A d-axis based current differential protection scheme for an active distribution network

Abstract

The emergence of distributed generators has changed the operational mode and fault characteristics of the distribution network, in a way which can severely influence protection. This paper proposes a d-axis-based current differential protection scheme. The d-axis current characteristics of inverter-interfaced distributed generators and synchronous generators are analyzed. The differential protection criterion using sampling values of the d-axis current component is then constructed. Compared to conventional phase-based current differential protection, the proposed protection reduces the number of required communication channels, and is suitable for distribution networks with inverter-interfaced distributed generators with complex fault characteristics. Finally, a 10 kV active distribution network model is built in the PSCAD platform and protection prototypes are developed in RTDS. Superior sensitivity and fast speed are verified by simulation and RTDS-based tests.

Fuse saving coordination scheme for active distribution systems: State‐of‐the‐art and a novel quasi‐voltage current based scheme

“…The structure of the protection system of modern distribution systems has been completely changed and becomes more complex than that of conventional ones [1]. These changes are in both the level of equipment and operations and the level of network management and communications [2][3][4][5][6][7].…”

“…These studies show that the presence of DG units affects the coordination and selectivity of the protection system [38,[49][50][51]. The previous works on the modification of fuse saving scheme can be generally categorized into two groups: (1) adaptive [12,14,15,22,23,25,27,30,[52][53][54][55][56][57][58][59][60][61][62][63][64] and (2) planning [13,24,28,[65][66][67][68][69][70]. One of the most important features of the adaptive schemes is the up-to-date protection settings in various operating conditions.…”

Characteristic analysis and diagnosis of short-circuit fault in armature winding of four-phase variable flux reluctance machine

“…Neglecting the higher harmonics, the armature current can be expressed as : (10) where I m is the amplitude of the phase current, ϕ i is the initial phase angle of phase current, and w e = N r w r .…”

“…Armature winding short-circuit(AWSC) fault is one of the most common faults in VFRMs [7], and the early features of the AWSC fault are not obvious. If the AWSC fault is not diagnosed and treated quickly in the early stage, it may damage the entire insulation of the power generation system and cause severe security threats [8,9,10,11]. Therefore, accurate AWSC fault detection of VFRMs is highly necessary.…”

Analysis of Fault Characteristics of Distribution Network with PST Loop Closing Device under Small Current Grounding System

“…As the distribution network structure becomes more and more complex, the actual bus parameters on both sides of the loop operation are difficult to meet the loop conditions, and the frequency difference in the distribution network is generally not large, and the loop conditions are mainly influenced by the voltage magnitude difference on both sides of the loop point. The distribution network in China allows for the loop operation under the conditions of "consistent phase sequence, voltage magnitude difference less than 20% on both sides of the loop point, and phase angle difference less than 5 • " [23]. At this stage, the actual loop closing operation is also based on the above conditions to judge the loop closing operation and then realize a smaller inrush current loop closing transfer.…”