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This paper presents an investigation into the impact that plug-in hybrid electric vehicles (PHEVs) could have to mitigate the effects of fault-delayed voltage recovery. The energy storage and conversion system in PHEVs, given potentially high levels of future market penetration, represent a sizable dispersed energy storage resource or reactive power source that electric utilities could leverage to...
This paper presents the nonlinear, time-domain model of a saturable-core inductor. The model is capable of accommodating high-order nonlinearities by representing the current-flux characteristic of the inductor by an analytical (closed form) polynomial function of high degree. An automated procedure is developed to transform the highly nonlinear model to a fully-equivalent quadratic model, without...
This paper provides a methodology to extract the dynamic real time model of an electric power system using phasor measurement unit (PMU) data (GPS-synchronized) and other SCADA data that are available in substations. In addition to typical voltage and current measurements, PMU data include frequency and rate of change of frequency. Such data are available in raw form, as time-stamped instantaneous...
This paper describes a laboratory setup as the scaled model of a three substation power system. The scaled model has been developed at the Power System Control and Automation Laboratory of Georgia Institute of Technology. Elaborate physical models for the power system components along with high fidelity models for signal generation and interfacing to the laboratory setup are among its unique features...
This paper elaborates on a newly introduced approach for time-domain transient simulation of electric power systems with highly nonlinear and/or switching subsystems. The new methodology is based on a numerical integration scheme that assumes that the system model states vary quadratically within a time step (quadratic integration). The proposed method is an implicit integration scheme which demonstrates...
This paper discusses distribution feeder related voltage recovery phenomena following typical faults in a power distribution system, considering the existence of dynamic loads. Such loads consist mainly of induction motors. A three-phase, physically based power system model is utilized, allowing inclusion of system asymmetries and imbalances, typically encountered in distribution systems. The proposed...
This paper presents a laboratory setup for transient testing of relays and GPS-synchronized devices. The setup relies on a unique, realistic scaled model of a small three substation system, along with its metering equipment. Lumped models of transmission lines are included that realistically represent the mutual couplings between the phases and asymmetries. Two phase shifters provide loading controllability...
Present state estimator performance is not 100% reliable. Specifically, there is significant probability that the state estimators may not converge to an acceptable solution. On an industry wide basis, the probability of non convergence is about 5%. The reasons for this performance have been investigated and have been reported in earlier papers. In this paper we report on a new approach that alleviates...
In power system planning and operation procedures, bulk power system reliability assessment plays an important role. The current practice of such assessment generally assumes that protection systems are perfect, and the effects of protection system hidden failures are ignored. Recent research, however, shows that protection system hidden failures have been recognized as a contributing factor to power...
This paper discusses voltage recovery phenomena following typical faults in a power system considering the existence of dynamic loads, consisting mainly of induction motors. A three-phase, physically based power system model is utilized, allowing inclusion of system asymmetries and imbalances. The proposed modeling and simulation is based on a quadratic power system model and on a numerical integration...
This paper proposes a comprehensive approach for bulk power system reliability assessment. Specifically, a framework of security-constrained adequacy evaluation (SCAE) based on analytical techniques is developed to assess the ability of a bulk power system to supply electric load while satisfying security constraints. This approach encompasses three main steps: (a) critical contingency selection,...
This paper presents a laboratory setup for a substation scaled model. A unique construction procedure is employed which yields a realistic scaled model of a small three substation system, along with its metering equipment. Lumped models of transmission lines are constructed that realistically represent the mutual couplings between the phases and asymmetries. Two phase shifters provide loading controllability...
Protection system hidden failures have been recognized as a contributing factor to power system cascading outages. However, in the current bulk power system reliability assessment practice, protection systems are generally assumed to be perfect, and the effects of hidden failures in protection systems are not taken into account. In this paper, the impact of protection system hidden failures on bulk...
A framework of security-constrained adequacy evaluation (SCAE) based on analytical techniques is proposed to assess the ability of a bulk power system to supply electric load while satisfying security constraints. It encompasses three main steps: (a) critical contingency selection, (b) effects analysis, and (c) reliability index computation. Effects analysis is the most essential but computationally...
Contingency simulation is an essential but computationally demanding procedure for power system security assessment, reliability evaluation, and real time operation. Simulation methods based on the traditional power flow (TPF) model usually suffer from lack of the realistic system model and slow convergence. To solve such problems, this paper proposes a contingency simulation methodology based on...
DERs in general have completely different dynamics than the traditional rotating machinery (generators and motors) based power system. Present DER technology uses converters for interfacing DERs to the power grid. These interfaces are inertialess and limit the electric current during faults and transients. At the same time, the converters have sophisticated feedback control loops that may interact...
This paper provides a methodology to characterize the accuracy of PMU data (GPS-synchronized) and the applicability of this data for monitoring system stability. GPS-synchronized equipment (PMUs) is in general higher precision equipment as compared to typical SCADA systems. Conceptually, PMU data are time tagged with precision better than 1 microsecond and magnitude accuracy that is better than 0...
This paper discusses voltage stability and voltage recovery phenomena following typical faults on a power system. A modeling approach is proposed that combines the efficiency of power flow techniques and capabilities of transient stability models. The proposed methodology is based on a quadratic model of the electric power system, including generators and dynamic loads consisting mainly of induction...
Relatively poor performance of state estimators is a well documented experience. Yet, control and operation of electric power system requires reliable state estimators. The poor performance is attributed to implementation simplifications that use single phase asynchronous measurements and the positive sequence model of the system. These simplifications have generated practical problems. The experience...
Expert-system-based approaches to complex computational procedures of transients in power systems are desirable because power systems contain complex and nonlinear elements. We propose the use of symbolically-aided modeling as the basis for the design of expert transient simulators. The symbolic approaches work well when (a) the user interface is "symbolized" and (b) the underlying computational...
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