A Dynamic State Space Model of an MHO Distance Relay
ABSTRACT Traditional relay analysis is based on steady-state concepts, while the performance of a relay depends greatly on system transient. To deal with the relay transient characteristics, a relay modeling technique is developed and presented in this paper. As an example, a ninth-order mathematical model of the electromechanical Mho distance relay has been constructed using state space approach and validated by digital simulation. A key point of the model, derivation of the nonlinear electromagnetic torque, is described in detail. Since the model is capable of accepting inputs with arbitrary waveforms from PT and CT in computing its transient response, a set of truly dynamic characteristics of the relay was obtained. Combining the relay model with well-developed PT and CT mathematical models, the transient behavior of relays during a system contingency can be precisely predicted.
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ABSTRACT: The teaching aspects of protective relaying is discussed. The existing practice is to teach fault analysis and protection methods on the basis of a steady-state concept of unbalanced power systems. However teaching protection relay design requires analysis of the fault transients associated with power apparatus and instrument transformers. Appropriate tools to simulate dynamic behavior of a power system are needed in this case. A dynamic testing simulator called DYNA-TEST, to be used as a teaching tool, is proposed. The simulator can be implemented with almost any common mainframe, using readily available supplemental hardware and software. As an example, teaching experiments involving digital algorithms for distance relaying are describedIEEE Power Engineering Review 09/1989; 9(8):71-72. DOI:10.1109/MPER.1989.4310924
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ABSTRACT: Mathematical models for power system dynamic analysis including the dynamics of the protective system are presented. The formulation of the equations is based on establishing explicit relations between the protection system and the rest of system dynamic elements through the node admittance matrix Y<sub>BUS</sub>. This relationship is achieved by representing the circuit breakers of interest as part of the transmission network elements. The protective relays, reclosing relays and circuit breakers are modeled as dynamic devices for tracking the dependence of these devices on the voltage and current inputs using the phasor state variables. A simple example illustrates the concepts. As a direct consequence of the analytical model, the concept of a protection success region is introduced and the implications for stability analysis, relay coordination, adaptive relaying and cascade tripping are discussedIEEE Transactions on Power Systems 12/1994; DOI:10.1109/59.331457 · 3.53 Impact Factor
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ABSTRACT: This paper derives, and explains the use of new numerical comparator concepts. These numerical techniques are new approaches to time domain based relaying algorithms. The initial treatment of the paper concentrates on the generalized idea of a phase comparator and the cylinder unit in particular. The focus in the cylinder unit is to extrapolate for digital relaying purposes, the benefits and characteristics of the well known and widely used relaying unit. The application of the numerical comparator techniques are illustrated with practical units. Distance, directional and over-threshold units illustrate the procedure to obtain protective relaying units using the numerical comparator conceptsIEEE Transactions on Power Delivery 08/1996; 11(3-11):1266 - 1273. DOI:10.1109/61.517480 · 1.66 Impact Factor