Digital Automatic Voltage Regulator Research Articles

Emergency Brushless Synchronous Generator Having Rotating Exciter Status Monitoring and Protection Functions

This paper presents an emergency brushless synchronous generator having rotating exciter status monitoring and protection functions. For monitoring the rotating exciter status, a wireless rotor status detector and a digital AVR(Automatic Voltage Regulator), which has a wireless communication capability, are proposed. The proposed rotor status detector detects temperatures of exciter armature and main field windings and input voltage and current of the main field. Therefore, it is possible to protect the generator from the over-temperature of windings and detect the exciter bridge diode fault. Furthermore, the proposed digital AVR has rotor status monitoring and protection function, and remote generator tuning, wireless group parallel operation function. So the operator can efficiently operate the generator using a smartphone from a remote area.

The integrated control strategy for interval Type-2 fuzzy logic power system stabilizer (IT2FLPSS) and compact digital fuzzy automatic voltage regulator (CDF-AVR) in electrical power system

The integrated control strategy for interval Type-2 fuzzy logic power system stabilizer (IT2FLPSS) and compact digital fuzzy automatic voltage regulator (CDF-AVR) in electrical power system

Modifikasi Topologi Pengendali PID untuk Automatic Voltage Regulator Generator Sinkron

Automatic voltage regulator (AVR) is one of key elements in an excitation system which controls the synchronous generator terminal voltage in an electrical power generation plant. PID control algorithm in an AVR has been designed to obtain good response towards voltage reference without considering the effect of torque disturbance. This paper proposes a PID with modified topology for a digital AVR in order to regulate the generator terminal voltage in more speedy and more accurate, while maintaining robustness against torque disturbance. Performance of the digital AVR has been compared with conventional PID controller through experiments using a hardware in the loop (HIL) system. The experiment results show that the proposed PID with modified topology provides better performance than the conventional PID controller. Under torque disturbance, the proposed algorithm provides 83% smaller steady state error and 4.8 second shorter settling time compared to the conventional PID controller. When the reference voltage changes, compared to the conventional PID controller, the proposed algorithm provides 15% smaller steady state error, 79% smaller overshoot, and 0.2 second shorter settling time.

고효율 영구자석 여자기 구조의 발전기 설계와 전압제어

This paper presents a high efficient generator with PM(Permanent Magnet) exciter. The proposed PM exciter for the generator can produce a linear output voltage according to the engine speed. This output voltage is directly used to control the field current of the generator to adjust the generator output voltage. In the proposed generator system, since the field winding current can be supplied by the PM exciter, the generator can self-start without any battery or an external power supply due to the low residential flux. Furthermore, the operating efficiency of the generator is higher than a conventional winding exciter. The main problem of the proposed generator system, the field winding current controller has to be embedded inside the generator, and it rotates according to the generator shaft. In this paper, the proper embedded current controller is designed for the proposed generator system. Due to the embedded controller cannot be connected to the outside the generator controller, the measured instantaneous output voltage of the generator is transferred by the photo isolated communication using shaft aligned infrared transmitter and receiver to keep the constant generator output voltage. In this paper, 10kW, 380V engine generator with PM exciter and the embedded DAVR(Digital Automatic Voltage Regulator) are described. The proposed high efficiency generator is simulated and tested to verify the effectiveness.

TO DESIGN AND FABRICATE A MICROCONTROLLER BASED TEST FACILITY FOR A THREE PHASE FILTER MODULE

In Industrial power plants,noise at high frequency at the generator output is very high. This noise has significant effect on Digital Automatic Voltage Regulator (DAVR).Thus resulting in more than two zero crossing per phase and these extra zero crossing per phase has resultedin channel change over from „AUTO TO MANUAL‟ in many of the power plants. To overcome this problem, BHEL developed a Three Phase Filter circuit(Electronic module 69203IA2AA) using active and passive components. This active filter will help in removing the high frequency noise on the generator output and gives near perfect clean AC input to the Interrupt Generator (Electronic module 69203GB1AA) of the Digital Automatic Voltage Regulator (DAVR) system for computation. To functionally test this filter circuit for its specification and performance, we developed a test facility using ' Microcontroller 89S51 and Digital Display Unit ' and is called as “The IA2A TEST JIG”. --------------------------------------------------------------------***----------------------------------------------------------------------

Digital automatic voltage regulator for synchronous generator considering sensor failure

