AC Power and Energy Measurements based on Physical Definitions

The article presents the AC power measurements based on physical definitions as introduced by the draft German standard DIN 40110 in 1970 and its practical application as a power signal processor. The power processor is an electronic device allowing separation of the measured power signal (obtained from the multiplier circuit of voltages and currents) in two components: P+ and P- defined as the input power Pv and return power Pr. The separation is obtained by shifting the phase angle between the current and voltage. The value of return power is negative. Such separation is natural because it is based on physical phenomena of delivered, useful energy and harmful return energy flows. Return power is considered harmful because it causes heating of cables and sources of AC power (as transformers). Presented concepts and meters can be useful for accurate billing purposes for delivered electrical energy as well as for dynamic compensation of nonlinear loads to reduce the return power. Experiments realized using the power meter WL-1 synchro (operating according to physical definitions) confirms high percentage of return power for nonlinear loads, as AC powered LED light sources where the amount of return power can reach 70% of delivered power

Koncepcje zabezpieczenia przeciwporażeniowego instalacji elektrycznych budynków jednorodzinnych wyposażonych w źródła odnawialne

Nieostrożne używanie sprzętu elektrycznego, naprawa urządzeń i instalacji elektrycznej przez osoby nie posiadające odpowiednich kwalifikacji, powoduje, że prąd elektryczny może stać się śmiertelnym zagrożeniem. Przyczyną około 70 % wypadków porażenia lub poparzenia prądem elektrycznym jest niewłaściwe postępowanie człowieka, wynikające z braku umiejętności, lekkomyślności lub niedoskonałością techniczną rozwiązań instalacji elektrycznych. Dlatego podstawowa znajomość przepisów bezpieczeństwa w tej dziedzinie powinna być znana społeczeństwu. Miarą oceny stanu bezpieczeństwa pod względem porażeniowym w skali kraju jest liczba wypadków śmiertelnych przypadających na milion mieszkańców w ciągu roku. W Polsce wskaźnik ten wynosi obecnie około 7,5. W innych, najbardziej uprzemysłowionych krajach Europy, tylko 1,3 – 2,0. W kraju wybucha też corocznie wiele tysięcy pożarów mieszkań i całych obiektów budowlanych, znaczna ich część, bo około 30%, jest przypisywana wadom instalacji i urządzeń elektrycznych. Jest to udział znacznie większy niż w innych krajach Europy. Stale prowadzone są prace nad poprawą jakości oraz skuteczności działania urządzeń i systemów ochrony przeciwporażeniowej. Może w przyszłości, dzięki temu doczekamy się w 100 % bezpiecznych instalacji elektrycznych. Adresatem niniejszej pracy są osoby, które chciałyby zapoznać się z podstawową wiedzą z zakresu zabezpieczenia instalacji fotowoltaicznej, szczególnie przy pracy na sieć (grid-on) jak również wszystkich wykonawców, którzy tę wiedzę posiadają, ale chcieliby ją przypomnieć i uporządkować

Analysis of Mathematical Modeling of PV Module with MPPT Algorithm

This paper presents the mathematical modeling of photovoltaic (PV) module with the effective comparison of two popular maximum power point tracking (MPPT) techniques; Generally, Maximum Power Point Tracking (MPPT) techniques are used in PV System to extract maximum possible power which in turn depends on solar irradiance and temperature of PV module. Two most widely used MPPT techniques namely incremental conductance (INC), and perturb & observe (P&O) method are analyzed in this paper. The PV models compared are simplified single diode model, improved two diode model and simplified two-diode model. The effectiveness of the comparison has been done through MATLAB/Simulink Environment and the results are analyzed

Wide-area system of registration and processing of power quality data in power grid with distributed generation Part I. System description, functional tests and synchronous recordings Part II. Localization and tracking of the sources of disturbances

This paper presents the developed and built comprehensive system of registration, archiving and data processing for the wide-area monitoring of power quality in a separated part of real power grid with distributed renewable generation. Real case studies related to localization of sources of voltage disturbances are presented

Analysis of SDFT based phase detection system for grid synchronization of distributed generation systems

