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Author: n.sene
Type: Publication
Date: 2015-04-01

DISPERSED ENERGY RESOURCES SCHEDULING FOR THE INTENTIONAL ISLANDING OPERATION OF DISTRIBUTION SYSTEMS

Description:
The paper presents an algorithm for the automatic optimal scheduling of dispersed energy resources (DERs) and of under-load tap changers (ULTCs) position. The aim of the scheduling problem consists in... see more the minimization of the voltage deviations with respect the rated value, of the DERs production deviation with respect the maximum efficiency point, and of the network losses.
The system incorporates also a procedure to facilitate the intentional islanding maneuver of the distribution network. The adopted approach is based on iterative solution of linear-constrained multi-objective optimization problems. The nonlinear power flow relationships are linearized by means of the calculation of sensitivity coefficients to small variations of the control variables (namely, controllable DERs power outputs and ULTCs positions). The algorithm is implemented in Matlab environment to exploit different solvers and suitably interfaced with EMTP-RV for three-phase power flow detailed calculations. In particular, two optimization solvers are adopted: the least square method and the goal attainment approach. The relevant results are compared using the IEEE 34-node distribution feeder as test case.

Authors: A. Borghetti, C.A. Nucci, M. Paolone, M. Bosetti

Tag(s): Dispersed generation, active distribution networks, islanding operation.

Author: n.sene
Type: Publication
Date: 2015-04-01

AN ADVANCED INTERFACE BETWEEN THE LIOV CODE AND THE EMTP-RV

Description:
Accurate evaluation of the response of overhead distribution lines to lightning electromagnetic pulse (LEMP) represents an important aspects in insulation coordination of distribution network. The imp... see morerovements of the accuracy of such an analysis call for the extension of the field-to-transmission line coupling models from single straight lines to multi-conductor/branched and complex systems. This paper deals with the description of a new interface between the LIOV (Lightning Induced OverVoltage) code and the EMTP-RV software. In particular, the paper illustrates the treatment of the boundary conditions – on which the link with the Augmented Nodal Analysis Technique adopted by the EMTP-RV is based – together with the main aspects related to the numerical integration of the Agrawal and al. LEMP-to-transmission line coupling model adopted in the LIOV code.
The proposed interface aims at improving the simulation capabilities of the previous version of the LIOV-EMTP, namely this new version completely removes the disadvantage of the time-delay associated to the use of a short Bergeron’s line needed to link the LIOV code with the EMTP. Additionally, this new version of the LIOV-EMTP code takes advantages of the Augmented Nodal Analysis Technique implementation in EMTP-RV. Comparison with experimental results is also presented in order to verify the accuracy of the proposed interface.

Authors: A. Borghetti, F. Napolitano, C.A. Nucci, M. Paolone, J. Masheredjian, F. Rachidi

29th Conference on Lightning Protection 23rd – 26th June 2008 Uppsala, Sweden

Tag(s): LIOV, EMTP-RV, LEMP

Author: n.sene
Type: Publication
Date: 2015-04-01

Analysis of black-startup and islanding capabilities of a combined cycle power plant

Description:
The paper presents the analysis of black-startup and islanding capabilities of an 80 MW combined cycle power plant. The analysis is carried out by means of a computer dynamic simulator suitably develo... see moreped in the EMTP-RV simulation environment in order to represent both the power plant and the local network with the relevant loads. The paper describes the main characteristics of the implemented models and presents the analysis of transients due to both energization and islanding manoeuvres. The former simulations aim at verifying the feasibility of the energization of the path from a turbo gas unit, with autonomous black-start capabilities, to the local distribution network loads. The latter simulations allow the analysis of different islanding strategies for rather large levels of power exported to the external transmission network.

Authors: A. Borghetti, C.A. Nucci, M. Paolone, M. Bosetti, G. Ciappi, A. Solari

Tag(s): black-startup, islanding, combined cycle, power plant, energization

Author: n.sene
Type: Publication
Date: 2015-04-01

Parameters Identification of a Power Plant Model for the Simulation of Islanding Transients

Description:
The paper presents a procedure for parameter identification along with its application to the model of a combined cycle power plant that includes the surrounding electrical network, built for the anal... see moreysis of islanding maneuvers transients. The paper illustrates both the power system computer model, implemented within the EMTP-RV simulation environment, and the developed identification procedure based on the interface between the developed model and Matlab. The parameter identification procedure is applied to experimental transient recordings that make reference to a similar power plant.

Authors: A. Borghetti, C.A. Nucci, M. Paolone, M. Bosetti

Tag(s): Islanding, Identification, Power Plant

Author: n.sene
Type: Publication
Date: 2015-04-01

Transient recovery voltages in vacuum circuit breakers generated by the early-interruption of the inrush current of large motors

Description:
The switching of medium voltage electrical motors is typically realized by means of vacuum circuit breakers (VCBs) essentially in view of their elevated number of switching cycles. As known, switching... see more of VCBs generates important transient recovery voltages (TRVs)
that need to be properly evaluated in both VCB sizing and in the power system insulation coordination. As large medium voltage electrical motors are installed into plants typically controlled by means of Supervisory Control And Data Acquisition (SCADA) systems,
maneuvers that involve the motor inrush followed by its sudden de-energization (due, in general, to the intervention of an automatic diagnostic function), resulting into important TRVs, are not unusual. The paper aims at investigating the TRVs due to this specific type of
VCB switching by means of a model implemented in the EMTP-RV simulation environment. By making reference to a real plant, the validation of the implemented models is obtained by comparing the simulation results with some experimental transients provided by the plant data fault recorder. The paper finally discusses the adequacy of different countermeasures by analyzing their effectiveness for the TRVs limitation.

Authors: A. Borghetti, F. Napolitano, C.A. Nucci, M. Paolone, M. Sultan, N. Tripaldi

CIGRE - International Symposium “Assessing and Improving Power System Security, Reliability and Performance in Light of Changing Energy Sources” Recife, Pernambuco, Brazil, April 3-6, 2011
Topic 3 – System technical performance
Subtopic 3.5 – Switching and lightning transient on power systems. Impact on performance and measurements

Tag(s): Transient recovery voltages, vacuum circuit breakers, motor inrush currents, EMTP simulations