ElectroMagnetic Transient studies

Overview

Electromagnetic transients (EMT) refer to sudden changes in circuit conditions of power systems and can be categorized depending on the origin of the disturbance. Considering the non-linear and dynamic nature of the power systems, these disturbances are classified to atmospheric and switching.

Τhe energy interaction between the electric and magnetic fields of the capacitance and the inductances may cause abnormal and excessive voltages or currents of the greatest magnitude in power systems. These transients can affect the performance and reliability of a network, damage the equipment and even lead to shut down of a plant or a citywide blackout.

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Power Generation
RES & BESS
Transmission & Distribution
Oil, Gas and Petrochemicals
Heavy Industries
Infrastructure
Data Centers

Insulation coordination is the selection of the insulation strength of the system in relation to the normal/steady state voltage levels and the expected overvoltages generated by lightning strikes, switching events, faults etc. Surge arresters play a crucial role in achieving an optimum cost-effective solution for the selected insulation. A critical asset is the assessment of the risk of failure and weigh the benefits of improving the insulation against cost.

Insulation coordination studies analyze and identify the potential risks related to insulation stress on system components, define the appropriate countermeasures and provide solutions to the abnormal and potentially hazardous overvoltages and limit them to acceptable levels.

In order to assess the selected insulation, digital simulations with detailed system modelling and real event simulations are necessary. PROTASIS' engineers possesses extensive experience in analyzing and studying power systems in time domain simulation software such as PSCAD and EMTP.

Insulation coordination studies consist of:

Lightning Αnalysis
Switching Transients
Temporary Overvoltages
Very Fast Transient

Shielding Power: Precision in Insulation Coordination for a Safer Grid

Key components

In an insulation coordination study for electrical power systems, several key components are considered and analyzed to ensure reliable operation and protection against overvoltages.

System Voltage Analysis: nominal and maximum operating voltages, voltage stress evaluation, highest voltage for equipment.
Transient Overvoltages: lightning and switching surges, phase-to-earth, phase-to-phase and longitudinal insulation.
Coordination of Insulation Levels: ensuring that insulation levels for different equipment are coordinated to prevent insulation breakdown under transient conditions.
Shielding failure: lightning strike to phase conductors.
Backflashover: lightning strike to ground conductor, insulation flashover.
Switching Overvoltages: switching of inductive and capacitive circuits.
Transient Recovery Voltage (TRV): circuit breaker operating capabilities, rate of rise of recovery voltage (RRRV).
Temporary Overvoltages: ground faults, load rejections, resonance and ferroresonance.
Switching inside Gas-Insulated High-Voltage Switchgear (GIS): very fast transient overvoltages.
Transmission Line Arresters: protection of transmission lines, prevention of backflashovers.
Protection Measures: surge arresters, pre-insertion resistors, synchronized switching.

Power Generation
RES & BESS
Transmission & Distribution
Oil, Gas and Petrochemicals
Heavy Industries
Infrastructure
Data Centers

Lightning studies analyze the impact of lightning strikes on electrical power systems, focusing on overvoltage disturbances and their effects on system components. These studies involve modeling lightning strikes and simulating their interaction with transmission line towers, the grounding system and the power network to select appropriate surge arresters and optimize the lightning performance.

Digital simulations in time domain software allow the representation of realistic events consisting of detailed modeling of lightning current waveform and power system components. By evaluating the performance of surge arresters, grounding systems, and insulation, lightning studies ensure system reliability and equipment safety, minimizing damage and operational disruptions caused by lightning events.

Insulation Stress due to Lightning Events and Mitigation Measures

Key components

The key components in lightning studies for electrical power systems include:

Lightning Characteristics and Behavior: lightning strike analysis and determination of strike locations.
Direct strike to the phase conductors: shielding failure.
Strike to the ground wires or tower top: backflashover.
Surge Protection: selection of the appropriate surge arresters and coordination with system withstand capabilities.
System Reliability: minimizing the risk of failures or outages.
Protection of Equipment: preventing equipment damage.
Simulation and Modeling: simulation of lightning strikes and detailed modeling of components.