scholarly journals Performance Assessment of Some Practical Loss of Excitation Detection Schemes Employing a Realistic Model

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5928
Author(s):  
Abbas Hasani ◽  
Claus Leth Bak ◽  
Filipe Miguel Faria da Silva
Keyword(s):  
Power Plants ◽  
Synchronous Generator ◽  
Realistic Model ◽  
Industrial Applications ◽  
Domain Model ◽  
Detection Methods ◽  
Synchronous Generators ◽  
Ieee Standard ◽  
Real Time Digital Simulator ◽  
Detection Schemes

Loss of excitation (LOE) relay is one of the most essential protection elements for synchronous generators in power plants. During the last few decades, several LOE detection methods have been proposed, while limited schemes such as admittance- and impedance-based ones have been adopted for industrial applications. This study investigates and compares the behavior of some practical LOE detection schemes through extensive simulation scenarios, and from the reliability, speed, and security points of view. The simulation scenarios are accomplished by using the real-time-digital-simulator, where the phase domain model of the synchronous generator is used to develop a realistic and typical power generation system. Employing such a system, different types of complete and partial LOE incidents can be applied according to IEEE Standard C37.102-2006, while the performance of any scheme can be assessed through accurate and realistic LOE scenarios.

scholarly journals Simulation of Three-Phase Salient Pole Generator under Operating Conditions

2019 ◽  
Vol 54 (4) ◽  
Author(s):  
Muayad A. Mukhlif ◽  
Khalid G. Mohammed ◽  
Settar S. Keream ◽  
Sara S. Mahdi
Keyword(s):  
Power Plants ◽  
Synchronous Generator ◽  
Operating Conditions ◽  
New Method ◽  
Impedance Method ◽  
Iron Core ◽  
Past Century ◽  
Synchronous Generators ◽  
Mathematical Methods ◽  
Three Phase

The three-phase synchronous generators are still the backbone of most electric power plants in the world. Many researchers still study synchronous generators in attempts to improve their performance and reduce losses in iron core, copper windings, friction ball bearings, and moments of inertia due to mass and rotor diameter. One of the important characteristics studied insynchronous generator behavior is the generator’svoltage regulation (VR%). Over the past century, researchers have developed four practical and mathematical methods to determine the value of the combined voltages of synchronous generators. This article describes a new method based on the impedance method, the magneto motive force (MMF) method, and the Potier method. The new method effectiveness evaluation is conducted via calculating the four methods and their application to a synchronous generator. The article also offers practical and theoretical recommendations to improve the results and increase flexibility in changing loads as their power factors change.

scholarly journals Voltage Fed Control of Distributed Power Generation Inverters with Inherent Service to Grid Stability

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2579
Author(s):  
Norbert Klaes ◽  
Nico Goldschmidt ◽  
Jens Fortmann
Keyword(s):  
Power Plants ◽  
Synchronous Generator ◽  
System Stability ◽  
Synchronous Generators ◽  
Power Sources ◽  
Distributed Power Generation ◽  
Laboratory Setup ◽  
Fault Ride Through ◽  
Distributed Energy Generation ◽  
Grid Operators

In many countries the percentage of power electronic interfaced power sources (PEIPS), especially renewable energies like wind power and photovoltaic (PV), has increased significantly during the last decade.Retaining system stability with a declining number of conventional synchronous generators is a new challenge that starts to be addressed by Grid Operators. The existing control schemes used in distributed energy generation inverters generally do not provide significant services to grid stability. This paper focuses on a control scheme that is in many ways similar to the control of conventional power plants, but avoids a higher rating of the inverters which is often required by control approaches emulating the response of a synchronous generator. The control parameters of the proposed scheme are derived analytically and their main dependencies from major system parameters are discussed. An add-on to achieve fault ride through capability for both balanced and unbalanced faults for voltage controlled inverters is presented. Model validation results in a laboratory setup show very good correlation and have proven practicability of the theory as well as fault ride through and islanding capability.

scholarly journals Voltage stabilization of a controlled autonomous magnetoelectric generator with a magnetic shunt and permanent magnet excitation