SUMMARYIn this paper, digital signal processor (DSP) based automatic voltage regulator (AVR) for synchronous generator is proposed. The control performance of AVR is guaranteed to be more reliable by the application of measurement validation method based on Polynomial Chaos Theory. Analysis and development of the proposed regulator is done by both computer simulations and DSP implementation. A hardware platform of the AVR, which consists of two DSPs as the microprocessor is set up, one DSP is used for calculation of the sampled data and sensor validation, the other is used for control algorithm application. Several other methods have also been adopted in the configuration of the hardware for a better dynamic performance. Steady state and dynamic control performance of the regulator are investigated on different working conditions (such as voltage establishment, load connection, and sensor failure). Experimental results show good consistency to the theoretical analysis. Copyright © 2011 John Wiley & Sons, Ltd.

Modernization, reconstruction and development of excitation systems for synchronous generators

This paper presents the previous results of work and development of excitation systems with digital automatic voltage regulators regarding their design, development, manufacturing and commissioning. A special attention was paid to the characteristics of excitation system voltage regulator.

Online estimation of distorted power system signal parameters

An algorithm based on the concept of Kalman filtering is proposed in this study for the estimation of power system signal attributes, like amplitude, frequency and phase angle. This technique can be used in protection relays, digital automatic voltage regulators (AVRs), distribution static compensators (DSTATCOMs), flexible AC transmission systems (FACTS) and other power electronics applications. Furthermore, this algorithm is particularly suitable for the integration of distributed generation sources to power grids when fast and accurate detection of small variations of signal attributes are needed. Practical considerations such as the effect of noise, higher order harmonics and computational issues of the algorithm are considered and tested in the study. Several computer simulations are presented to highlight the usefulness of the proposed approach. Simulation results show that the proposed technique can simultaneously estimate the signal attributes, even if it is highly distorted due to the presence of non-linear loads and noise.

Fuzzy Based Digital Automatic Voltage Regulator of a Synchronous Generator with Unbalanced Loads

Voltage stability and power quality of the electrical systems depend on proper operation of the Automatic Voltage Regulators (AVR) of generators. Nowadays, design technology of the AVRs is being broadly improved. According to wide range operating conditions of the generators and loads, the fuzzy AVRs are going to be the modern type of regulators, particularly, for the genset alternators operating in distribution systems. There are many research presented on the optimum performance of the fuzzy AVRs. They are focused mostly on the balanced loads with minor attention to the unbalanced loads and voltages that are very common for the generating sets embedded in distribution systems. In this study, performances of a simulated digital fuzzy AVR evaluated for a wide range of unbalanced loads operating conditions. Feedback signals, sampling time and scaling factors of fuzzy logic based controller have significant impacts on the overall system performance. A few quality indices are specified and their values are compared for different feedback signals and various unbalanced operating conditions and accordingly, the optimum feedback signal is introduced.

Field Verification of an Advanced High Side Voltage Control at a Hydro Power Station

An advanced high side voltage control (HSVC) that can improve power system stability by adding supplemental control to conventional generator excitation systems has been developed. Since the introduction of this advanced HSVC at the IEEE PES 2000 Summer Meeting, additional development has further improved the advanced HSVC as reported in a companion paper. This paper describes field verification results for the HSVC that were carried out on a hydro power plant of the U.S. Army Corps of Engineers on the Columbia River at The Dalles. The advanced HSVC was temporarily added to the existing digital automatic voltage regulators (AVRs) of two generators in a 22-machine hydro power plant. Various tests, such as confirmation of droop, performance of the cross-current suppression function, switching on and off of a nearby capacitor bank, and others, were successfully carried out. It was confirmed through these field verification tests that the advanced HSVC displayed beneficial impacts on voltage control and system stability as compared to a conventional AVR.

DSP-BASED H∞ CONTROLLED DIGITAL AUTOMATIC VOLTAGE REGULATOR FOR USE ON ENGINE GENERATOR

This paper presents a DSP-based high performance digital automatic voltage regulator (D-AVR) for use on engine generator. The H∞ control approach is applied to the engine generator excitation control system (ECS) for the purpose of tracking a r.m.s. of sinusoidal ac voltage to a specified value. Since the implementation of the control laws has tended to the digital microprocessor, the paper extends the reformulized H∞ control to the discrete time domain. The design procedure of H∞ based ECS is explained for the purpose of constructing robust, low noise, and high performance tracking system. Simulation and experimental results show that the proposed scheme can supply a high-quality voltage power source in the presence of load disturbance.

