Synchronous Generator Excitation System Research Articles

Анализ электромагнитных процессов блока возбуждения трехкаскадного стартер-генератора для авиационной энергосистемы

This article discusses the excitation system of a three-stage synchronous generator for aviation use in two distinctive modes of operation: as an electric power generator for an on-board power supply system and an electric starter for gas turbine engines of the aircraft. The article presents the calculation of the starter and generator operating modes of the excitation system. The basic design relations for the semiconductor converter circuit have been obtained and confirmed by simulation modeling in the PowerSIM environment. The problem of synthesizing an automatic control system for the TSG excitation unit operating as part of an on-board power supply system using a method for calculating the parameters of regulators based on the motion separation method has been solved. A two-circuit control system has been created for the generator mode of operation, including PI and PID regulators with output voltage regulation of the main generating stage. To control the excitation unit in the electric star¬ter mode of operation, a single-circuit control system for the current of the excitation winding with the addition of a resonant component has been designed. The evaluation of the efficiency of the designed control systems was carried out on the basis of simulation modeling using PowerSIM and MATLAB/Simulink application software packages for a generator feeding a three-phase AC network in accordance with the requirements of GOST R 54073-2017.The results of mathematical modeling formed the basis for the design of an experimental sample of the power unit in a hybrid integrated design for the TSG voltage regulation system.

Calculated Values of Three-phase Short-circuit Currents in the Power Supply System of the Synchronous Generator Excitation System

In this article, the calculated values of three-phase short-circuit currents in the power supply system of the excitation system of the STS type are considered-2100-250-2,5 UHL4 synchronous generator type SV-1130-220-44- UHL4.

Improving power system low-frequency oscillations damping based on multiple-model optimal control strategy using polynomial combination algorithm

In this paper, the damping of low-frequency oscillations (LFOs) in a power system containing Static VAR Compensator (SVC) is investigated based on Multiple-Model Linear Optimal Control (MMLOC) Strategy. The performance of MMLOC is enhanced using Polynomial Combination Algorithm (PCA). A linear optimal controller (LOC) generates the optimal control signal with linearization the nonlinear state equations of the system and solving the Riccati equation. One LOC generates synchronized control signals for the synchronous generator excitation system as well as SVC. The LOC is assigned to generate each model’s control signal. The final control signal is made by interpolating the LOC output signals obtained from each model using PCA. Considering a three-phase symmetrical fault on a near bus to the generator, the proposed control strategy is evaluated. This strategy not only maintains stability but also reduces LFO effectively. Furthermore, steady state error of rotor speed and rotor angle tend to zero favorably. Simulations are done for single- and multi-machine power systems via a MATLAB m-code.

Динамическое имитационное моделирование системы возбуждения синхронных генераторов стационарных дизель-генераторных установок аварийного электроснабжения атомной станции

In the article, using MatLab dynamic simulation modeling, a study was made of the excitation systems of powerful synchronous generators of stationary diesel generator sets, which are the main sources of emergency power supply for nuclear power plants. The optimal structural complexity mathematical model of a synchronous machine in relative units and orthogonal synchronous coordinate system is used. A comprehensive simulation of diesel generator sets was carried out with the reproduction of both the dynamics of the automatic control system for excitation of a synchronous generator and the diesel engine control system. The simulation takes into account the features of starting a diesel generator to accelerate a synchronous machine, its initial excitation from a battery. Particular emphasis is placed on the study of self-excitation modes through a transformer connected to the stator circuit of the generator and a thyristor rectifier with an excitation winding as a load, as well as parallel operation with the power system. As a result, the processes of starting a diesel generator set in idle mode, effective self-excitation, autonomous operation of the generator at idle, and applying a load to the generator up to the values of permissible overload were simulated. The work of all channels of the control system is shown, including the signals of the regulators of the automatic control system and mechanical variables that are inaccessible in practice. The adequacy of the developed model is proved by comparison with a real physical experiment when testing a diesel generator at a nuclear power plant. The possibility of using the model developed in MatLab as a virtual test site for testing a diesel generator set and a computer simulator for specialized engineering personnel of a nuclear power plant is demonstrated.