2021 ◽  
Vol 6 (5 (114)) ◽  
Author(s):  
Vadim Chumack ◽  
Volodymyr Bazenov ◽  
Oksana Tymoshchuk ◽  
Mykhailo Kovalenko ◽  
Serhii Tsyvinskyi ◽  
...  
Keyword(s):  
Power Plants ◽  
Permanent Magnets ◽  
Quantitative Difference ◽  
Synchronous Generator ◽  
Synchronous Generators ◽  
External Characteristic ◽  
Generator Voltage ◽  
The Stability ◽  
Main Magnetic Flux ◽  
Magnetic Shunt

The paper presents the results of testing and research of the characteristics of a controlled autonomous magnetoelectric synchronous generator with a magnetic shunt. Structurally, the studied generator is a modified asynchronous machine in which the rotor is made with permanent magnets and an additional system in the form of a magnetic shunt. By adjusting the winding current of the magnetic shunt, the output voltage of the generator is regulated. The following characteristics were investigated: the no-load characteristic during operation with permanent magnets and when the winding current of the magnetic shunt changes with forward and reverse polarity. Also, the external characteristic for active and active-inductive loads; the control characteristic when the load current changes at a constant generator voltage. Analysis of the obtained characteristics makes it possible to determine the limits of regulation of the external characteristic, which is ≈40 % relative to the main magnetic flux. The obtained regulation depth allows maintaining the stability of the external characteristic for power factors not exceeding 0.9, which is the usual passport value for autonomous power plants based on synchronous generators. Comparison of the data of research conducted on the experimental setup shows sufficient convergence for engineering and practical tasks. The maximum quantitative difference is 9.3 %, which suggests the adequacy of the previously developed mathematical model. The control characteristic, constructed experimentally at constant generator voltage, is the control law of the magnetic shunt winding for the studied generator. The investigated version of a synchronous generator with a magnetic shunt should be used for autonomous power plants, renewable energy systems, and autonomous power supply systems.

scholarly journals Electromechanical Design of Synchronous Power Controller in Grid Integration of Renewable Power Converters to Support Dynamic Stability

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2115
Author(s):  
Mostafa Abdollahi ◽  
Jose Ignacio Candela ◽  
Andres Tarraso ◽  
Mohamed Atef Elsaharty ◽  
Elyas Rakhshani
Keyword(s):  
Dynamic Stability ◽  
Power Plants ◽  
Power Converters ◽  
Power Grids ◽  
Synchronous Generators ◽  
Power Controller ◽  
Renewable Power ◽  
Grid Connection ◽  
Control Technologies ◽  
Control Layer

Nowadays, modern power converters installed in renewable power plants can provide flexible electromechanical characteristics that rely on the developed control technologies such as Synchronous Power Controller (SPC). Since high renewable penetrated power grids result in a low-inertia system, this electromechanical characteristic provides support to the dynamic stability of active power and frequency in the power generation area. This goal can be achieved through the proper tuning of virtual electromechanical parameters that are embedded in the control layers of power converters. In this paper, a novel mathematical pattern and strategy have been proposed to adjust dynamic parameters in Renewable Static Synchronous Generators controlled by SPC (RSSG-SPC). A detailed dynamic modeling was obtained for a feasible design of virtual damping coefficient and virtual moment of inertia in the electrometrical control layer of RSSG-SPC’s power converters. Mathematical solutions, modal analysis outcomes, time-domain simulation results, and real-time validations of the test in IEEE-14B benchmark confirm that the proposed method is an effective procedure for the dynamic design of RSSG-SPC to provide these dynamic stability supports in grid connection.

scholarly journals Development of a Hydropower Turbine Using Seawater from a Fish Farm

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 266
Author(s):  
Md Rakibuzzaman ◽  
Sang-Ho Suh ◽  
Hyoung-Ho Kim ◽  
Youngtae Ryu ◽  
Kyung Yup Kim
Keyword(s):  
Power Plants ◽  
Guide Vane ◽  
Cross Flow ◽  
Synchronous Generator ◽  
Fish Farm ◽  
Hydropower Plant ◽  
Fish Farms ◽  
Data Simulation ◽  
Small Hydropower ◽  
Hydropower Plants

