In response to industry requests to have calibration services for distorted power instrumentation, NIST is developing a new sampling system to provide this service. This development effort is aimed at providing calibration of instruments that will make measurements in accordance with the IEEE Trial Use Standard 1459-2000 on power measurements in distorted and unbalanced conditions. The system will make use of several NIST developed instruments and sensors.
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The variations in the low frequency dielectric spectra of mass impregnated insulation depending on its moisture content have been investigated. For the calibration purposes a number of the impregnated paper samples was kept in the desiccators where different relative humidities were maintained. Thus obtained moisture content in the samples ranged from 1% up to 6%. The variations of the complex capacitance in a frequency range of 0.001-1000 Hz were measured on these samples as well as on paper previously dried at elevated temperatures under vacuum. The moisture content of the dried samples determined was in a range 0.2-0.5%. Moreover the study of water penetration in a 12 kV mass impregnated cable sample was carried out. Continuous measurements of the dielectric spectra revealed the dynamics of water ingress in the cable insulation.
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The preparation of research proposals by university faculty in electric power engineering should include several key elements. These are factors relating to: special elements required by the funding agency; the nature of the support funds; what must be incIuded (and what must not be included) in the proposal; and background research on the program. Of course, the technical content of the proposal is another critical element. Many persons who prepare research proposals are so focused on the technical content that other ‘common sense’ factors are overlooked. In this presentation, the following elements are discussed in their roles as factors that determine the success of the proposal:
Many definitions have been formulated to characterize, detect and measure active and nonactive current and power for nonsinusoidal and nonperiodic waveforms in electric power systems. This paper presents definitions and compensation of nonactive current from the compensation standpoint
This paper presents the power quality research work on the distribution system of the University of Queensland, St. Lucia campus. The Alternate Transient Program (ATP) was used in modelling the distribution system components and simulating the processes of harmonic distortion, capacitor switching, voltage-sag caused by system faults and large motor starting. The simulation results were analysed and compared with relevant standards for evaluating the quality of power in the distribution system.
The application of artificial neural networks (ANNs) to the real-time load forecasting (RTLF) problem is presented. The term RTLF is used for the prediction of the power system load over an interval ranging from one hour to several hours. This issue is becoming increasingly important with the approach of the open access market with the scheduling of buy/sell transactions as short as half an hour in advance. Separate ANNs are utilized for load forecasting of one hour to four hours ahead. The load forecast of these networks are compared with the of one day ahead load forecast results. Based on simulation results, by utilizing ANN, two objectives are obtained: (1) a more accurate hourly load is predicted; and (2) any near-term buy/sell transactions are fitted in the optimal MW dispatch scheduling. The authors' approach is demonstrated by detailed study of New Brunswick Power data.
Summary form only given as follows. This paper reports the development of a computer approach for evaluating the general performance of stand-alone wind/photovoltaic generating system. Simple models for different system components are developed, integrated and used to predict the behavior of generating systems based on available wind/solar and load data. The model is useful for evaluating the performance of stand-alone generating system and gaining a better insight in the component sizes needed before they are built. Simulation results are presented for performance evaluation of a stand-alone generating system that has been previously designed to supply the average power demand of a typical residential house. An electric water heater model is used as a dump load, and the excess available wind/solar-generated power is used to heat the water. The heated water is used as the inlet water to the main house water heater, which is assumed to be nonelectric. It is shown that this strategy can be effective in reducing the amount of fuel used by the main residential water heater
Ancillary Services are those services performed by generators, transmission and control equipment, which are necessary to support basic services and to maintain reliable operations and system security. in this paper, we focus our attention on one of these services, load following, and propose a competitive way to provide this service through bilateral contracts between supplier and customer.
This presentation discusses an example of a Market Simulator that has been developed to simulate various functions of the electricity market in Ontario. It has been specifically designed for the Ontario Transmission Service Company. At the present stage of development, the Simulator represents:
This paper describes power electronics technology relevant to active filtering and energy storage for the purpose of power conditioning. The combination of active filtering and energy storage leads to a versatile system in terms of compensation under nonperiodic conditions. However, energy storage is much more difficult and costly in realization than active filtering because modern science offers only chemical action, electromagnetic or electrostatic field, and kinetic or potential energy as viable ways of energy storage. This paper is focused on the present status of active filters, and energy storage systems for power conditioning, along with a 200 MJ/20-MW flywheel energy storage system which was commercially installed on a 66 kV power system for the purpose of line-frequency regulation in 1996.
