ISO 14044 standard procedures. The analysis is done using SimaPro software 8.0.3.14 multi-user, Ecoinvent database version 3.01, and ReCiPe 2008 impact assessment method. The assumed operational lifetime as a baseline is 20 years. The average midpoint environmental impact of Ethiopian wind power system per kWh electricity generated is for climate change: 33.6 g CO2 eq., fossil depletion: 8 g oil eq., freshwater ecotoxicity: 0.023 g 1,4-DCB eq., freshwater eutrophication: 0.005 g N eq., human toxicity: 9.9 g 1,4-DCB eq., metal depletion: 18.7 g Fe eq., marine ecotoxicity: 0.098 g 1,4-DCB eq., particulate matter formation: 0.097 g PM10 eq., photochemical oxidant formation: 0.144 g NMVOC, and terrestrial acidification: 0.21 g SO2 eq. The pre-operation phase that includes the upstream life cycle stage is the largest contributor to all the environmental impacts, with shares ranging between 82 and 96%. The values of cumulative energy demand (CED) and energy return on investment (EROI) for the wind power system are 0.393 MJ and 9.2, respectively. The pre-operation phase is the largest contributor to all the environmental impact categories. The sensitivity and scenario analyses indicate that changes in wind turbine lifespans, capacity factors, exchange rates for parts, transport routes, and treatment activities would result in significant changes in the LCA results.

RETRACTED: Control strategy and security of small and medium-sized wind power grid-connected inverter

Smart city has become an important direction of urban development. Focusing on the construction of smart city, it can reflect the ideal practical effect in many aspects, effectively improve the level of urban development and operation, and also show better in urban planning. Strong influence requires urban planning for adaptive adjustment. This paper from the core of a small wind power system is the grid-connected inverter. According to the main topology of small wind power generation inverter and grid-connected system, a systematic modeling of small wind power generation system is built. In order to make up for the deficiency of the traditional control strategy for small wind power grid-connected inverter, this paper puts forward a fuzzy control and quasi-PR control method to be applied to the synchronization control of grid-connected inverter. The simulation experiment is conducted by using MATLAB/SIMULINK platform, and the test is conducted by means of combining self-designed system hardware circuit, and the results show that compared with the PR method, the grid current synchronization error can be reduced to smaller, adaptability, and anti-disturbance can be greatly improved through the proposed method and, consequently, has a better application value for small wind power grid-connected inverter.

Dual Closed-Loop Linear Active Disturbance Rejection Control of Grid-Side Converter of Permanent Magnet Direct-Drive Wind Turbine

In the permanent magnet direct-drive wind power grid-connected system, in order to solve the coupling problem between d -axis and q -axis currents and to improve the disturbance rejection performance of direct current (DC) bus voltage under grid faults, a new dual closed-loop structure based on linear active disturbance rejection control (LADRC) is proposed. This new dual closed-loop control includes current inner loop decoupling control and DC bus voltage outer loop control with first-order LADRC. As the LADRC has the advantages of decoupling and disturbances rejection, it is applied to the control of wind power grid-connected inverter. Through analysis, it is demonstrated that the current decoupling control is simpler than proportional integral (PI) control algorithm, the dynamic response speed is faster, and the DC bus voltage control has better anti-disturbance. Finally, a 1.5 MW direct-drive permanent magnet wind power system was established through digital simulation, and the control effects of the two control modes under different working conditions are compared. The simulation results verify that the proposed dual closed-loop control based on first-order LADRC is superior to PI double closed-loop control in terms of decoupling performance and disturbance rejection performance under grid faults.

Improving the dynamic performance of grid connected wind farms using modern UPFC

Reliable power from Wind energy is one of the promising non-conventional energy sources for the future. But the fluctuating nature of wind introduces power quality problems affects the stability of the entire grid. Another issue is that power system grid is non-linear dynamic system which needs plenty of real and reactive power to provide its load and power loss is unreliable. Nowadays Flexible AC Transmission Systems (FACTS) controllers are handling a transmission line power surges which magnify the entire grid operation. This manuscript aims at reducing the power quality issues using Unified Power Flow Controller (UPFC) which is interconnected at the Point of Common Coupling (PCC) to improves the transmission ability of the system and enhance the dynamic response of ac grids. The distortions in the waveform are reduced by the proper switching of the semiconductor devices of the UPFC. The switching is controlled using a PI controller with current controlled Pulse Width Modulation (PWM). The gains of the PI controller are tuned using Modified Particle Swarm Optimization Technique (MPSO). The power quality is then analyzed with Total Harmonics Distortion (THD) and the performance is simulated in SIMULINK/MATLAB. These results are acquired by means of modified Particle Swarm Optimization (MPSO), to demonstrate the superiority of the proposed method, the simulation conceded out on grid connected wind power system with Proportional Integral Controller, Fuzzy Logic Controller, Artificial Bee Colony Algorithm and Modified Particle swarm Optimization.

