Intriguing mal-operations and fail-to-trip of the differential protection of the converter transformer in the HVDC system are reported. In this paper, the mechanism of these abnormal operation behaviors is analyzed. By virtue of deliberately designed models of the converter transformer and the HVDC transmission system, a variety of simulation tests are carried out and above mentioned strange op...

Autotransformers (ATs) have been widely used for many years. For large size ATs, a tertiary winding is usually included. Sometimes the tertiary winding is loaded for station service, local loads, VAR compensation, etc. Other times, the tertiary winding is buried and acts as stabilizing winding which provides a path for zero-sequence current and 3rd harmonic current. Three-winding ATs present so...

The reliability of the transformer differential protection is under threat from multiple interferences, including inrush condition, current saturation and arc fault condition. For improvement, a new method proposed to discriminate conditions other non-fault conditions. Firstly, identifies unidirectional via index, since only it exhibits characteristic. Then, remaining signals are classified by ...

This paper presents an efficient wavelet and neural network (WNN) based algorithm for distinguishing magnetizing inrush currents from internal fault currents in three phase power transformers. The wavelet transform is applied first to decompose the current signals of the power transformer into a series of detailed wavelet components. The values of the detailed coefficients obtained can accurate...

With the evolution of Process Bus (IEC 61850-9-2), there is a need to assess the performance of protection schemes using process bus against those where traditional copper wires are implemented. Differential protection is the fundamental and most commonly used protection for transformers, motors and generators. In this paper a power system is modelled in SimPowerSystems and is executed in real-...

Abstract: Power transformers are one of the most important electrical equipment that are used in power transmission system as they perform the function of transforming the voltage levels. Hence maintenance of power transformer is mandatory; as they are located at different geographical areas periodical monitoring is not possible all the time due to insufficient man power. Due to this reason tra...

This paper is concerned with the protection of wind energy systems against the direct effects of lightning. As wind power generation undergoes rapid growth, lightning damages involving wind turbines have come to be regarded as a serious problem. Nevertheless, very few studies exist yet in Portugal regarding lightning protection of wind energy systems using numerical codes. A new case study is p...