The paper presents a new method for on-line temperature calculation taking into account change in the tap changer position. The method introduces accurate calculation of the losses, depending on the current, average temperature of the winding, and tap changer position (it affects both Joules (DC) losses and stray losses). The thermal model itself is the common three-body model (for a transforme...

The paper presents a concept of utilizing wind farms in a process of voltage control in 110 kV distribution grids. It has been shown that when properly controlled, a wind farm can assist in decreasing voltage variations in a HV grid caused by daily load variations.It has been also shown that stabilization of HV grid voltage caused by the influence of a wind farm is reflected with decreased freq...

In the future grid, power equipment will need to work with distributed generation, deregulation, and accelerated ageing. To this end, a model-based framework for the optimization of usage of power equipment is proposed. The framework uses a predictive health model of the equipment in order to optimize the usage of the equipment. In particular, the predictive health model predicts the hot-spot t...

Discrete-event systems (DES) can be found as essential integrated subsystems in many complex systems, e.g. electrical power systems. Under-load tap-changing (ULTC) transformers which obviously have discrete-event behavior are widely used in transmission systems to take care of instantaneous variations in the load conditions in substations. In this paper, the voltage control problem in ULTC is s...

The transformers which connect the different voltage levels in transmission and distribution systems are supplied with on-load tap changing mechanism. The on-load tap changer maintains the voltage amplitude within the predefined limits at the so called regulation bus. In a radial feeder, the on-load tap changers are cascaded. Poor coordination between cascaded tap changers causes improper volta...

Transmission System Operators (TSOs) are currently experiencing a voltage rise problem on their network, especially during the periods of low demands. It is costly to mitigate the excessive voltages by installing reactors or Var compensators in transmission network. Recently, an alternative method of utilising the existing parallel transformers of distribution network is proposed. It uses a tap...