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The paper presents a brief overview of the standard IEC60255–121 and focusses on the challenges and advantages of using transient simulation for assessing protective relays. The importance of the use of statistical methods to investigate the behaviour of algorithms is discussed. Finally a new solution for performing these kinds of tests is introduced.
A new method for detection occurrences of CT saturation is presented in this paper. The presented algorithm applies only first order derivatives of signals which is possible it has been designed in a new innovative methodology in which phase current signals are considered as coordinates of a 3D vector. The proposed algorithm is compared with standard one applying secondary current signal combined...
A transient fault information based IED integrating protection fault location, fault record, measurement and control functions for transmission line is proposed in this paper. IED hardware scheme adopts multiple CPU distributed structure, and includes mainly the following modules: process level communication module, protection module, fault location and record module, measurement and control module,...
A single-machine-equivalent (SIME) based emergency control (EC) scheme that incorporates synchronized measurements is described in the paper. This EC scheme resolves the transient stability problems experienced when serious disturbance occurs on critical transmission lines. The control actions are based on modifying the impedance of a thyristor controlled series compensator (TCSC). The SIME approach...
Autoreclosure provides a means of improving power transmitting ability and system stability. The conventional reclosure adopts the fixed dead time interval strategy, that is, the reclosure is activated after a time delay to restore the system to normal as quickly as possible without regard to the system conditions; however, these simple techniques cannot give the optimal operating performance. For...
This paper presents a new multi-criteria stabilization algorithm of transformer differential protection. Proposed scheme bases on new criteria signals and appropriate operation thresholds. New algorithm employs fuzzy reasoning technique for better discrimination of inrush conditions. The developed stabilization algorithm has been tested with ATP-EMTP generated signals, proving to be reliable and much...
The paper describes a Transient Bias technique designed to overcome the effects of Current Transformer (CT) saturation, which might severely affect the behaviour of a protection system. This Transient Biasing, as the name implies, is only active during transient conditions in the power system, and it decays quickly once the transients disappear. A complementary algorithm for fast detection of external...
This paper presents a novel protective concept for EHV Three-terminal transmission line, teed circuit. The proposed protective relaying techniques use the fourth sequential overlapping derivative, SOD, concept at all line terminals. The SOD signals represent the transient components initiated due to fault occurrence. Such signals are free of both dc and fundamental components. Two protective relaying...
Protection of an inverter dominated microgrid is always a great challenge, as inverters are well known for their insufficient contribution to the fault current, undermining the accuracy and viability of traditional overcurrent protection schemes. Based on the wide review of solutions developed in the past, this paper proposes a novel protection strategy, with the main protection method based on the...
Transformer differential protection schemes normally use multi slope characteristics to provide stability during CT saturation with 2nd harmonic restraint or blocking for inrush conditions. This paper presents new algorithms that have been developed to improve the performance of the differential protection. Extensive testing has been used to demonstrate that the transient bias algorithm can reduce...
Based on the basic voltage and flux equations of the Doubly Fed Induction Generator, this paper derived expressions of short-circuit current of wind turbines, which are expressed by transient equations of stator and rotor flux. The transient equations of stator and rotor flux were functions of initial values of stator and rotor flux and transient time constants of stator and rotor windings. The initial...
Due to the distributed capacitance, the conventional current differential protection has unsatisfying performance. Considering matrix pencil algorithm can accurately analyze the composition of fault transient currents, a novel pilot protection principle using only current data is proposed in this paper to solve the above problem. This principle adopts model recognition concept. Firstly, the theoretical...
The present transmission systems are rapidly changing principally due to an increasing demand for better utilisation of existing lines resulting in lower transient stability limits, and also due to an increase in the complexity of the networks with small-scale distributed generation being connected into the existing networks. The current protection/fault location techniques are not conducive to such...
This paper presents an approach based on the wavelet transform for analysing transmission line transients in order to locate faults. The basic theoretical aspects related to fault transients are first presented. Then, a methodology is proposed to estimate the fault location taking into account voltage signals only, measured from one terminal. The mother wavelets are inferred from the analysed signals,...
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