Phase Grounding Fault Research Articles

Ground distance relaying algorithm for high resistance fault

This study proposes a new fault impedance estimation algorithm of phase-ground fault for ground distance relaying based on the negative-, zero- and comprehensive negative–zero-sequence current component. The principle is based on the assumption that fault path is purely resistive, and the phase angle of fault point voltage and fault path current is equal to construct the fault impedance estimating equations for ground distance relay, which can eliminate the effect of fault path resistance, load current and power swing. PSCAD software simulations show the accuracy of proposed algorithm.

Performance of the .+-.80MVA GCT STATCOM Under Commercial Operation

This paper presents a newly developed an 80MVA GCT STATCOM for the Kanzaki substation of the Kansai Electric Power Co., Inc. The commercial operation was started in June, 2004. The main purpose of the STATCOM is to maintain voltage during single circuit connection of source to the substation resulting from an AC system fault in order not to break down load system of the substation. The developed STATCOM has three distinctive features: (1) a high-efficient, compact and AC filter-less system using multistage three-level GCT converter and customized harmonics reduction PWM; (2) a coordinated voltage regulator with tap control of main transformers; and (3) a continuous operation from a single phase-ground fault through reclosing of the faulted circuit by limiter adjustments of the reactive current reference. This paper describes characteristics of the coordinated voltage control in the substation, and shows performance of the continuous operation during AC system faults using data of commercial operations and the simulation results.

퍼지클러스터링 기법과 신경회로망을 이용한 고장표시기의 고장검출 능력 개선에 관한 연구

본 논문은 전력계통의 배전계통시스템에서 FRTU(Feeder remote terminal unit)의 고장검출 알고리즘의 개선에 관한 연구이다. FRTU는 상과 지락에 관한 고장검출을 할 수 있다. 특히 고장픽업 기능과 돌입억제기능은 일반적인 부하전류로부터 고장전류를 구별할 수 있다. FRTU는 돌입전류 또는 설정값을 초과한 고장전류가 발생하면 고장표시기(FI)로 고장을 발생한다. 짧은 시간 푸리에 변환(STFT) 분석은 주파수와 시간에 관한 정보론 제공하고, 퍼지 중심 평균 클러스터링(FCM) 알고리즘은 고조파의 특성을 추출한다. 고장 검출기의 신경회로망 시스템은 최급강하법을 이용하여 고장상태로부터 돌입전류를 구별하도록 학습된다. 본 논문에서는 FCM과 신경회로망을 이용하여 고장검출기법을 개선하였다. 검증에 사용된 데이터는 22.9KV 배전계통 시스템에서 실제 측정된 데이터이다. This paper focuses on the improvement of fault detection algorithm in FRTU(feeder remote terminal unit) on the feeder of distribution power system. FRTU is applied to fault detection schemes for phase fault and ground fault. Especially, cold load pickup and inrush restraint functions distinguish the fault current from the normal load current. FRTU shows FI(Fault Indicator) when the fault current is over pickup value or inrush current. STFT(Short Time Fourier Transform) analysis provides the frequency and time Information. FCM(Fuzzy C-Mean clustering) algorithm extracts characteristics of harmonics. The neural network system as a fault detector was trained to distinguish the inruih current from the fault status by a gradient descent method. In this paper, fault detection is improved by using FCM and neural network. The result data were measured in actual 22.9kV distribution power system.

A nonpilot phase selector based on superimposed components for protection of double circuit lines

This paper gives details of a new phase-selection scheme for simultaneous phase-ground faults on both circuits of double circuit EHV transmission lines. Fast phase selection (within half a cycle) can be achieved by using the information contained within the fault transients. The theory is presented along with results obtained through simulations using EMTP. The scheme enables single pole tripping to be employed for simultaneous faults. The proposed scheme does not require communication between the two ends of the line. Limitations due to the low bandwidth of CVTs have not caused problems and the method has shown immunity to system noise.

Transient performances of the 20 kVA superconducting synchronous generator in power systems

This paper describes the electrical transient performance of the experimental superconducting synchronous generator. The generator is connected to a regional power system through two artificial transmission lines in parallel. Several experiments to make clear the transient behavior of the SCG in the power system have been performed. The experiment items are as follows; (1) Steady state stability test by a quasi-stationary increase of the generator output. (2) Disconnecting and reclosing of either line of the transmission lines in parallel. (3) Three-phase grounding fault at the midpoint of the transmission line with reclosing after clearing the fault. (4) Transient stability test by three phase grounding fault with reclosing after clearing the fault. The variations of the terminal voltage, the armature current and the output power of the SCG for these tests have been measured and discussed. In order to understand the transient behavior of SCG's, the transient analysis by a computer simulation was carried out for the experiments. The simulation results are in good agreement with the experimental results. By use of the simulation results, we calculate the torque and the Joule heating of the cold and the warm dampers for the transient state.