Gotowa bibliografia na temat „PV BASED MICRO GRID”

<p> With the increasing trend of utilizing renewable energy generators such as photovoltaic (PV) cells and wind turbines, power systems are transforming from a centralized power grid structure to a cluster of smart micro-grids with more autonomous power sharing capabilities. Even though the decentralized control of power systems is a reliable and cost effective solution, due to the inherent heterogeneous nature of micro-grids, optimal and efficient power sharing among distributed generators (DG&rsquo;s) is a major issue which calls for advanced control techniques for voltage stabilization of the entire micro-grid cluster. The proposed consensus based algorithm in this thesis is a solution to overcome these control challenges, which only requires each DG to exchange information with its directly connected neighboring DG&rsquo;s, in order to maintain the power balance and voltage stability of the entire micro-grid cluster. The proposed method in this thesis is simulated in PSCAD and its effectiveness is demonstrated using several realistic and practical cases including micro-grid topology changes, communication delays, and load changes.</p>

Nearly one fifth of the global population lacks access to electricity and electricity access is essential for economic growth and human well-being. SHSs and micro-grids both have the possibility of increasing the electricity access in developing countries. The decision to choose either SHSs or micro-grids for rural electrification is a complex task that must consider both the technological factors that separate these two systems and the non-technological factors. Separate times of peak load between households (inter-class diversity) has shown to be one major advantage for the use of micro-grids. Studies have shown that the diversity factor present in micro-grids can scale down the necessary capacity of PV modules and energy storage of up to 80%, in comparison to stand-alone systems (e.g. SHSs). These reductions are nevertheless based on assumed diversity factors, not using real load profiles and the necessary capacities are calculated using intuitive methods (known to be inexact). From interviews in a rural community of Nicaragua, the author generated load profiles and determined the diversity factor of the community. The load profiles were generated with a specially designed software to formulate realistic load profiles for off-grid consumers in rural areas. These load profiles were later used in the software HOMER where the diversity’s influence on required capacity and NPC were determined by comparing SHSs to a PV based micro-grid. The study showed that the required capacity and NPC of the inverter and charge controller are clearly decreased as an influence of inter-class diversity. The required PV and battery capacity are also decreased when a micro-grid is utilized, but these reductions are most likely a result from the limited nominal power per component considered in HOMER.<br>Nästan en femtedel av världens befolkning saknar tillgång till elektricitet. Nicaragua är ett av de länder där en stor del av befolkningen saknar eltillgång och det gäller speciellt hushållen på landsbygden. Utbyggnader av elnätet till dessa områden är ofta låg-prioriterade på grund av höga kostnader för att tillgodose ett många gånger lågt energi och effektbehov. En alternativ lösning för att ge dessa hushåll tillgång till elektricitet är att använda off-grid system, system frikopplade från det nationella elnätet. Två vanligt förekommande off-grid system är solar home systems (SHSs) och micro-grids. Det faktum att flera hushåll ofta använder sin toppeffekt vid olika tillfällen (sammanlagring av effekt) har visat sig vara till stor fördel för micro-grids. Tidigare studier har visat att sammanlagringsfaktorn i ett micro-grid kan reducera nödvändig kapacitet av solceller och energilager upp till 80%, i jämförelse med enskilda system (t.ex. SHSs). Dessa studier bygger dock på antagna sammanlagringsfaktorer, overkliga lastprofiler och nödvändig kapacitet beräknas med intuitiva metoder. Med data från intervjuer i ett landsbygdssamhälle i Nicaragua skapas lastprofiler och en sammanlagringsfaktor beräknas för samhället. Lastprofilerna skapas i en programvara utvecklad för att formulera realistiska lastprofiler för off-grid konsumenter i landsbygdsområden. Lastprofilerna används senare i programvaran HOMER där sammanlagringens påverkan på nödvändig kapacitet och kostnad undersöks genom en jämförelse mellan SHSs och ett solcellsdrivet micro-grid. Studien visar att nödvändig kapacitet och nuvärdeskostnad för växelriktare och laddningsregulator tydligt minskar till följd av sammanlagring. Nödvändig kapacitet på solceller och batterier minskar också när ett micro-grid används. Dock beror detta med stor sannolikhet inte på sammanlagring utan är ett resultat från de begränsade märkeffekter på komponenter som användes i HOMER.

