Speed Governor Research Articles

Dynamic Performance Extraction and Recognition of the PT Speed Governor Based on Mathematical Morphology

How to eliminate the noise effectively is always a difficult problem when detecting and recognizing the weak signal under complex electromagnetic environment. In order to improve the effect of denoising, the method based on the mathematical morphology was used. Base on the erosion and dilation operations of mathematical morphology, the correct extraction and recognition of dynamic performance of the PT speed governor was realized by the multi-mix operations of plus-minus and open-close, and the result provides a basis for the performance analysis and fault diagnosis of the PT speed governor.

Research on Control Strategy and Experiment of Electronic Mechanical Continuously Variable Transmission

Nowadays, most of continuously variable transmissions (CVT) adopt hydraulic system to exert pressure on the cone-plate, in order to realize variable speed control. Electronic Mechanical Continuously Variable Transmission (EMCVT) studied in this paper, however, used rolling screw mechanism instead of the energy-hungry hydraulic system. Mechanical speed governor controlled by electro was adopted in EMCVT to regulate speed, which not only reduced the automobile’s fuel consumption, but also brought down the transmission’s manufacturing cost and failure rate obviously. Further study on the ratio control strategy of EMCVT was made and digital PID control algorithm with target ratio tracing was raised. Moreover, an improved PID control algorithm, that was integral separation and differential precession algorithm, was given. Platform experiment of EMCVT was finished, thus, the functionality and rationality of this transmission’s mechanical structure was proved, so was the feasibility and rationality of the speed ratio control strategy.

Modeling of the dynamic response of a Francis turbine

The paper presents a detailed numerical model of the dynamic behaviour of a Francis turbine installed in a hydroelectric plant. The model considers in detail the Francis turbine with all the electromechanical subsystems, such as the main speed governor, the controller and the servo actuator of the turbine distributor, and the electrical generator. In particular, it reproduces the effects of pipeline elasticity in the penstock, the water inertia and the water compressibility on the turbine behaviour. The dynamics of the surge tank on low frequency pressure waves is also modelled together with the main governor speed loop and the position controllers of the distributor actuator and of the hydraulic electrovalve. Model validation has been made by means of experimental data of a 75MW—470m hydraulic head—Francis turbine acquired during some starting tests after a partial revamping, which also involved the control system of the distributor.

Autonomous Distributed Vehicle-to-Grid for Ubiquitous Power Grid and its Effect as a Spinning Reserve

This paper propose an autonomous distributed vehicle-to-grid control scheme of grid-connected (plug-in hybrid) electric vehicle. Grid-friendly charge and discharge maintaining user convenience for plug-out and battery state-of-charge is realized based on frequency measurement at the plug-in terminal. Implementing proposed scheme to automotive power electronics circuit, (plug-in hybrid) electric vehicle works as a smart storage which is an alternative to stationary battery. The smart storage is expected to be a spinning reserve because of its high-speed response without information exchange to a central load dispatch center. An effect of the autonomous distributed vehicle-to-grid and cooperation with centralized speed governor control and load frequency control of conventional thermal power generator is evaluated.

Design of Transmission Endurance Tester with Electric Energy Recycle Technology

Endurance test of vehicle transmission usually takes long time and spends a lot of electric energy. In order to save energy, a new kind of transmission endurance tester equipped with a DC brake motor and a digital DC reversible speed governor is developed. The tester can transfer electricity generated by the brake motor back into the electric grid. The experiment result shows that the average ratio of electricity recycle is as high as 68 percent. The tester can be used for transmission endurance test of various kinds of construction machineries and vehicles.

Nonlinear Steam Valve Adaptive Controller Design for the Power Systems

Considering generator rotor and valve by external disturbances for turbine regulating system, the nonlinear large disturbance attenuation controller and parameter updating law of turbine speed governor system are designed using backstepping method. The controller not only considers transmission line parameter uncer-tainty, and has attenuated the influences of large external disturbances on system output. The nonlinear con-troller does not have the sensitivity to the influences of external disturbances, but also has strong robustness for system parameters variation, which is because of the transmission line uncertainty being considered in internal disturbances. The simulation results show that the control effect of the large disturbance attenuation controller more advantages by comparing with the control performance of conventional nonlinear robust controller.

Effect of physical constraints on the AGC dynamic behaviour in an interconnected power system

This paper aims to demonstrate the effect of re-heat and non-reheat turbines and some important physical constraints such as generation rate constraint (GRC), time delay and speed governor dead band on the dynamic behaviour of automatic generation control (AGC) in an interconnected power system. The mentioned constraints imposed to power system by governor-turbine, thermodynamic process, and communication channels. Simple structure beside acceptable response of the conventional integral controller makes it attractive for power system AGC issue. Optimum integral gains are computed by genetic algorithm (GA) technique for an interconnected three control areas with non-reheat/reheat generating units to achieve an optimal performance. Simulation results reveal that the scope of optimum solutions was limited by considering physical constraints in addition to the increasing of settling time and over/under-shoots.

