Speed Governor Research Articles

Optimum selection of speed regulation parameters for automatic generation control in discrete mode considering generation rate constraints

The paper deals with the optimum selection of a governor speed regulation parameter R in the design of an appropriate governor for automatic generation control of an interconnected power system in discrete mode taking into consideration the generation rate constraint (GRC). Investigations reveal that there is no necessity for a very low value of R as is usually the practice because under realistic operation of an AGC, a larger value of R can be acceptable and can even provide better dynamic responses. A governor designed with a larger value of R will be simpler and cheaper. A sensitivity analysis for an AGC system with a higher value of R reveals that the optimum integral gain setting obtained for nominal system parameters is quite robust for a ±25% change in system parameters.

STUDY ON THE HYDRAULIC STABILITY AND THE BEHAVIOUR OF RESPONSE TO POWER FREQUENCY FLUCTUATION OF THE HEADRACE TUNNEL-SURGE TANK-PENSTOCK SYSTEM

Analysis on the stability of oscillation in a hydraulic system equipped with a surge tank has been made. The Thoma condition of stability is modified by taking account of the effect of inertia of flowing water in the penstock, hydraulic characteristics of turbine, characteristics of the turbine speed governor, inertia of rotating part of turbinegenerator, and paralleled running of power plants. Extensive numerical computation has been made basing on the theory derived herein, and the effect of them is examined in detail. Stability regions are shown in diagrams by the use of suitably chosen dimensionless parameters.Stability of oscillation in the hydraulic system having no surge tank has also been analysed and is compared with the result in the case when a surge tank is equipped.Furthermore, the response of the whole hydraulic system to the periodic variation of power demand has been analysed. The theoretical result thus derived is compared with the result of field measurement in an electric power plant. Good agreement is shown between the theory and measurement.Basing on this study, guidelines for deciding whether the installation of a surge tank is necessary or not in a relevant case are proposed.

A software tool for coordination of controllers in power systems

A report is presented on the theoretical background and the methodology of development of a software tool for offline coordination of power system controllers in either a high-frequency (5-55 Hz) or a low-frequency (0.2-2.0 Hz) range. The controllers considered for coordination are: voltage regulators, power system stabilizers (PSSs), speed governors, main and auxiliary controllers of HVDC converters, and main and auxiliary controllers of static VAr compensators (SVCs). The software package calculates the eigenvalues associated with a prespecified number of least-stable oscillatory modes of the system using a modified version of the S matrix method, and it adjusts the controller parameters to increase a damping of the least-stable mode, using a gradient optimization technique. The software tool is referred to as EICO (EIgenvalue program of COordination of controllers). EICO is coded in Fortran. The application of EICO is demonstrated by coordinating the controllers of a power system with 371 state variables and 140 controller parameters, in the high-frequency range. EICO results are verified by detailed digital simulation of the system, using the electromagnetic transients program (EMTP). The study results demonstrate the technical advantages of the coordinated controllers as compared with the noncoordinated scheme.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A new model for setting complex regulator channel's parameters in hydroelectric power systems

The Subject Paper is mainly devoted for presentation of an integrated hydroelectric Power System equations in the state space form. Due to the advent of fast response electronic and solid state technologies, the interaction between both the reactive power-Voltage (QV) and the active power - frequency (PF) channels becomes more complex as the time span between both channel's time domains becomes more narrower. These new coming inputs render the operation of simultaneous tunning of parameters of both channels a very difficult task for operation planners, specially when changing system topology, or loading level. It is the task of operation planners to maximize the merits and simultaneoualy minimize demerits of such interaction. This is the main objective of this paper. The investigated system constitutes a remote hydroelectric power plant feeding a metropolitan area represented by an infinite bus through a long transmission System. The hydro-generators are provided with multi-channel derivative type excitation regulators (deviation, 1 st and 2 nd derivative of line voltages, currents, excitation voltages, currents, and rotor angles) and P.I.D (proportional, Integral and Derivative) electric-hydoraulic speed governors.

Improving Nuclear Generating Station Response for Electrical Grid Islanding

This paper describes problems associated with the performance characteristics of nuclear generating stations which do not have their overall plant control design functions co-ordinated with the other grid controls. Some design changes to typical nuclear plant controls are presented which can result in a significant improvement in both the performance of the grid island and reduce the need to isolate nuclear units during the disturbance. Four areas of the overall unit controls and turbine governor controls which could be modified to better co-ordinate the control functions of the nuclear units with the electrical grid are discussed. Some simulation results are presented to show the performance of a typical electrical grid island containing a nuclear unit with and without the changes. By reviewing data from two islanding events and supplementing that with computer simulation studies, some conclusions are made. The first of these is that overall unit controllers which are not designed with grid disturbances and islanding requirements in mind can cause frequency control problems. On detection of grid islanding the turbine power should be regulated by the speed governor only while the overall unit controls maintain appropriate operation of the reactor and steam bypass system. As well, turbine auxiliary governors whose settings and time delays are not co-ordinated with the operation of the main governors and underfrequency load shedding relays on the system can cause frequency oscillation and limit cycles. Turbine auxiliary governor design and settings should be co-ordinated with other grid controls, including other unit governors.

