Search

The increased demand for power transfer in combination with environmental and economic issues which set constraints to building new lines, force the implementation of new technologies into the existing system in order to improve its power capability. This paper investigates the use of specific FACTS devices and WAMS systems to maximize total transfer capability generally defined as the maximum power transfer transaction in Central-East-Europe power system. Optimal allocation and control of these devices will be very important for TSO or other power market regulators. Effectiveness, optimal allocation and utilization of phasor measurement units (PMUs) for different types of FACTS devices designed for power flow control and increasing transfer capacity were investigated. Paper also compares the economic aspects of these devices.

This paper deals with modelling of a photovoltaic power plant in combination with a battery energy storage system and their cooperation in order to better renewable energy utilization at local level. In this paper, the model of grid on a hybrid system that is formed by the battery energy storage system, a photovoltaic power plant, a utility grid and a small commercial load is proposed. Battery energy storage system based on lithium ion technology is connected by a DC-DC bidirectional power converter to the DC bus together with a photovoltaic power plant. Avltage source converter is used for conversion of DC to AC power. Utility grid and commercial load are connected to the AC side. Modeling of a hybrid system and simulation of the system’s behaviour during a random day of the year was performed in Matlab/Simulink environment employing SimPowerSystems toolbox. The results show the cooperation of the battery energy storage system and the photovoltaic power plant using system control in order to satisfy load requirements.

This article deals with the problems of electricity metering under non-sinusoidal loads that consume non-sinusoidal currents from network and/or generate distortions into the network. The equations for determination of estimated values of active and reactive electric energy under the presence of higher harmonics are deduced. It is shown and experimentally confirmed that the meters of active and reactive power have unaccounted inaccuracies, which can exceed allowable metrological ranges. Frequency characteristics of some meters, used in the power grids of the Slovak Republic, are received, and they confirm the conducted theoretical studying.

This paper deals with the solution of transient phenomena during the connection of the photovoltaic power plants. There was investigated the impact of the failure of current protection for renewable energy sources during the network disconnection. There was verified the possibility of network operation during the islanding operation. Failure of network protection represents the significant hazard for employees of distribution system operator so it is necessary to solve the accurate current and voltage values during the connection of particular renewable energy sources.

This article deals with sizing of hybrid renewable sources applications that are suitable in remote areas where grid connection is unavailable or connection to grid is expensive. Depending on the size of installed capacity of each photovoltaic, wind power and small water power plant, such a system can be used to power small systems with hundreds watts consumption and also can be used to supply entire villages where the connected load has a power in the order of up to megawatts. All depends on the installed performance of different sources, types and sizes of the storage device and the equipment, to be an island power system. Such hybrid renewable sources systems are strongly dependent on the weather conditions of the site of their construction. The present paper is about a small grid-off system that powers a small single house. This house is modelled as family house with a two-membered family. The system consists of a photovoltaic cell field, a wind turbine, a small hydroelectric power plant, and a battery bank as a cumulating source. This system is designed to power a whole daily consumption load without electricity outages.

This paper deals with creating a mathematical model of ideal photovoltaic module. The performance of the model is demonstrated with output characteristics which also show the effect of changes in temperature and solar radiation on the output parameters of cell, module, and field. The model is realized in Matlab/Simulink environment due to frequently using and complexity of this software.

This paper deals with the problematic of the actual short-circuit power determination in real conditions. Presented principle of a real value of short-circuit power determination in arbitrary node of the power system is based on the measurement of one cycle RMS voltage and current changes. Described should be useful for determination of short-circuit power in the nodes electrically far enough from any synchronous machines (mainly from a generators of big power plants), in which the subtransient and transient effects of synchronous machines can be neglected. The comparison of the maximum short-circuit power computed according to the IEC 60909-0 standard and the actual short-circuit power obtained from the measurement of RMS voltage and current changes in the island operation of a small network is presented in this paper.

Most important issue in electricity markets is the maximizing of Net Transfer Capacity (NTC). This paper presents an approach for the placement of one Unified Power Flow Controller (UPFC) in interconnected power systems to increase NTC. Detailed analysis is presented for Slovak - Czech and Slovak - Hungary interconnection in Central East Europe network. Simulation results with and without UPFC are used to analysis the impacts of UPFC on the NTC between Slovakia - Czech Republic and Slovakia - Hungary.

This paper describes the impact of renewable energy sources on stability of EWIS transmission system. EWIS is modeled in simulation program MODES. This model consist of 25 control areas, and includes photovoltaic power plants with 18, 7 GW of installed capacity and wind power plants with 15, 9 GW. This article examines the effectiveness of support services in Slovak power system.

This paper discusses the influence of growing amount of electrical energy produced in photovoltaic (PV) power plants to power system stability, according prognosis of PV growth for year 2020. A few different scenarios were created according to PV development outlook documents listed in references. The simulations were performed in MODES on the continental Europe power system model which was upgraded to adapt to the grid topology predicted for year 2020.

Large-scale power systems operation is faced with many challenges. One of many criteria, which should be fulfilled are stability criteria. Interconnecting separated power systems into interconnected network results in large system complexity, and therefore mixed influences from one power system to another part. Also, new devices are introduced to improve power system performance, like FACTS devices. Main goal of this paper is to examine influence of one of these devices to power system stability.

This paper discuses the influence of the renewable energy sources to the islanding operation of the power system. Constantly increasing number of renewable energy resources such as photovoltaic and wind power plant has a significant impact on the stability of electricity transmission. In this article there are three different scenarios considered. Scenarios were made according to photovoltaic (PV) development outlook documents listed in references. The simulation was made in MODES on the Slovak power system model.