Output Feedback PID Based Governor Control to improve Generator Damping for Power System Stabilization

AbstractThis paper presents a new governor control scheme based on an Output Feedback PID controller which guarantees the control stability associated with the feedback gain and improves damping of the generator. The proposed control scheme of speed governor is developed on the basis of the PID controller in the previous study. The differential feedback has been replaced by the nonlinear output feedback. The proposed output feedback control has two advantages: first, it guarantees the wide-range of stable region for any change in the frequency regulation droop R with differential and integral feedback gains chosen in some proper range, and second remarkably improves generator damping free from havoc by the differential feedback. This paper discusses the possibility that the proposed governor control can be utilized as one of the means for power system stabilization (PSS). The computer simulations have been conducted on three cases, which show that generator damping can be remarkably improved by the proposed frequency control scheme.

Impact of wind power in autonomous power systems—power fluctuations—modelling and control issues

AbstractThis paper describes a detailed modelling approach to study the impact of wind power fluctuations on the frequency control in a non‐interconnected system with large‐scale wind power. The approach includes models for wind speed fluctuations, wind farm technologies, conventional generation technologies, power system protection and load. Analytical models for wind farms with three different wind turbine technologies, namely Doubly Fed Induction Generator, Permanent Magnet Synchronous Generator and Active Stall Induction Generator‐based wind turbines, are included. Likewise, analytical models for diesel and steam generation plants are applied. The power grid, including speed governors, automatic voltage regulators, protection system and loads is modelled in the same platform. Results for different load and wind profile cases are being presented for the case study of the island Rhodes, in Greece. The scenarios studied correspond to reference year of study 2012. The effect of wind fluctuations in the system frequency is studied for the different load cases, and comments on the penetration limits are being made based on the results. Copyright © 2010 John Wiley & Sons, Ltd.

Development and field tests of a damping controller to mitigate electromechanical oscillations on large diesel generating units

This paper presents the development and field tests of a digital damping controller designed to mitigate intra-plant electromechanical oscillations via the speed governor system of fast acting units. The controller performance is assessed on an 18-MVA diesel generating unit, at Santana Power Plant (Amapá State, Amazon Region at Northern Brazil). In order to design the damping control law, a set of parametric ARX models representing the plant dynamics at several load conditions, are previously identified from data collected on field tests. The damping controller gains are calculated by using the identified ARX models parameters as inputs to a discrete-time pole-placement design method (pole-shifting) and then embedded on a DSP based microcontroller digital system, for field tests assessment. The digital damping controller modulates the diesel engine inlet valve position according to the observed oscillation on the measured electric power, using a PWM device, which is specially developed to this application. The experimental results shown the good performance of the developed controller on damping efficiently the electromechanical oscillations observed between generating units at Santana Power Plant.

Performance comparison of several classical controllers in AGC for multi-area interconnected thermal system

This paper presents automatic generation control (AGC) of interconnected two equal area, three and five unequal-areas thermal systems provided with single reheat turbine and generation rate constraints of 3% per minute in each area. A maiden attempt is made to apply integral plus double derivative (IDD) controller in AGC. Controller gains in the two-area system are optimized using classical approach whereas in the three and five area systems controller gains and governor speed regulation parameters ( R i) are simultaneously optimized by using a more recent and powerful evolutionary computational technique called bacterial foraging (BF) technique. Investigations reveal on comparison that Integral (I), Proportional–Integral (PI), Integral–Derivative (ID), or Proportional–Integral–Derivative (PID) controllers all provide more or less same response where as Integral–Double Derivative (IDD) controller provides much better response. Sensitivity analysis reveals the robustness of the optimized IDD controller gains and R i of the five area system to wide changes in inertia constant ( H), reheat time constant ( T r), reheat coefficient ( K r), system loading condition and size and position of step-load perturbation.