BRUSHLESS EXCITATION SYSTEM ELECTROMAGNETIC DESIGN AND ANALYSES

The brushless synchronous generator (SG) excitation system consists of a main exciter, a permanent magnet generator (PMG) of consequent rotor poles type, and an automatic voltage regulator (AVR). Both exciter machines have been properly designed and analysed. The machines performances are obtained by time stepping finite-element method (FEM) coupled with the external electrical circuit. An experimental machine is built and the measured results are given.

Diagnosis of the Static Excitation Systems of Synchronous Generators with the Use of Hardware-In-the-Loop Technologies

In this paper, testing and diagnosis methods for the static excitation systems of power plant synchronous generators using Hardware-In-the-Loop technology are described. These methods allow a physical excitation system to be connected to a real-time model of a power plant unit. A feature of a static excitation system is the presence of generator self-excitation—that is, when the input voltages of the excitation system are defined by a synchronous generator. These voltages are determining by the digital model, which creates additional difficulties with combining a digital model with a real excitation system. Various ways to solve this problem are described in this article; in particular, we focus on the option in which the gate-impulses of a thyristor converter are applied to the digital model by a real static excitation system. The real-time models are based on the method of average voltages in the integration step. This method is effective for providing numerical stability for the models of power schemes and their functioning in real time mode over a long period. A synchronization method for the calculation time of the model with real time is described. The adequacy of the described method is proved by the results of the static excitation system of synchronous generators testing in operating and fault modes.

Research on Intelligent Control of Synchronous Generator Excitation System Based on Computer Technology

With the maturity and development of industrial technology, power system is continuously optimized and improved. And rely on the continuous innovation of the computer, the power system is also constantly improving and upgrading. In the power system, whether in thermal power plant, wind power plant, nuclear power plant or hydropower plant, the generator is always an indispensable part of the power system, has a pivotal position. There are many types of generators, including many internal systems. In the electric power system, the generator, without any doubt, is used to convert the mechanical energy into the electric energy, and finally transmits the electric energy to the electric network through the transformer, the main generating set and so on, thus realizing the ultimate goal of power generation. This paper studies the intelligent control of synchronous generator excitation system based on computer technology, which is of great positive significance. It has a great influence on the synchronous transformation of generator, performance improvement and power system optimization.

Synchronous Generator Excitation System for a Ship Based on Active Disturbance Rejection Control

To solve synchronous generator oscillations in marine power systems which cannot be effectively suppressed, according to the nonlinearity and time variability of the ship power system, a method of synchronous generator excitation control for a ship based on active disturbance rejection control (ADRC) is proposed. Under different working conditions, three methods are automatic voltage regulator (AVR), automatic voltage regulator with power system stabilizer (PSS), and ADRC methods, which are applied to the two-generator parallel-running excitation system of a ship in simulations. The simulation results show that the excitation control system based on ADRC is faster and has better anti-interference ability and has a better restraining effect on synchronous generator oscillation.

Use of Bulk Superconductors in the Excitation System of Low-Speed Synchronous Generators

This work focuses on implementing HTS bulks in the excitation circuit of low-speed synchronous generators as permanent magnets. In addition to the implementation study, it is also addressed to remagnetize HTS bulks in electric generators. To reduce the maintenance costs and time required for the magnetization process, an in-loco remagnetization is used. The HTS bulks are magnetized in their position inside the machine's magnetic circuit. A pulse-field magnetization (PFM) technique is used, using the stator coils of a linear generator. YBCO and GdBCO samples are tested. The experimental procedure starts with the in-loco PFM to magnetize the HTS bulks and, by applying an oscillatory movement to the linear generator's moving part, measuring the magnetic flux density induced voltage is done. Experimental tests show that, for the FeSi core used in the generator, the YBCO material is most suitable for the excitation circuit.

