Search

This paper presents the theory and methodology for the adjustment of the negative sequence current protection function (PF) ANSI 46 of a synchronous generator with poles and poles, for a multifunctional relay SIEMENS 7UM62 that uses for its logic of decision the curve of time of heating allowed of the machine before the increase of the magnitude of negative sequence Also the consequences and the damages that can be caused by the excess of current of negative sequence circulating by the stator of the generator are explained. In addition, its functional diagram is illustrated by identifying its input signals: data (settings), analog and binary signals; It also describes in detail its decision process and exit signals. This logical diagram was divided into 3 sub-diagrams to identify the causes that originate their outputs: alarms, startup, firing or blocking, this way of illustrating the process by stages allows greater clarity, since the explanation process is more didactic than the one presented by the manufacturer in the manual. As an example of an illustration, the calculations of the adjustment criteria of the ANSI 46 PF applied to a salient pole generator from Unit 1 of the Salvajina Hydroelectric Plant are presented in detail. This protection function protects the machine by heating load imbalance and asymmetric faults. [ABSTRACT FROM AUTHOR]

In this work, a black-box model for the estimation of the rotor angle of a synchronous generator is developed by using voltage and current measurements at the terminals. The model is based on neural networks of the multilayer perceptron (MLP) type. From time-domain simulations for a basic power system, which consists of a generator connected to an infinite bus bar, voltage and current records are collected, which are used as a database to train and validate the neural network that is proposed for the estimation of the rotor angle. It is found that the neural-network based model adapts itself very well to the classic model of the generator, exhibiting a mean square error of 1x10-10. The results show the validity of the estimation method and foster its potential use for stability studies of the synchronous generator. [ABSTRACT FROM AUTHOR]

In this paper, we make an evaluation of the complete ground-fault protection of the stator of synchronous generators by use of the subharmonic injection method. Firstly, we describe two approaches for the complete protection of the stator: the third harmonic method and the method of subharmonic injection. Secondly, we analyze the error in the determination of the ground-fault resistance for an 11.4 kV synchronous generator from the consideration of various operating conditions. This error is related to the type of voltage transformers being used, the occurrence of signal noise, the digitalization process, and variations in the numerical values of the required parameters. Lastly, we show that the subharmonic injection method is very useful for the determination of the ground-fault resistance and performs well for the complete protection of the stator. [ABSTRACT FROM AUTHOR]