Alterations in the follow-up circuit of the speed changer of �RG-M turbine speed governors for operation in the active power group control system

1. Alteration of the follow-up circuit of the SC in the type EGR-M SG during operation of the units in a group control system provides the possibility of smooth transfer of the unit out of the APGC system, which increases the operating reliability of the APGC system in an overcurrent control regime and in eliminating emergency situations. 2. After an additional check, the alteration of the follow-up circuit of the SC can be used for a second modification of the type EGR-2M governors of turbines.

The design of turbine-generator optimal controllers including the effect of torsional modes of oscillation

Optimal linear control has been suggested for designing supplementary signal controllers for turbine-generators. It is shown that the design of the controller should include consideration of the torsional modes of oscillation of the rotor to obtain the best performance. The exciter voltage ceiling is shown to limit the sum of the synchronizing and damping torques. Practical designs normally require that tradeoffs be made. It is shown how advantage would be gained by using the supplementary signal. Normally fed to the speed governor controlling the main steam valve, for a second governor that would merely act on a fast interceptor valve. >

Caterpillar’s 3600 PEEC Locomotive Governor (Programmable Electronic Engine Control)

Caterpillar Inc. recently introduced the 3600 Series medium speed, 280 kW/cylinder diesel engine to its product line. Offered in 6 and 8 cylinder inline and 12 and 16 cylinder vee configurations, the 3600 Series engines will be used for marine, electrical power generation, industrial, and locomotive applications. Caterpillar has also developed a microprocessor-based digital electronic control to meet the applications of these engines. The control system can be tailored for many applications; however, this system was developed primarily for locomotive use. The PEEC (Programmable Electronic Engine Control) locomotive speed and load control governor provides minimum fuel consumption and increases productivity of locomotives in both mainline and switch yard service. This paper describes the PEEC locomotive system as applicable to 3600 Series engines.

The politics of speed control

This paper examines the range of responses to one of the recommendations made in the psi (policy studies institute) research report, danger on the road: the needless scourge (see IRRD 276490), and further discussed in the subsequent psi road safety conference (see IRRD 810546). It sets out the grounds for proposing top speed governors and speed alerting devices as potentially major contributors to traffic law enforcement, and thereby to accident prevention. It discusses the nature of the objections that have been raised to their adoption and concludes that none has sufficient substance to justify not doing so. It therefore suggests that there is now an alternative policy approach to the current one for minimising the number and severity of road casualties attributable to speed. It is no longer necessary to rely on improvements in vehicle handling and crash worthiness and on appeals for higher standards of driving -and on the law-abiding instincts of most drivers.(a) for the covering abstract of the seminar see IRRD 812997.

A Microprocessor-Based Model Reference Adaptive Control System for Hydroelectric Generating Set

This paper describes an adaptive speed governor of hydroelectric generating set, which can adjust its parameters automatically with the variation of operating conditions. An 8086 16-bit microprocessor supports the governor with the aid of special software. A new configuration of direct model reference adaptive control (MRAC) system is developed which can be used in non-minimum phase systems. The hydroelectric generating sets have wider stable ranges and higher frequency-following accuracy using the adaptive governors than those using conventional PID regulators.

Identification and Digital Control of a Turbocharged Marine Diesel Engine

The dynamic characteristics of turbocharged diesel engines can vary greatly with load and speed. Existing Royal Navy diesel prime movers are fitted with hydraulic speed governors which do not take account of these variations. This paper describes the start of a study into the design of an improved diesel engine governor which will produce better transient response performance throughout the speed and load range. First, input/output mathematical models are identified for different speeds using simple step and PRBS stimuli in conjunction with a number of estimation algorithms. The variation in model parameters provides adequate justification for an improved controller design and a simple digital controller is described.

Improved lyapunov function for synchronous machine transient stability study

The transient stability of a synchronous machine is analysed by utilizing Lyapunov's direct method. Lyapunov functions of Lur'e-type are developed, which include the effects of first and second-order speed governor. The used Lyapunov functions have been developed essentially by a systematic procedure based on the nonlinear control theory, Kalman's transformation and the second Lyapunov theorem. The paper evaluates the maximum region of asymptotic stability in the state-plane of a swinging synchronous machine while the computed critical clearing times are compared with those obtained by numerical integration. A numerical example is given.

