Ana Maria Dumitrescu

Measurement data aggregation for active distribution networks

Power Quality indicators are still conveyed into a classical paradigm of power systems where the steady state operation is governed by quasi-constant frequency. Moreover, distribution grids are considered as network structures with solely load behavior. The standards proposing power quality descriptors are built on models, which seem to limit the possibilities of achieving real time control targeting highly efficient energy transfer, at least in all-electric grids. In this paper the measurement data aggregation algorithms proposed in the well-known standard IEC 61000-4-30 are discussed based on an analysis performed on voltages and frequency measurements. Raw data are obtained from PMUs installed in various nodes of active distribution grids with reporting rate of 50 frames per second. New aggregation algorithms for frequency, rate of change of frequency and unbalance coefficient appear to be needed.

Analysis of distribution grids: State estimation using model uncertainties

The development of smart grid technologies for distribution grids requires a more accurate knowledge of the energy transfer in such grids. Uncertainties in the measurement chain and in the network model (mostly from incomplete knowledge of the model electrical parameters) have to be estimated and further used together with control algorithms, including those based on state estimation procedures. In this paper, several model components are considered and described along with associated uncertainties: the equivalent circuits of the low voltage cable belonging to a generic distribution grid, power transformers and an aerial short medium voltage line. In order to minimize the uncertainty associated with the state estimation variables, only phasor measurement units (PMU) are considered in the measurement layer.

Model validation of distribution feeders using synchronous measurements

As the distribution grids are an important part of the electrical system, their components need to be known in order to achieve optimal control of energy transfer. The present paper considers one component of the distribution grid namely the power line, aerial or cable, its model parameters leading to pseudo measurement uncertainties that can propagate through the entire grid when, for example, state estimation algorithms are applied. The paper discusses the case of short lines in order to decide whether it is important to have a better knowledge on the power lines parameters in estimating the losses of the electrical power system and also for various control strategies in active distribution grids. The validation of estimated parameters is made considering different load conditions for the aerial distribution line.

Stationarity hypothesis in power systems data aggregation. Verification algorithm

In the case of electrical power networks using the RMS values for the measured voltages in order to determine its state is the accepted procedure. This method is based on the stationarity hypothesis. In this paper the validity of this hypothesis is studied based on numerical and experimental data. Practical examples of its non-validity are shown using the data aggregation algorithm.

Robustness against measurement component for controllers in LV active filters

Performance of active power filters is a function not only of the inverter design but also of the type of controller. Among different active filters control strategies, there are two different controller configurations with generally accepted good performance: the classical PI controller and the harmonic controller. Their robustness against the measurements is evaluated in this paper, while both are implemented in (d, q) frame. The influence of measurement uncertainties in the current and voltage measurement chain on the overall performance of the control part of the active filter is considered. Based on numerical simulation data, it is concluded that the method based on harmonic controllers implemented on the synchronous referential is more appropriate for the control of active filters.

A project-based Robotics laboratory

This paper presents a Robotics laboratory conceived for the Electrical Engineering students. The laboratory work comprises two stages - a preliminary one, in which they apply Robotics concepts by means of ready to use platforms, and a second one, when the students are engaged in a complex project, whose goal is to develop their own platform. There are detailed the work stages, emphasizing both the trainer and the students activities.

Flexible and mobile deployment of synchronized measurement systems for active distribution grids

The emergence of next generation WAMS and WAMPAC networks offers promising advantages for ensuring the stability of the distribution grid. Thanks to the revolutionary synchrophasor technology, the power system observability is no longer an unknown quantity. However the deployment of such systems is heavy and rigid. We implemented a mobility-oriented lightweight deployment consisting in several PMUs and a couple of PDCs for monitoring certain segments of active distribution grids, which can be moved across geographic regions with ease and, at the same time, can be reconfigured and adjusted to integrate easily to any existing network topology. This paper presents the challenges involved by this new mobility approach, the structure of our existing flexible deployment and the results we have achieved in one of the active grid segments where we have recently performed an on-field installation of the whole deployment scheme.

Smart grid topics in the UPB electrical engineering curricula

Smart Grids is already considered an attractive topic in the power engineering education programs. Politehnica University of Bucharest has a unique profile in the engineering higher education landscape by including among its 14 Faculties, one dedicated to Power Engineering and another one to Electrical Engineering. In this paper we focus on the smart grids topics that the students enrolled in non-power engineering programs are exposed to. We believe that these courses reflect in a high degree the smart grids philosophy, seen as a mix of communication, power transfer and information processing layers. In this paper, several courses outlines are presented as an example of developing the missing link between equipment providers and the grid stakeholders (customers, network operators and energy providers).