Methods Adopted for Detailed Modelling of Alternators in State Space for Stability Analysis
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ORIGINAL CONTRIBUTION
Methods Adopted for Detailed Modelling of Alternators in State Space for Stability Analysis Milan Basu1 • Avik Ghosh2 • Arabinda Das3 • Amarnath Sanyal4
Received: 27 December 2019 / Accepted: 28 October 2020 Ó The Institution of Engineers (India) 2020
Abstract The earlier methods adopted for stability analysis of synchronous machines were based on approximations and idealizing assumptions. As such, the accuracy of prediction was limited. The advent of fast-acting computers having large memory space opened up the avenue for accurate analysis by handling detailed modelling. The earlier methods were based on equal area criterion or on swing equation or some of its modified form. But, the methods applied nowadays uses state space representation of the dynamic equations. The paper shows the steps to develop state space models (both with current and fluxlinkage states) for transient stability analysis and the methods of linearizing the model about the operating point to assess dynamic stability. Two case studies have been given at the end to illustrate the methods.
CMR AVR O.C.C. S.C.C.
Continuous Maximum Rating Automatic Voltage Regulator Open Circuit Characteristic Short Circuit Characteristic
Introduction
Abbreviations SCR Short Circuit Ratio TPS Thermal Power Station
Alternators seldom operate in isolated mode. They run in parallel in a power station and the power stations are connected to form the grid. In a large grid system, the load supplied by an alternator is insignificant [1, 2]. So, they are individually considered as one machine on infinite bus, connected through series impedance to the bus as shown in Fig. 1. Multi-machine representation makes the dimension of the model very large and untractable. The alternators may be of the cylindrical pole type (driven by steam turbine) or salient pole type (driven by water turbine). The alternators and hence the parts of the power system, remain synchronized to each other by rotating magnetic field produced by the multiphase windings [3].
& Avik Ghosh [email protected]
The Reactance of Alternators
Keywords Swing equation Transient stability Dynamic stability State space Equivalencing One machine on infinite bus
1
Department of Electrical Engineering, Techno International, New Town, Kolkata, India
2
Department of Electrical Engineering, Ideal Institute of Engineering, Kalyani, India
3
Department of Electrical Engineering, Jadavpur University, Kolkata, India
4
Power Engineering Department, Jadavpur University, Kolkata, India
In the classical analysis, a synchronous generator is represented by a source of emf behind an impedance (or simply a reactance as the effect of resistance is too small), summing up the effect of armature reaction with that of armature leakage. For cylindrical pole machines only a single synchronous reactance suffices but for salient pole machines two synchronous reactance, one for the polar (d-
123
J. Inst. Eng. India Ser. B Fig. 1 One machine on infinite bus through series reactance
axis) and
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