Technical Presentations

Impact of Power Transformer Energization on Relay Protection Operation844

Abstract
One of the main causes of the incorrect operation of transformer relay protection are inrush currents. The transient inrush current occurs when energizing the unloaded transformer, and it is a consequ... see moreence of the transformer core saturation. This paper presents analysis of transients caused by energization of 300 MVA three-phase autotransformer with stabilizing winding and voltage ratios 400/115/10,47 kV.

Using the PAMSUITE Toolbox in EMTP, many simulations were performed to show the impact of model’s parameters on the amplitude and duration of inrush currents as well as the probability of 2nd harmonic differential current amplitude occurrence. Simulation results show that controlled switching reduces inrush currents amplitudes and increases 2nd harmonic content in differential currents. A Protection Toolbox in EMTP was used for modelling CT saturation and operation of transformer’s differential protection relay.

Based on the simulation results the optimal differential protection settings were determined, and the probability of false relay protection operation was calculated.

Tag(s): transformer, energization, inrush, differential, protection, harmonics, bctran, pamsuite

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

Wind & Solar Generation Impact on Negative Sequence & Power Swing Protection759

Abstract
<p>This presentation investigates the impact of wind generation on the performance of negative-sequence-based protection.</p><p>
Overview: - Main differe... see morence between EMT-type and phasor domain software. - Load-flow simulations - Time-domain simulations - Frequency Scan - Statistical runs for Insulation Coordination studies - Switching - Lightning - Transient Recovery Voltage (TRV) - Ferroresonance - FACTS/HVDC - Transient stability - Renewable - Power quality - LVTR/OVRT - Sub-synchronous resonance (SSR) - Overcurrent protection - Differential protection - Distance protection - Power-swing and out-of-step detection - Loss of field protection - Open-phase</p>