A fast and exact detection of phase and fundamental frequency of grid voltage/current is essential for calculating accurate reference signal in order to implement the control algorithm of inverter-interfaced distributed generation (DG) system and realize precise harmonic compensation. However, the methods adapted in the literature based on phase locked loop (PLL) exhibits large phase error, be difficult to implement, and their performance is also indistinct under conditions where the grid frequency varies or the supply is distorted with low frequency harmonics. This paper explores an improved phase detection system for DG system based on Sliding Discrete Fourier Transform (SDFT). The proposed SDFT based phase detection shows a robust phase tracking capability with fast transient response under adverse situation of the grid. Moreover, SDFT phase detection system is more efficient as it requires small number of operations to extract a single frequency component, thereby reducing computational complexity and simpler than DFT. The superior performance of proposed SDFT phase detection system is analysed and the obtained results are compared with Discrete Fourier Transform (DFT) filtering to confirm the feasibility of the study under different grid environment such as high frequency harmonic injection, frequency deviation, and phase variation etc

Determining of Fault Locations with Hilbert – Huang Transformation on XLPE Cables between Land and Offshore Substations

Using of mathematical transformations and digital signal processing (DSP) methods of recorded voltage and currents in power systems in order to extract important informations about physical processes is already known. Higher resolution of measurements and massive introduction of PMU devices in the power systems allows appliance of DSP - based fault location methods in complex power networks. High availability of power systems is required in the modern societies. Fast fault location algorithms and consequent fast repairing of faults is necessary condition for high availability of power networks. Here is represented a numerical procedure for fault location and testing of method already introduced in scientific literature on complex configuration of power network consisting of XLPE underground submarine and land cables between land and offshore substation connecting large wind park with main power system

Analysis of Recursive DFT Filtering Based Grid Synchronization of Distributed Generation System

A converter-interfaced distributed generation (DG) system, like, wind power system, photovoltaic (PV) and micro-turbine-generator system, requires a fast and exact detection of phase and fundamental frequency of grid current in order to implement the control algorithm of power converters by generating reference currents signals. Moreover, a desired synchronization algorithm must detect the phase angle of the fundamental component of grid currents as fast as possible while adequately eliminating higher order harmonic components. This paper presents a grid synchronization algorithm for converter-interfaced DG systems based on recursive Discrete Fourier Transform (DFT) filtering. The proposed recursive DFT filtering shows a robust phase tracking capability with fast transient response under abnormal grid conditions. The overall performance of studied recursive DFT filtering is analysed and the obtained results are compared with Synchronous rotating reference frame (SRF) PLL to confirm the feasibility of the study under different grid environment such as high frequency harmonic injection and frequency deviation

Error Compensation in Distance Relays Caused by Wind Power Plants in the Power Grid

This article presents the Prony method as a filtering technique for distance relays. First, the effect of non-filtered frequency components generated by Wind Power Plants in distance relays is evaluated in a simplified model of a doubly fed induction generator, resulting in an error of apparent impedance measurement. Then, the effects of non-filtered frequency components for typical distance relay are presented. The error in apparent impedance measurement is evaluated in reach and operation time of the relay; a distorted characteristic of the mho distance relay is shown in the impedance plane. Finally, Prony method as a filtering technique is implemented as a solution of the apparent impedance measurement error, and the simulated case and a real fault event are evaluated to validate the proposed distance relay algorithm. Thus the asynchronous frequency components of voltage and current signals are identified and filtered, as a result the performance of the distance relay is enhanced

Pollution flashover of single unit metal oxide arresters

Flashover voltage of uniform and non-uniform polluted metal oxide arresters and their porcelain housings without internal parts was measured

Temperature monitoring of metal oxide surge arresters

Varistor overtemperature above the ambient is an important state parameter of metal oxide surge arresters. The temperature monitoring using passive SAW sensors enables realisation of a surge counter function, an energy monitor, monitoring of electrical ageing and pollution stress. For temperature measurements during pollution tests of metal oxide arresters the not so advanced, TINY TALK sensors could be used. This method of temperature measurement was also applied in the field for temperature control of arresters tested at the pollution station near Głogów, Poland. The preliminary results during the first year of monitoring are presented and compared with results of similar measurements conducted in Germany close to the seacoast