Grid Connected Wind Power System Research Articles

Power quality management using statcom for grid interfaced wind turbine controlled by microcontroller

Input source for wind power generation in wind turbine is wind. Variation of wind is uncontrolled. Quality of power gener- ated in a windmill is very poor due to uncontrolled and fluctuated nature wind. As per International Electro-technical Commission standard, IEC-61400 norms the power quality and measurements of wind turbine is to be calculate. Electrical energy generated from wind power is based on minimum pollution of environment as comparative to conventional sources of generation. In a grid connected wind power system there are some power quality issues. In grid integrated wind power systems, quality of power is measured by active power, reactive power & variation of voltages measured under guidelines of national & international standards. In this proposed system, the energy generated by wind turbine is converted to DC & DC bus is charged. A microcontroller regulated PWM inverter convert this DC voltage to AC to feed it to grid. The pro- posed DC Bus is augmented by PV (photovoltaic) charged Battery Based PWM controlled STATCOM.

Simulation of STATCOM based control scheme for grid connected wind power system.

Simulation of STATCOM based control scheme for grid connected wind power system.

Life cycle energy and carbon footprint analysis of large MW scale grid connected wind power systems in India

The centralized grid is the main electrical supply to the country. About 80% of the installed generation capacity is fossil fuel fired power plants, though there is increase in share of renewable generation over the years. India has significant wind potential, and a major share in the renewable generation of the country. The energy and carbon footprint sustainability of wind power systems in Indian conditions is the focus of this research. This paper presents a study of large grid connected wind storage systems with reference to the cradle to grave primary energy requirements and carbon emissions in an Indian scenario.

Research on the virtual synchronous generator control strategy of grid-connected permanent-magnet direct-driven wind power system

Renewable energy, distributed generation, and micro-grid technology have been widely concerned for a long time. The traditional grid-connected inverter control strategy does not take into account the problem of inertia which is short and fast to cause the frequency change. The virtual synchronous generator control strategy is adopted to simulate the synchronous generator characteristics, which enhanced the inertia and damp of the system. For the micro-grid of wind power grid-connected, the storage battery is arranged on the AC side of the permanent magnet direct-drive wind turbine, and the model of the virtual synchronous generator is established. Thus the grid-connected performance of large-scale wind farm is improved. Here, the effect of moment of inertia in the virtual synchronous generator and the grid-connected regulation of virtual synchronous generator are verified by using PSCAD/EMTDC. The simulation results show that the grid-connected inverter controlled by the virtual synchronous generator is approximately equivalent to the synchronous generator in external characteristic. The grid-connected inverter based virtual synchronous generator control has a beneficial to adjust frequency and voltage, and can enhance the standby inertia of new energy and grid power generation

Type-2 Fuzzy Logic Predictive Control of a Grid Connected Wind Power Systems with Integrated Active Power Filter Capabilities

This paper proposes a real-time implementation of an optimal operation of a double stage grid connected wind power system incorporating an active power filter (APF). The system is used to supply the nonlinear loads with harmonics and reactive power compensation. On the generator side, a new adaptive neuro fuzzy inference system (ANFIS) based maximum power point tracking (MPPT) control is proposed to track the maximum wind power point regardless of wind speed fluctuations. Whereas on the grid side, a modified predictive current control (PCC) algorithm is used to control the APF, and allow to ensure both compensating harmonic currents and injecting the generated power into the grid. Also a type 2 fuzzy logic controller is used to control the DC-link capacitor in order to improve the dynamic response of the APF, and to ensure a well-smoothed DC-Link capacitor voltage. The gained benefits from these proposed control algorithms are the main contribution in this work. The proposed control scheme is implemented on a small-scale wind energy conversion system (WECS) controlled by a dSPACE 1104 card. Experimental results show that the proposed T2FLC maintains the DC-Link capacitor voltage within the limit for injecting the power into the grid. In addition, the PCC of the APF guarantees a flexible settlement of real power exchanges from the WECS to the grid with a high power factor operation.

Transient Power Characteristics of Direct-driven Permanent Magnet Wind Power Grid-connected System

The transient power characteristic of wind power grid-connected system will affect the operation and management of power grid. In this paper, the transient model of direct-driven permanent magnet wind power unit is established by PSCAD/EMTDC. The simulation shows that the direct-driven permanent magnet wind power unit operates with high current during low voltage. The transient reactive load characteristic of wind power collection line is revealed. The influence factors on transient reactive power characteristic is studied. Additionally, how the wind power output, the collecting line impedance, the current amplitude limiting, control strategy and reactive power control affect the transient reactive power characteristics of the collection line are also analyzed.

