Power-system protection

About: Power-system protection is a research topic. Over the lifetime, 6353 publications have been published within this topic receiving 117961 citations.

Analysis of electric power system disturbance data

Abstract: In this paper, NERC (North American Reliability Council) records of power System disturbances for the year 1984 through 1999 are explored. The disturbance sizes show a power law distribution, which confirms the early results [2]. Further, we find that the probability density of time intervals between disturbances can be given an exponential fit. Based on this observation, the suitability of applying SWV analysis to power system disturbance data is questioned. An artificial time series is constructed to support our idea. A fuse model using DC load flow and fuse protection is presented to simulating the cascading events in power transmission networks. Some initial simulation results are shown to be consistent with NERC data. Besides SOC and HOT, this model gives another way to investigate power law behavior in power system disturbances.

New technique for frequency and amplitude estimation of power system signals

Abstract: This paper describes the design, analysis and computational aspects of a technique for the measurement of power system voltage, current and frequency. This technique can be used in a digital AVR for the state estimation of turbine-generator terminal quantities or in a digital relay for protection of a power system. This technique provides fast and accurate estimation of power system frequency, and is used in a Kalman-filtering algorithm to estimate power system voltage and current signals. Practical considerations such as the effect of power system harmonics, noise, frequency changes, mechanical and electrical load changes are taken into account during implementation of this technique. Several computer simulation tests are presented to highlight the usefulness of the technique. Simulation results show that the technique can simultaneously estimate the amplitude and frequency of a sinusoidal signal, even in the case that the signal is distorted by harmonics or noise or encounters frequency changes.

A new digital directional transverse differential current protection technique

Abstract: Recently, several papers have discussed the protection of parallel transmission lines connected to common buses. The main purpose of this paper is to discuss problems associated with parallel line relaying schemes, which depend upon the theory of transverse differential protection relaying, and to present a new advanced technique to overcome these problems. The suggested technique relies on current incremental signals in corresponding phases instead of current magnitude. This method eliminates many of the associated problems typically encountered in this area. The possibility of applying the suggested technique on parallel three-terminal power transmission lines was investigated and satisfactory results were recorded. The voltage signal and the communication channel have been excluded from this study.

Short-Circuit Fault Protection Strategy for High-Power Three-Phase Three-Wire Inverter

Abstract: This paper proposes a four-stage fault protection scheme against the short-circuit fault for the high-power three-phase three-wire combined inverter to achieve high reliability. The short-circuit fault on the load side is the focus of this paper, and the short-circuit fault of switching devices is not involved. Based on the synchronous rotating frame, the inverter is controlled as a voltage source in the normal state. When a short-circuit fault (line-to-line fault or balanced three-phase fault) occurs, the hardware-circuit-based hysteresis current control strategy can effectively limit the output currents and protect the switching devices from damage. In the meantime, the software controller detects the fault and switches to the current controlled mode. Under the current controlled state, the inverter behaves as a current source until the short-circuit fault is cleared by the circuit breaker. After clearing the fault, the output voltage recovers quickly from the current controlled state. Therefore, the selective protection is realized and the critical loads can be continuously supplied by the inverter. The operational principle, design consideration, and implementation are discussed in this paper. The simulation and experimental results are provided to verify the validity of theoretical analysis.