In this thesis, a new method has been proposed for calculating the frequencydependent parameters of underground cables. The method uses full wave formulation for calculating the modal electromagnetic fields and corresponding voltages and currents and then extracting frequency-dependent per unit length parameters of underground cables. The proposed method can be used for any cross-sectional shape of cables.

In this thesis, a new method has been proposed for calculating the frequencydependent parameters of underground cables. The method uses full wave formulation for calculating the modal electromagnetic fields and corresponding voltages and currents and then extracting frequency-dependent per unit length parameters of underground cables. The proposed method can be used for any cross-sectional shape of cables.

A microgrid is a local energy grid that could be disconnected from the larger grid and operate autonomously. This particular segment of the power industry is growing due to its reliability during times of emergency and crisis. Among these benefits are improved efficiency, lower operating costs, renewable generation sources, and improved resiliency of the regional electric grid. Communities can better prepare for unprecedented weather like wildfires, hurricanes, and other natural disasters. Regions that produce renewable energy can export their surplus through high voltage transmission lines to balance power supply and demand needs. This Underground High-Voltage Transmission Network project aims to design a blueprint for an underground high voltage transmission network that connects the Cal Poly Solar Farm to campus via an underground network. This Solar Farm produces 4.5MW and provides a quarter of Cal Poly’s power demand, making it essential to everyday operations on campus. The safety of the communities living around these areas is a top priority. The project develops methods to examine network resiliency and analyze load growth or demography trends. These methods include: using GIS to properly locate any existing underground infrastructure and utilizing CYMCAP software to size cable. We use ETAP software to run load flow analysis and device coordination simulation.

No description available.

Dala Energi has large-scale plans for grid development and wants to have a better understanding of their current reactive power levels along with a future prognosis based on their plans. Changes in line inductance, shunt capacitance, area and placement put Dala Energi on the path to higher charging currents and higher reactive power generation. In addition to causing concerns in their own grid, the increased reactive power generation can present challenges for the owner of the overlying grid. Transmission of reactive power upwards is not permitted in the current contract. Dala Energi’s grid is divided into 3 separate regions with a total of 19 larger substations, 12 of which are points of connection with the overlying grid. At times, 8 of the substations have transmitted reactive power upward and soon it will be all 12. Region 1, where the 20-kV grid is located, is the biggest problem-area today, with upward-transmissions of 1 to 3 MVAr quite common and a considerable increase expected. Region 3 contains more than double the underground cable as the other two areas and might have had much greater side effects from the high shunt capacitance were it not for 3 industrial customers who consume a large portion of reactive power. In the coming years, however, Region 3 is expected to have capacitive reactive power levels nearly equal to those of Region 1. The combined reactive power baseline for all regions is expected to drop by 8.24 MVAr in the coming years. The owner of the overlying grid controls Dala Energi’s 5 largest capacitor banks which have a rated capacity of 11.6 MVAr. With the entire capacity almost always connected, the upward transmission of reactive power becomes much greater. It would be very advisable to meet with the owner, discuss interaction between the two grids and examine the details of the current contract. Compensation for excessive generation of reactive power is needed and is going to be essential in the future. The short-term variation of reactive power levels is so great that the use of fixed rating shunt reactors is ill-advised, especially under the current contract. Compensation with variable shunt reactors is recommended.

The objective of the proposed research is to develop statistical algorithms for controlling failure trends through targeted maintenance of at-risk components. The at-risk components are identified via chronological history and diagnostic data, if available. Utility systems include many thousands (possibly millions) of components with many of them having already exceeded their design lives. Unfortunately, neither the budget nor manufacturing resources exist to allow for the immediate replacement of all these components. On the other hand, the utility cannot tolerate a decrease in reliability or the associated increased costs. To combat this problem, an overall maintenance model has been developed that utilizes all the available historical information (failure rates and population sizes) and diagnostic tools (real-time conditions of each component) to generate a maintenance plan. This plan must be capable of delivering the needed reliability improvements while remaining economical. It consists of three facets each of which addresses one of the critical asset management issues: * Failure Prediction Facet - Statistical algorithm for predicting future failure trends and estimating required numbers of corrective actions to alter these failure trends to desirable levels. Provides planning guidance and expected future performance of the system. * Diagnostic Facet - Development of diagnostic data and techniques for assessing the accuracy and validity of that data. Provides the true effectiveness of the different diagnostic tools that are available. * Economics Facet - Stochastic model of economic benefits that may be obtained from diagnostic directed maintenance programs. Provides the cost model that may be used for budgeting purposes. These facets function together to generate a diagnostic directed maintenance plan whose goal is to provide the best available guidance for maximizing the gains in reliability for the budgetary limits utility engineers must operate within.