Multimachine System Transient Stability Improvement using Transient Power System Stabilizers (TPSS)

Power system stabilizers (PSS) have been designed and installed [1,2] to improve the dynamic (smnall signal) response of multimachine systems. This paper presents the theory and test results for improving the transient (large disturbance) behaviour of a multimachine system by supplementing the conventional PSS with a transient power system stabilizer (TPSS). Each generator unit is fitted with a TPSS which, after computation, injects supplementary control signals into both the automatic voltage regulator (AVR) and speed governor control loops.

Operational transform technique for generating Lyapunov functions: Part II. Extension to multimachine power system with flux decay, voltage regulator and speed governor

In the first part of this paper an operational transform technique (OTT) was presented to generate Lyapunov functions for a single-machine, infinite-bus system. This paper presents an extension of OTT to a multimachine power system, taking into account the effects of flux decay, voltage regulator and speed governor. Inclusion of transfer conductances into the Lyapunov function for a second-order model of a multimachine power system is examined and presented.

Lyapunov stability analysis of a synchronous machine with damping fluxes Part I: Extension of the ‘equal-areas’ stability criterion

A Lyapunov function is presented for a one-machine, infinite-bus system schematized by means of a seventh-order dynamic model. This model takes into account five state variables describing the synchronous machine (namely: the rotor angle, the electric speed, the field flux, and the direct and quadrature axis damping fluxes), and two additional variables referring to a first-order linear speed governor and to an equivalent first-order voltage regulator, respectively. A synthetic and closed-form condition for ‘stability in the small’ is derived which extends the well known condition applicable to a second-order machine model. Also, a closed form condition for ‘stability in the large’ is derived, which may be regarded as representing the generalization of the condition expressed by the classical equal-areas criterion. Because of the direct method of accounting for the effects of the damper winding fluxes, the results represent significant progress on previous work reported in the literature.

Optimal and multivariable control of a turbogenerator

This paper describes an investigation into the use of modern control methods to design multivariable controllers which improve the performance of a turbogenerator. It presents the turbogenerator non-linear mathematical model from which a linearized model is deduced. The inverse Nyquist array method and the theory of optimal control are both applied to the linearized model to generate two alternative control schemes. The schemes are then implemented on the non-linear model for simulation by computer in order to assess their dynamic performance. Results from these modern multivariable control schemes are compared with those of the classical familiar automatic voltage regulator and speed governor systems.

Effects of Governor Characteristics on Turbo-Generator Shaft Torsionals

Some of the torsional modes of oscillation of turbine-generator multimass shaft systems can be destabilized through the control action of high speed electrohydraulic turbine governing systems. This form of destabilization surfaced during the commissioning of one of Ontario Hydro's 665 MVA nuclear units. The causes of the problem were identified by measurements taken during the commissioning process and a detailed study of the control system. Conclusions reached as to the causes were supported by computer modelling. More accurate valve linearization circuits and filtering of shaft torsional components in the governor speed signal resolved the problem. A recommendation is made for direct monitoring of shaft torsional components, at least during the commissioning process.

Transient stability analysis of large-scale power systems with speed governor via vector Lyapunov functions

In the paper, transient stability analysis of an N-machine power system is carried out using the decomposition-aggregation method. In the study, transfer conductances, mechanical damping, electromagnetic damping and speed governor action are taken into consideration. The system decomposition is performed so that every subsystem includes three machines, instead of only two machines as for the pair-wise decomposition.The system mathematical model is derived and decomposed into (N – l)/2 sixth-order and one second-order interconnected subsystems. A vector Lyapunov function, whose elements are Lyapunov functions of the free (disconnected) subsystems, is constructed and used for the system aggregation.A seven-machine power system is used as an illustrative example, and an asymptotic stability domain estimate is determined for the system. It is found that the proposed decomposition scheme can lead to a considerable reduction in the conservativeness of the decomposition-aggregation method. It is found also that the pair-wise decomposition-aggregation approaches developed so far are not suitable for stability analysis of largescale power systems.

Multivariable optimal control of generator excitation and speed governor system

Multivariable optimal control of generator excitation and speed governor system

Proportional and integral optimal control of a turbogenerator

Abstract This paper describes an investigation into the use of integral and proportional optimal control methods to design multivariable controllers which improve the performance of a turbogenerator. It presents the turbogenerator nonlinear mathematical model from which a linearized model is deduced. The theory of optimal control is applied to the linearized model to generate two alternative control schemes. The schemes are then implemented software-wise on the nonlinear simulation model in order to assess their dynamic performance. Results from these modern multivariable control schemes are compared with those of the classical familiar automatic voltage regulator and speed governor systems.