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Distance protection is popular in transmission networks and constitutes a large installed base across grid systems. The most widely accepted implementation of distance protection is based on voltage and current phasors. Today the electric grids are becoming increasingly complex and dynamic in nature. With power electronic converter interfaced systems such as renewables, HVDC, FACTS, etc., there is a need for fast, secure and reliable protection decisions. The phasor-based distance protection is prone to reliability issues in such networks and is inherently limited in speed. Recently, ultra-fast protection solutions based on fault induced traveling waves are commercially available. Although promising, such solutions may miss faults near voltage zero-crossing, falsely detects nonfaulty disturbances as faults and as such lack wider acceptance in contemporary transmission lines where protection security is a non-negotiable requirement. In comparison, time-domain based distance protection solutions have appeal in terms of reliability and speed. In addition, an ideal time-domain distance protection should be applicable to various networks such as series compensated lines, lines connected to renewables and long underground/sub-sea cables. In this paper, we propose a method for time-domain based distance protection to meet these requirements. The method operates based on current based operating quantity and a novel dynamic restraining quantity which is calculated for the fault zone boundary point. The proposed method inherently overcomes influence of series compensation, renewable integration and provides a fast and reliable identification of in-zone and out-of-zone faults. It is tested for various networks using laboratory experimental data and field records. Further it is implemented in an IED platform and tested with RTDS simulations in hardware-in-loop mode. The method is found to work satisfactorily and consistently over the extensive test scenarios.

Differential protection normally detects short circuits and ground faults in the windings of a power transformer and its terminals. Inter-turn faults refer to flashovers among the electrodes that arise only in a similar type of physical winding. Inter-turn faults can be examined when the adequate sum of turns is served as short-circuited. In electrical protection, it is difficult to detect inter-turn faults. An inter-turn fault of small magnitude is based on the limited number of turns that resultantly provide a large quantity of current. Due to this reason, protection that comes from the differential scenario possesses a higher degree of sensitivity without causing unwanted operations during external faults. In this paper, a protection-based stability method is proposed whereby external voltages are applied at the low-voltage (LV) side of the transformer while keeping the high-voltage (HV) side short-circuited. This was conducted using a three-phase power transformer (rating: 100 MVA, 380 kV/13.8 kV) at SWCC Shoaiba Power Plant, Saudi Arabia. In this work, differential protection (87T) and high-impedance differential protection for HV-restricted earth faults (REFs) were verified by creating In-Zone and Out-Zone fault conditions to ensure current transformer (CT) circuits and tripping logic. All of the IEDs, protection, and control schemes involved were designed by ABB. This method verifies protection stability for power transformers by implementing differential protection (87T) and high-impedance restricted earth fault (64HV) schemes through creating In-Zone and Out-Zone fault conditions. [ABSTRACT FROM AUTHOR]

Rational partitioning method of power grid is the premise and foundation to implement wide‐area backup protection with multi‐source information. This study shows the universal structure of a wide‐area backup protection system based on regional centralised decision‐making mode, and presents a multi‐objective optimisation method of power grid partitioning. Under the premise of reliable protection, a multi‐objective function is built, comprehensively considering the communication performance, overlap rate, and the balance of regional workloads. To obtain the optimal result, the brain storm optimisation (BSO) algorithm is used in this study. The method is applied on IEEE 11‐bus and 39‐bus test systems and simulated data is used to verify the effectiveness and feasibility of the optimisation method. [ABSTRACT FROM AUTHOR]

The conventional travelling wave protection is susceptible to the high frequency transient quantities, which can reduce the protection reliability. A directional‐relay algorithm based on positive sequence superimposed components is proposed in this study. In microprocessor relays, the extraction of fundamental frequency voltages and currents is, conventionally, provided by phasor estimation methods such as the Fourier algorithm. The common required time for fault detection in these relays is approximately one to two cycles. This study presents a high‐speed algorithm for the extraction of fundamental frequency positive sequence voltages and currents superimposed components based on Park transformation. In the meantime, specially designed high speed algorithms to solve the difficult problems that exist in a real system are proposed. Extensive simulations are performed to evaluate the performance of the proposed algorithm. The results show that the algorithm is fast and reliable for power transmission line protections. Also it is immune to fault resistances and system condition. [ABSTRACT FROM AUTHOR]