Program of the User Conference & Workshop

Wednesday 8th August 2018: Welcoming cocktail reception

The EMTP team will have the pleasure to open this 2-day User Conference and Workshop with a beer tasting from 6:30 to 9:00 pm in Room D133 of the Oregon Convention Center.

Oregon Convention Center Address:
777 NE Martin Luther King Jr. Blvd
Portland, OR 97232

Thursday 9th August 2018: User Conference

08:00 Breakfast and Registration
09:00 Opening Remarks 

Recent developments and RoadmapJean Mahseredjian, Lead Developer of EMTP at PGSTech

Upcoming EMTP developments and versions. 


Geomagnetic Disturbance Simulation Studies: Recent Developments and Challenges, Aboutaleb Haddadi, Polytechnique Montréal & Afshin Rezaei-Zarei, York University

During a Geomagnetic Disturbance (GMD) event, geomagnetically-induced currents (GIC) may cause transformer saturation, hot-spot heating or damage, elevated harmonic distortion levels, increased reactive power demand, and loss of reactive power sources, the combination of which may result in voltage collapse and blackout. To ensure safe operation, NERC standard TPL-007 requires vulnerability assessments to establish requirements for transmission system planned performance during GMD events. Existing phasor domain packages face challenges particularly with regard to the simulation of harmonics and network nonlinearities which limits their use for GMD simulation studies. By contrast, EMTP enables such studies by accurately modeling nonlinearities and representing the system at a very high precision level in a wideband range of frequencies. This presentation studies how to perform a GMD study in EMTP in compliance with the NERC requirements. Required modeling details and data have been identified using a GMD simulation case study in EMTP.


Reproducing the 1989 GMD event in EMTP, Luc Gérin-Lajoie, Hydro-Quebec, TransEnergie

Development of Hydro-Quebec network in EMTP for GMD studies. Methodology for GMD sensitivity analysis. Analysis of simulation results.


Coffee break


The new frequency dependent line and cable model: Wideband Model, Ilhan Kocar, Polytechnique Montréal

The new WB model encapsulates many improvements including state-of-the-art research results. It eliminates the modeling problems encountered with the existing universal line model (ULM) approach. 
In the new model, there is no limitation on the number of conductors. For symmetric coaxial cable systems with several cables, numerical problems are avoided by using the new cable correction function. The newly added DC correction scheme together with frequency band partitioning ensures high precision both at low frequencies and high frequencies. Frequency partitioning also improves the numerical conditioning of the system of equations. Unrealistic delays are avoided thanks to the new routines for the identification and adjustment of time delays. The delay adjustment is a search routine with boundaries for optimized fitting.
The state space formulation in time domain is reformulated using a precise discrete integration method. It minimizes the numerical integration and interpolation errors. This allows achieving stable simulations with larger time steps. The object oriented programming approach with vectorized variables and new memory allocation routines significantly improves the simulation speed and use of memory. The new initialization routines allow seamless transition from steady state solution into time domain simulations.


Impact of Wind & Solar Generation on Negative Sequence and Power Swing Protection, Evangelos Farantatos, Electric Power Research Institute (EPRI)

Inverter-based resources have much more complex fault current characteristics compared to conventional synchronous generators. Hence, legacy protective relays set under the assumption of a conventional power system with predominantly synchronous generation, may misoperate under high level of renewables. 
This presentation first investigates the impact of wind generation on the performance of negative-sequence-based protection. In many applications, wind generators are designed to suppress negative sequence current partially or entirely. Negative sequence current suppression control may result in the misoperation of protection schemes whose operation relies on the assumption of negative sequence quantities being present in substantial levels during unbalanced faulted conditions. The impact of wind generation on negative-sequence overcurrent and negative-sequence-based directional elements is investigated in this work. 
In addition, the impact of renewable resources on the performance of power swing protection is investigated. Case studies with examples of Power Swing Blocking (PSB) and Out-of-Step Tripping (OST) elements misoperation under wind generation will be presented.”

