Adaptive Impedance Relay with Composite Polarizing Voltage
Fault resistance can bring some disadvantages for an impedance relay while a single-phase-to-ground fault occurs on transmission line. Taking advantage of the compensated voltage changing with fault resistance, this paper presents a kind of adaptive impedance relay with composite polarizing voltage to enhance the capability against fault resistance. On the other hand, the operating boundary of the adaptive relay may enter into "in-phase" region along with the increase of fault resistance. To prevent the adaptive relay from the "in-phase" problem, a new additional blocking component is proposed in this paper. Both the adaptive relay and the blocking component are all analyzed in the voltage plane and the impedance plane. Theoretical analyses show that both of them have circular characteristics with greater resistive tolerance. The performance of the relay has been demonstrated on a two-source 500 km line 750 kV system.
TWO NEW EARTH-FAULT REACTANCE RELAYS BASED ON FAULT-COMPONENT
Based on the theoretical analysis of high-resistance earth-fault characteristics of HV/EHV transmission line, two kinds of new type earth-fault reactance relays based on fault-component are proposed in this paper, these relays can overcome the overreach problem existed in the earth-fault distance protection with excellent performance within the protective zone. The steady-state characteristics of these protective relays are studied thoroughly in the paper.
ANALYSIS OF BOLT′S ANCHORING QUALITY BASED ON WAVELET NEURAL NETWORK
The dynamic response of bolt achieved by impact-echo method can be effected easily by some factors.It′s difficult to classify bolt′s anchoring quality according to the dynamic response of bolt.In this paper,a new analytical method of bolt′s dynamic response is put forward.The new analytical method combing with advantages of wavelet analysis and artificial neural network is presented.Firstly,the dynamic response of bolt by numerical simulation software FLAC3D is obtained.Secondlyt,he features are extracted from the dynamic response of bolt by wavelet analysis.Thirdlyt,hese features are fed into the artificial neural network for training.Finallyt,his artificial neural network to classify the bolt′s anchoring quality intelligent according to the dynamic response of bolt is employed.In order to validate this new analytical method,some practical signals of bolt′s dynamic response are used for the test.The results indicate that the new analytical method is practicable.