3,277 research outputs found
An innovative transient-based protection scheme for MV distribution networks with distributed generation
No full textThis paper presents a new transient based scheme to detect single phase to ground faults (or grounded faults in general) in distribution systems with high penetration of distributed generation. This algorithm combines the fault direction based approach and the distance estimation based approach in order to determine the faulted section. The wavelet coefficients of the transient fault currents measured at the interconnection points of the network are used to determine the direction of fault currents and to estimate the distance of the fault. The simulations have been carried out by using DigSilent software package and the results have been processed in MATLAB using the Wavelet Toolbox
Investigation on unintentional disconnection of photovoltaic plants in LV distribution networks
No full textWith the growing number and capacity of photovoltaic installations connected to distribution networks, power quality issues related to voltage regulation, are becoming relevant problems for power distribution companies and for PV owners. In this context, the paper investigates on unintentional disconnection of photovoltaic plants connected to weak low voltage distribution network. Measurement results put in evidence frequently disconnections of the photovoltaic system, related to relevant voltage fluctuations at the connection point of the active customer, during the operation of its photovoltaic syste
MV network planning under uncertainties on distributed generation penetration
No full textThe necessity for flexible electric systems, changing regulatory and economic scenarios, energy savings and environmental impact are providing impetus to the development of distributed generation, which is predicted to play an increasing role in the future electric power system; with so much new distributed generation being installed, it is critical that the power system impacts be assessed accurately so that DG can be applied in a manner that avoids causing degradation of power quality, reliability and control of the utility system. Considering that uncertainties on DG power production are very relevant and different scenarios should be taken into consideration, traditional deterministic planning techniques cannot be sufficient to take the right decisions. For these reasons, this paper proposes a new three steps procedure, based on an heuristic optimization algorithm for the optimal network planning, considering all technical constraints, like feeder capacity limits, feeder voltage profile and three-phase short circuit current in the network nodes and on the application of the decision theory. Finally a case study is proposed and discussed to show the applicability of the proposed methodology and its main advantage
Smart inverter operation in distribution networks with high penetration of photovoltaic systems
No full textWith the growing number and capacity of photovoltaic (PV) installations connected to distribution networks, power quality issues related to voltage regulation are becoming relevant problems for power distribution companies and for PV owners. In many countries, like Italy, this has required the revision of the standards concerning the connection to the public distribution network of distributed renewable generation. The new standards require a flexible operation of generation plants that have to be capable to change the active and reactive power dynamically in function of the network parameters (i.e. frequency and network local voltage) in local control or following external commands. Therefore, this paper investigates the use of smart inverter in a critical PV installation, where relevant voltage fluctuations exist. A case study, with real network parameters monitoring data and measurements, is discussed in the paper with the aim of showing how ‘smart’ features of new inverters can be implemented to increase PV plant integration in low voltage distribution networks
Penetration Level Assessment of Distributed Generation by means of Genetic Algorithms
No full textThe large amount of Distributed Generation (DG), that
will be installed in the near future, drastically changes the
behaviour of the typical passive MV distribution network.
If it is not correctly applied, it can cause degradation of
power quality, reliability and control of the power system,
vanishing the advantages it can introduce. This context
determines the need of new tools that help the planner to
correctly evaluate the DG impact on the distribution
network and to find the best size and location of the DG
for feeder voltage support and loss reduction. For these
reasons, the paper proposes a software procedure, based
on a Genetic Algorithm, able to establish the optimal
distributed generation allocation on an existing MV
distribution network, considering all technical constraints
like feeder capacity limits, feeder voltage profile and
three-phase short circuit current. The objective function
implemented includes among its terms the costs of buying
energy from the transmission system and from the DG
units. This allows assessing the more convenient
penetration level of DG in a distribution network.
Application examples are presented to illustrate the
algorithm effectiveness
A Distributed Parameter Model for Grounding Systems in the PSCAD/EMTDC Environment
No full textABSTRACT: The study of grounding system behavior under lightning condition is a very hard problem to handle. The high frequencies that characterize the lightning phenomena require the use of distributed parameter models instead of lumped parameter ones. This fact makes hard to model and simulate complex earth system architectures and complete power system circuits. Aim of the paper is to develop a distributed parameter model to be implemented in an electromagnetic transients simulator (PSCAD/EMTDC), simple to use in different electric circuits in order to study lightning effects on power system. Computed results are compared to published experimental ones and to those obtained by different models reported in literature
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