Summary form only given as follows. A model of the fossil fuelled generating power plant with once through boiler for power system frequency simulation studies is presented. In the model, the plant control system is modeled to represent the fundamental response of the coordinated boiler-turbine control in the large-size supercritical plants under change in the system frequency. The model is based on a survey of configurations of the plant control systems used in the major units commercially operated in Japan. The values of the parameters in the model are described through the comparisons with plant responses in a field test and with simulation results from a detailed model of the plant manufacturer. Sample simulation results from the model is presented for demonstrating the fundamental response of the once-through plants under change in system frequency.
Transient stability assessment, preventive control measures and dynamic ATC calculations are addressed for a new deregulated EMS system. The combination of time domain analysis, SIME and optimal power flow provide a reliable solution for future transaction requirements and the current operating point
Summary form only given, as follows. An increasing number of electricity markets employing some form of spot pricing. However, limited experience of the behaviour of spot prices exists. This paper introduces and investigates one particular aspect of pricing behaviour observed in the New Zealand spot market, known as “price inversion”. Spot prices are generally calculated using some form of OPF or power-flow software. The phenomena of price inversion is investigated using the DC power-flow implemented in the New Zealand spot market, and using a full AC power-flow. Price inversion is shown to be dependent on the physical characteristics of the power system. The economic implications of price inversion are also discussed
This paper discusses the adaptation of the settings of distance relays for multi-terminal lines employing agents. Agents are software processes capable of searching for information in networks, interacting with pieces of equipment and performing tasks on behalf of their owners (relays). Results illustrating the performance of the adaptive method proposed compared to conventional fixed settings are presented. It is shown that the digital relays and agents acting within a communication structure (also called middleware) can alter adaptive settings to ensure correct performance over a wide variety of operation conditions, without the need of an additional communication link. The proposed relaying scheme can also be utilized for first zone clearing over the entire line.
Summary form only given, as follows. This paper describes new structures for stability-enhancing excitation controllers designed using a nonlinear multi-machine system model and Lyapunov's direct method. Two control structures are presented: a hierarchical structure in which the AVR is the master controller and the PSS the slave controller and a traditional structure in which the PSS constitutes a supplementary loop to the main AVR. Both controllers are shown to be robust, as the damping they introduce into the system is insensitive to changes in both the system topology/parameters and the pattern of network flows. Each individual controller contributes positively to the overall system damping with no undesirable interaction between controllers. These features should allow a decentralized approach to the design of the AVR+PSS. Such a design approach is compatible with the new competitive market structures and should result in savings on commissioning costs. Simulation results for a multi-machine power system are presented that confirm the above and show that the two control structures are very effective in damping both local and inter-area power swings
Summary form only given as follows. This paper summarizes many of the considerations in the application of series capacitors on radial distribution circuits. The effects of series capacitors on receiving end voltages are illustrated via phasor diagrams and power-voltage characteristics. The unique voltage profile of the compensated distribution circuit is presented. Discussed are the various types of distribution circuit problems that series capacitors typically used to solve. Application guidelines are presented to help minimize oscillatory interactions with transformers and motors. The various protection schemes used in practical series capacitor banks are discussed. The information required to specify distribution series capacitor banks is outlined.
Summary form only given as follows. A model and solution approach to a daily energy and spinning-reserve electricity markets clearing system is presented in this paper. The model considers offers for energy supply and spinning reserve, bids for demand of energy and re-schedulable bilateral contracts. System security is taken into account by using a direct-current model. The model represents the clearing system used by an ISO in charge of both the market and system security. The clearing system is formulated as an optimization problem which is solved using an interior-point method (IPM), taking advantage of the problem's special structure.
Summary form only given as follows. This paper concerns power regulation of variable-speed wind energy conversion systems. These systems have two regions of operation, depending on the tip speed ratio of the wind turbines. They are distinguished by a minimum phase behavior in one of these regions and a nonminimum phase one in the other. A sliding mode control strategy is proposed that assures stability in both regions of operation and imposes the ideally designed feedback control solution in spite of model uncertainties. Moreover, power regulation by the proposed sliding control in the minimum phase region is completely robust to wind disturbances and parameter uncertainties
