Thermal and Arc Flash Analysis of Electric Motor Drives in Distribution Networks

The paper presents thermal analysis and arc flash analysis taking care of protection relays coordination settings for electric motor drives connected to the electrical network. Power flow analysis is performed to check if there are any voltage and loading violation conditions in the system. Fault analysis is performed to check the short circuit values and compute arc flash energy dissipated at industrial busbars to eliminate damage to electrical equipment and electrical shocks and hazard to personnel. Computers enable the use of smart algorithms used by electrical engineers in providing accuracy of these actions. A fast and accurate procedure for proper incident arc flash energy computation and overcurrent relays coordination in distribution networks is presented. The paper presents the use of the Arc Flash module for arc flash energy computation during the short circuit on LV and HV busbars with soft motor starters. A sample case of one real network is presented which uses soft motor starters as well as the influence on arc flash energy in one transformer station supplying the industrial network in Bosnia and Herzegovina

An Adaptive Neuro-Fuzzy Inference System in Assessment of Technical Losses in Distribution Networks

The losses in distribution networks have always been key elements in predicting investment, planning work, evaluating the efficiency and effectiveness of a network. This paper elaborates on the use of fuzzy logic systems in analyzing the data from a particular substation area predicting losses in the low voltage network. The data collected from the field were obtained from the Automatic Meter Reading (AMR) and Automatic Meter Management (AMM) systems. The AMR system is fully implemented in EPHZHB and integrated within the network infrastructure at secondary level substations 35/10kV and 10(20)/0.4 kV. The AMM system is partially implemented in the areas of electrical energy consumers; precisely, in accounting meters. Daily information gathered from these systems is of great value for the calculation of technical and non-technical losses. Fuzzy logic in combination with the Artificial Neural Networks implemented via the Adaptive Neuro-Fuzzy Inference System (ANFIS) is used. Finally, FIS Sugeno, FIS Mamdani and ANFIS are compared with the measured data from smart meters and presented with their errors and graphs

Generator Assessment of Hydro Power Station Adequacy after Reconstruction from Classical to HIS SF6 Substation

Reliability analysis of substations and generator assessment of power plant stations are very important elements in a design and maintenance process. This paper presents a generator adequacy assessment of a classical “H” scheme for an open conventional substation, which is often used, and a new HIS - High Integrated Switchgear with SF6 gas isolation. Generator adequacy indices of both types of classical and HIS switchgear were compared and the results showed a high level of reliability and availability of the HIS presented substation. The input data were the annual reports of Croatian TSO-Transmission System Operator (HOPS) and statistics of operation events of Croatian National Electricity (HEP Inc.). For the HIS substation, the input reliability data were used from relevant international literature since only few of HIS substations are installed in Croatia. The generator is modelled with a three-state Markov state space model and Monte Carlo simulations were used for the generator assessment analysis. Adequacy indices LOLP and EDNS were obtained using DIgSILENT software

ANFIS Used as a Maximum Power Point Tracking Algorithm for a Photovoltaic System

Photovoltaic (PV) modules play an important role in modern distribution networks; however, from the beginning, PV modules have mostly been used in order to produce clean, green energy and to make a profit. Working effectively during the day, PV systems tend to achieve a maximum power point accomplished by inverters with built-in Maximum Power Point Tracking (MPPT) algorithms. This paper presents an Adaptive Neuro-Fuzzy Inference System (ANFIS), as a method for predicting an MPP based on data on solar exposure and the surrounding temperature. The advantages of the proposed method are a fast response, non-invasive sampling, total harmonic distortion reduction, more efficient usage of PV modules and a simple training of the ANFIS algorithm. To demonstrate the effectiveness and accuracy of the ANFIS in relation to the MPPT algorithm, a practical sample case of 10 kW PV system and its measurements are used as a model for simulation. Modelling and simulations are performed using all available components provided by technical data. The results obtained from the simulations point to the more efficient usage of the ANFIS model proposed as an MPPT algorithm for PV modules in comparison to other existing methods

Assessment of Step and Touch Voltages for Different Multilayer Soil Models of Complex Grounding Grid

In this paper the influence of different soil models on step and touch voltages are presented. Soil resistivity is the basic characteristic of soil which affects a number of parameters (temperature, humidity, salt content). Basic methods of measuring soil resistivity presented in this paper are: Wenner method, Schlumberger method, General method, Driven rod (3-probe) method and the Dipole-Dipole method. Soil resistivity measurements are used to obtain an equivalent soil model (uniform model, two-layer horizontal model, multi-layer horizontal model, vertical model and others). The CDEGS software package is used for computing GPR (Ground Potential Rise), touch and step voltage with several different soil models. The resulting effect of soil models on the grounding resistance, GPR at the surface, touch and step voltages are shown. The 3D spatial distribution and 2D presentation of all characteristic values for safety analysis are presented and plotted

Comparative Analysis of Power Quality Indices for Different Lighting Techniogies in Public Lightning

