Technical Presentations

Sub-Synchronous Resonance (SSR) Phenomena for Synchronous machine – Simulation & Analysis using EMTP and mitigation technique890

Abstract
Synchronous generators are exposed to oscillatory stresses due to their proximity to statcom devices and other power electronics devices, such as FSCs, HVDC controllers, and STATCOMs, which generate s... see moreub-harmonic frequencies. The interaction between sub-harmonic frequency components and mechanical mass can lead to Sub-Synchronous Resonance (SSR), an unstable and dangerous condition that causes torsional oscillation in the turbine generator shaft. This can reduce machine life, cause fatigue and damage to the shaft, and even result in its breakage. To avoid this, SSR detection/protection should be installed in generator units close to series compensated transmission lines. Different SSR modes can occur depending on the network condition and degree of compensation provided. Comprehensive Torsional Vibration Monitoring & Analysis systems are expensive, but there are cost-effective solutions to sense sub-harmonic quantities reliably at low amplitudes based on desired magnitude of sub-synchronous voltage and/or current. The offered solutions are supported by simulations, studies, modeling, and detailed analysis carried out in EMTP®.

Tag(s): Protection, Stability Studies, HVDC, STATCOM

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,

Closed-loop Synthetic Inertia Control of a Variable-speed Wind Turbine Generator834

Abstract
This presentation introduces a closed-loop SIC scheme of a doubly-fed induction generator (DFIG), which relies on the measured frequency. The SIC scheme employs an additional control loop that operate... see mores in conjunction with the MPPT control loop. Simulation results using an EMTP simulator will be presented under various wind and system conditions for the IEEE 14-bus system.

Tag(s): synthetic inertia, wind park, inverter, stability, frequency control

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).

Eigenvalue stability analysis of subsynchronous torsional interactions770

Abstract
It is well-known that an LCC HVDC may deteriorate damping of torsional modes of nearby turbine-generators, and for weak AC grid connections the HVDC may even destabilize the system. There are fewer dy... see morenamic studies with MMC although recent literature indicates that an MMC HVDC connected in close proximity of an LCC HVDC may generally improve stability. However, these studies do not consider the generator-HVDC torsional interactions in the subsynchronous domain (SSTI).

This article investigates the risk of the SSTI in a dual-infeed HVDC system (LCC and MMC) and in comparison to a single HVDC system. The test topology is inspired by the North French system in which a 2 GW LCC HVDC cross-channel link IFA2000 (1986) is connecting the French and the English AC grid. The HVDC is coupled on the French side with a 1.12 GW nuclear generator in the Gravelines plant and experimental studies showed that there may be a substantial risk of SSTI, particularly with respect to the dominant 6.3 Hz torsional mode.

This system is now becoming a hybrid dual-infeed HVDC since a 1 GW MMC HVDC Eleclink is being installed in proximity of the existing LCC HVDC, on the French side. This raises concerns of new SSTI stability issues.