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EN
Wind turbine generator (WTG) installation has been rapidly growing globally in the last few years. In the year of 2017, the WTG installation has reached a global cumulative installation of about 539 GW. Among several types of WTG, the doubly fed induction generator (DFIG) has been taking a large portion of the overall WTG installation since 2004. This popularity is due to the DFIG several advantages that include more extracted energy when compared with the fixed speed type and low cost due to the one-third size of the used converters when compared to the full converter type. However, the DFIG is vulnerable to grid faults. In this paper, a new application of Vector Based Hysteresis Current Regulator (VBHCR) of STATCOM is introduced to enhance the dynamic performance of DFIG-based wind turbine farm. The system under study is investigated using Matlab. Robustness of the proposed VBHCR is investigated through exploring the system performance under various levels of voltage sags. Simulation results show that for certain level of voltage sags at the point of common coupling (PCC), VBHCR-STATCOM can effectively improve the performance of the DFIG. As a result, voltage profile at the PCC can comply with the fault ride through codes of Spain to avoid the disconnection of the DFIGs from the grid.
PL
Zaprezentowano nowy sterownik do turbiny wiatrowej DFIG – Vector Based Hysteresis Current Regulator VBHCR systemu STATCOM umożliwiający poprawę dynamiki. Zbadano pracę układu przy różnych poziomach zapadu napięcia. Stwierdzono poprawę dynamiki i zabezpieczenie przed odłączeniem generatora od sieci.
EN
Although the multitude benefit of wind power, the randomness of wind speed and the fluctuations of wind power are the most disadvantages of wind energy. So, for more efficiency and better performances, wind rotor must be driven at specific optimal rotational speed under each particular wind speed. Therefore, to extract the maximum power from wind turbine, a Maximum Power Point Tracking (MPPT) controller is required. In this paper, modeling of wind energy conversion system WECS using tip speed ratio (TSR) MPPT controller using PID controller tuned by genetic algorithm is investigated. The wind energy conversion is based on a doubly-fed induction generator (DFIG), which it is controlled by robust sliding mode control technique using a generator of 3.6 MW . The obtained results are presented and analyzed, where the performances of both proposed control strategies (MPPT based PID-GA, sliding mode control) have been shown.
PL
W pracy przedstawiono system energii wiatrowej wykorzystujący sterownik śledzący szcztową prędkość . W sterowniku zastosowano regulator PID strojony z wykorzystaniem algorytmu generycznego. Jako generator wykorzystano układ DFIG sterowany za pośrednictwem sterownika ślizgowego.
EN
Wind energy becomes a popular source for renewable energy based power plants since a recent decade ago. Within many types of wind turbine generator (WTG), Doubly Fed Induction Generator currently dominating the market niche by about 64% on all installed capacity all around the world in 2015. A DFIG consists of two converters that linked by a capacitor or so-called as DC link that works to allow the transfer energy from WTG to the grid and vice versa. These converters are very sensitive to any faults particularly when the DC link voltage reach beyond the safety margin, it may be ended with the disconnection of DFIG to avoid any damage on the DFIG's converters. This paper aims to investigate the impact of SMES Unit on DC link voltage of DFIG during various types and levels of faults. The study was conducted through a simulation program and shows that SMES Unit is very effective in reducing the voltage at DC link during grid swell events and slightly affecting the voltage overshoot during grid sag and short circuit events. For the last two cases, the SMES Unit control system is designed to work properly and optimally, therefore, impact of SMES rather insignificant due to the DC link voltages are within the safety margin, however, when DC particularly for the case where the DC link voltage tends to increase and potential to damage the switching parts of DFIG, the SMES Unit could significantly compensate the faults and maintain the voltage within the safety margin.
PL
W artykule analizowany jest wpływ układu SMES (superconducting magnetic energy storage) na pracę układu generatora DFIG typu. DC-link przy różnych typach zakłóceń na przykład zapadów napięcia lub zwarć w sieci. Układy konwerterów w systemie DFIG są bowiem bardzo czułen na przekroczenie przez napięcie marginesu bezpieczeństw co skutkować może odłączeniem generatora.
