Conference Agenda

This paper presents an Electromagnetic Transient (EMT)-based study about the IEEE 2800-2022 standard benefits for transmission line protection functionalities in the presence of Inverter-Based Resources (IBR). Seven functions are evaluated, namely: 1) Self-polarized distance protection, 2) Memory-polarized distance protection, 3) Memory-Cross-polarized distance protection, 4) Negative sequence-based directional function, 5) Zero sequence-based directional function, 6) Incremental phasor-based phase-selection function, and 7) Current angle-based phase-selection function. To do so, massive EMT simulations are carried out in the PSCAD environment to emulate contingency scenarios in a typical transmission circuit that interconnects an IBR to a synchronous power grid. The evaluated protection functions are implemented and validated with the routines applied in commercial relays, providing a practical perspective on the importance of recent advances in IBR control standards, such as the IEEE 2800-2022. The results demonstrate that the IEEE 2800-2022 significantly improves the transmission line protection performance, being the EMT-based analysis crucial to provide a detailed study on these benefits.

Half-wavelength transmission line protection is a challenge that hinders the implementation of this technology. However, this line is considered an interesting alternative to transmit bulk power blocks over very long distances and to connect wind and photovoltaic generation to an electrical power system. This study introduces a method to protect a half-wavelength transmission line. The proposed complex plane-based protection algorithm uses a differential complex power in the sequence domain to detect faults along the entire line. The embedded spark-gap mitigation device is properly considered because it is a necessary apparatus to remove severe resonant fault conditions. A time-domain analysis shows that the proposed algorithm achieves robust performance for both internal and external faults.

Overvoltage protection of substations connecting hydro power plants (HPP) to the transmission network depends on numerous factors such as: type of HPP connection (air-insulated substation AIS or gas insulated substation GIS), overhead line/cable connection, location, and characteristics of installed equipment, specific operating conditions, and topology. This paper deals with analysis of overvoltage protection in the underground located HPP considering AIS and GIS connection to 220 kV transmission network with specific emphasis on lightning overvoltages. Detailed model for analysis of lightning overvoltages was developed, and simulations are carried out to determine optimum overvoltage protection configuration. Due to specific topology of HPP connection and underground location of step-up transformer, it is necessary to determine the level of transferred overvoltages over transformer to check the necessity for installing additional surge arresters for protection of generator.

Microgrids emerged as an efficient way to integrate distributed energy resources and local loads into power distribution systems, allowing the local system operation in gridconnected and islanded modes. However, the microgrids imply several challenges for the protection systems, such as the changes in fault current path and the decrease of the fault current amplitude during islanded operation. Therefore, conventional overcurrent protection does not guarantee selectivity, coordination, reliability, and adequate trip time in AC microgrids. Under this perspective, voltage-based relays have been widely investigated as a potential protection for AC microgrids. Thus, this paper critically reviews voltage-based protection and proposes improvements to an existing technique, aiming to simplify the settings and guarantee reliability and selectivity among various voltage-based protection devices. The results showed that our modifications improved the selectivity and reliability of the voltage-based protection compared with the original technique and the traditional overcurrent protection devices for different topologies of an AC microgrid.

This paper proposes a one-terminal traveling wave (TW)-based transmission line protection for line commutated converter (LCC) of high-voltage direct current (HVDC) systems. The method requires the first and second wavefronts to reach the local bus and considers the boundary conditions of the system. A detailed mathematical analysis of the sampling frequency effects, as the basis for a number of innovations of practical interest, is presented here. Firstly, a definition of a minimum sampling frequency is formulated. This is crucial when dealing with the high sampling frequencies traditionally needed by TW-based methods. Secondly, mathematical expressions of protected, unprotected, and uncertainty zones on the transmission line are defined. Thanks to these calculations, the method is also capable of distinguishing faults at the line terminals from faults on the protected transmission line. Thirdly, the non-requirement for the TW propagation speed estimation is proven. Some TW-based protection elements require knowledge of the TW propagation speed, which is a source of errors. The proposed function presented good dependability and was able to operate below 15 ms for a transmission line of 2900 km in length.

Digital fault recorders (DFRs) and some conventional relays operate typically with sampling frequencies up to a few kHz. Conversely, traveling wave (TW)-based methods are usually designed to operate at sampling frequencies in the order of MHz. However, this paper demonstrates that two-terminal TW-based protection that considers the effects of the sampling frequency and TW propagation velocity uncertainties can protect transmission lines using sampling frequencies of a few kHz instead of MHz. This demonstration considers a performance validation based on challenging real-world faults recorded in transmission lines equipped with DFRs operating with a sampling frequency of 15,360 Hz. The low-sampling frequency two-terminal TW protection was
implemented in hardware as a protective relay to evaluate actual data in real-time analysis, representing a significant step towards the practical application of the TW concept readily available in real protection devices with a low-sampling frequency.