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This paper presents the first results of the project “Optimization of fuel cell CHP systems as a component for future building energy supply in smart cities” at Bielefeld University of Applied Sciences. Main focus on modeling and simulating a fuel cell-based micro-CHP-system and scrutinizing electrical and thermal driven operating modes.
This paper discusses the application of PMU measurements in real-time estimation of transmission line power losses. Instead of directly computing the difference between sent and received power, the losses are estimated as separate components, calculated from line equations. On one hand, this provides more information about the operation of the line—active losses are split into Joule and corona losses...
This paper presents a new method of fault loop resistance measurement in low voltage systems with residual current devices. The method enables measuring fault loop resistance without nuisance tripping of residual current devices, by application an unconventional waveform of measurement current. It is important for proper verification of the effectiveness of protection against electric shock.
The design and implementation of Smart Grids takes usually into account the participation of LV electrical energy consumers (through techniques such as Demand Response). However, there is still a lack of cost effective hardware and software solutions that would allow these consumers to monitor their installation, comprehend their electrical energy consumption, take action towards achieving energy...
This paper presents improved algorithm for directional earth-fault relay without voltage inputs. This relay has only currents inputs and it is intended for use in isolated neutral networks. Instead of zero sequence voltage or three phase currents as reference quantities, only one phase current is used as a reference quantity. To obtain reference signal for two other phases, measured phase current...
In recent years the energy consumption, decentralised feed-in, storage of renewable energies [1] and the power system complexity have grown rapidly worldwide. Hence, some electrical networks are already working at their stability limits because they were not originally designed for today's load. Consequently, the risk of power system instability has greatly increased. Therefore, protecting electrical...
This paper reports a study about the inclusion of voltage and current synchronized phasor measurements in the process of Power System State Estimation (PSSE). In order to do this, a least square state estimator that processes both SCADA and synchronized phasor measurements were developed. The effects of synchronized phasor measurements inclusion in the process of PSSE are analysed in terms of observability,...
In order to identify the dynamic signature of power systems, it is important to monitor the generator rotor angles. The rotor angles can be obtained either by direct measurements of the rotor position or by indirect calculation of rotor angle from voltage and current measurements. Considering limited availability of direct measurements of rotor angles the indirect method is used in this paper taking...
Widespread interconnection of Photovoltaic (PV) systems in the distribution system may create voltage rise problem. In this paper, a decentralized voltage control method by use of voltage regulators (VRs) and demand side management using consumer controllable load has been proposed for voltage rise compensation. The proposed method includes a novel determination method to find dynamic line drop compensation...
The paper describes the co-simulation platform that integrates a mobility simulator adapted to represent e-mobility with a dynamic simulator of the power distribution network and with an UMTS communication network simulator. The platform appears useful in order to assess the effects of the transients caused by the concurrent charging of a large number of electric vehicles to the operating conditions...
The rapid spread of the Dispersed Generation (DG) in Distribution Networks (DNs) pushes the Distribution Company to actively manage and control the DN. In order to make this possible, a thorough knowledge of the system state is mandatory and the well-known state estimation techniques used by Transmission System Operators (TSOs) could be applied, but the DNs lack of redundancy due to very limited number...
The integration of distributed generation causes an increase of the voltage magnitude in low voltage (LV) grids. In addition to classical grid expansion distribution system operators have various options at their hands to reduce the voltage rise, e.g. by installing distribution transformers with on-load tap changers or voltage regulators. But for efficient control the network operators need information...
This research project addresses the problem of erroneous measurements for distribution grid state estimation (DGSE) by using bad data detection. A method based on artificial neural networks is developed and tested in combination with DGSE. The necessary steps in order to create the neural networks are presented and training parameters are investigated. The method replaces identified measurement errors...
A saturated core Fault Current Limiter (FCL) is a fault current reducing device that has attracted significant attention from both researchers and electricity utilities. The behaviour of saturated core FCLs has so far been characterised largely through experimentation and/or Finite Element Analysis (FEA) simulations, primarily due to the intricate nonlinear magnetic characteristics of the device....
This paper discusses a decision-support model for asset managers to prioritise assets requiring additional maintenance or replacement, by estimating asset remaining-lifetime and failure impact. The asset health and risk model (AHRM) being the heart of this model is based on dedicated asset-condition assessment functions in combination with usage-based condition estimations and a statistical approach...
Power quality levels in public low voltage grids are influenced by many factors which can either be assigned to the electrical environment (connected consumers, connected generation, network characteristics) or to the non-electrical environment (e.g. climatic conditions) at the measurement site. Type and amount of connected consumers (consumer topology) are expected to have a very high impact on power...
This paper assesses time synchronization sources suitable for Phasor Measurement Unit (PMU) applications in power systems. The paper investigates PMU phase error due to PMU timing inaccuracy and the presence of current and voltage transformers. This paper also shows that in practical on-field applications of commercial PMUs, the required accuracy of the time source should be better than the 31.8µs...
The high penetration of photovoltaic systems in low voltage distribution networks can cause power quality problems due to the increased level of harmonics. In this paper an overview of the relevant power quality standards is provided along with an investigation of the harmonics generation in LV networks. Hardware experiments of harmonics measurements of PV inverters are conducted where the influence...
This paper reviews typical circuit topologies and control algorithms for on-board unidirectional single-phase electric vehicle battery chargers (EVBCs) and provides simple yet reasonably accurate component-based models for their representation for power system analysis. The accuracy of the developed models is validated against measurements of actual EVBCs, for both ideal voltage supply conditions...
This paper proposes a Real Time Load Estimator (RTLE) for the obtaining of accurate information on the real-time operating state of Distribution Systems (DSs) feeders. The RTLE is based on off-line information (customers consumption and typical load curves); a computationally efficient load-flow algorithm that uses a data structure named Node-Depth Encoding, and available real-time measurements. Using...
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