Анализ возможности возникновения перенапряжений на обмотке возбуждения синхронного генератора автономной системы электроснабжения при внешнем симметричном коротком замыкании

Reliable supply of consumers with electric energy largely depends on the reliability of power source function-ing. In the context of this paper it depends on synchronous generators operating in autonomous power supply sys-tems. In contrast to the power plant generators which are part of power systems and are protected from the loads by sufficiently large resistances, power supply systems withautonomous generators are characterized by rather low resistances. Abrupt changes in the supply load parameters, their own transient and emergency modes, for example, short circuits at the generator terminals, forcing excitation, etc. may lead to various failures in the synchronous gener-ator operation. This paper discusses the possibility of over-voltage in the valve excitation system of a synchronous generator with external three-phase short circuits. On the basis of analytical expressions describing the physical pro-cesses occurring in the excitation system of synchronous generators, the conditions for the occurrence of overvolt-ages are identified

Research and Analysis of Step Intelligent Model Predictive Control of Generator Excitation System Based on the Field of Building Installation

The traditional hydroelectric unit control system mostly adopts proportional integral derivative (PID) control strategy, which has simple control algorithm structure and is easy to understand and realize by the operation and maintenance personnel of the power station. However, its control objective is single, and the dynamic process and internal state information of the system water machine electricity coupling are less considered, especially the lack of the ability to constrain the system state variables In order to meet the increasingly complex operating environment in the regulation system of hydropower units high-quality control needs. Therefore, a step intelligent model predictive control method for synchronous generator excitation system based on tree algorithm is proposed. The step control and intelligent optimization algorithm are introduced into the rolling optimization of model predictive control, which effectively reduces the dimension of nonlinear programming solution in the rolling optimization and improves the feasibility of the control algorithm. In order to ensure the closed-loop stability of the control system, the concept of "quasi infinite time domain optimization" is introduced into the design process of the model predictive control of the excitation system of synchronous generator. The terminal penalty term and the terminal inequality domain are added in the rolling optimization link, and the "virtual" local linear feedback controller outside the prediction domain is designed. Compared with the traditional excitation control method in single machine and multi machine systems, it is proved that the predictive control method has stronger ability of generator terminal voltage maintenance and electromechanical oscillation damping than the conventional excitation control method.

High performance of excitation system for synchronous generator based on modeling analysis

Mathematical description of electromechanical systems operation is powerful parameter to get high performance with practical implement of the systems. This paper describes a mathematical presentation for the behavior excitation system of synchronous generator based on the optimal values of the parameters. The study of the mathematical modeling for dynamics of excitation system required the knowledge for the effect of each parameter to get the typical values provided by the manufacturer implementing. The simulation of the final model which obtained was conducted on Matlab version 2019b. The final results of simulation for the mathematical model are satisfactory, and it proves the ability of independence this model as practical implement.

Research on excitation system of synchronous generator

With the rapid development of power grid, large capacity units are continuously put into operation, which makes the small interference. This paper analyzes the influence of different regulation modes of AC exciter excitation system on the performance of generator excitation control system, demonstrates that PID excitation regulation can effectively improve the quality of excitation control, and simulation test is an effective measure to adjust the parameters of excitation system.

Method for testing output limit of AVR in AC exciter excitation system

The excitation system of synchronous generator plays an important role in the static and dynamic stability of power system. ‘Guide for modelling generator excitation system’ requires that the excitation system of new generators should be modelled and remodelled when the excitation system is upgraded. Testing the output limit of AVR is an important content of modelling. Considering inability of tetsing the output limit of AVR in AC exciter excitation system, this paper analyzes the reason using test data firstly, then proposes a new method to test the output limit of AVR, by modifying the maxim firing angle, the output limit can be got, the new method is verified during modelling test of a 145MW generator finally.

Optimal robust disturbance observer based sliding mode controller using multi-objective grasshopper optimization algorithm to enhance power system stability

Power system stabilizer (PSS) has operated as an auxiliary controller for the synchronous generator excitation system to suppress the power system low frequency oscillations. This paper aims to design an optimal robust disturbance observer based sliding mode controller (RDO-SMC) acting as PSS to enhance the power system dynamic stability through the nonlinear control of excitation system. Indeed, the sliding disturbance observer has expeditiously estimated the accumulated consequence of unknown nonlinearities, parameter uncertainties, non-ideal dynamic models and exterior time-varying interferences in support of sliding mode controller. The sliding surface trajectory has been mathematically derived using Lyapunov theory. RDO-SMC has investigated the low frequency suppression of both the terminal voltage and angular speed. Due to multi-objective nature of the designed control problem, multi-objective grasshopper optimization algorithm (MOGOA) has been implemented to optimally tune the parameters of RDO-SMC and other understudy controllers. To verify and validate the performance of proposed controller, the analyses have been performed in single-machine infinite-bus and multi-machine power systems under different disturbance conditions. At last, the comprehensive simulation results have certainly confirmed the dynamic capability of the optimal RPO-SMC.