EN
Integration of large-scale wind power plants (WPPs) in power systems faces high short circuit current and low-voltage ridethrough (LVRT) challenges under fault condition. The use of superconducting fault current limiters (SFCLs) was found to be a promising and cost effective solution to solve these problems. This paper presents a theoretical analysis of Bridge-type SFCL (BTSFCL) performance supported by PSCAD/EMTDC based simulation to enhance the LVRT capability of doubly-fed induction generator (DFIG)-based WPPs. It suppresses the transient fault current without any delay time and prevents from instantaneous voltage sag in the connecting point at fault inception time. The main advantages of BTSFCL are: simplicity, high reliability and automatic operation under fault condition for enhancing the LVRT performance. The studied WPP is modeled based on an aggregated doubly-fed induction-generator (DFIG) wind turbine. Simulation results reveal that BTSFCL limits the transient short circuit current contribution of WPP and enhances the LVRT capability of the DFIG-based WPP. Also, the performance of BTSFCL is compared with the static synchronous compensator (STATCOM) for enhancing the LVRT capability.
EN
In this paper, a power production system containing a variable speed wind turbine equipped with a Doubly Fed Induction Generator (DFIG) is presented, the DFIG stator is connected directly to the grid, and the rotor is connected by a three level three phase inverter with a Neutral Point Clamping structure (NPC). This last must be then dimensioned to forward only the available power of the rotor. In this work, a comparative study of two command strategies of the inverter is detailed, by separate order control: Firstly Sinus Pulse Width Modulation (SPWM) and secondly Sinus Vectorial Pulse Width Modulation (SVPWM). All the simulation models are built in MA TLAB/Simulink software and the performance of the control system is evaluated through FFT analysis of results.
6
Content available remote Energy Management Method for Doubly Fed Induction Generator with Energy Storage
EN
The paper describes metod of energy management in standalone doubly fed induction machine supported by supercapacitor energy storage coupled to the DC link of main back-to-back converter through additional bidirectional DC/DC converter. The main finding presented in the paper are the rules according to which the management of energy in this system is feasible. The implementation of this management presented in the paper, based on PI controllers, is only one way, but the rules that govern the behavior of the system may be adapted to other ways eg. based on fuzzy control.
PL
W artykule opisany jest sposób zarządzania rozpływem energii w układzie prądnicy dwustronnie zasilanej pracującej na wyspę wspomaganej superkondensatorowym zasobnikiem energii sprzężonym z obwodem DC przekształtnika back-to-back prądnicy za pomocą dodatkowego dwukierunkowego przekształtnika DC/DC. Głównym osiągnięciem przedstawionym w artykule jest znalezienie zasad według których zarządzanie energii w tym układzie jest możliwe do zrealizowania. Realizacja tego zarządzania oparta na regulatorach PI jest tylko jednym ze sposobów, ale reguły rządzące zachowaniem układu mogą być adoptowane również do innych sposobów np. opartych o sterowanie rozmyte.
EN
This paper presents high performance improved direct power control (DPC) based on model reference adaptive control (MRAC) and neuro-fuzzy control (NFC) for grid connected doubly fed induction generator (DFIG), to overcome the drawbacks of conventional DPC which was based only on PID controllers, namely the speed/efficiency trade-off and divergence from peak power under fast variation of wind speed. A mathematical model of DFIG implemented in the d-q reference frame is achieved. Then, a direct power control algorithm for controlling rotor currents of DFIG is incorporated using PID controllers, and space-vector modulation (SVM) is used to determine a fixed switching frequency. The condition of the stator side power factor is controlled at unity level via MPPT strategy. The MRAC which is based on DPC is investigated instead of PID regulators. Also, the performances of NFC based on DPC are tested and compared to those achieved using MRAC controller. The results obtained in the Matlab/Simulink environment using robustness tests show that the NFC is efficient, has superior dynamic performance and is more robust during parameter variations.
