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Chaotic nature of renewable energy sources connected with nonlinear loads may cause serious problems to the utility grid, e.g. voltage and frequency disturbances, harmonic pollution. Due to that, many European governments have set strict regulations to the grid energy injection. As a result, the power quality has become one of the major obstacles for nearly zero energy buildings to be connected with...
The paper presents an approach for modelling a Battery Energy Storage System (BESS). This approach consists of four stages. In the first stage a detailed model is developed taking into consideration all the electrical details of the original system. In stage two the detailed model will be validated using real measurements. In the third stage the complexity of the detailed model is reduced resulting...
Electricity price based control models for thermal storages to balance fluctuations of price have become increasingly important. A number of previous studies in the field of demand side management deal with price based load control to balance the power grid. However, inadequate attention has been paid to comfort and profitability issues of end users. Therefore, insufficient solutions towards profitability...
Startup is known as the most critical phase of any power electronic converter. Uncharged capacitors and resonance circuits cause high current spikes during startup that reduce the lifespan of semiconductors or in the worst case, immediate break down. Although the startup of power electronic converters is a very practical and necessary topic, only few papers cover different startup algorithms. No papers...
Estonian distribution grid operators have to cope with increasing investment risks due to decreasing consumption in sparsely populated areas, which makes finding cost-efficient solutions crucial. To identify typical topologies of Estonian weak rural low voltage grid subject to voltage problems, about 9% of feeders were analysed and classified. Awareness of typical topologies of a weak low voltage...
Energy efficiency is the focus for different organizations. On a global scale, it is related to climate change and initiatives towards reduction of greenhouse gases, such as Paris Agreement Within the United Nations Framework Convention on Climate Change. According to the agreement, each county has its targets on reduction of greenhouse gas emissions. By the United States Environmental Protection...
The aim of the case study was to determine profitability of Energy Management System (EMS) in the intraday market like Elbas (Nord Pool Spot). To optimize the operation of EMS, a Demand Response (DR) algorithm was used for the calculation of a battery bank charge-discharge schedule (BCDS) taking into account the volatility in the Real-Time price (RTP). The profits are gained from importing and storing...
Increase in photovoltaic (PV) systems integrated into low-voltage (LV) distribution networks has created a pressing need for analysis of the effects of these systems on power quality and supply reliability. The main aim of this study was to analyze the effects of small-scale PV-system power generation on voltage quality in a rural LV distribution network. In the analysis based on real field measurements,...
The growing demand for utilization of solar energy and thus increasing number of photovoltaic (PV) systems installed in low voltage (LV) distribution networks has given rise to the studies focusing on the effects of these systems on power quality (PQ) and supply reliability. The aim of this study is to analyze the effects of small-scale PV-system power (P(PV)) generation on voltage quality in a rural...
Large apartment buildings dated from 1960 to 1992 compose 79% of Estonian residences. Since design and construction, load profile of these buildings has changed significantly: 30–50 years ago, peak loads were much lower than today and simultaneity factor values used for in-house electrical system design were different. Implementation of demand side management (DSM) and load aggregation results in...
The paper presents a new optimization method for PI controllers of back-to-back voltage source converters using a vector control scheme to enable the control of active and reactive power transmission between two independent grids, for example, an emulator as a load or a source between the medium voltage distribution grid and a low voltage island grid. The control principle based on three phase systems...
In the perspective of network operators, demand response (DR) is a form of shaping of the overall consumption in the system by peak clipping and shifting. Bearing the necessity and importance and the role of DR in the overall system in focus, the objective of the paper is to extend an analysis on the flexibility of the demand. The potential and the corresponding cost for demand flexibility of different...
Demand side response enables cost optimization for energy systems and industrial consumers. In many countries, it is not widely used because of implementation complexity. One of the solutions for applying demand side response is industrial process scheduling according to the energy market needs. From the energy system point of view, process scheduling implies load scheduling. The aim of this paper...
This paper deals with the analysis and simulation of a stationary battery system for microgrid application, where the system structure including battery cells, inverters, filters, transformers, control system and a simplified grid model is described and modeled mathematically. For the simulation of the whole system the software PSCAD™ is used. In the first part several equivalent circuit models for...
Public lighting is an important factor in ensuring safety in public areas. However, its costs to be covered by local municipality are heavy. Focus in this paper on the use of motion detection devices on the street. The aim is to help increase the sense of safety in an urban environment and at the same time to reduce the costs on urban lighting. According to the study, motion detection devices may...
Our goal was to define a possible profit resulting from the use of batteries as an electric energy storage (EES) device in apartment buildings or small houses as typical households. Focus was on the theoretical and practical studies of an energy management system (EMS) and financial analysis of investments return. Use of a battery bank charge-discharge-schedule (BCDS) allows an optimal operation of...
The aim was to determine probable profit by using electric energy storage (EES) device in a typical household. Focus is on theoretical and practical studies of an energy management system (EMS) based on VRLA battery storage. Use of a battery charge-discharge-schedule (BCDS) enables an optimal operation of EES taking advantage of the low price periods by importing more energy and storing it, while...
One of the traditional load shifting motivations in use for long time already is the two-level time-of-use tariff scheme. The nighttime lower energy has been known to provide lower cost for the homeowners who are using electric energy for space heating. The measurements of residential areas, presented in this paper, confirm that the load shift towards the times of lower pricing is used by many homeowners...
This paper analyses the increasing wind energy integration impacts on the Estonian power system, particularly wind energy production forecast errors. It proposes a solution to integrate wind parks with Estonian power grid, which is mainly based on large thermal power plants utilizing fossil fuels, together with a grid-scale energy storage system, particularly pumped-hydro energy storage, in order...
This paper presents the principal solution for a real time load control application in the industry under the conditions of open electricity market. The aim of the study is to create the basic concept of a PLC controlled load optimization system for the group of energy intensive machines. The optimized load curve calculations for the specific machine or for the aggregated group of machines in the...
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