Future power systems with a high share of intermittent renewable energy sources (RES) in the energy portfolio will have an increasing need for active power balancing. The integration of controllable ...and more flexible distributed energy resources (DERs) at the distribution-grid level represents a new solution and a sustainable alternative to conventional generation units for providing balancing services to the transmission system operator (TSO). Considering that the extensive participation of DERs in ancillary services may lead to the violation of limits in the distribution network, the distribution system operator (DSO) needs to have a more active role in this process. In this paper, a framework is presented that allows the DSO, as the central coordinator of the aggregators, to participate in the balancing market (BM) as a balancing service provider (BSP). The developed mathematical model is based on the mixed-integer second-order cone programming (MISOCP) approach and allows for determination of the limits of active power flexibility at the point of the TSO–DSO connection, formation of the dependence of the price/quantity curve, and achievement of the optimal dispatch of each DER after clearing the balancing market. The simulation results are presented and verified on modified IEEE distribution networks.
An optimization model which determines optimal spatial allocation of wind (WPPs) and PV power plants (PVPPs) for an energy independent power system is developed in this paper. Complementarity of the ...natural generation profiles of WPPs and PVPPs, as well as differences between generation profiles of WPPs and PVPPs located in different regions, gives us opportunity to optimize the generation capacity structure and spatial allocation of renewable energy sources (RES) in order to satisfy the energy needs while alleviating the total flexibility requirements in the power system. The optimization model is based on least squared error minimization under constraints where the error represents the difference between total wind and solar generation and the referent consumption profile. This model leverages between total energy and total power requirements that flexibility resources in the considered power system need to provide in the sense that the total balancing energy minimization implicitly bounds the power imbalances over the considered time period. Bounding the power imbalances is important for minimizing investment costs for additional flexibility resources. The optimization constraints bound the installed power plant capacity in each region according to the estimated technically available area and force the total energy production to equal the targeted energy needs. The proposed methodology is demonstrated through the example of long-term RES planning development for complete decarbonization of electric energy generation in Serbia. These results could be used as a foundation for the development of the national energy strategy by serving as a guidance for defining capacity targets for regional capacity auctions in order to direct the investments in wind and solar power plants and achieve transition to dominantly renewable electricity production.
The problem of frequency stability becomes more concerning as the presence of converter-interfaced units increases and conventional generators are suppressed. A decrease in total system inertia, ...inherently delivered by synchronous generators, results in abrupt frequency changes and jeopardizes power system stability. Therefore, securing sufficient flexible resources with frequency support capability is necessary. The rotational masses of wind turbines (WTs) are a significant and economical source of flexibility in power systems. However, the available kinetic energy (KE) of the WTs’ rotational masses depends on wind conditions and can only be exploited when the wind speed is sufficient for their rotation. When the wind speed is low, the WT is stopped and cannot support the frequency recovery. In this paper, a new concept of WT operation is proposed, which enables the permanent rotation of the WT under low and no wind conditions, making them reliable flexible resources that can continuously provide frequency support. Due to its widespread presence, the doubly-fed induction generator (DFIG) type of machine was considered. The variable-speed WT’s converter management allows rotational speed control, fast power injection, and release of the turbine’s stored KE even when no wind energy is available. The estimated accessible KE in the WT justifies the proposed concept, and the energy consumption due to motoring operation under low and no wind conditions is shown to be acceptable. A case study is performed for the South Banat region in Serbia to demonstrate the presented management concept. Additionally, a dynamic simulation was implemented to illustrate the permanent operation strategy’s impact on frequency stability in a low-inertia system under low and no wind conditions. Besides virtual inertia continuous capability, the proposed concept provides reduced wear of the WT mechanical components due to a lower number of on/off events.
The paper deals with the modeling and analysis of the effects of integrating photovoltaic systems into the body elements of electric vehicles. The aim of this paper was to examine the capacities, ...opportunities and effects of local electricity generation in real electric cars. Given the complex geometry of the vehicle and its mobility, this task posed a relatively complex engineering challenge. A mathematical model in MATLAB software has been developed that enables the estimation of the time diagram of photovoltaic panels production integrated into moving objects of complex geometry. Based on real irradiation measurement data for several locations in Serbia, analyses and calculations of the energy balances of electric vehicles with and without integrated photovoltaic panels in the car body were carried out. The results of the paper show the cost effectiveness for the application of this solution in the automotive industry. In addition to the local production of clean energy, the effects of increasing vehicle autonomy and longer range, less frequent visit to the charging station, less dependency and less impact of vehicles on power system are also achieved.
