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This paper proposes into determining an appropriate electrical vanadium redox flow battery (VRB) model and its integration with a typical stand-alone wind energy system during wind speed variation as well as transient performance under variable load. The investigated system consists of a 3 kW variable speed wind turbine with permanent magnet synchronous generator (PMSG), diode rectifier bridge, buck-boost...
The latest distribution management systems tend to incorporate optimization functions for the short-term scheduling of the various energy and control resources available in the network (e.g., embedded generators, reactive power compensators and transformers equipped with on-load tap changers). The short-term scheduling procedure adopted in the paper is composed by two stages: a day-ahead scheduler...
We can observe in all electrical systems in the world, cc. 0.2,..., 0.35 Hz oscillations in state variables in steady state operation. The amplitude of these - so called inter-area oscillations - is growing going away from the centre of a large electrical power system. In the UCTE (European) system in the centre (near the German-French border) the amplitude of oscillations in frequency deviation time...
This paper examines the impact of distributed generation to loss reduction in power distribution networks. In specific, the way that penetration level and allocation of PV units in a distribution medium voltage feeder affects power losses is investigated. Different approaches, regarding PV units placement across the feeder and their capacity, are analyzed and useful conclusions regarding the penetration...
In this paper we revisit the synthesis of the Power System Stabilizers (PSSs) following some recent objectives and constraints imposed by the evolution of the European interconnected power system. Some principles of approaches used in an independent and even concurrent way are combined and enriched to provide a coordinated way to adjust the parameters of standard (IEEE-type) PSS loops of several machines...
Local concentration of future thermal power plants and wind farms in northern Germany cause network congestions that are in most cases resolved by interventions into generation schedules of thermal power plants or curtailment of wind power production. Right now, improving wind integration by dynamic thermal ratings is discussed. This investigation shows that there is a potential for avoiding the redispatch...
There is a need to improve the delivery of energy services, and utilizing distributed energy resources offers significant potential. We propose an energy service modeling technique that would capture temporal variations of its demand and value, and differentiate it from the electric energy consumed by the end-use equipment. We then use this technique with a novel energy service simulation platform...
This paper carries out a stability analysis of HV networks in presence of large wind farms. In particular, wind generators at partially variable rotation speed will be deeply analyzed in comparison with the fix rotation speed ones. The transit of a wind plant at variable speed from the doubly-fed functioning to classic asynchronous one will be studied to evaluate the system stability. Many simulations...
This paper describes an approach to demonstrate the operation of virtual synchronous generators (VSG) in practical distribution systems. After an extensive simulation phase at laboratory scale, the field demonstration is planned at two sites located in the Netherlands and in Romania, for small VSGs of 10 times 5 kW and one large VSG of 100 kW respectively.
The cross-flow water turbine generation system is, as any distributed grid connected generator, sensitive to all kind of power grid disturbances. The goal of this paper is to show how this system, by the means of its controls, is able to reject polluting harmonics. The fault ride through following voltage gaps is also proven. Experimental results obtained with a hybrid real-time test rig validate...
This paper aims to determine an energetic operation policy (EOP) for hydrothermal power systems. In order to determine the EOP, the optimal solution of a deterministic hydrothermal scheduling model was utilized. The EOP was calculated to follow the trajectories obtained by the optimization model. The resulting trajectories were parameterized in terms of the system total energy storage. Using the system...
This paper presents the results of a study to determine the statistical distribution of the amplitude of the short duration impulse currents discharged by surge arresters installed in medium voltage systems. This procedure considers the survey of the currents discharged by silicon carbide surge arresters taken from the field. The objective of this analysis is to define improved strategies for surge...
In this paper, the performance of the most popular non-linear programming solvers (e.g. IPOPT, KNITRO, LOQO, MINOS and SNOPT) is evaluated for applications in power systems and treatment of ill-conditioned systems related to optimal power flow (OPF) solutions. Regarding the applications, the maximum loading point problem modeled as an optimization problem is used as an OPF example. Also, it is used...
The aim of this work is to design intra-daily recourse strategies which may be used by operators to decide in real-time the modifications to bring to planned generation schedules of a set of units in order to respond to deviations from the forecasted operating scenario. Our aim is to design strategies that are interpretable by human operators, that comply with real-time constraints and that cover...
This paper deals with bifurcations and loadability issues in power systems. A single machine system with dynamic state space represented by a set of differential algebraic equations is considered. It is emphasized that this small system can give a first step in understanding the issues discussed in this paper. Using system loading as a bifurcation parameter and considering two methodologies for calculating...
The reconfiguration of the distribution network feeders can be defined as the restructuring of the feeders through the changing of the open/close states of the sectionalizing and tie switches. This creation of a new distribution network topology is normally required to improve the performance of the network, and thus sometimes the efficiency of the electricity supply. For optimum loss reduction, feeder...
The paper analyses structural changes in deregulated electric power systems (EPS), which should take place in the future if the current trends and conditions remain. The circumstances are considered which define the current EPS functioning and its future structural changes. The mechanism of the restructuring and the boundary conditions, which will start the mechanism, are described.
In the regulated business environment in which many transmission system operators supply their services, the connection of new generation involves ever more complex analysis. The process to identify a suitable connection location and to determine the installed capacity of the new generator usually goes through several stages. Each of the stages should be tackled through activities that provide a balanced...
In a Bayesian selectivity technique has been introduced to identify the faulty feeder in compensated medium voltage (MV) networks. The proposed technique has been based on a conditional probabilistic method applied on transient features extracted from the residual currents only using the Discrete Wavelet Transform (DWT). In this paper, the performance of this selectivity technique is evaluated when...
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