Technical Presentations

Lightning Overvoltages Transferred Through Power Transformers - EMTP® Simulations & Measurements880

Abstract
In this presentation, different wideband transformer models will be presented: extended BCTRAN model and black-box model based on measurements of frequency-dependent admittance matrix. These models ar... see moree validated using transferred overvoltages measured in high voltage laboratory. Afterwards, the results of the EMTP simulations of the lightning overvoltages are presented and compared to the onsite measurements at power transformer terminals.

Tag(s): Step-Up Transformer, Short-Circuit, Protection Schemes, Real-Time Implementation, Sensitivity Analysis

Data driven and machine learning based approach for microgrid protection using EMTP873

Abstract
Modern intelligent digital relays embedded with phasor measurement units have facilitated easy access and collection of electrical signals in a microgrid. ? In this work, a model for detection, locati... see moreon and isolation of faults in AC microgrids is presented. The real time voltage, frequency and current data are processed via simple formulations to detect the fault. The tripping command is promptly communicated to the incumbent line relays within fault tolerance time, after fault detection. The proposed scheme assures reliable protection in grid connected and islanded mode of operation with added security in case of primary protection failure. Post tripping, the exact location of fault in any distribution line from the utility grid is predicted using a fault locator module. This module is designed and developed by gaussian process regression technique. Further, various machine learning techniques used for fault location has been explored and compared to establish the superiority of GPR method over others. Also the features extracted for model training is quite simpler, which imposes less computational burden on central protection computer. An IEEE 15 bus distribution system with synchronous and solar photovoltaic based DG is simulated in EMTP platform to generate the electrical data. Further the required calculations are performed in MATLAB 2020a.

Tag(s): Machine Learning, Protection Schemes, Fault Detection, Fault Isolation, Real-Time Implementation

Frequency and Voltage Data Processing789

Abstract
The complexity of an active distribution system with distributed generation (DG) is increasing day-by-day. Therefore, a reliable protection system is very necessary to satisfy customer demand. Apart f... see morerom main grid supply, active sources are also available near load centers due to which traditional protection schemes fails to function properly.

The magnitude of fault current during grid connected mode of microgrid, is much higher than islanded operation. Therefore, in most of the previous works, overcurrent protection crashes if its pickup current value is not changed when microgrid is shifted to islanded mode. In this work, the current, voltage and frequency data sampled through PMU is processed to protect the system in both the operating modes. A centralized protection scheme is employed that takes frequency data and voltage phasor to differentiate between islanding and fault condition. Further, it detects the faulted feeder and sends trip command to respective relays within a tolerant time.

This method is devised to work as backup protection when main utility grid is available. However, it can work as a primary protection during islanded mode, when local overcurrent relay fails to operate due to settings based on grid connected mode. A standard IEEE 15 bus system modeled in EMTP is taken as test system for every analysis.

Impact of Renewables on System Protection768

Abstract
The presentation will describe how EMTP with its wind turbine model library, as well as its relay model library are being used at EPRI research projects to perform case studies for EPRI member utiliti... see morees.

The integration of inverter based resources (IBRs) into power systems introduces several technical challenges. One major challenge is the impact on system protection, resulting from the complex fault response characteristics of IBRs which are interfaced with the grid through power electronics and do not behave similar to conventional synchronous generators. EPRI is investigating the performance of legacy protection schemes in systems with high levels of IBRs, and potential misoperations which will compromise the grid reliability.

Impact of Wind & Solar Generation on Negative Sequence and Power Swing Protection741

Abstract
<h6 class="text-black" style="padding-bottom: 30px; padding-top: 30px; text-align: justify;">Speaker: <strong>Evangelos Farantatos&l... see moret;/strong>, <em>Electric Power Research Institute (EPRI)</em></h6> <p class="text-black">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.<br><br> 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.<br> 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.</p>