As with any other product, having electricity of a certain quality is very important for consumers. Its quality has become the key feature that can be disturbed by loads based on power electronic devices. Electricity producers are striving to provide reliable and quality electricity supply to consumers. Public lighting systems that are based on LED lighting technology can potentially positively or negatively affect the power quality because they contain power electronics components in LED drivers. Because of that, two 7-day measurements were conducted on the same public lighting branch but with different lighting technologies (high pressure sodium, known as HPS and LED technology). Results of the measurements were analysed and compared. By analysing the results, other problems were also identified by using LED lighting technology. These problems are addressed in the conclusion of the paper

Designing Automatic Meter Reading System Using Open Source Hardware and Software

The importance of quality of the measured values is very dependent on the device that measures these values: the size of the sample, the time of measurement, periods of measurement, the mobility and the robustness of the device, etc. Contemporary devices intended for the measurement of physical quantities that are on the market vary in price, as well as and the quality of the measured values. The rule "the more expensive the better" is not necessarily always a rule that is valid because it all depends on the characteristics and capabilities of the device, and the customer’s needs. In this paper, a device based on "Open Source" components of hardware and software will be presented. Device was used to measure voltages and currents on low voltage networks, on which a virtually unlimited number of sensors can be added, and the device is assembled of components available on electronic components Internet

Postupak za određivanje harmonične distorzije uzduž distribucijske mreže

This paper underlines the importance of permanent power quality measures in distribution network and proposes the interval and event (change in topology) based time schedule of measurements in depth of the network. Some nodes do not need to be measured during 7 days according to EN 50160 to realize that there are great problems to solve in a new technical resolution. Similar to the trend of entropy, true harmonic distortion (THD) in distribution power system is expected to increment, so - momentary measures are sufficient to mark subparts of the power system with unsatisfactory level of power quality. The most important problem to solve is to mark the consumer\u27s generated harmonic distortion. Importance and benefit of the proposed method is to save the time needed to name causes of disturbances (consumer or device) and to anticipate the repairing of power quality. A new flow-chart is suggested for recognition of the consumer THD generation amount. Also, it leads to better technical or managing decision making during maintenance and investment planning activities. Further results of systematic planned measures that need to be done along the distribution power network, will enable global recognition of THD causes in network and simultaneously give exact solutions.Ovaj članak naglašava važnost stalnog mjerenja kvalitete električne energije u distribucijskoj mreži i predlaže vremenski raspored mjerenja po dubini mreže određen vremenskim intervalom ili događajem (promjena u topologiji mreže). Neki čvorovi ne moraju biti stalno mjereni tijekom 7 dana prema normi EN 50160 da se zaključi da postoje veliki problemi vezani za kvalitetu za novo stanje mreže koje treba riješiti. Slično kao ponašanje entropije, za udio harmoničnog izobličenja (THD-a) u distribucijskoj mreži očekuje se da isključivo raste tako da su trenutačna mjerenja dovoljna da se označe dijelovi distribucijskog sustava koji nemaju zadovoljavajuću razinu kvalitete. Najvažniji problem kojega treba riješiti je odrediti kupca koji proizvodi harmonično izobličenje. Važnost i korisnost predložene metode je ušteda vremena za određivanje uzroka poremećaja (kupca ili uređaja) kao i za predviđanje načina za poboljšanje kvalitete električne energije. Predložen je novi dijagram toka za prepoznavanje količine proizvedenog THD-a od strane određenog kupca. Također, uporabom ove nove metode mjerenja kvalitete olakšava se donošenje odluka u tehničkom i organizacijskom segmentu tijekom aktivnosti održavanja i planiranja investicija. Daljnji rezultati sistematski planiranih mjerenja uzduž distribucijske mreže omogućit će globalno prepoznavanje veličine uzroka harmoničnog izobličenja i istovremeno dati određena rješenja

Frequency and Time Response of Power Plant Grounding System Exposed to Lightning Strike

This paper examines the frequency response of power plant grounding system exposed to the lightning current. Large amount of current generated by the stroke flow in the grounding system of power plant and dissipate in the soil.  The electric and magnetic field generated by such high voltages and currents may cause damage of equipment and may be dangerous for the personnel in power plant.  For the every given frequency obtained using Fast Fourier Transformation (FFT) of lightning current impulse, electromagnetic field theory approach is used to solve Maxell’s equation and compute scalar potential, electric and magnetic field. Also, the influence of the point in which lightning current is diffused in the grounding system is presented. Three dimensional plots of spatial distribution of scalar potential, electric and magnetic field are presented. The time domain response of scalar potential, electric and magnetic field on one profile is also presented

Protection Coordination and Anti Islanding Protection Solution for Biomass Power Plant Connected on Distribution Network

Protection coordination as well as anti-island protection play significant role in the process of biomass power plant connection on the distribution network. Distribution generation island operation in Croatia is unacceptable according to the existing National grid code Paper presents a protection coordination of all passive protections used in the real biomass power plant and connected distriubution network feeder. Short-circuits three phase, two phase and single line to ground faults and generator islanding simulations have been performed and simulated in the time domain at the different network  locations using DIgSILENT Power Factory software. The time-current plots coordination of protective devices are made using Smart PDC module in Easy Power Protector software tool