12:15 Buffet Lunch

Safe Operation of DFIG based Wind Parks in Series Compensated SystemsUlas Karaagac, Hong Kong Polytechnic University

Subsynchronous control interaction (SSCI) is the interaction between the power electronics control and the series compensated transmission system that occurs at frequencies below the system nominal frequency. SSCI may occur between the doubly-fed induction generator (DFIG) control system and the series compensated transmission line, to which the wind park (WP) is connected. Not only the DFIG control system parameters, but also the WP operating conditions have significant impact on SSCI.

This presentation will demonstrate the impact of WP operating conditions and DFIG control system parameters on SSCI. Guidelines will be also presented for modifying the DFIG control system parameters to ensure safe operation and acceptable transient responses due to faults. In addition, the accuracies of various analytical tools used for SSCI problem identification will be discussed.


Investigation of Undesirable Impacts of Voltage Control Actions from Smart InvertersJens Schoene, EnerNex  

We present the results of an investigation of undesirable impacts of voltage control actions from autonomously acting residential Smart Photovoltaic generators (PVs) in response to abnormal voltage conditions. The smart PV capability we investigated is Volt-var Control (VVC), which provides dynamic reactive power (var) output (absorption or injection) through autonomous responses to local voltage measurements. The investigation was performed on a real-world secondary distribution system using an innovative simulation process involving time-series simulations. The simulation process was verified by comparing the time-series simulation results with results from time-domain simulations performed in EMTP-RV. For the EMTP-RV simulations, we developed an rms (root-mean-square) PV model that captures the dynamic behavior of the smart PV system. The var output can be controlled by either a Volt-var curve, a Volt-Watt curve or by specifying the power factor (i.e., fixed var output) operating in Watt or var priority mode. In addition, we developed an EMTP-RV model of the split phase 240 transformer that was used on the real-world secondary system. Our simulations have shown that some Volt-var curve settings without var ramp rate limit can result in unacceptable sustained oscillation, which can be particularly severe for curves without a deadband.


Advanced Topological Transformer Model, Afshin Rezae, York University

A new topological transformer model for low- and mid-frequency transients is presented. Various core constructions and winding configurations can be incorporated in the model derived from the principle of duality between magnetic and electric circuits. Among the existing transformer models in the electromagnetic transient programs, this is the first model incorporating the transformer tank in the model and provides the relevant important parameters which affect some low-frequency transients. The model provides options for the user to determine the model parameters based on the factory test results, design data, and typical values. The transformer leakage network is represented based on the coupled leakage circuit and thereby avoid negative leakage impedances. This new transformer model is a reversible model which means that the model is capable of representing various air-core inductances seen from different windings. The winding capacitances are also calculated, based on a new formulation and their effects are taken into account in the transformer transients. In the developed model, the transformer saturation curves and the core loss characteristics are determined based on an optimization process through interfacing the time domain simulation within the EMTP-RV with the optimization algorithms of MATLAB. This way the effects of all parameters are taken into account when obtaining the core nonlinearities. The modeling approach, data input, Graphical User Interface (GUI), and other details are presented.


Coffee Break


Electric studies implemented by the Mexican system operator (CENACE) using the electromagnetic transients tool – the system planning perspective, Luis Daniel Anaya Pérez, CENACE

To guarantee the efficient operation of the National Electric System in terms of quality, reliability, continuity, safety and sustainability, CENACE, as an independent system operator, has been responsible for carrying out various functions, many related to system planning. This infers the implementation of multiple studies and the need for different software tools, within which are those necessary for analysing electromagnetic transients. With the EMTP-RV tool, it has been possible to perform specific studies, particularly those associated with meeting the specifications of certain projects, such as the High Voltage Direct Current Transmission Lines of southeast Mexico, Baja California Norte and Baja California Sur, for which planning is in place to interconnect them to the Mexican system over the following years. Likewise, the tool has been used in key activities such as verifiying compliance to the Grid Code -mainly the quality energy parameters- to analyze the interconnection of generators and the connection of loads, as well as other uses, such as the determination of parameters of electrical elements, systems’ testing, among others. This presentation will briefly explain the functions of CENACE as the Mexican system operator, as well as an analysis of how the EMTP-RV tool has been used for the planning of the system.