School and school gym buildings represent a relevant potential for construction of photovoltaic panels, to be integrated into roofs of these buildings. Given that roof structures are passive, ...construction of photovoltaic systems does not interfere with the building functionality, does not it in any way adversely affect the environment. Installation of photovoltaic systems on building roofs brings the production and consumption of electricity closest possible, therefore such systems ensure significant reduction in power losses in transmission and distribution grids. In addition to locally produced electricity, construction of photovoltaic systems on the school buildings’ roofs produces an educational effect as well. By installing a measuring and acquisition system which would include the measuring data on the photovoltaic power plant production parameters and school electricity consumption into school labs, technology would be closer to students, as well as possibilities to meet the demand for electricity from this basic renewable energy source. This paper presents the results of evaluations of the available roof surfaces of school buildings in Serbia for the photovoltaic panels installation. For each category of school building, an estimate of possible annual production per unit of average roof area was made. Summarizing all the results, estimates of possible installed capacity and annual electricity production for different scenarios are given.
This paper deals with a conceptual solution for the supply of a part of electrical energy for the needs of Aluminium Plant Podgorica (KAP) in Montenegro from a large Floating Photovoltaic Power Plant ...(FPPP), that would be installed on the nearby lake. The recommended FPPP, with an innovative azimuth angle control method and total installed power of 90 MWp, would consist of 18 power plants having an installed power of 5 MWp each. An analysis using the NREL solar insolation database ascertained that the recommended FPPP power plant can achieve a significantly higher production in comparison with previous solutions. An economic analysis has shown that the recommended power plant would yield positive economic indicators. Additionally, such a power plant would significantly contribute to the reduction of CO2 emissions.
•Significant voltage variations in a distribution network with dispersed generation.•The use of SVC devices to improve the voltage profiles are an effective solution.•Number, size and location of SVC ...devices are optimized using genetic algorithm.•The methodology is presented on an example of a real distribution system in Serbia.
Intermittent power generation of wind turbines and photovoltaic plants creates voltage disturbances in power distribution networks which may not be acceptable to the consumers. To control the deviations of the nodal voltages, it is necessary to use fast dynamic control of the reactive power in the distribution network. Implementation of the power electronic devices, such as Static Var Compensator (SVC), enables effective dynamic state as well as a static state of the nodal voltage control in the distribution network. This paper analyzed optimal sizing and location of SVC devices by using genetic algorithm, to improve nodal voltages profile in a distribution network with dispersed photovoltaic and wind power plants. Practical application of the developed methodology was tested on an example of a real distribution network.
Balancing of variable renewable energy sources is one of the main problems of integrating renewable energy sources into the power electricity system. This paper performs a statistical analysis of the ...dependence of the error in the prediction of wind farm production in the region of southern Banat, on the forecasted power. The main contribution of the paper is the proposal of the methodology for the calculation of the required balance reserve in the electric power system of Serbia for day ahead for the existing condition of the installed wind power plants that are connected to the transmission network. All stakeholders have practical significance and benefit from the proposed methodology, the wind farm owner who can plan the necessary lease of balancing capacities, the transmission system operator who can plan uncertainties in wind farm production and the balancing responsible party that should plan balancing capacities.
The current structure of electricity production in Serbia is not sustainable and it is necessary to consider the possibilities of decarbonisation of electricity production in the future. Renewable ...energy sources are the only sustainable resource for implementing the decarbonisation strategy. This paper presents the results of research of the potential of solar and wind energy in the territory of the Republic of Serbia. The spatial depressiveness of these sources is presented and the energy potential is estimated for each region. Based on the available global databases, the potential was considered and the possible installed capacity and gross annual electricity production for each region were defined. It was concluded that the technically usable potential of wind energy in the territory of the Republic of Serbia (excluding Kosovo and Metohija) is about 11,500 MW, from which about 29.5 TWh of electricity could be produced annually. The technically usable solar potential in Serbia is estimated at about 24 GWp, of which about half is on roof surfaces. The estimated production of electricity from solar capacities is about 30.5 TWh per year.
Models for the calculation of the production of large photovoltaic (PV) power plants with different types of modules (monofacial or bifacial) have been developed in detail in the literature. In ...addition, detailed models have been developed for PV power plants that have fixed modules as well as PV power plants with tracking the azimuth angle of the Sun and/or the tilt angle of the PV module. On the other hand, due to the increasing installation of PV power plant, their construction is often imposed on the field with complex geometry, so it is interesting to develop models that can optimize the spatial layout and geometric elements of panels on sloping surface in relation on horizontal. Namely, during various analyses in the literature, production models for PV power plants that are planned on sloping terrains have not been developed. Accordingly, in this paper, a procedure was developed for the calculation of the production of PV power plants that are placed on terrain that is not flat, but oriented towards the arbitrary side of the World and with an arbitrary tilt angle.
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