Characteristics Analysis of Inertia Damping of Grid-Connected System of Direct-Drive Wind Power Generation

As large-scale direct-drive wind turbine generator set is connected to the grid, the power system will face problems such as reduced inertia and insufficient frequency modulation capability. The control of wind turbine virtual inertia is an important way to solve this problem. Therefore, this paper takes the direct-drive wind power generation system as the research object, draws lessons from the multi-time scale modeling idea, and based on the electrical torque analysis, establishes the DC voltage time model with the wind turbine virtual inertia control. Based on this, inertia damping characteristics of direct-drive wind power grid-connected system are analyzed. The results show that the dynamic characteristic parameters of the system are affected by many factors, among which the equivalent inertia coefficient of the system is mainly affected by DC capacitance, DC bus voltage and wind turbine virtual inertia control parameters. Damping coefficient is mainly affected by steady-state operating point and DC voltage proportional control parameter K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pu</sub> . The synchronization coefficient is mainly affected by steady-state operating point and DC voltage integration control parameter K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">iu</sub> . The correctness of mechanism analysis of inertia damping characteristics of the whole system is verified by simulation, which provides a certain theoretical reference for inertia damping research of electronic power system.

Research on the Control Strategy of Maximum Energy Utilization and Disordered Disturbance Suppression in Distributed Generation System

The ultimate goal of distributed renewable energy control is to minimize disorder disturbance to the power grid while ensuring maximum energy utilization. Taking wind power as an example, a coupling system using flywheel energy storage system to balance the output variables of wind power system was proposed while using hill climb searching (HCS) to maximize the utilization of wind energy. These methods can obtain stable DC output voltage. In the case of wind speed variation, as a limited capacity energy pool structure, flywheel energy storage system can ensure the maximum utilization of wind energy. Based on fully utilization of wind energy resources, the rapid and comprehensive compensation of wind power output can effectively smooth the output voltage of grid-connected wind power system, thus achieving the purpose of improving the power quality of grid-connected wind power system.

Wind power grid-connected frequency regulation strategy based on ESO control and PI control

Frequency fluctuation of wind power grid-connected system is difficult to adjust, aiming at this problem, this paper proposed a control strategy based on the combination of inner loop control and outer loop to restrain frequency fluctuation. extended state observer (ESO) is used as the outer loop. The error and disturbance which cannot be reflected directly in the system structure are estimated by linearization. The inner loop PI controller is designed through the parameters of proportional link and integral link to realize the reasonable allocation of internal model poles and achieve better damping effect. Simulation show that the control strategy can effectively suppress the system frequency fluctuation caused by load fluctuation and maintain frequency stable. The research results can be used to guide engineering practice.

Linear Active Disturbance Rejection Control for DC Bus Voltage of Permanent Magnet Synchronous Generator Based on Total Disturbance Differential

The wind power grid-connected inverter system has nonlinear, strong coupling, and is susceptible to grid voltage fluctuations and nonlinear load effects. To achieve satisfactory control results, the voltage outer loop is controlled by an improved linear active disturbance rejection control (LADRC). LADRC has strong adaptability, robustness and operability. It can automatically detect and compensate for internal and external disturbances, and correct complex controlled objects to integrator series. The total perturbation differential signal is introduced in the traditional linear extended state observer (LESO), which improves the dynamic perturbation observation ability of LESO. The frequency response characteristics analysis shows that the new LADRC has better anti-interference performance. The effectiveness of the improved controller under multiple operating conditions is verified by simulation.

Wind – Hydro Coordination for Enhanced Worth of Wind Power and Potentials in Karnataka State of India

The augmented demand for the power across the globe has resulted in the growth of non-conventional sources of energy as an appendage to the conventional sources. The large scale grid connected wind power systems have become one of the better alternatives among renewable energy based power generation methods. However the intermittency of wind power is one of the major limitations in the effective harvesting of energy leading to its reduced worth. Several methods are proposed and implemented to overcome the issue of wind power intermittency. In this paper a coordinated approach between wind and dispatchable and geographically proximal hydro power station is proposed to enhance the value of wind power. A MATLAB SIMULINK model of a wind power station is developed. Three potential sites with the conducive operating conditions for the implementation of the proposed scheme have been considered for the analysis. The results obtained are correlated to the enhanced worth of wind power.