Automatic generation control of interconnected power system with diverse sources of power generation

In this paper, automatic generation control (AGC) of two area interconnected power system having diverse sources of power generation is studied. A two area power system comprises power generations from hydro, thermal and gas sources in area-1 and power generations from hydro and thermal sources in area-2. All the power generation units from different sources are equipped with speed governors. A continuous time transfer function model of the system for studying dynamic response for small load disturbances is presented. A proportional-integral-derivative (PID) automatic generation control scheme is applied only to power generations from thermal and gas sources and power generation from hydro source is allowed to operate at its scheduled level with only speed governor control. The two area power system is simulated for different nominal loading conditions. Genetic algorithm (GA) is used to obtain the optimal PID gains for various cases using integral squared error plus integral time absolute error (ISE+ITAE) performance index for fitness evaluation. Some of the transient responses are shown for different nominal loading conditions due to step load disturbances in the system. Keywords: Two area power system, Diverse sources of power generation, Automatic generation Control , Genetic algorithm, PID controller

Effective active power control of a high penetration wind diesel system with a Ni–Cd battery energy storage

High penetration (HP) Wind Diesel Hybrid Systems (WDHS) have three modes of operation: Diesel Only (DO), Wind Diesel (WD) and Wind Only (WO). The HP-WDHS presented in this article consists of a Wind Turbine Generator (WTG), a Diesel Generator (DG), the consumer Load, a Ni–Cd Battery based Energy Storage System (BESS), a discrete Dump Load (DL) and a Distributed Control System (DCS). The DG includes a friction clutch which allows the Diesel Engine (DE) to be engaged (DO and WD modes)/disengaged (WO mode) to the Synchronous Machine (SM). The DCS consists of a sensor node which measures the SM speed and active power, calculates the reference active power P REF necessary to balance the active power in the WDHS and communicates this P REF value through a message to the BESS and DL actuator nodes. In the WD mode both the DG and WTG supply active power to the system and the DE speed governor regulates the system frequency. However in an HP-WDHS the power produced by the WTG ( P T) can be greater than the one consumed by the load ( P L). This situation means a negative power in the DG (power inversion) with its speed governor unable to regulate frequency. To avoid this situation, the DCS must order coordinated power consumption to the BESS and DL in order to keep the DG produced power positive. In this article it is shown by simulation how the DCS manages both a temporary power inversion and a permanent one with the mandatory transition from WD to WO mode. The presented graphs for frequency, voltage, active powers of the system elements and battery voltage/current show the effectiveness of the designed control.

Independent power producer parallel operation modeling in transient network simulations for interconnected distributed generation studies

The main task in this paper is to present a performance analysis of a distribution network in the presence of an independent power producer (IP) synchronous generator with its speed governor and voltage regulator modeled using TACS – Transient Analysis of Control Systems, for distributed generation studies. Regulators were implemented through their transfer functions in the S domain. However, since ATP- EMTP (Electromagnetic Transient Program) works in the time domain, a discretization is necessary to return the TACS output to time domain. It must be highlighted that this generator is driven by a steam turbine, and the whole system with regulators and the equivalent of the power authority system at the common coupling point (CCP) are modeled in the “ ATP-EMTP – Alternative Transients Program”.

Identification, digital control and fuzzy logic techniques applied to a synchronous generator

The experimental results obtained in the design and implementation of an decoupled digital speed and voltage controller for a micro-energy system are reported in this work. The studied system is formed by a 9Kw DC motor driving a 10KVA synchronous machine. There are two control loops in the proposed controller: the speed control (Speed Governor) and the control of the stator's voltage (Automatic Voltage Regulator). Each control loop was designed using linear control techniques and Fuzzy control techniques. Tests on the system show the performance of the proposed controllers.

Maiden Application of Bacterial Foraging-Based Optimization Technique in Multiarea Automatic Generation Control

A maiden attempt is made to examine and highlight the effective application of bacterial foraging (BF) to optimize several important parameters in automatic generation control (AGC) of interconnected three unequal area thermal systems, such as integral controller gains (K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ii</sub> ) for the secondary control, governor speed regulation parameters (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> ) for the primary control and frequency bias parameters (B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> ), and compare its performance to establish its superiority over genetic algorithm (GA) and classical methods. Comparison of convergence characteristics of BF, GA, and classical approach reveals that the BF algorithm is quite faster in optimization, leading to reduction in computational burden and giving rise to minimal computer resource utilization. Simultaneous optimization of K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ii</sub> , R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> , and B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> parameters which surprisingly has never been attempted in the past, provides not only best dynamic response for the system but also allows use of much higher values of R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> (than used in practice), that will appeal to the power industries for easier and cheaper realization of governor. Sensitivity analysis is carried out which demonstrates the robustness of the optimized K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ii</sub> , R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> , and B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> to wide changes in inertia constant (H), reheat time constant (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ), reheat coefficient (K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> ), system loading condition, and size and position of step load perturbation.

A Real-Time Regulator, Turbine and Alternator Test Bench for Ensuring Generators Under Test Contribute to Whole System Stability

A new Test Bench for speed governors has been developed and successfully tested in a simulation laboratory and in a Hydro-Québec hydroelectric powerhouse. Equipped with a Real-Time Simulator, the RT-LAB BERTA Test Bench makes it possible to cause the speed governor and turbine to react as though they are operating in an islanded power system, while remaining connected to the main grid. This ensures that the generating unit under test actually contributes to the stability of the whole power system. On-site testing has demonstrated that previous speed governor settings which were thought to be very stable were in fact generating undesirable power oscillations. Through the use of the proposed Test Bench, more accurate settings can be made on-site without the need to conduct laborious analyses.

