Technical Presentations

Time-Domain Protection Scheme for Microgrids with Aggregated Inverter-Based Distributed Energy Resources897

Abstract
This paper proposes a time-domain-based protection scheme for radial and loop microgrid systems with inverter-based resources (IBRs), such as solar photovoltaic (PV) systems and type-4 wind turbines. ... see moreThe protection scheme is designed to function during both grid-interconnected and grid-isolated modes. The proposed scheme provides an ultra-high-speed sub-cycle directional element aided with low bandwidth communication between relays. Like directional comparison schemes, relays identify whether faults are in-zone or out-zone. The directional element is based on time-domain superimposed quantities and Park`s transformation algorithms. Specifically, the element calculates the superimposed positive-sequence direct component of transient energy during faults. Superimposed voltage and current quantities are calculated using delta filters and decoupled double synchronous reference frame (DDSRF) filters. The proposed filtering method improves the reliability of the superimposed directional element when IBRs are the main source of fault current. The protection scheme is evaluated on a modified IEEE 34-bus distribution system simulated using an electromagnetic transients program (EMTP).

Tag(s): Microgrid, Protection Scheme, Inverter-Based Resources (IBRs)

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

Ground Fault Detection and Feeder Protection of 2x25kV Railway Traction System840

Abstract
In a new 2X25 kV System, Scott transformer is used as a traction transformer and to supply the power to the railway traction system. It is protected using the percentage differential relay.

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However, region from the low voltage side of the Scott transformer to the first autotransformer is unprotected at the field and to protect the system during fault on this region is very important. Thus, development of protection scheme is required. Herein, we modeled 2X25kV traction system in EMTP, simulate faults and developed a specific relationship to provide the protection for this scheme. We have taken the current input from feeder current transformers and observed its current during the faults.


This performance of this scheme is verified using EMTP. Further, impedance to distance ratio is non-linear due to the autotransformer between catenary, rail and feeders in 2x25kV railway traction system. To observe this behavior as per field details and provide the accurate relay setting, we simulate the faults over the length of protected line in EMTP and field test are carried out. In the event of a fault on unprotected region and on the protected line, trip occurs and relay recorded fault details at the field.

Tag(s): Fault Detection, protection, railway, traction

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.