An Improved Detection Method for Short Circuit Fault of Excitation Winding of Turbine Generator

Abstract

The invention discloses an improved short-circuit fault detection method for the excitation winding of a turbogenerator, which comprises the following steps: A. Obtaining generator parameters and characteristic curves; B. Establishing a two-dimensional numerical simulation model of the generator and calculating the stator current load Value, the excitation winding applies a small initial value If1, and calculates the electromagnetic torque TM1'; C. Keep the three-phase current loading value of the stator unchanged, increase the excitation current cyclically at intervals of ΔIf, and calculate the electromagnetic torque, and get (Ifi , TMi') array; D, carry out quadratic function fitting to above-mentioned array, obtain function TM'=f(If); E, calculate the actual value of generator electromagnetic torque; F, make TM=TM', solve excitation Current value; G, cyclically change the value of P and Q, and calculate the If of each working condition; H, use If, ​​P and Q to form a three-dimensional grid-like surface to calculate If of any working condition; I, the excitation current value obtained in step H Compare with the measured value to judge whether there is a failure. The invention can improve the deficiencies of the prior art and improve the diagnostic sensitivity of the excitation current method.

Description

technical field [0001] The invention relates to the technical field of turbogenerators, in particular to an improved on-line detection method for short-circuit faults of excitation windings of turbogenerators. Background technique [0002] Excitation winding short circuit is a common turbogenerator fault, and it has a growing trend in my country in recent years. Experience has shown that minor turn-to-turn faults in the rotor winding will not have a serious impact on the generator, and the fault characteristics are not significant, making the fault hidden; however, if the fault is not dealt with in a timely and effective manner, it may further develop and Especially when there is a strong negative-sequence magnetic field in the generator, the current flowing through the inter-turn short-circuit point is relatively large, which may lead to further deterioration of the fault and pose a greater threat to the safe and stable operation of the unit itself. [0003] Excitation win...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that when a slight short-circuit fault occurs in the excitation winding of the turbogenerator, the deviation between the theoretical value of the excitation current and the actual value is not large. There is a direct proportional relationship between the no-load electromotive force and the excitation current during operation. In fact, the linearity between the two is not ideal, which leads to an increase in the calculation error of the theoretical value of the excitation current. Diagnosis System (RDST) User Manual "When using the excitation current method to diagnose the short circuit fault of the excitation winding, the diagnostic threshold is set to 5%, and only when the deviation between the theoretical value of the excitation current and the actual value exceeds 5% can it be determined that there is a short circuit between turns of the rotor failure, its sensitivity is clearly insufficient

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