Modeling and analysis of large DC grids with EMTP – new CIGRE benchmark with mixed VSC / LCC technologies, Sébastien DENNETIERE, RTE – Centre National d’Expertise Réseaux

A high voltage direct current (HVDC) grid is a power transmission system which consists of multiple HVDC terminals interconnected through DC lines. The advantages of a DC grid are increasing system flexibility and reliability and providing redundancy at a lower cost by sharing resources, resulting in lower power losses. In order to test and compare technical solutions that can be applied on a realistic DC grid, CIGRE B4 Study committee decided to propose a VSC based DC Grid test system with ac and dc parts with all input data suitable for EMT simulation. This first benchmark has been developed in 2014 in EMTP-RV and different simulation tools in order to validate the completeness of data provided in the Technical Brochure #604. The test system has 11 AC/DC VSC converters, 2 DC/DC converters and 2 DC voltage levels (±400kV and ±200kV). The main purpose of the test system is to provide a common basis for all CIGRE SC B4 WGs that work on the research of DC grids. This benchmark model generated a high interest. Some limitations on this benchmark (topology, equipment included…) have been identified so far. In order to provide common study platforms to meet the most different HVDC grid study purposes and needs, seven HVDC grid test models have been established by the B4-72 CIGRE WG. These models have been designed to cover most HVDC grid applications including collection, integration and transmissions of onshore/offshore renewable power generation over long distance, LCC-HVDC grids, LCC-VSC hybrid HVDC grids, AC system interconnections for different types of studies with appropriate and applicable sizes. The presentation will address the issues related to the modeling of the largest DC grid test system proposed by this WG. This grid model includes 22 VSC converter stations, 4 LCC converter stations, PV and wind generations.

16:45 Closing Remarks
17:00 End of the EMTP User Group Meeting

* Conference information and program are subject to change without notice.

Friday 10th August 2018: Workshop

The objective of this workshop is to give to beginner participants a good first hands-on experience on EMTP and an overview of the EMTP capabilities. The workshop is based on the usage of EMTP for demonstrating concepts and teaching through practical problem cases.


Part 1: EMTP get started, EMTP team

The objective of this first part of the workshop is to get familiar with the usage of EMT-type software and the study of power system transients. How to model power systems, what scenarios to run and how to interpret and verify results are as many questions that will be addressed. The software EMTP is used for demonstrating concepts and teaching through practical cases. Prior experience with EMTP is not required. Simulating Power System transients with EMTP is easy! Study how to build networks from small to large scale, from load-flow to time-domain.

10:30 Coffee break 

Part 2: TRV analysis, Henry Gras, EMTP Team

The objective of this second part of the workshop is to get familiar with TRV analysis concepts. Two study cases will be presented: TRV on transfmission lines and TRV on transformer-limited fault scenarios. 


Buffet Lunch


Part 3: Wind turbine modelling and Sub-Synchronous-Control-Interaction (SSCI) Studies, Ulas Karaagac, Hong Kong Polytechnic University

The objective to learn how to simulated networks with wind turbine models. Both average value and detailed models will be discussed. The presentation will include Wind Park integration studies and analysis methods for sub-synchronous interaction problems.


Coffee break


Part 4: GMD analysis in EMTP: compliance with the NERC requirementsAboutaleb Haddadi, Polytechnique Montréal

Presentation of network cases for GMD studies. Modeling details and topological impact on GMD.

16:45 End of the workshop session

Computer and temporary EMTP license:

Each participant will have to bring a personal computer
EMTP temporary licenses will be provided for the duration of the course.