The maximum length of an high voltage underground cable (HV UGC) cable is oftenconstrained by the criterion that the cable cannot have more than 50% reactivepower compensation. If this limit is exceeded the current in the circuit breaker maynot have a zero crossing after energization, which is referred to as the zero missingphenomenon. This is problematic if a fault occur shortly after energization. Inthe past 10 years, different methods have been proposed which would allow greaterreactive power compensation. These methods either prevent the zero missing phenomenon(preventive methods) or provide a way to open the circuit breaker if afault occurs (handling methods).A new 200 km, 220 kV line has been proposed in Iceland referred to as Sprengisandslína.One proposed option is to build it as an OHL-UGC-OHL line as the voltagecriteria is not fulfilled if Sprengisandslína is built as an UGC with a 50% reactivepower compensation. The aim of this thesis is to see whether the zero missing phenomenoncan be avoided by implementing countermeasures - this gives a preliminaryresults whether Sprengisandslína can be built as an UGC. In this thesis the four differentpreventive methods are analyzed with a transient study for Sprengisandslína:(1) Pre-insertion resistor, (2) simultaneous synchronized switching, (3) synchronizedswitching where the cable is energized before the shunt reactor, and (4) synchronizedswitching where the shunt reactor is energized before the cable.Preliminary steady state studies were performed to determine the minimum numberof shunt reactors needed to fulfill the voltage criteria. The results showed thatthe minimum number needed were three assuming they are all of equal size locatedevenly along the cable (one at each end and one in the middle). Additionally, it isnecessary to see whether the generators would become underexcited if the cable isiiienergized with 100% reactive power compensation as it can reduce the lifetime ofthe generators. The results showed that the generators did not become underexcited.The countermeasure of synchronized switching where the shunt reactor is energizedbefore the cable and the countermeasure of simultaneous synchronized switchingwere shown to eliminate the zero-missing phenomenon when the cable was energizedwith 100% reactive power compensation. Synchronized switching where theshunt reactor is energized before the cable was seen to have lower switching overvoltages,21% higher than the nominal value, and the lower inrush current of 2.38kA. However, the method of simultaneous synchronized switching is cheaper andthe switching overvoltages and inrush current were within an acceptable margin(switching overvoltages were 35:9% higher than the nominal value and the inrushcurrent was 4.01 kA).The results of the study indicate that Sprengisandslína can be energized as an UGCwith 100% reactive power compensation if either the countermeasure of simultaneoussynchronized switching or synchronized switching where the shunt reactor isenergized before the cable are used. However, a detailed frequency study must beperformed before either of the countermeasures can be recommended. / Högsta längden på en högspänning underjordisk kabel begränsas ofta av de kriteriersom kabeln inte kan ha mer än 50% reaktiv effektkompensation. Om denna gränsöverskrids kan strömmen i strömbrytaren inte ha noll genomgang efter aktivering,kallad noll saknad fenomen. Detta är problematiskt om ett fel inträffar strax efteraktivering. Under de senaste 10 åren har olika metoder föreslagits, vilket skullemöjliggöra större reaktiv effektkompensation. Dessa metoder hindrar antingen detnollbristande fenomenet (förebyggande metoder) eller ger ett sätt att öppna strömbrytarenom ett fel uppstår (hanteringsmetoder).En ny 200 km, 220 kV linje har föreslagits på Island kallad Sprengisandslína. Ettföreslaget alternativ för att den här linjen ska byggas är att bygga den som en OHLUGC-OHL-linje, eftersom spänningskriterierna inte är uppfyllda om Sprengisandslínaär byggt som en UGC med en 50% reaktiv effektkompensation. Syftet meddenna avhandling är att se huruvida det saknade fenomenet kan undvikas genomatt genomföra motåtgärder - detta ger ett preliminärt resultat om Sprengisandslínakan byggas som en UGC. I denna avhandling analyseras de fyra olika förebyggandemetoderna med en övergående studie för Sprengisandslína: (1) Förinsättningsresistor,(2) Synkroniserad samtidigkoppling, (3) Synkroniserad inkoppling där kabelnaktiveras före shuntreaktorn och (4) ) synkroniserad inkoppling där shuntreaktornaktiveras före kabeln.Preliminära steady state studier utförs för att bestämma det minsta antalet shuntreaktorersom behövs för att uppfylla spänningskriterierna. Resultaten visade att detminsta antalet som behövdes var tre förutsatt att de alla är lika stora som liggerjämnt längs kabeln (en i varje ände och en i mitten). Dessutom är det nödvändigtatt se om generatorer skulle bli underexiterad om kabeln är energiserad med 100%iiiivreaktiva effektkompensation eftersom det kan minska generatorns livslängd. Resultatenvisade att generatorer inte blev underexiterad.Motståndet för synkroniserad omkoppling där shuntreaktorn aktiveras före kabelnoch motmätningen av samtidig synkroniserad omkoppling visades för att elimineradet nollmissande fenomenet när kabeln aktiverades med 100% reaktiv effektkompensation.Synkroniserad omkoppling där shuntreaktorn aktiveras innan kabeln visadesig ha lägre omkopplingsvolymer, 21% högre än nominellt värde och den lägre inbrusningsströmmenpå 2,38 kA. Metoden för samtidig synkroniserad omkopplingär emellertid billigare och omkopplingsvolymen och inströmmen var inom en acceptabelmarginal (omkopplingsvolymer var 35; 9% högre än nominellt värde ochinströmningsströmmen var 4,01 kA).De resultaten av studien indikerar att Sprengisandslína kan energiseras som en UGCmed 100% reaktiv effektkompensation om antingen motspelet av samtidig synkroniseradomkoppling eller synkroniserad omkoppling där shuntreaktorn aktiveras innankabeln installeras. En detaljerad frekvensstudie måste dock utföras innan någon avmotåtgärderna kan rekommenderas.