Financial Viability of Grid-connected Solar PV and Wind Power Systems in Germany

Abstract The German electricity sector is in a period of transition, spurred by the German government's endeavor to maintain a sustainable, secure, climate-friendly and affordable energy supply system. The most important aspects of this Energiwende are the phase out of nuclear energy, promotion of renewable energy technologies, and reduction of greenhouse gas (GHG) emissions. As a consequence, huge investments in power generation systems and infrastructure are needed. Wind and solar photovoltaics (PV) are important renewable energy sources for achieving the goals, but power generation depends on spatial and meteorological conditions on site. For new build PV systems, the level of on-site solar irradiation is crucial, whereas the yield of wind turbines is mainly determined by the wind speed on site. In the model-based analysis with the RETScreen software, we distinguish between three different regions in order to take differences in climatic and geographical conditions in Germany into account. For each region, six locations with specific site conditions are used for the calculations. Projections are made for the base year 2015 and the future year 2030. We find that PV systems achieve levelized cost of electricity (LCOE) below 11 €-ct/kWh in 2030, with a GHG reduction potential of 133-289 €/tCO 2 . The LCOE of wind power ranges from 5.1-16.1 €-ct/kWh and the related GHG mitigation costs from 101-321 €/tCO 2 . In light of these results, it seems to be possible to restructure the German electricity generation system in a cost-effective and environmentally efficient way. Due to decreasing unit investment costs and increasing capacity, solar PV and wind power become increasingly competitive against conventional power generation. Hence efforts are needed to enhance and optimize the grid integration of wind energy and PV and to maintain the long-term security of electricity supply during the transition process.

Grid-Connected Dual Stator-Winding Induction Generator Wind Power System for Wide Wind Speed Ranges

This paper presents a grid-connected dual stator-winding induction generator (DWIG) wind power system suitable for wide wind speed ranges. The parallel connection via a unidirectional diode between dc buses of both stator-winding sides is employed in this DWIG system, which can output a high dc voltage over wide wind speed ranges. Grid-connected inverters (GCIs) do not require booster converters; hence, the efficiency of wind energy utilization increases, and the hardware topology and control strategy of GCIs are simplified. In view of the particularities of the parallel topology and the adopted generator control strategy, we propose a novel excitation–capacitor optimization solution to reduce the volume and weight of the static excitation controller. When this excitation–capacitor optimization is carried out, the maximum power tracking problem is also considered. All the problems are resolved with the combined control of the DWIG and GCI. Experimental results on the platform of a 37 kW/600 V prototype show that the proposed DWIG wind power system can output a constant dc voltage over wide rotor speed ranges for grid-connected operations and that the proposed excitation optimization scheme is effective.

Optimal sizing of a hybrid grid-connected photovoltaic and wind power system

Abstract Hybrid renewable energy systems (HRES) have been widely identified as an efficient mechanism to generate electrical power based on renewable energy sources (RES). This kind of energy generation systems are based on the combination of one or more RES allowing to complement the weaknesses of one with strengths of another and, therefore, reducing installation costs with an optimized installation. To do so, optimization methodologies are a trendy mechanism because they allow attaining optimal solutions given a certain set of input parameters and variables. This work is focused on the optimal sizing of hybrid grid-connected photovoltaic–wind power systems from real hourly wind and solar irradiation data and electricity demand from a certain location. The proposed methodology is capable of finding the sizing that leads to a minimum life cycle cost of the system while matching the electricity supply with the local demand. In the present article, the methodology is tested by means of a case study in which the actual hourly electricity retail and market prices have been implemented to obtain realistic estimations of life cycle costs and benefits. A sensitivity analysis that allows detecting to which variables the system is more sensitive has also been performed. Results presented show that the model responds well to changes in the input parameters and variables while providing trustworthy sizing solutions. According to these results, a grid-connected HRES consisting of photovoltaic (PV) and wind power technologies would be economically profitable in the studied rural township in the Mediterranean climate region of central Catalonia (Spain), being the system paid off after 18 years of operation out of 25 years of system lifetime. Although the annual costs of the system are notably lower compared with the cost of electricity purchase, which is the current alternative, a significant upfront investment of over $10 M – roughly two thirds of total system lifetime cost – would be required to install such system.

