Technical Presentations

Slideshow of the projects from our grand prize winners857

Abstract
During this webinar, our two winners of the EMTP® Research Contribution Prize Program 2021 will present their work. The aim of the award is to recognize student contributions to the technology associ... see moreated with power system transients. The two competition categories are:
- Best accepted IEEE, IET, PSCC, EPSR or IPST journal or conference paper on EMT simulations;
- Best EMTP® model developed.

Discover our winner and the topics of their presentation:

o Husam Samkari, Ph.D. and P.E. in Electrical Engineering
Impact of Distributed Inverter-Based Resources on Incremental Quantities-Based Protection

Abstract:
This paper studies the impact of distributed inverter-based resources (IBR) on time-domain incremental quantities-based relays. One implementation of the incremental quantities for protection is a high-speed sub-cycle directional element. The incremental, also known as superimposed, quantities are fault-generated instantaneous components of voltages and currents. The directional element indicates fault direction based on the transient voltages and currents’ relative polarities. It is essential to ensure that the element does not fail to indicate the correct direction if IBRs fault current responses impact the quantities. IBRs’ fast control response impacts the current quantities by changing both magnitude and angle.

This paper characterizes the incremental quantities-based relay response to IBRs’ nonlinear fault currents. A modified IEEE 34-bus distribution with an IBR system is modeled and simulated using the electromagnetic transients program (EMTP) for demonstration.

o Rafael Castillo Sierra, Electrical Engineer, Ph.D. Student
Model category for his model on Power System with a Transmission Line operating at low frequency

Abstract:
The transmission of electric power with alternating current (AC) faces constraints that are inherent both to the stable operation of the power system and to the physical properties of the transmission lines or cables. Many factors stand to motivate the alleviation of these constraints without a need to construct new transmission lines or cables. One demonstrated method to accomplish this is to lower the electrical frequency of a transmission branch or section of the network, an approach known as low frequency AC (LFAC) transmission. The resulting lower reactance of the lines improves the transmission under the stability concerns which arise with long, inductive overhead lines, as well as under thermal concerns that can be substantial due to charging currents in underground cables. In this order of ideas, the Modular Multilevel Matrix Converter (MMMC) offers the necessary frequency conversion for low-frequency transmission, while allowing controllability of power through the transmission line.

For this reason, this presentation focuses on the EMTP modeling and simulation of this converter starting from a design that meets the typical voltage and power requirements for a transmission line. The averaged model of the converter has been implemented to evaluate its performance as a frequency converter and how it interacts with the power system. Simulations have been carried out under nominal operating conditions in a study case power system.

Tag(s): EMTP, Prize winners, IBR, Protection, Power system, Transmission Line, Low frequency,

Ground Fault Overvoltage with Inverter-Based Distributed Energy Resources841

Abstract
A Ground Fault Overvoltage (GFO) can occur in situations where an ungrounded transmission line and associated ungrounded transmission equipment is energized from distribution connected Distributed En... see moreergy Resource (DER) during a transmission single-phase-to-ground (SLG) fault. The condition could result in 1.73 pu overvoltage on phase to ground connected equipment which will be sustained until the DER ceases to energize the substation distribution transformer. Transmission equipment on the isolated circuit will be subjected to the above phase to ground overvoltage, also if there is frequency shift, the isolating transmission circuit breakers could potentially see up to 2.73 pu phase to ground overvoltage. Such an overvoltage can cause damage to customer or utility equipment and must be avoided. GFO concerns are already becoming a barrier to large-scale DER deployment either by posing low hosting capacity or by necessitating installation of costly mitigation equipment. Utilities need to study GFO risks and identify low-cost mitigation options to enable large-scale DER deployment. Given the fundamental differences in mechanisms and phenomena driving a GFO under DERs, classical GFO analysis methods do not apply to inverters, and advanced simulation methods and tools are required.