The dissertation describes several types of low and high voltage distribution networks including their implementation in specified location with regards to the reliability and quality of electric power supply. The distributions networks are classified according to ways of cable routing, distribution line voltage levels as well as according to types of network interconnections. The high and low voltage distribution networks are further categorized based on used cable types, where, more attention is paid to insulated lines used in the Czech Republic, low voltage lines called „AES“ and „PAS“ high voltage lines used more and more during the distribution network reconstruction. Attention is also given to the description of used methodology for the calculation of network performance stability. An individual part of the dissertation is devoted to a low voltage distribution network proposal in the village of Kovalovice. Based on performed analysis of distribution network conditions, several reconstruction versions were proposed with the help of „KASI“ software, the description of which is also included. The proposed versions are further analysed for both, technical and economical aspects and is selected most suitable version of the distribution network.

Until a few decades ago few people could imagine that the photovoltaic, solar thermal and other power based on renewable resources, will become a reality. Today people from all over the world on the contrary try at full blast derive benefit from of all possible available source. Using sunlight as a source of energy is first enforced only for small devices such as calculators for charging the battery, but now we are able to produced energy from the sun to supply people around the world. Of course it is not possible supply consumer sector plus firm only from performances renewable power supply. Therefore endeavour is derive benefit from classical energy production at the same time with others power supply. The basic components of photovoltaic and solar thermal power are panels. The panels are made of different materials in different shapes and sizes. During production, the resulting effect looks in addition to costs associated with production. For photovoltaic and solar thermal power plant requires sufficient sunlight. The sunshine has biggest intensity on south of ours planets. Therefore endeavour is build lump these power station just in stand with bigger intensity sunshine. One of them is just Cyprus, too.