Distance protection blocking and re-opening scheme in multi-machine power system oscillation scenes

Abstract

In view of frequent multi-machine power system oscillations in power grid which may cause traditional oscillation blocking and re-opening schemes to be completely invalid, a distance protection oscillation blocking and re-opening scheme in multi-machine power system oscillation scenes is proposed in this paper. First, the ride-through trajectory of measured impedance in multimachine power system oscillation cases and its effect on the operation characteristic of distance protection is analyzed, and the oscillation blocking scheme is formed by combining the operation status information of protection components on 2 line ends. And then, in the oscillation blocking duration, by calculating the estimated error of the dynamic phasor of measured current at the relaying point, the protection re-opening scheme for symmetrical fault during oscillation is established. Finally, simulation tests on PSCAD in 3-machine system and IEEE 39-bus system verify that the proposed scheme could reliably block the protection when oscillation occurs in multi-machine power system, and re-open the protection accurately and reliably when symmetrical fault occurs during oscillation. KEYWORDS distance protection, dynamic phasor, multi-machine power system oscillation, oscillation blocking 1 | INTRODUCTION When power system is disturbed by factors such as transmission line fault and heavy-load line switch on/off, etc., oscillation will easily result. 1 The incorrect operation of distance protection on transmission line which identifies whether fault occurs by calculating the measured impedance during oscillation will enlarge the influence range of oscillation, greatly endangering the safe and stable operation of power system. 2 In regional inter-connected power grid that is becoming ever more complicated, the probability of multi-machine power system oscillation is also increasing rapidly, 3 in which case the oscillation center may move dynamically along different routes, causing traditional double-source analysis model to be invalid. 4,5 Therefore, it is urgent to study in depth the effect of multi-machine power system oscillation on existing protection policy and put forward effective oscillation blocking and protection re-opening scheme.Currently, research on oscillation blocking is mostly based on 2-generator model and is mainly focused on the following aspects. First, identification criteria based on swing center voltage (SCV) could realize re-opening for symmetrical fault during oscillation, with certain time delay. 6,7 Second, identification criteria based on the compensation principle could determine whether it is oscillation or short circuit fault that occurs within the protection range, but it is difficult to set the compensation value when the line is heavily loaded. 8,9 Third, identification criteria based on the apparent

Métodos de Bloqueio por Oscilações de Potência: Uma Análise em Linhas de Transmissão de Três Terminais

“…Segundo Mohamad et al (2012) contribuição de corrente IC, é também chamada de corrente infeed quando está em fase com IA, e como outfeed quando sua fase é oposta à de IA. A equação 1 mostra que a impedância aparente Zapp, vista pelo relé 1, do terminal A, quando a derivação (T) estar em fase com IA, é superior a impedância factual à falta: (ZAT + ZAF) (MA et al, 2018). Sendo assim, há variação em relação ao comprimento de LT para cobertura do relé de distância em situação em que o terceiro terminal não esteja presente.…”

Improved zone-3 distance protection based on adjacent relays data

“…The abovementioned methods in the literature [6][7][8][9][10][11][12] have the advantage of using local data. However, they could not consider all possible circumstances, because of their limited access to the power network data.…”

“…To solve the problem using local data, some algorithms are proposed in the literature based on derivatives of voltage and current, fault and circuit breaker opening traveling waves, and derivative of impedance in combination with the conventional zone‐3 scheme . In Ma et al, a blocking and re‐opening scheme is proposed for distance relays to improve their performance during power swings based on calculating dynamic phasors through least squares optimization. A zone‐3 protection scheme based on combining the steady state and transient components of the voltage signal has been discussed in Kim et al However, for implementing such a high‐frequency component‐based method, special measurement devices are required.…”