Reduction of the Induced Voltage in the Synchronous Generator Shaft Using Active AC / DC Converter

Today, synchronous generators are broadly employed in the industry. The thyristor rectifier in the static excitation system of synchronous generators is responsible for supplying the DC voltage of the excitation winding. In these rectifiers, a high-frequency component is generated at the output of the DC voltage, during turning on and off of the thyristor. These high-frequency components charge the generator’s parasitic capacitors. The voltage induced in these capacitors induces the voltage in the synchronous generator shaft. In this paper, the induced voltage analysis in the generator shaft is performed. Then, modeling, simulation, and experimental laboratory results of pulse width modulation are performed in the static generator excitation system. The induced voltage of the generator shaft is examined by applying this rectifier and it is compared and analyzed with the results of the thyristor rectifier. The hiring of a pulse width modulation rectifier has had a great impact on reducing the induced shaft voltage.

Methods and Technologies for Ensuring the Reliability of Excitation of Synchronous Generators of Small Hydroelectric Power Stations in Uzbekistan

The paper considers a method for protecting a direct current exciter from remagnetization in transient modes. A schematic diagram of the synchronous generator excitation system with an exciter protection device and a description of its operation are given. The proposed technical solution eliminates the violation of the excitation mode and provides high reliability of uninterrupted operation of synchronous generators of small hydroelectric power stations (HPS) by eliminating the possibility of damage to the device that protects the exciter from demagnetization and remagnetization.

Excitation procedure for brushless wound‐rotor synchronous starter generator with seamless transitions

An analytical model of excitation system of brushless wound-rotor synchronous starter generator for aircraft applications is developed and presented in this study. During engine start-up process, the starter generator operates as a motor to start the aircraft turbine and to assist it up to the self-sustaining speed. On the basis of rotation speed of the starter generator in the engine start-up process, there are three excitation modes for the exciter and two transient modes for the field current of the main generator (MG). In this study, for each excitation mode, the relationship between the excitation current (field current of the exciter) and the field current of MG is investigated by taking into account the influence of power electronic parts. This study also proposes a control method for the generator field current in all excitation modes which can detect optimum operating points for transition between excitation modes. Furthermore, a seamless transient control strategy is proposed for the transient modes of the generator field current. Simulation and experimental results are provided to demonstrate the feasibility of the proposed solution.

Unified Reduced Model for a Dual-Control Scheme of the High-Speed Response Brushless Excitation System of Synchronous Generators

Developments of the high-speed response brushless excitation systems (HSRBESs) are ongoing in the power industry. This is because the transient response of the excitation system (ES) is a key performance indicator for the grid owner. In dealing with this problem, accurate prediction and control of the ES ceiling voltage are desirable. However, the brushless exciters’ nonlinear armature reaction causes the ceiling voltage to be unknown under varying operating conditions. This article proposes a numerical average-value model (AVM) that captures all the main dynamics of the HSRBES. It is shown that the AVM relationships can be utilized for online prediction of the ceiling voltage and employed in a dual-control scheme. The proposed model is validated against a dynamic voltage build-up test. Moreover, it is derived from a detailed model, which is verified from instantaneous field measurements and further from finite-element analysis. Finally, the accuracy and effectiveness of the AVMs’ transient relationships prove the feasibility of the proposed dual-control scheme and shows that it can be easily implemented in existing systems.

Modeling and Simulation of Excitation System for Third Harmonic Brushless Synchronous Generator

The excitation system of third harmonic excitation brushless synchronous generator (HESG) can improve the voltage stability and is widely used in small and medium generator set. In order to establish the model of harmonic brushless excitation system, the formula of third harmonic EMF is derived. Then, based on the traditional synchronous generator model, the influence of harmonic windings is counted in. Finally, the simulation model of closed-loop excitation system is analyzed with the automatic voltage regulator (AVR) as the core. On the basis of theoretical analysis, simulation and comparative analysis are carried out according to parameters from actual system. The results show that compared with normal synchronous generator, HESG has the advantage of excellent dynamic characteristics and automatic voltage adjustment.