Analysis of losses in cables and transformers under power quality related issues (original) (raw)

This paper deals with the topic of power quality in a local distribution grid. It is aimed to analyze the individual influences, which aggravate the power quality of the distribution grid. Based on the analysis, the most adverse effects were determined, and they were the voltage drops and supply voltage interruptions, supply voltage unbalance, load power factor, and also higher harmonics. These influences cause the technical losses in a distribution grid, which subsequently have a financial impact not only on the distribution, but also on the transmission of electricity. Only the load voltage unbalance, the load power factor, and the higher harmonics, which mainly cause the technical losses, were analyzed in this paper. The measurement of the influences of the adverse effects was performed on the model of a 22-kV distribution grid. The measurement was performed on the basis of three types of power line conductors and their different lengths, three types of active power consumption, ...

Normally, the electric networks are considered as linear balanced systems; as a result, their analysis based on positive sequence representations was generally satisfactory. The situation has changed significantly in the recent years, as more and more harmonic-producing equipment connected to the public distribution systems represents three-phase unbalanced loads. On the other hand the effects of single phase non-linear loads are also becoming important. As a consequence, it is necessary to investigate more detailed the effects of these new operation conditions on the components of the power systems, especially for power transformers. Transformers' power losses can be divided into two main components: no-load losses (hysteresis and eddy current losses) and load losses (ohmic heat losses and conductor eddy current losses). There are, however, other two types of losses in the above mentioned working conditions, namely extra losses created by harmonic and unbalanced currents, resp...

In recent years, by the construction of electricity market and introduction of electric energy as a commodity, power loss reduction is of paramount importance for utilities. Distribution system losses are comprised of technical and nontechnical parts. Technical and non-technical losses are related to physical features and impermissible use of electricity, respectively. The first step toward power loss reduction is to determine the reasons behind power loss and its quantity. Recent researches mainly focused on overall power loss in a wide region. However, it is required to initiate with partial power loss of a transformer and reach a large region step-by-step in order to determine the contribution of each part. In this paper, methods are proposed to calculate power loss in a typical distribution transformer feeder and then the obtained results are compared with actual measurements. Therefore, a distribution transformer equipped with a data logger (DL) in Mashhad City (Ommat 9region) ...

Today, the electric power systems have a working state characterized by the existence of electromagnetic perturbations. Nonlinear devices are becoming a bigger part of electrical load in industrial and commercial networks. The modern electronic equipment and technologies existing to the domestic and industrial consumers, and the modern artificial lighting sources whose working principle is based on electric arc discharging represent the main cause of the harmonic pollution. The unbalanced loads are also presented in great number. The paper presents a method for determination of power losses in electrical networks working in different conditions: balanced and harmonic polluted, unbalanced but not harmonic polluted, and unbalanced and harmonic polluted. An evaluation of the economic impact produced by the pollution level is performed for several typical electric conductors.

Due to high application of non-linear loads and energy-saving devices at low voltage networks, power quality (PQ) assessment and investigation becomes an important requirement for electrical systems. Such a step is required to reveal the current situation of power quality, identify the margin from the unsafe boundary and take necessary remedial actions. The purpose of this paper is to investigate and assess the current situation of power quality of a low voltage distribution system within the Jordanian electrical system. The study was conducted for aggregated commercial and residential facilities. Several power quality parameters are monitored: Voltage distortion, current distortion, and power factor. Detailed measurement results and analysis are presented and explained. Among different power quality disturbances, load unbalance and distorted waveform of the current are observed. The results show that current unbalance reaches as high as 56% of the phase current. High total harmonic distortion (THD) level in the current is also observed. Its maximum value reaches 30.36%, while the Total Current Demand Distortion (TDD) level reaches as high as 10%.

The paper inhere discusses the impact of renewable distributed generation sources upon the power and energy losses in electrical distribution power networks where these sources are attached. In addition a set of mathematical expressions to calculate these active power and energy losses are presented with the respective examples and implementation.

Efficient use of energy, the increase in demand of energy and also with the reduction of natural energy sources, has improved its importance in recent years. Most of the losses in the system from electricity produced until the point of consumption is mostly composed by the energy distribution system. In this study, analysis of the resulting loss in power distribution transformer and distribution power cable is realized which are most of the losses in the distribution system. Transformer losses in the real distribution system are analyzed by CYME Power Engineering Software program. These losses are disclosed for different voltage levels and different loading conditions.