Basic Modeling and Simulation Tool for Analysis of Hydraulic Transients in Hydroelectric Power Plants

In this paper, the simulation system of a typical hydroelectric power plant was developed in a MATLAB/Simulink-based software environment, which has a high water head and a long penstock with upstream and downstream surge tanks and is equipped with a Francis turbine. With MATLAB/Simulink, the models of the proposed simulation system are all modularized and visualized, and can be reused easily. No complex codes have been programmed and the proposed simulation system adapts varieties of hydroelectric power plants. The nonlinear characteristics of hydraulic turbine and then inelastic water hammer effect were considered to calculate and simulate hydraulic transients. Moreover, the influences of different parameters, such as hydraulic turbine speed governor proportional-integral-derivative (PID) gains, pressure water supply system, as well as surge tanks, were analyzed for the dynamic performance of hydraulic turbine regulating system. The digital simulations of a sudden full load rejection for an actual hydroelectric power plant in China were performed, and the results indicate that the proposed MATLAB/Simulink-based hydroelectric power plant simulation system is accurate and effective enough to represent and simulate hydroelectric power plant's nonlinear dynamics as well as to design hydraulic turbine speed control system. The proposed simulation system has also been proved to be useful for preliminary designs or assessments of hydropower projects.

Pattern of maxillofacial and associated injuries in road traffic accidents

Road Traffic Accidents (RTAs) are a major cause of morbidity and mortality in Kenya. Victims may suffer multiple injuries including maxillofacial injuries. In most developing countries RTAs are the leading cause of maxillofacial injuries. In an attempt to reduce RTAs, the government of Kenya has enacted a legislation requiring mandatory fitting of speed governors and safety belts by passenger service vehicles. To describe the characteristics and pattern of maxillofacial and associated injuries sustained in road traffic accidents. A cross-sectional study. Kenyatta National Hospital (KNH). All patients involved in RTAs brought to casualty and the dental department of KNH as well as accident victims admitted to the KNH mortuary over a four- month period from September 2004 to December 2004. Four hundred and thirteen (85.7%) had non-fatal injuries whereas 69 (14.3%) had sustained fatal injuries. Males in the 21-30-year age group were the most affected. Most accidents occurred during weekends with pedestrians being the leading casualties in 59.5% and 71.4% of non-fatal and fatal cases respectively. Most accidents were caused by passenger service vehicles (matatus) which were responsible for 62% and 40.6% of non-fatal and fatal injuries respectively. Non-use of safety belts was reported in 56.6% of the cases who suffered non-fatal injuries. In the non-fatal category 89.6% of the casualties had soft tissue injuries (STIs) involving the craniofacial region with facial cuts being the majority (69.2%). Two hundred and seventy three (66.1%) incidents of other STIs than those of the head region were noted, the lower limbs accounting for 45.4% of these. Only 5.1% of the casualties with non-fatal injuries had fractures involving the maxillofacial skeleton. Skeletal injuries other than those involving the maxillofacial region were found in 142 (34.1%) incidents. In the fatal category head injury alone was the leading cause of death accounting for 37.7% of the cases followed by head and chest injuries combined which were responsible for 13% of the cases. Injuries to the maxillofacial skeleton appear to be uncommon in this series. Pedestrians in their third decade of life are most affected with passenger service vehicles being responsible in the majority of the cases. Interventional programmes targeting pedestrians and those in the third and fourth decades of life should be enacted.

Automatic generation control of single area power system with multi-source power generation

In the current paper, automatic generation control (AGC) of a more realistic single area power system with multi-source power generation is studied. The system transfer function model comprises hydro, thermal, and gas power generations with speed governor models and system load for studying the dynamic response for small load disturbances. A proportional plus integral load frequency control scheme is applied only to thermal and gas power generations and hydro is allowed to operate at its scheduled generation level with only speed governor control. Genetic algorithm (GA) is used to optimize the conventional proportional—integral controller gains. Integral squared error (ISE) and integral time absolute error (ITAE) performance indices are used to obtain optimal AGC parameters. The effects on transient performance of the system are investigated for common and individual AGC controller gains of thermal and gas power generations. It is shown that the optimum values of the AGC controller parameters for a single area power system obtained by assuming single source plant dynamics (hydro or thermal) are considerably different than that of a multi-source single area system. The study is also conducted by considering generation rate constraint (GRC) on thermal and hydro generating units. Finally, transient responses are shown for different scheduled loading conditions.