EN
Purpose: In this paper, a regulate of a variable wind energy conversion system, based on a doubly fed induction generator DFIG is proposed, the system we considered is controlled to generate maximum energy while minimizing loads. In low to medium wind speeds, the generator and the power converter control the wind turbine to capture maximum energy from the wind, in the high-wind-speed regions, the wind turbine is controlled to maintain the aerodynamic power produced by the wind turbine. Generator torque and Pitch angle are controlled simultaneously to maximize energy capture. Design/methodology/approach: Two methods for adjusting the aerodynamic power have been studied: For generator load control, The DFIG control structure contains rotor currents and stator powers loops where PI controllers are used. This control could be obtained by applying a DFIG active and reactive power decoupling strategy based on stator flux orientation method, Another controller based on a sliding mode theory is adopted to maximize the extracted power has been used , both of which are employed to regulate the operation of the DFIG. For the pitch control, a nonlinear controller based on artificial intelligence techniques: genetic algorithms, to regulate the blade pitch angle and rotate speed of the wind turbine system. Findings: Proposed DFIG and pitch control algorithms provide good static and dynamic performances. Validity the strategies proposed was analyzed by simulations. Originality/value: The intelligent controller is proposed to blade pitch position control above the rated wind speed in this paper; Genetic Algorithm based controller gave better results. Simulated wind turbine parameters are obtained from a real turbine and generating system. Hence, proposed controllers can be easily adapted to real time applications and operated with real wind turbines. Compared simulation results validate the proposed method in the paper is an effective method.
PL
Niniejsza praca prezentuje możliwości wykorzystania farm wiatrowych (FW), pracujących ze zmienną rezerwą wirującą, do poprawy stabilności napięciowej dynamicznej. Porównuje przebiegi wartości napięć węzłowych w funkcji czasu w dwóch przypadkach pracy generatorów wiatrowych.
EN
In the submitted paper the real-time analysis of WF, including variant with reduced real power (emergency mode), impact on EPS are presented. The tested study case shows the potential of the proposed method in short term voltage stability improvement.
10
Content available remote Problematyka stabilności kątowej morskich systemów elektroenergetycznych
PL
W artykule zostały omówione zagadnienia dotyczące morskich systemów elektroenergetycznych ze szczególnym uwzględnieniem kwestii stabilności kątowej. Omówiono zasadnicze elementy wchodzące w skład typowych morskich systemów elektroenergetycznych: źródła wytwórcze, odbiory mocy, sieci elektroenergetyczne. Przedstawiono główne czynniki mające wpływ na stabilność morskich systemów elektroenergetycznych. Rozważanie teoretyczne uzupełniono o przykładowe wyniki badań stabilności kątowej lokalnej, bazujące na analizie wartości własnych.
EN
The paper discusses the issues related to the offshore power systems, particularly regarding to rotor angle stability. Main offshore power systems components: generating units, power load, transmission network, have been described and characterized. The paper shows the important factors that affecting stability of the offshore power systems. Theoretical considerations were supplemented with results of rotor angle stability study based on eigenvalues analysis.
EN
The aim of this paper is hybrid fuzzy sliding mode control of a Doubly Fed Induction Generator (DFIG) in the form of a wind turbine. This type of control is introduced to avoid the major disadvantage of variable structure systems, namely the chattering phenomenon. Variable structure ensures the high dynamic of convergence and robustness towards parametric variations and disturbances. Fuzzy control is introduced here in order to remove residual vibrations in high frequencies. That approach is used to control the mechanical speed and the reactive power exchanged between the stator circuit and the grid. Those variables are decoupled through vector control. The feasibility of this work is proven by mathematical and simulation models based on MATLAB.
