Showing papers by "Jovica V. Milanovic published in 2002"
07 Aug 2002
TL;DR: It was found that embedded generation collectively enhanced the overall performance whilst individually, synchronous machines offered greater benefits in comparison to the induction machines.
Abstract: The paper investigates the collective and individual influence of synchronous and induction embedded generators (EG) on stability of a generic distribution network. With a model of the network developed in IPSA computer software package simulations were performed to determine the behavioural characteristics of the system (voltage and angular stability) with a varied mix of embedded generators, system loads and operating conditions. It was found that embedded generation collectively enhanced the overall performance whilst individually, synchronous machines offered greater benefits in comparison to the induction machines.
38 citations
01 Nov 2002
TL;DR: In this article, the effectiveness of a power system stabiliser (PSS) connected to the exciter and/or governor in damping electromechanical oscillations of an isolated synchronous generator is examined.
Abstract: Dynamic interactions among various controllers used for stabilising a synchronous generator are investigated. The effectiveness of a power system stabiliser (PSS) connected to the exciter and/or governor in damping electromechanical oscillations of an isolated synchronous generator is examined. The interaction(s) among power system stabiliser(s) connected to the exciter and/or the governor loop, automatic voltage regulator, governor and multi-stage double-reheat turbine and dynamic load are considered. It is shown that depending on the type and number of controllers used and dynamics modelled, interactions can result in unstable operation of the system for a range of operating conditions. It is also shown that the power system stabiliser connected to the governor loop provides better damping of low-frequency oscillations and better robustness of the generator to a change in operating conditions than the PSS connected to the exciter loop.
31 citations
TL;DR: In this article, the problem of large numbers of combinations of certain load parameters needed for trustworthy results of the analysis is solved by using uniformly distributed sequences in hyperspace of load parameters, which leads to robust results and requires a small computational time.
Abstract: The problem of load ranking in power systems is revisited, and a new robust method for revealing loads having the biggest influence on power system small distucbance stability is described. The problem of large numbers of combinations of certain load parameters needed for trustworthy results of the analysis is solved by using uniformly distributed sequences in hyperspace of load parameters. This approach leads to robust results and requires a small computational time. The method further allows evaluation of the range of power system damping uncertainty and the obtaining of a maximum increment of system model accuracy using a limited number of field tests and such reducing overall costs associated with system field measurements.
24 citations
06 Oct 2002
TL;DR: In this article, the authors describe computer simulations used as an initial phase in process of designing a three-phase voltage sag generator and investigate the influence of various parameters, different circuit topologies and different control strategies.
Abstract: The paper describes computer simulations used as an initial phase in process of designing a three-phase voltage sag generator. The influence of various parameters, different circuit topologies and different control strategies is investigated and discussed in the paper. The main results and conclusions are illustrated numerically and graphically. The investigation resulted in selection of optimal design and control parameters for voltage sag generator. The PSCAD/EMTDC software environment was used in all computer simulations.
16 citations
TL;DR: In this article, the analytical formulae for calculation of the damping and frequency of the electromechanical modes in large interconnected power systems were presented, and the results were verified through numerical simulations.
13 citations
07 Aug 2002
TL;DR: In this paper, an optimisation-based method for modelling uncertainties in a power system for small-disturbance stability studies is discussed, which enables robust co-ordinated tuning of a power systems stabiliser for a variety of operating conditions and uncertainty in model parameters.
Abstract: An optimisation-based method for modelling uncertainties in a power system for small-disturbance stability studies is discussed. The proposed method enables robust co-ordinated tuning of a power system stabiliser for a variety of operating conditions and uncertainty in model parameters. The proposed technique allows the evaluation of the ranges of damping of critical system modes and stability limit uncertainty due to the uncertainties in the power system model. A numerical example for two test power systems illustrates the effectiveness of the proposed method.
10 citations
17 Apr 2002
TL;DR: In this paper, the results of the transient performance of a combined cycle gas turbine (CCGT) plant when connected to the distribution network are presented, and the results show that the gas turbine is used extensively in these new schemes.
Abstract: Distribution networks in the UK have been designed in order that electrical power is provided by large scale generating stations via the transmission network. A distribution network typically operates at voltages up to and including 132 kV with the end customers directly connected. Legislations introduced by the present UK government state that 10% of the total UK energy should be provided from renewable sources, and 10GWe of combined heating power (CHP) should be provided by 2010. This will inevitably lead to a large increase in distributed generation in the UK by 2010. Distributed (embedded) generation is defined as that generation connected directly to the distribution network. The gas turbine is used extensively in these new schemes. It is commonly used in CHP schemes where use is made of the waste heat present in the gas turbine exhaust gases for industrial processes or domestic heating. A far more beneficial practice with respect to the distribution network is to utilize the gas turbine in a combined cycle gas turbine (CCGT) plant. This paper presents the results of the transient performance of a CCGT plant when connected to the distribution network (Chilvers (1)).
6 citations
TL;DR: In this paper, the authors describe some of the simulations of measurements taken using EMTDC to estimate power system load models and show how different load structure and non-ideal conditions in power systems influence results of the measurements.
Abstract: The paper describes some of the simulations of measurements taken using EMTDC to estimate power system load models. It shows how different load structure and non-ideal conditions in power systems influence results of the measurements. On the basis of simulations performed different load models are proposed for various classes of load compositions. An example of load parameter estimation from measured results is given.
3 citations
06 Oct 2002
TL;DR: In this article, a dedicated software was developed in Matlab for the extraction of voltage sag characteristics from recorded waveforms, which was illustrated on voltage waveforms obtained from IEEE P1159.2 Working Group on Power Quality Event Characterisation.
Abstract: The paper proposes new approach for extraction of voltage sag characteristics from the recorded waveforms. A dedicated software was developed in Matlab for the extraction of voltage sag characteristics from recorded waveforms. The method and capability are illustrated on voltage waveforms obtained from IEEE P1159.2 Working Group on Power Quality Event Characterisation.
2 citations
17 Apr 2002
TL;DR: In this paper, the influence of enhanced generator excitation control on voltage and angular stability of a power system is discussed, and a simple, six busbar power system model is considered which has two distinct oscillatory modes that are of frequencies relevant to the UK network.
Abstract: The subject of the paper is the influence of enhanced generator excitation control on voltage and angular stability of a power system. A simple, six busbar power system model is considered which has two distinct oscillatory modes that are of frequencies relevant to the UK network. Dynamic performance of the system is assessed through time response analysis for both small and large disturbances. The recently developed generator transfer function regulator (GTFR) is used as a part of a generator excitation control system. The performance of generators with enhanced excitation control is compared with that of a conventional scheme. It is demonstrated that the GTFR based excitation system exhibits superior control performance, particularly as limiting conditions are approached. The proposed scheme also extends the range of stable operation of the system.
Proceedings Article•
01 Jun 2002
01 Jan 2002
TL;DR: It is demonstrated that the GTFR based excitation system exhibits superior control performance, particularly as limiting conditions are approached, and the proposed scheme also extends the range of stable operation of the system.
Abstract: The subject of the paper is the influence of enhanced generator excitation control on voltage and angular stability of a power system. A simple, six busbar power system model is considered which has two distinct oscillatory modes that are of frequencies relevant to the UK network. Dynamic performance of the system is assessed through time response analysis for both small and large disturbances. The recently developed generator transfer function regulator (GTFR) is used as a part of a generator excitation control system. The performance of generators with enhanced excitation control is compared with that of a conventional scheme. It is demonstrated that the GTFR based excitation system exhibits superior control performance, particularly as limiting conditions are approached. The proposed scheme also extends the range of stable operation of the system.