Les travaux de thèse s’inscrivent dans les problématiques des travaux de recherche de l’équipe thématique : Maitrise des Energies Renouvelables et systèmes de Stockage (MERS) du laboratoire GREAH-EA3220. Ils englobent le dimensionnement des éléments constitutifs du système et la gestion optimale de l’énergie électrique pour un système hybride (Diesel à vitesse variable, Eolien, PV et Batteries) dédié aux sites isolés. Les sources de production d'énergie alimentent des charges par le biais de convertisseurs multi-niveaux d’électronique de puissance. Le groupe électrogène comportant un moteur diesel à vitesse variable est considéré comme la principale source d’énergie utilisée pour contrôler la tension continue du point de couplage. Ce type de groupe électrogène est choisi pour optimiser la consommation du carburant. Il est sollicité pour délivrer une puissance électrique compatible avec le régime du moteur qui supporte mal les variations fréquentes et rapides. Les sources d’énergie renouvelables dont on cherche à augmenter la part d’énergie pour satisfaire la demande sont pilotées de manière à extraire instantanément le maximum de puissances disponible par les ressources (ensoleillement, vent). Celles-ci imposent ainsi leurs dynamiques et leurs intermittences au point de couplage. Le pack des batteries sert à compenser les fluctuations rapides de l’énergie provenant des sources d’énergie renouvelables par rapport à une évolution plus lente prise en charge par le groupe électrogène. La gestion des interactions au sein du système électrique hybride résultant est assurée au moyen de convertisseurs statiques multi-niveaux (AC / DC, DC / DC et DC / AC). Une approche de gestion d’énergie électrique fondée sur la répartition fréquentielle des perturbations induites au point de couplage par les sources renouvelables. Une plateforme expérimentale à échelle réduite (1/22) a été développée pour valider expérimentalement les approches théoriques et les simulations. Les résultats de simulations obtenus dans l’environnement logiciel Matlab/Simulink/SimPowerSystems et ceux issus du dispositif expérimental réalisé et piloté par dSPACE-1104 prouvent l’adéquation des méthodes de contrôle proposées<br>The thesis works are part of the research work of the thematic team: Mastery of Renewable Energies and Storage Systems (MERS) of the GREAH-EA3220 laboratory. They include the dimensioning of the constituent elements of the system and the optimal management of electrical energy for a hybrid system (Variable speed Diesel, Wind, PV and Batteries) dedicated to isolated sites. Power sources supply loads through multi-level converters of power electronics. The generator set with a variable speed diesel engine is considered to be the main source of energy used to control the DC voltage at the coupling point. This type of generator is chosen to optimize fuel consumption. It is used to deliver an electrical power compatible with the engine speed which does not tolerate frequent and rapid variations. Renewable energy sources whose share of energy is sought to meet demand are managed so as to instantly extract the maximum power available from resources (sunshine, wind). These thus impose their dynamics and their intermittences at the coupling point. The battery pack is used to compensate for rapid fluctuations in energy from renewable energy sources compared to a slower evolution supported by the generator. Interactions within the resulting hybrid electrical system are managed by means of multi-level static converters (AC / DC, DC / DC and DC / AC). An electrical energy management approach based on the frequency distribution of disturbances induced at the coupling point by renewable sources. An experimental platform on a reduced scale (1/22) has been developed to experimentally validate theoretical approaches and simulations. The results of simulations obtained in the Matlab / Simulink / SimPowerSystems software environment and those from the experimental device produced and piloted by dSPACE-1104 prove the adequacy of the proposed control methods

In this thesis, an evaluation of a stand-alone hybrid micro grid for the Wawashang Complex is presented. A solution for a new electricity supply and distribution system for the complex is proposed with a focus on optimal configuration of the system. A field trip to Wawashang was conducted in April 2014 in order to collect data regarding biomass potential for electricity production and information for a possible distribution system design. The demand to be covered is divided into two systems; the micro grid, which denotes all buildings excluding the carpentry workshop and is the system for which the distribution system is designed, and the carpentry workshop. A single-phase/three-wire (split-phase) solution is suggested for the distribution system configuration, presenting the advantage of considerably smaller conductor size requirements than single-phase/two-wire systems for the same voltage drop and power loss. The total power loss of the distribution system is 896 kWh/year or 2.4 % of the demand. The production system for the micro grid consists of a PV array and a battery bank, and for the carpentry workshop a diesel generator. Additionally, a biomass based generator is available for both systems according to a defined schedule. The simulation software HOMER is used to run simulations for the two systems simultaneously, with the intention of obtaining optimal operation of the biomass generator. Two cases are evaluated on both technical and economical aspects. In Case I, the high frequency AC power output from the biomass generator is rectified to DC power and then connected to the single-phase AC bus of the micro grid through a DC-AC converter and similarly to the three-phase AC loads of the carpentry workshop. In Case II, the output from the biomass generator is connected to the DC bus of the micro grid after rectification. The simulation results shows that the optimal solution in both cases is to operate the biomass generator as much as possible in the carpentry workshop with the diesel generator available to cover peak loads. In Case I, the biomass generator is operated with a load following strategy, while in Case II a cycle charging strategy is applied, resulting in a higher exploitation of the available biomass resource in the latter. Both cases present advantages and disadvantages and are similar in reliability and cost. Case II is evaluated as the optimal solution for the Wawashang Complex, as it is the overall least expensive, most reliable and least unbalanced system when it comes to seasonal variations. The system consists of a 9 kW converter, a PV array with a global power of 30 kWp, producing a total of 37 254 kWh/year and a battery bank with a nominal capacity of 294 kWh (for the micro grid), a 15 kW biomass generator producing a total of 38 477 kWh/year divided between the micro grid (19.4 %) and the carpentry workshop (80.6 %) and a 15 kW diesel generator producing 5 400 kWh/year for the carpentry workshop. Total excess electricity is 6.3 % and unmet load is 0.21 %. Total NPC is US$ 311 224 and levelized COE is US$ 0.285/kWh.