12
Content available remote Symulator turbiny wiatrowej na bazie silnika prądu stałego
PL
W artykule opisano układ symulatora turbiny wiatrowej, do budowy którego wykorzystano silnik prądu stałego. Silnik ten jest sprzężony mechanicznie z maszyną asynchroniczną dwustronnie zasilaną (MDZ) i służy do badania układów sterowania MDZ w zastosowaniach generacyjnych. Układ zasilania silnika DC sterowany jest mikroprocesorowo i zapewnia generację momentu w zależności od prędkości silnika oraz dodatkowego parametru, jakim jest zadana prędkości wiatru. Charakterystyka symulatora odpowiada charakterystyce przykładowej turbiny wiatrowej. W artykule omówiono schemat układu połączeń i przybliżono ideę sterowania. Pokazano też wyniki badań laboratoryjnych układu.
EN
This paper describes the simulation system of the wind turbine, based on a DC motor. System composed of a doubly fed induction machine mechanically coupled with a DC machine is used to develop and test power control systems based on a wind turbine. Power electronics converter supplying DC motor is controlled by a microprocessor and provides generation of the torque depending on the speed of the machine and an additional parameter, which is the reference wind speed. Simulator characteristics correspond to the exemplary characteristics of the wind turbine. The article discusses the connection diagram and presents the idea of the control system. It also shows the results of laboratory tests.
EN
The paper describes calculation methods of reference components of instantaneous power for control of DFIG connected to unbalanced power grid. The methods allow to operate with constant electromagnetic torque without exceeding power and current limits of DFIG’s stator side. The comparison between different strategies is shown and discussed. Whole control and calculation are performed in αβ reference frame without voltage decomposition into positive and negative sequence. Classic, well-known DPC is used as the main control algorithm.
PL
W artykule opisany jest algorytm wyznaczania referencyjnej chwilowej wartości mocy użytej w sterowanej zgodnie z algorytmem DPC w maszynie dwustronnie zasilanej współpracującej z siecią asymetryczną. Opisana metoda pozwala na pracę ze stałym momentem elektromagnetycznym bez przekroczenia ograniczeń mocy i prądu stojana MDZ. Artykuł prezentuje porównanie i analizę różnych strategii, w których nie została użyta dekompozycja napięcia na składową zgodną i przeciwną a całe sterowanie zrealizowano we współrzędnych αβ.
EN
This paper proposes a novel control strategy for doubly fed induction generator (DFIG) low voltage ride through (LVRT) under asymmetrical grid voltage dip. The proposed strategy, named as direct power control based multi-objective control, enables the DFIG operating under asymmetrical grid voltage dip and operating at different control objectives (the current distortion limitation mode, the power oscillation limitation mode and the torque oscillation limitation mode) by adjusting only one parameter. Furthermore, the proposed method can achieve a smooth switch between the steady state operation and the voltage dip operation with an improved dynamic performance. The simulation results verify the correction and effectiveness of the proposed method.
PL
W artykule przedstawiono nową metodę sterowania generatorem DFIG, pracującym przy przejściowo niskim napięciu. Proponowany algorytm umożliwia pracę w takich warunkach, poprzez zmianę nastawy tylko jednego parametru. Osiągnięto płynność przejścia między stanem ustalonym a stanem zapadu napięcia. Przedstawiono wyniki badań symulacyjnych, potwierdzające skuteczność rozwiązania.
15
EN
This paper proposes a decoupled control of active and reactive power for doubly-fed induction generators (DFIG) through the rotor currents using sliding mode control (SMC). In order to decouple the active and reactive power generated, stator-flux-oriented vector control is applied. The sliding mode control strategy proposes is based on two sliding modes plus PI controllers whose main advantage is the easy implementation. Simulation and experimental results are presented to validate the proposed control scheme for a 2 kW DFIG during stator active and reactive power steps and speed variation. During transient operation it is checked good dynamic response.
PL
W artykule opisano sterowanie mocą czynną i bierną w podwójnie zasilanym generatorze indukcyjnym DFIG za pośrednictwem prądu wirnika z wykorzystaniem metody ślizgowej SMC. Zastosowano sterowanie wektora strumienia stojana. Symulacje i badania eksperymentalne potwierdziły założenia możliwości sterowania systemem DGFIG 2 KW przy różnych prędkościach. Badano także właściwości dynamiczne.