Hybrid PSO-Optimized ANFIS-Based Model to Improve Dynamic Voltage Stability

The objective of this paper is to perform a hybrid design for an Adaptive Neuro-Fuzzy Inference System (ANFIS) optimized by Particle Swarm Optimization (PSO) to improve the dynamic voltage stability of a grid-connected wind power system. An onshore 99.2MW wind farm using Doubly Fed Induction Generator (DFIG) is studied. To compensate the reactive power absorbed from the power grid of the wind farm, a Static VAR Compensator (SVC) is proposed. To demonstrate the performance of the proposed hybrid PSO–ANFIS controller, simulations of the voltage response in time-domain are performed in Matlab to evaluate the effectiveness of the designed controller. From the results, it can be concluded that the proposed hybrid PSO-optimized ANFIS-based model can be applied to enhance the dynamic voltage stability of the studied grid-connected wind power system.

Two-Variable Admittance Model for D-PMSG-Based Wind Turbine and Stability Criterion Based on Magnitude and Phase Contour Plot

Recently, wind power technology has been developed rapidly. The interaction between the wind turbine generator and the grid may cause the stability issue and threats the reliable operation of the power system. So, it is vital to analyze the stability of the wind power grid-connected system. Due to the fluctuation of wind speed, the operation characteristics of the system vary, and the system exhibits different stability characteristics at the varied operating points. Thus, it is important to analyze the system stability in the entire operation space. The impedance-based analysis is an effective tool for the stability analysis of the grid-connected system. However, it is difficult to apply the conventional impedance/admittance model to characterize the system performance due to the fact that the system operating point often varies continually. To overcome this challenge, this paper proposes a two-variable admittance model that incorporates the wind speed into the conventional admittance model. In addition, a new stability criterion based on the magnitude and phase contour plot is developed to enable the stability analysis. Simulation and experimental results are presented to demonstrate that the proposed two-variable admittance model and the stability criterion are effective tools for stability analysis of the wind power grid-connected system.

Model Reduction of DFIG Wind Turbine System Based on Inner Coupling Analysis

The doubly-fed induction generator (DFIG) wind turbine system, which is composed of the wind turbine, generator, rotor-side converter, grid-side converter, and so on, is a typical multi-time scale system. The dynamic processes at different time scales do not exist in isolation. Furthermore, neglecting the coupling of parameters of different time scales to reduce the order of the model will lead to deviation between the simulation results and the actual results, which may not be suitable for power system transient analysis. This paper proposes an electromechanical transient model and an electromagnetic transient model of the DFIG wind turbine system that consider the interaction of multiple time-scale dynamic processes. Firstly, the paper applies the modal analysis method to explain the multi-time scale characteristics of the DFIG wind turbine system. Secondly, the variation in the eigenvalues of the DFIG wind turbine system before and after the order reduction and the coupling between variables and the system, as well as the coupling between variables of different time scales, are analyzed to obtain the preliminary 21-order simplified model. Thirdly, considering the weak coupling characteristics between the mechanical part and the electromagnetic part of the DFIG wind turbine system, the 21-order simplified model is decomposed into a 15-order electromagnetic transient model and a six-order electromechanical transient model on the basis of their time scales. Then, according to the balance between simulation time and simulation accuracy, the 14-order electromagnetic transient model and the 10 or 12-order electromechanical transient model are finally obtained. Finally, the rationality of the simplified models is verified by simulations under two large disturbance conditions, namely wind speed abrupt change and voltage sag. The obtained simplified models have reference significance for improving the simulation speed of a wind power grid-connected system and analyzing the internal mechanism of the DFIG wind turbine system’s stability.

Voltage stability improvement of wind power grid‐connected system using TCSC‐STATCOM control

Aiming at the voltage stability problem of wind power grid-connected systems, a cooperative control scheme of Thyristor Controlled Series Compensator (TCSC) and Static Synchronous Compensator (STATCOM) is proposed in this study. The proposed scheme is applied in the wind power grid-connected system, a combined control strategy based on STATCOM double closed-loop feedback control and TCSC device is used to ensure that the system has enough reactive power to maintain its normal work during operation. The corresponding simulation model of wind power grid-connected system is built in MATLAB/Simulink. By analysing and comparing the waveforms of the operating examples with only TCSC, only STATCOM and TCSC-STATCOM, it is shown that the cooperative control of TCSC and STATCOM can quickly and effectively recover the bus voltage at the point of grid-connected wind farms after fault, which has a good performance on improving the voltage stability of wind power grid-connected system and increasing the low-voltage ride-through capability, and the cooperative control effect of TCSC and STATCOM is better than only using the control of TCSC or STATCOM.