Discharge water from fish farms is a clean, renewable, and abundant energy source that has been used to obtain renewable energy via small hydropower plants. Small hydropower plants may be installed at offshore fish farms where suitable water is obtained throughout the year. It is necessary to meet the challenges of developing small hydropower systems, including sustainability and turbine efficiency. The main objective of this study was to investigate the possibility of constructing a small hydropower plant and develop 100 kW class propeller-type turbines in a fish farm with a permanent magnet synchronous generator (PMSG). The turbine was optimized using a computer simulation, and an experiment was conducted to obtain performance data. Simulation results were then validated with experimental results. Results revealed that streamlining the designed shape of the guide vane reduced the flow separation and improved the efficiency of the turbine. Optimizing the shape of the runner vane decreased the flow rate, reducing the water power and increasing the efficiency by about 5.57%. Also, results revealed that tubular or cross-flow turbines could be suitable for use in fish farm power plants, and the generator used should be waterproofed to avoid exposure to seawater.

scholarly journals A low-cost ac-dc rectifier for variable-speed wind energy conversion systems

2021 ◽  
Author(s):  
Zhenhan. Luo
Keyword(s):  
Control System ◽  
Low Cost ◽  
Synchronous Generator ◽  
Voltage Source ◽  
Current Loop ◽  
Variable Speed ◽  
Synchronous Generators ◽  
Wind Turbine System ◽  
Synchronous Reference Frame ◽  
Energy Conversion Systems

In this thesis, a novel AC-DC rectifier is adopted to convert the variable AC voltages from wind generator to a constant dc-link voltage. A DC-AC inverter is used to transfer the energy to fixed ac grid as well as maintain dc-link voltage constant. The rectifier is connected to the generator, which has two sets of three-phase windings. Electrical exited or permanent magnetic synchronous generators are suitable for this rectifier. The AC-DC rectifier features low cost, low power losses and simple control structure. The major content of this thesis consists of four parts. The first part investigates the operation of the AC-DC rectifier. The analysis illustrates the current paths in the rectifier and the remarkable voltage-boosting capability. A simulation model of the converter is built and verified. The second part models the synchronous generator with two sets of windings. The model is developed in the d-q synchronous reference frame. The simulation results from the model are verified by the experimental results.Then the third part is the design of the control system, which involves the generator, the AC-DC rectifier and constant dc-link voltage source. The control system composites of the inner current loop and the outer speed loop. The control system achieves the variable-speed operation of the generator and the regulation of the dc-link current. Finally, a prototype of wind turbine system is established in the lab to verify the analysis of rectifier, synchronous generator and control system design. The steady-state and transient responses of the wind system are compared. Simulation and experiment verify the analysis in this thesis.

scholarly journals A Test Device for Optimize PMU-Based Islanding Detection Technology

2015 ◽  
Vol 10 (2) ◽  
Keyword(s):  
Power Systems ◽  
Power Plants ◽  
Detection Method ◽  
Detection Methods ◽  
Islanding Detection ◽  
Algorithm Optimization ◽  
Test Device ◽  
Photovoltaic Power ◽  
Detection Technology ◽  
Bulk Power

Islanding detection is a necessary function for grid connected distributed generators. Usually, islanding detection methods can be classified as two catalogues: remote detecting methods and local detecting methods. Most of them have limitation and defects when they are applied in photovoltaic power stations. Recently synchronous phasor measuring units (PMU) is proposed to be applied for islanding detecting. Although the islanding detection method is supposed to be applied for traditional bulk power systems, it is also suitable for renewable generation power plants. To do this islanding detection will be implemented on central management unit of photovoltaic power station instead of on grid-tied inverters as traditionally. In implementing, the criteria of this method and the threshold of algorithm are needed to be optimized. This paper develops a test device which can optimize PMU-based islanding detection technology to validate the proposed islanding detection method applying in PV station. Then using simulation to discuss how to set a reasonable threshold for the researched islanding detection method applied in PV stations. Finally the paper provides a platform for the algorithm optimization.

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