EN
This paper presents the control strategies and digital simulation for the double-fed induction generator (DFIG)-based wind generators for transient stability studies. The wind turbine power tracking characteristics and the power flow mechanism of the DFIG-based wind plant are analyzed. The rotor-side converter (RSC) control, grid-side converter (GSC) control and the pitch angle control scheme are presented based on the phasor model of the DFIG system. The voltage-regulation mode and var-regulation mode are analyzed using control block diagram, and the simulation results of the benchmark system using Matlab/Simulink are presented. The voltage regulation mode and reactive power capabilities are found to be highly effective for low-voltage ride-through (LVRT) capabilities and transient stability enhancement of the DFIG-based wind generators.
PL
W artykule przedstawiono metodę sterowania silnika typu DFIG w zastosowaniu do elektrowni wiatrowej. Analizie poddano charakterystykę turbiny oraz obwodu mocy z maszyną. Zaprezentowano schematy blokowe zastosowanych struktur sterowania. Otrzymane wyniki symulacyjne potwierdziły wysoką skuteczność i stabilność proponowanego algorytmu także przy obniżonym napięciu sieci (LVRT).
17
EN
In this study, voltage dip analysis of the wind power plant that is connected to 6 MW Double Feed Induction Generator (DFIG) was performed. During the operation of Multi-machine wind farm that is connected to network adaptation between 10 MVAr STATCOM and system was provided. Purpose of this adaptation, 3-phase fault analysis is to be able and the elimination of problems that may occur with induction motor runstop.
PL
Zaprezentowano analizę spadku napięcia w elektrowni wiatrowej podłączonej do generatorów indukcyjnych 6 MW typu DFIG. Analizę przeprowadzono na przykładzie wielomaszynowej farmy wiatrowej podłączonej do sieci z systemem 10 MVAr STATCOM. (Analiza spadków napięcia w wielomaszynowej farmie wiatrowej z układem STATCOM)
EN
To study the influence of power system voltage drop on the doubly-fed induction generator (DIFG) shaft, this paper analyzes the electromagnetic torque change of the DFIG through approximated analytical expression of the stator fault current and rotor fault current obtained by the superposition between transient current based on vector method and steady-state current based on equivalent circuit method, and then the DFIG torque change situations under the following circumstances: the three-phase symmetrical voltage dip of stator terminal, the converter of the rotor side is cut off, and the crowbar circuit is put into the operation, will be analyzed through the method. Furthermore, on the basis of theoretical analysis, a 2MW DFIG model is established by PSCAD, and the simulation results validate that the torque changes of the DFIG shaft could be analyzed by the expression of the DFIG torque during the grid voltage drops through the superposition of the transient current and steadystate current. At last, the optimizing value of the crowbar resistance is given.
PL
W artykule analizuje się zmiany momentu elektromagnetycznego podwójnie zasilanego generator indukcyjnego DFIG poprzez ocenę prądów wirnika i stojana otrzymaną przez superpozycję prądów przejściowych (metoda wektorowa) i prądu stanu ustalonego (metoda obwodów zastępczych). Badania symulacyjne potwierdziły słuszność metody.
EN
Measurements at a test-bench of a wind energy converter performed with an ideal balanced and sinusoidal voltage source instead of a grid are necessary for the identification of the harmonics or subharmonics caused by the generator and converter. The produced significant frequencies as well as their interaction with the voltage source are analyzed. The stator side collective power components are calculated and their effect on the time variable asymmetry of the stator current of the three-phase system is investigated.
PL
Identyfikacja harmonicznych i subharmonicznych wprowadzanych przez generatory i przekształtniki energii wiatrowej wymaga pomiarów laboratoryjnych w warunkach zasilania napięciem sinusoidalnym i symetrycznym. W artykule analizowane są wytwarzane w takich układach znaczące składowe częstotliwościowe a także ich oddziaływanie na źródło zasilania. Obliczane są także składowe mocy po stronie stojana oraz badany jest ich wpływ na czasową zmienność asymetrii prądu stojana.
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