ANALIZA TEORETYCZNA POWSTAWANIA I KOMPENSACJI MOCY BIERNEJ W ELEKTROWNIACH FOTOWOLTAICZNYCH

The paper is focused on the theoretical analysis of potential options of reactive power origin and its compensation in photovoltaic power plants. In the first part of paper parts of photovoltaic power plants, which can be a source of inductive or capacitive reactive power are described. The second part describes a compensation of reactive power and reasons of requirement of reactive power compensation. Further we describe the basic types of the presently most frequently used reactive power compensation equipment in photovoltaic power.Artykuł poświęcony jest teoretycznej analizie potencjalnych możliwości powstawania mocy biernej w elektrowniach fotowoltaicznych i jej rekompensacji. W pierwszej części opisano elementy składowe elektrowni fotowoltaicznych, które mogą być źródłem indukcyjnej lub pojemnościowej mocy biernej. W drugiej części opisano kompensację mocy biernej i ze przyczyny wymogu kompensacji mocy biernej. Następnie analizowane są podstawowe typy najczęściej obecnie stosowanych urządzeń do kompensacji mocy biernej w elektrowniach fotowoltaicznych

Comparison of Reconfigurations Using Deterministic Approach for Global Assessment of Operational State in Power System

This article deals with the analysis of impact reconfiguration on the power system operational state. The stated analysis assess results of the simulated calculations of N-1 events with the aim to obtain a more complex view of the security criterion N-1 use in comparison with the current methods and procedures being in practice. Methodologies based on the deterministic approach arising from calculations of steady states with the global assessment of the power system operational states are presented. The article objective is to comprehensively compare the selected operational states especially different reconfiguration variants in a power system

AUTOMATED SYSTEM FOR SMART METER TESTING

AbstractSmart metering is debated issue currently. It is a consequence of the introduction of this technology into practice,a many of pilot operations and the effort find the optimum technology for each area. The aim of the paper is asystem for testing of selected functionalities of smart meters. In particular, the ability to evaluate the power qualityparameters such as waveform distortion, detection of maximum and minimum values and other parametersdefined in the standard STN EN 50160. Described system is under development and testing, so some functionalitywill put the finishing touches according to current requirements.Key wordsSmart meter, measuring, harmonics, testin

IMPACT OF FAULTS IN TRANSMISSION AND DISTRIBUTION NETWORK ON VOLTAGE SAGS

AbstractThis article deals with the issue of evaluation of voltage sags based on the analysis of the impact of different faulttypes in power systems. The aim is to identify a range of influences of considered faults on voltage sags in theindustrial low voltage network. The analysis is based on the simulation calculation of selected faults to classifynegative effects causing potential improper operation of industry equipment due to faults in the power system. Inthe paper are also described options of proposed measures for minimization of these phenomena.Key wordsShort-circuit, earth fault, voltage sag, industrial network, distribution system, simulation

Stochastic Approach for Increasing the PV Hosting Capacity of a Low-Voltage Distribution Network

In recent years, the emerging fear of an energy crisis in central Europe has caused an increased demand for distributed energy resources (DER), especially small photovoltaic rooftop installations up to 10 kWp. From a technical point of view, distributed PV in low-voltage networks is associated with the risk of power quality violation, overvoltage, voltage unbalance, harmonics, and violation of the thermal limit of phase conductors, neutral conductors, and transformers. Distribution system operators (DSO) are currently in a position to determine the amount of installed PV power for which reliable and safe network operation is ensured, also known as the photovoltaic hosting capacity (PVHC). The presented study describes a stochastic methodology for PVHC estimation and uses it to analyze a typical LV rural network in the Slovak Republic. Detailed and precise calculations are performed on the 4-wire LV model with accurate results. In this study, we, thus, profoundly analyze the problems with voltage violation, unbalanced voltage energy losses, and the thermal loading effect of increasing PV penetration. The results show that overvoltage events are the main factor limiting the PVHC in LV systems. This conclusion is in accordance with the experience of the DSO in the Slovak and Czech Republic. Subsequently, the study focuses on the possibilities of increasing PVHC using those tools typically available for DSO, such as changes in PV inverter power factors and no-load tap changer transformers. The results are compared with those derived from similar analyses, but we ultimately find that the proposed solution is problematic due to the high variability of approaches and boundary conditions. In conclusion, the paper discusses the issue of the acceptable risk of overvoltage violation in the context of PVHC and lowering losses in LV networks

Three-Phase and Single-Phase Measurement of Overhead Power Line Impedance Evaluation

Calculation and measurement of the overhead power lines electrical parameters is common practice in today’s electrical engineering industry; however, there is very little data to actually compare these two approaches because measured data in such detail are mostly unavailable for academic purposes. Based on the very detailed model of an overhead power line in MATLAB Simulink environment and conducted experimental measurement, this article specifically covers the exact evaluation of the impedance of the investigated overhead power line. Differences between calculation and experimental measurement are shown and discussed accordingly, where, surprisingly, the biggest deviation was observed in the positive resistance parameter. The connection between different measurement techniques (multiple single-phase and three-phase methods), as well as the power line asymmetry reflection in the impedance matrix is explained as well as compared to expected values from the computations. The complete mathematical approach for electrical parameters evaluation from different measurement methods is explained step-by-step, and the final equations are introduced for each method. Proposed methods of obtaining the electrical parameters of the power line are then concluded as the ones with great accuracy and wide usage in practical applications. It shows the great importance of correct input data for the electrical parameters’ theoretical computations and the need to know the measurement methodology and apparatus perfectly to process the measured data and interpret them correctly