Simplified Analytic Approach of Pole-to-Pole Faults in MMC-HVDC for AC System Backup Protection Setting Calculation

Abstract

AC (alternating current) system backup protection setting calculation is an important basis for ensuring the safe operation of power grids. With the increasing integration of modular multilevel converter based high voltage direct current (MMC-HVDC) into power grids, it has been a big challenge for the AC system backup protection setting calculation, as the MMC-HVDC lacks the fault self-clearance capability under pole-to-pole faults. This paper focused on the pole-to-pole faults analysis for the AC system backup protection setting calculation. The principles of pole-to-pole faults analysis were discussed first according to the standard of the AC system protection setting calculation. Then, the influence of fault resistance on the fault process was investigated. A simplified analytic approach of pole-to-pole faults in MMC-HVDC for the AC system backup protection setting calculation was proposed. In the proposed approach, the derived expressions of fundamental frequency current are applicable under arbitrary fault resistance. The accuracy of the proposed approach was demonstrated by PSCAD/EMTDC (Power Systems Computer-Aided Design/Electromagnetic Transients including DC) simulations.

Traveling Waves-Based Method for Fault Estimation in HVDC Transmission System

“…Lots of discussions were carried out to find the relationship between natural frequency of traveling wave and distance of fault point from terminal under all system boundary conditions. The significant advantages of the natural frequency-based fault location detection technique are that it does not need to observe traveling wavefront and it does not require two terminal measurements for accuracy as are required in fault location techniques based on satellite time references and wavelets [7,[49][50][51][52][53][54][55]. In the proposed research, this problem is solved by finding the DC component, dominant AC component and THD values of traveling wave for fault estimation.…”

A Non-Standard Characteristic Based Protection Scheme for Distribution Networks

“…In addition, increase in reliability of protection systems is provided by coordination between primary and backup protective equipment, which is also referred to as protection coordination. However, coordination requirements increase the primary response time of protective equipment due to the nature of the traditional protection approach [2].…”

Investigate on a Simplified Multi-Port Interline DC Power Flow Controller and Its Control Strategy

“…To ensure the consumption and efficient use of the large scale new energy, effective transmission technology is needed as a support [1]. As the multi-terminal high-voltage direct current (HVDC) transmission system has the advantages of long transmission distance capability, large capacity and a flexible operation mode, etc., it has therefore become one of the main means to facilitate grid connections of large-scale renewable energy [2].…”

“…This kind of control scheme is simple to implement, but it can only adjust the equivalent resistance of the line in one direction, which limits its power flow control ability. (2) For the DC voltage control type DCPFC, according to the voltage regulation means, it can be further divided into three main types, which are 1 a DC transformer type [6][7][8][9][10], 2 an auxiliary voltage source type [11][12][13][14][15]] and 3 a capacitor-based interline energy-exchanged type [3,[16][17][18][19][20][21][22][23][24]. In comparison, the DCPFC of capacitor-based interline energy-exchanged type has more advantages and better application prospects.…”