摘要:

AbstractBased on the results of its inspection items, the failure diagnosis system identifies the cause of system failure. The role of failure diagnosis is to identify the system state correctly. However, diagnosis errors may be caused by sensor failure or operator errors, which lead to serious damage or unnecessary protective actions. The effect of an error depends on the system condition. In the design of a failure diagnosis procedure, not only diagnosis error probabilities, but also the effect of diagnosis error on the system must be considered.This paper proposes the optimization of failure diagnosis procedures based on diagnosis error loss. The optimal procedure that minimizes the expected loss caused by inspection errors is developed for two cases: one where all results of inspection items are given simultaneously, and one where an inspection item is examined sequentially. In the former case the optimal failure diagnosis logic is obtained, while in the latter case the optimal test sequence is developed. Illustrative examples show the merits and details of the proposed method.

ISSN:0424-7760    

DOI:10.1002/eej.4391160111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY

摘要:

AbstractIt is difficult to determine the subtransient (transient) reactance and subtransient (transient) short‐circuit time constants of medium and large synchronous machines by the sudden three‐phase short‐circuit test because large‐capacity equipment is required.This paper describes a new method of measuring these constants by means of a simple test using a small dc power supply.The key points of this method are as follows.(1) A dc voltage is applied to the armature winding (two terminals with the third one open) of a stationary synchronous machine through a resistance. When the two terminals are closed, the winding is short‐circuited and the current in the armature winding decays. The whole process of decaying current is recorded.(2) The value of the transient phenomena of the winding calculated from circuit equations (armature, field winding and damper winding circuits) is compared with actual data, and the unknown equivalent circuit constants are identified by the least squares method.(3) Transient phenomena of the sudden three‐phase short‐circuit are calculated by the two‐reaction theory using identified constants, and, hence, these constants are calculated.The transient constants of synchronous machines obtained by the new method agree closely with the

ISSN:0424-7760    

DOI:10.1002/eej.4391160112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1996

数据来源: WILEY