A self-tuning automatic voltage regulator designed for an industrial environment

Examination of the performance of fixed parameter controllers has resulted in the development of self-tuning strategies for excitation control of turbogenerator systems. In conjunction with the advanced control algorithms, sophisticated measurement techniques have previously been adopted on micromachine systems to provide generator terminal quantities. In power stations, however, a minimalist hardware arrangement would be selected leading to relatively simple measurement techniques. The performance of a range of self-tuning schemes is investigated on an industrial test-bed, employing a typical industrial hardware measurement system. Individual controllers are implemented on a standard digital automatic voltage regulator (AVR), as installed in power stations. This employs a VME platform, and the self-tuning algorithms are introduced by linking to a transputer network. The AVR includes all normal features, such as field forcing, VAr limiting and overflux protection. Self-tuning controller performance is compared with that of a fined gain digital AVR.

Transputer implementation of adaptive control for a turbogenerator system

The paper describes the design and implementation of digital self-tuning automatic voltage regulators for excitation control of a synchronous generator. Practical aspects such as controller robustness and processing power are discussed. Conventional microprocessor technology is unable to achieve the sampling periods required for industrial application. A parallel architecture using INMOS transputers combined with an advanced VME bus-based measurement system provide an open-ended solution to this problem, and enable the adaptive controllers to operate within the required 10 ms sample period. The scheme was initially evaluated on a computer simulation of a three-phase turboalternator. A laboratory model turbogenerator was then controlled to test the performance and reliability of the system under realistic conditions.

Design and Test of Fuzzy Controller for Power System Stabilization

The paper describes the simulation and experimental studies of a fuzzy control scheme applied to an electric power system. The fuzzy control scheme, which was recently proposed by the other authors, is implemented on a digital processor with A/D and D/A converters and is Rested on our laboratory system. The fuzzy controller is designed to produce a supplementary stabilizing signal, which is added to a digital AVR (Automatic Voltage Regulator) of a generator to increase the damping of system oscillations. The design procedures of the on-line controller using the combination of simulation and experimentation are presented in detail. The results show that the proposed fuzzy controller with optimal parameter settings gives a better performance than the conventional power system stabilizer. The problems encountered throughout the experiment are also discussed.

A POVER ANGLE AND ROTOR SPEED MEASUREMENT DEVICE FOR SYNCHRONOUS MACHINES STABILITY STUDIES

A device for measurement of power angle and rotor speed of a synchronous generator has bi-en designed and realized. The device is supplying a signal proportional to the phase angle between the terminal voltage and generated e.m.f. phases of the synchronous machine. A second signal proportional to the rotor speed is also generated. These output signals can be used for both measurement and control purposes. The device under consideration can also be used in conjunction with digital systems through an analog to digital converter (A/D) to perform on-line computation and control. The design and realization of the device depend on high speed digital and linear integrated circuits. The time delays introduced by the device components are negligible compared to the machine time constant , therefore the device is most suitable for applications in both transient and dynamic conditions in synchronous machines. The device is capable of monitoring the variations in the power angle and the rotor speed for both measuring and control purposes. Further, this device can be used as a part of a digital control system to provide stabilizing signals to digital automatic voltage regulator of synchronous machines. The test and calibration results obtained show the capability of the device to monitor the power angle and rotor speed in both steady state and transient conditions.

Influence of Self-Tuning Control Techniques on the Dynamics of a Synchronous Generator Unit

ABSTRACT The recent development In microprocessor technology makes Implementation of advanced control strategies feasible at the generating level. A self-tuning (ST) proportional-plus-lntegral-plus-derivative (PID) digital automatic voltage regulator (DAVR) for a large synchronous machine is proposed and the influence of this regulator on the generator dynamic and transient stability is investigated. The algorithm for this regulator combines a least-square estimator with a digital PID control algorithm. The parameters of the PID control algorithm are computed and updated according to the estimated model. The dynamic performance of the machine when equipped with a digital PID governor is also presented. A comparison of the computer results as obtained from the simulation study are compared with the available experimental results.

Design and test results of a software based digital AVR

The design and test results of a digital automatic voltage regulator are described in the paper. The basic control unit is a mini-computer supported by a digital hardware interface, signal transducers and a teletype. The flexibility of the digital AVR software has been exhibited in both open-circuit and synchronized tests. Digital AVR operation has been categorized into two modes, i.e., normal and special. Observations made from various tests allow guidelines to be laid as to the best possible manner in which to operate the digital AVR. A large number of features and control options have been incorporated into the design and have proven very useful in determining the best approach to be taken in digital control of a generating unit.