Inga Zicmane

Analysis of vulnerability of the Latvian electrical power system

The electric power system (EPS) is exposed to small and large impacts during operation, such as changes of loads, commutation of circuit elements, changes of generation of active and reactive power, the impact of automation, (all of them are examples of normal relatively small disturbances), as well as short circuits, large load resets and load surge, unauthorized shutdown of equipment, work of protections and anti-damage automation (those are examples of large disturbances). The purpose of this paper is to provide methods for detection of network parameters that are most vulnerable (voltage drop) to external impacts (sensors), determine their relationship with EPS parameters, try to use this information for improvement of EPS behavioural properties. Thus, availability of information on the location of sensors allows determining and controlling nodes, in which the biggest oscillations of operational parameters are observed due to disturbances in the system.

Elimination of nodes with voltage dependent load characteristics in electrical network models

This paper presents a new technique for the reduction of large power system. It is based on Jordan elimination of nodes represented with their static or dynamic load characteristics dependent on voltage. Thus the reduced network models preserve their past behavior with the same final outcomes in problems of steady states, static and dynamic electromechanical transient processes. We report an example of solving a nonlinear problem in Eurostag software

Market and environmental dispatch of combined cycle CHP plant

This paper considers economic dispatch and unit commitment of the combined cycle (CCGT) CHP plant in electricity market conditions and taking into account new environmental challenges. The proposed algorithm was verified on example of CCGT CHP plant.

Assessing the impact of registering of weak points calculating the power system operating modes

The electric power system (EPS) is exposed to small and large impacts during operation, such as changes of loads, commutation of circuit elements, changes of generation of active and reactive power, the impact of automation, (all of them are examples of normal relatively small disturbances), as well as short circuits, large load resets and load surge, unauthorized shutdown of equipment, work of protections and emergency power control (those are examples of large disturbances). The purpose of this paper is to provide methods for detection of network parameters that are most vulnerable (voltage drop) to external impacts (sensors), determine their relationship with EPS parameters, try to use this information for improvement of EPS behavioural properties. Thus, availability of information on the location of sensors allows determining and controlling nodes, in which the biggest oscillations of operational parameters are observed due to disturbances in the system.

Interconnection of power systems with different under-frequency load shedding schemes

Development of power systems leads to new interconnections that can join power systems with different approaches regarding under-frequency load shedding (UFLS). Parallel operation of different UFLS schemes is analyzed in this paper considering possible UCTE / NORDEL and IPS / UPS interconnection. It is shown that due to differences between UFLS schemes the interconnections stability can be endangered.

Prediction of latvian electrical power system for reliability evaluation including wind energy

Within the last two decades, increase in electricity demand and environmental concern resulted in fast growth of power production from renewable sources. Wind power is one of the most efficient alternatives. Therefore, the issue on integration of a new renewable power plant into the existing electrical power system(EPS) is the topical terms of stability. The goal of this paper is to ensure approach for finding of EPS options, which are most weak to outer impacts, identify their relations with the EPS parameters, use this data for enhancement of power system behavioural properties. Thus, accessibility of data on the location of weak spot allows identify and control nodes, in which the biggest oscillations of operational parameters are observed due to perturbations in the network.

Impact of smart electric thermal storage on transmission grid limitations

This paper examines the potential benefits smart and quickly controllable load can provide for transmission network congestion management if end-users give the transmission network operator or an independent aggregator service access to disconnect their devices in case of contingencies. The necessary amount of available quickly controllable load for the fulfilment of N-1 criteria is found for the case study of the Latvian power system. Of particular interest is the possibility to increase the maximum available transfer capacity between the Latvian and Estonian bidding areas by removing the N-1 provision from the calculation of the cross-border trading capacity if it can be supplied by the controllable load instead. For this purpose, a steady-state power flow model of the 330 kV transmission network and its interconnections with neighboring countries is used for simulations.

Optimal PV electrical energy storage of office building's communal space lighting

Due to the advances in photovoltaic material research and solar panel price reduction over last years, the usage of this alternative energy source in northern countries seems more attractive. Usage of energy storage devices can help use the solar power more efficiently and smarter. This paper deals with the optimization of proposed solar panel array of renovated office buildings communal lighting in Riga, using storage devices and demand side management of the produced power.

Impact of controlled load on the Latvian power system stability

In most countries, electricity is bought and sold at regulated and non-regulated prices. Non-regulated prices are mainly set on the wholesale electricity market and can significantly increase during peak periods due to input of more expensive generation. Another problem, which leads to an increase in prices on the market, is to achieve the carrying capacity of certain sections that does not allow transferring the necessary amount of electricity in the deficit area. At that, overloaded network elements are more prone to emergency shutdown that is not allowable in the peak periods, because it can cause serious system failures. One of the problem solutions may be a load regulation, which, in its turn, may provide both long-term and short-term perspectives. Long-term perspective is aimed to improve energy efficiency carrying out the modernization and reconstruction of the main equipment or the construction of generation sources, etc. Short-term perspective is focused directly on demand management. This article discusses the possible scenarios of the impact of regulated load on the stability of the Latvian power system, based on the power system model circuit created in the software ETAP POWER STATION.

New methods and approaches for monitoring and control of complex electrical power systems stability

Stability of complex electrical power systems (EPS) is an important technical property, indicator of reliable and efficient operation of the EPS. The concept of stability can be divided into three types: the static, dynamic and resulting one. Static stability is the ability of the system to restore normal operation after minor perturbations, in its turn, dynamic and resulting stability is the ability of the system to restore normal operation after large disturbances. The most dangerous system condition is asynchronous operation, when the system loses resulting stability. This paper is devoted to the evaluation issues of static stability of operation mode on the example of the Latvian power system 330 kV. It is separately described the principle of operation of the elimination automatic device of asynchronous operation (AGNA, out of step protection), as a modern reliable means of emergency automation to preserve resulting stability.