Wind Power Forecasting Based on Improved Biased Wavelet Neural Network

Wind power prediction is the key to grid-connected wind power system. In this paper, first of all, we decompose and reconstruct the power sequence by wavelet analysis, and reduce the noise of the detail signal, to obtain the strong-regularity subsequence. We adapt the biased wavelet neural network rolling forecast model for the processed sequence to obtain seven days of rolling forecast results through several amendments. For the sequence of 5 minutes interval the prediction accuracy is 98.63%, for the sequence of 15 minutes interval the prediction accuracy is 99.88%.

STATCOM for Dynamic Performance Optimization of Grid Connected Wind Power System

STATCOM for Dynamic Performance Optimization of Grid Connected Wind Power System

STATCOM for Dynamic Performance Optimization of Grid Connected Wind Power System

Large disturbances in an induction generator-based wind system necessitate rapid compensation for the reactive power. This article addresses the application of Static Synchronous Compensator (STATCOM) in optimizing the performance of grid connected wind power system. The functionality of the static synchronous compensator in maintaining system stability and reliability during/post diverse severe disturbances is thoroughly investigated. A design procedure for STATCOM, particularly the capacitor in the DC side was advised.

Analysis of Power Flow on Power System with Wind Power Grid

With the continuous development of wind energy resources, wind power technology has been integrated into the modern power system. In this paper, according to the Power System Incorporating Wind Farm, selecting typical data distributed Power flow calculation of Built power network. According to data from the results show that grid-connected wind power system, Due to the directly affected by the influence of the wind speed size into the injection power, cause the whole trend distribution network is presented in a state of random changes, thereby affecting the network power loss of change. In order to improve the network voltage change, this paper puts forward some feasible measures to improve the network voltage method.

The Grid-Connected Inverter of Simulation on Direct-Drive Wind Power System Based on MATLAB

Based on working Principle of the direct-drive wind power systems grid-connected inverter was research, the mathematical model for inverter in Three-phase rotating coordinate was established and analyzed. A double-loop control strategy that based on feed forward decoupling were introduced, Meanwhile, combining the implementation effective control of the AC-side output current by the Space Vector Pulse Width Modulation method (SVPWM), it could generate sine wave current that had the same frequency and the same phase with network voltage. To a great degree, reduced harmonic pollution in power system, moreover, improved the Grid-connected wind power systems efficiency and reliability.

Energy storage system-based power control for grid-connected wind power farm

Wind power is characterized as intermittent with stochastic fluctuations, which can result in deviation of grid frequency and voltage when the wind power ratio is high enough. These effects have a definite impact on stability and power quality of grid operation. This paper proposes an energy storage system (ESS) based power control for a grid-connected wind power system to improve power quality and stability of the power system. Vanadium redox flow battery (VRB), as an environmentally-friendly battery provided with many advantages, is employed in the ESS. A dynamic mathematical model of VRB is built by using an equivalent circuit, and its charging and discharging characteristics are analyzed. The VRB’s stable voltage is available in a wide range (around 20–80% state of charge), which is suitable for utilization of a single-stage AC/DC converter in the VRB-based ESS. With a proposed energy storage control method, VRB-based ESS is added at the exit of the grid-connected wind farm to filter fluctuations of wind power, which ensures that smooth power will be injected into the grid and which improves power quality of the power system. Simulations and experiments are carried out to verify the proposed power control method for these grid-connected wind power systems. The grid-connected wind farm with VRB-based ESS, wind speed (characterized as gust and stochastic wind), and wind turbines are modeled in simulations. Simulation results show that the grid-injected active power from the wind farm is effectively smoothed, and reactive power support can be provided for the grid by the designed VRB-based ESS. Experimental verification is achieved with a low power bench, where a RT-LAB real-time simulation platform and a direct torque controlled induction motor simulate a real wind turbine and a wind speed model is built in the RT-LAB real-time simulation platform. The experimental results verify the proposed scheme through demonstrating a stable and smooth power flow injected into the grid though the wind power fluctuated.

SMES Based Excitation System for Doubly-Fed Induction Generator in Wind Power Application

This paper proposes a Superconducting Magnetic Energy Storage (SMES) based excitation system for doubly-fed induction generator (DFIG) used in wind power generation. The excitation system is composed of the rotor-side converter, the grid-side converter, the dc chopper and the superconducting magnet. The superconducting magnet is connected with the dc side of the two converters, which can handle the active power transfer with the rotor of DFIG and the power grid independently. Utilizing the characteristic of high efficient energy storage and quick response of superconducting magnet, the system can be utilized to level the wind power fluctuation, alleviate the influence on power quality, and improve fault ride-through capability for the grid-connected wind farms. According to the system control objective, the system can contribute to the stability and reliability of the wind power grid-connected system. Using MATLAB SIMULINK, the model of the SMES based excitation system for DFIG is established, and the simulation tests are performed to evaluate the system performance.

