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Author: n.sene
Type: Publication
Date: 2015-04-02

lCT -power Co-simulation Platform for the Analysis of Communication-based Volt/Var Optimization in Distribution Feeders

Description:
The paper presents an ICT and power co-simulation platform for the analysis of the voltlvar control and relevant optimization in medium voltage distribution feeders, achieved by means of a system of d... see moreistributed controllers coordinated via a shared band-limited digital communication network. The platform has been built by realizing the interface between two specific simulation environments:
the Electromagnetic Transient Program EMTP-RV and the communication network simulator Opnet Modeller. The preliminary results provide basic indications on the expected performances of the considered communication-based strategies for ditJerent tratlic congestion levels and load/generation dynamic variations.

Authors: Riccardo Bottura, Alberto Borghetti, Fabio Napolitano, Carlo Alberto Nucci

Tag(s): Co-simulation, Networked Control Systems, Power distribution feeders, Voltlvar optimization.

Author: n.sene
Type: Publication
Date: 2015-04-02

Simulation of the Volt/Var Control in Distribution Feeders by Means of a Networked Multiagent System

Description:
The adoption of networked multiagent systems (MAS) has been recently proposed for the solution of the volt/var control (VVC) problem in distribution feeders. However, constraints and limitations due t... see moreo the communication network, to the dynamic behavior of power system components and regulators, as well as to the measurement uncertainties of the adopted sensors need to be specifically analyzed for the design of the MAS. For this purpose, a cosimulation platform has been built by the integration of two simulation tools:
1) the electromagnetic transient program EMTP-rv; and 2) the communication network simulator Riverbed-OPNET Modeler. This paper presents the modeling and simulation of an asynchronous leaderless MAS-based approach that coordinates the reactive power outputs of a set of power compensators equipped with phasor measurement units via a shared band-limited packet-switched digital communication network. The effects of communication network latency and packet loss on the VVC performances are analyzed for two unbalanced IEEE Test feeders equipped with on-load tap changer transformers. The paper compares the results obtained by using a transmission control protocol (TCP) and a user datagram protocol (UDP), for different levels of background traffic (BT) and different packet discard ratios (PDRs) in the communication links.

Authors: Riccardo Bottura, Student Member, IEEE, and Alberto Borghetti, Senior Member, IEEE

IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 10, NO. 4, NOVEMBER 2014

Tag(s): Cosimulation, medium voltage distribution feeders, multiagent systems (MAS), networked control systems (NCS), phasor measurement unit (PMU), volt/var control (VVC).

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

On the Mitigation Effect of Surge Arresters on the Lightning Performance of Overhead Distribution Lines

Description:
For the accurate statistical assessment of the lightning performance of distribution lines one needs to
take into account the presence of protection devices such as surge arresters and shielding ... see morewire/neutral
groundings. Indeed, the presence of those devices can significantly modify the indirect lightning
response of the overhead line and, therefore, the relevant lightning performance.
In particular, this paper aims at investigating the impact of the presence of surge arresters on the
indirect lightning performance of overhead distribution lines having realistic configuration.
Specifically, reference is made to typical Italian distribution lines. The investigation is performed with
the help of a statistical procedure developed by the authors – based on the Monte Carlo method and of
the use of an accurate modelling/calculation tool for the induced surges – that has been recently
compared with one proposed in the IEEE 1410 Std for the same purpose, and shown to be more
complete and suitable for the problem of interest. The paper also aims at investigating the influence of
the presence of surge arresters on the indirect lightning surges transferred through power transformers.
Such an additional investigation is performed by means of a suitable high-frequency power
transformer mode integrated with the lightning-induced computation tool.

Authors: A. Borghetti, F. Napolitano, C.A. Nucci and M. Paolone - University of Bologna, Italy

CIGRE – Colloquium Cavtat - Application of Line Surge Arresters in Power Distribution and Transmission Systems

Tag(s): Lightning statistics, induced overvoltages, lightning performance of distribution lines, surge arresters, shielding wires groundings, Monte Carlo method.

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