This presentation highlights EPRI’s work on GFO analysis, concerns, and evaluation of mitigation options using EMTP. The objective is to determine if or when high DER penetration presents a GFO problem and how to prioritize the mitigation and equipment evaluation. This includes evaluating the impact lightning arresters can have in reducing or clamping the overvoltage, the application and performance of high voltage substation overvoltage protection, and DER on-board voltage/frequency protection. The presentation further provides modeling recommendations for such a study using EMTP. As DER deployment increases, utilities will need to perform similar analysis to identify potential overvoltage risks and develop low-cost mitigation methods. This work provides a basis for such a study.

Tag(s): gfov, tov, ibr, DER, inverter, islanding, load rejection, inverter based resources

EMTP Development Roadmap: New Line/Cable data in EMTP 4.2829

Abstract
1. Brief review of transmission line equations

2. Per unit length parameter
- Traditional line data and cable data
- MoM-SO and Extended TL theory

3. New Line/Cable dat... see morea
- Mask options
- Application examples

Tag(s): EMT simulations, transmission, cable data,

Single Pole Auto Reclosure and NGR Analysis 794

Abstract
Unsuccessful auto reclosure has been observed in 765 kV HVAC transmission lines connected with Generation Bus. Back up Impedance Protection of Line reactor triggered during AR dead time due to power f... see morerequency oscillations in faulty phase (disconnected phase). It triggered tripping of Non Switchable Line Reactor at one end, which resulted tripping of 765 kV HVAC Line and avoidable Generation loss.

These Unsuccessful AR operations triggered us to study and model entire phenomena in Power System Analysis software (EMTP).


Initially, two circuits of 765 kV Transmission Line commissioned between Generation Station and Transmission Station with Line Reactor and NGR in both line at either end. Successful auto reclosure observed during single-phase faults on these lines. Intermediate Switching station constructed and both lines were divided in 4 section as per new requirement. Same configuration (rating) of Line Reactor and NGR adopted at newly constructed station on each line. Unsuccessful AR observed during AR running cycle on these lines after new configuration. Backup Impedance protection of Line Reactor found operated during AR Dead time.
Different sets of simulations has been carried out to understand the phenomena:

- Single Phase fault and Auto reclosure in 765 kV Transmission line in different section of entire corridor with Varying Shunt compensation (Value of Line Reactor)
- Different NGR values and observations for above simulations
- Trip the Line Reactor Breaker during Auto Reclosure Phenomena to avoid operation of Backup Impedance protection and its consequences

After EMTP Simulations and study, it was concluded that:

- Line Reactor (Degree of compensation) should be adjusted with adequate value while line length altered from its original design.
- NGR re-sizing can address the issues at some extent. Suitable value of NGR (based on Line Length and amount of shunt compensation) should be employed
Appropriate Solution and mitigation suggested after detail simulation & study.

Tag(s): single pole, analysis, auto reclosure, line reactor

POWERGRID experience with EMTP793

Abstract
To meet the increasing power demand, a number of extra high voltage (EHV) transmission lines is being added to the power system network, which enhances the complexity of power system network. It is es... see moresential duty of power engineer to fulfill the growing demand ensuring the reliability, stability & security of GRID. Transient simulation tools like EMTP play a vital role to provide the flexibility to power engineer for simulating/studying the various case scenarios which couldn’t be simulate in physical power system.


Such tools eventually help power engineer to build a sustainable and secure GRID. In POWERGRID, being a central transmission utility, various studies are being carried out to arrive the technical particular of new transmission system and optimize or fine tuning of existing system. Some of them i.e. Transient Recovery Voltage (TRV) study of 1200kV Transmission network, Smart Power from insulated earth wire of EHV transmission line and 1200kV Transformer Inrush current study are discussed in presentation. 1200kV National Test Station was established & successfully charged along with the transmission line in state of BINA in India.


TRV study was carried out for assessment of various test duties of 1200kV Circuit Breaker. Presentation cover the detailed discussion of 1200kV TRV study and a brief about the facilities like HIL, HVDC control Replica setup, STATCOM replica setup available at Powergrid Advanced Research and Technology Centre (PARTeC).