계통 연계형 풍력 발전 시스템의 LVRT 제어 전략

본 논문은 계통 전압 사고 상황에서 계통 연계형 풍력 발전 시스템이 만족시켜줘야 할 LVRT(Low Voltage Ride Through) 제어 전략을 제안한다. LVRT 규정은 계통 전압 사고 시 풍력 발전 시스템이 지켜야 할 부분들을 전압 감소율과 사고 시간에 대해 나타내고 있다. 특히 전압 감소율이 10% 이상일 경우에는 풍력 발전 시스템은 규정된 무효 전류를 전력 계통에 제공하여 계통 전압 확보에 이바지해야 한다. 본 논문에서의 LVRT 규정은 세계적으로 가장 엄격한 규정인, 독일 계통 연계 규정(German Grid Code)을 기준으로 하고 풀 스케일(Full-scale) 가변 속도 전력 변환 시스템을 고려하여 제어 전략을 수립한다. 본 LVRT 제어 전략은 계통 사고 시 LVRT 규정을 모두 만족시킴과 동시에 직류단 전압 제어의 추가적인 알고리즘으로 직류단 전압의 제어를 통하여 전체 풍력 발전 시스템의 전력 균형을 기할 수 있다. 3상 전압 지락 사고의 경우 계통으로의 전력 제어가 불가능하여 계통 측 컨버터가직류단 전압을 제어할 수 없으므로, 전력 제어의 기능을 발전기 측 인버터로 이행 시켜 상황에 따라 유연한 직류단 전압 제어가 가능함을 보였다. 시뮬레이션과 실험을 통해 LVRT 제어 전략의 타당성을 검증하였다. This paper proposes a LVRT (Low Voltage Ride Through) control strategy which should be satisfied by grid-connected wind power system when grid faults occur. The LVRT regulation indicates rules or actions which have to be executed according to the voltage dip ratio and the fault duration. Especially the wind power system has to support the grid with specified reactive current to secure the grid stability when voltage reduction ratio is over 10%. The LVRT regulation in this paper is based on the German Grid Code and full-scale variable speed wind power conversion system is considered for LVRT control strategy. The proposed LVRT control strategy satisfies not only LVRT regulation but also makes power balance between wind turbine and power system through additional DC link voltage regulation algorithms. Because it is impossible to control grid side power when the 3-phase to ground fault occurs, the DC link voltage is controlled by a generator side inverter using the DC link voltage control strategy. Through the simulation and experiment result, the proposed LVRT control strategy is evaluated and its effectiveness is verified.

A Research on the Control System of Wind Power Grid-Connected Inverter

PWM inverter, as the main part of wind power grid-connected system, directly determines the quality of the power sent finally to grid. It has become the focus of research to develop a high-performance inverter control system. Based on the analysis and establishment of the mathematical model of the grid inverter system, the vector control strategy based on the voltage directional technique is analyzed in this paper. It consists of two closed loops. The fluctuation of direct voltage is suppressed due to the existence of voltage outer loop. Current inner loop realizes the independent control over meritorious electric current and reactive current through the feedforward of grid voltage and the decoupling of grid-connected current, which makes the inverter power factor close to 1.

Hardware Simulator Development for a 3-Parallel Grid-Connected PMSG Wind Power System

This paper presents the development of a hardware simulator for a 3-parallel grid-connected PMSG wind power system. With the development of permanent magnetic materials in recent years, the capacity of a PMSG based wind turbine system, which requires a full-scale power converter, has been raised up to a few MW. Since it is limited by the available semiconductor technology, such large amounts of power cannot be delivered with only one power converter. Hence, a parallel connecting technique for converters is required to reduce the ratings of the converters. In this paper, a hardware simulator with 3-parallel converters is described and its control issues are presented as well. Some experimental results are given to illustrate the performance of the simulator system.

SUPERVISORY CONTROL OF GRID CONNECTED WIND POWER SYSTEMS TO GUARANTEE SAFE OPERATION

This article proposes a supervisor synthesis for a two level hierarchical control structure of a grid connected wind power system to ensure its safe and optimal operation. The global hybrid dynamics may roughly be captured into a hybrid automaton. The optimization tasks, specific to different operating regimes, are performed by the low level continuous controllers. A supervisor placed on a higher level must guarantee the safe transition from an operating regime to another, triggered by some discrete events. The interest is focused on the design problem on the higher level: the discrete event modelling and the supervisor design in the supervisory control framework.