A fault warning for inter-turn short circuit of excitation winding of synchronous generator based on GRU-CNN

Synchronous generators are important components of power systems and are necessary to maintain its normal and stable operation.To perform the fault diagnosis of mild inter-turn short circuit in the excitation winding of a synchronous generator,a gate recurrent unit-convolutional neural network(GRU-CNN)model whose structural parameters were determined by improved particle swarm optimization(IPSO)is proposed.The outputs of the model are the excitation current and reactive power.The total offset distance,which is the fusion of the offset distance of the excitation current and offset distance of the reactive power,was selected as the fault judgment criterion.The fusion weights of the excitation current and reactive power were determined using the anti-entropy weighting method.The fault-warning threshold and fault-warning ratio were set according to the normal total offset distance,and the fault warning time was set according to the actual situation.The fault-warning time and fault-warning ratio were used to avoid misdiagnosis.The proposed method was verified experimentally.

Nonlinear vibration of iced cable under wind excitation using three-degree-of-freedom model

High-voltage transmission line possesses a typical suspended cable structure that produces ice in harsh weather.Moreover,transversely galloping will be excited due to the irregular structure resulting from the alternation of lift force and drag force.In this paper,the nonlinear dynamics and internal resonance of an iced cable under wind excitation are investigated.Considering the excitation caused by pulsed wind and the movement of the support,the nonlinear governing equations of motion of the iced cable are established using a three-degree-of-freedom model based on Hamilton's principle.By the Galerkin method,the partial differential equations are then discretized into ordinary differential equations.The method of multiple scales is then used to obtain the averaged equations of the iced cable,and the principal parametric resonance-1/2 subharmonic resonance and the 2:1 internal resonance are considered.The numerical simulations are performed to investigate the dynamic response of the iced cable.It is found that there exist periodic,multi-periodic,and chaotic motions of the iced cable subjected to wind excitation.

Problems Related to Excitation Winding Surface Temperature Measurement of a Salient Pole Synchronous Generator in Rotation

This paper addresses some of the problems related to direct surface temperature measurement of a salient pole synchronous generator excitation winding in rotation. Excitation winding temperature is used for determining the dynamic limit in a PQ diagram. The paper also addresses procedures of improving the accuracy of surface temperature measurement using the contact DS 18B20 digital temperature probes. The paper also provides experimental results of direct temperature measurement of the excitation winding surface conducted in the salient pole synchronous generator in the rotation.

Influence of Temperature Probes Installation on the Salient Pole to Temperature Measurement

Accurate and reliable information about the temperature of the synchronous generators excitation winding hot spot is necessary to determine the dynamic limit caused by excitation winding overheating in the PQ diagram. For good estimation of a position and the hot spot temperature it is decided to mount 19 temperature probes on one pole of the 6-pole, 400 kVA. 50 llz synchronous generator. Due to a large number of the probes and because the probes should be glued with the metal epoxy it was assumed that mounting of the probes will disrupt the temperature field of the excitation winding. To get the answer to this question the excitation winding resistance was measured betbre and after mounting the probes, in a hot and a cold state. Temperature rise can be estimated if the resistance ratio in the hot and the cold state is known. The paper also addresses the analysis of the measurement accuracy. The result shows that, there is no significant influence on the temperature when mounting the 19 temperature probes which covered 10% of the pole excitation winding surface.