An Accurate Noniterative Fault-Location Technique for Low-Voltage DC Microgrid

Abstract

The least erroneous knowledge on fault location in distribution system helps for restoration process, expedite maintenance and reduce power outage duration. A fault location method using probe power unit (PPU) in DC microgrid assumes that the natural frequency of the system is equal to damped resonant frequency of probe current. This assumption leads to prominent error in fault location calculation. To estimate location of fault in low voltage DC microgrid system, a noniterative fault location technique using PPU is proposed in this paper. Considering damping frequency and attenuation of the probe current, which is a function of fault distance and damping coefficient, fault location is obtained. The technique is tested for high resistance fault and radial and looped topologies and found to be more accurate.

System Configuration, Fault Detection, Location, Isolation and Restoration: A Review on LVDC Microgrid Protections

“…Moreover, the term of fundamental frequency is no longer a predefined default value to define the impedances of a DC system in transient [81]. Deriving from similar concept of distance protection of AC systems, active distance estimation methods for DC Microgrids protections are proposed [24,107]. In such methods, power injecting unit (which is named as a probe power unit) is employed to inject low-power current or voltage signals of predefined frequency spectrum to the faulty loop.…”

“…Therefore, it is essential to carefully consider all the variables and dynamics of the system during fault transient. This is further elaborated and explained by comparing different research works carried out in Ref [24] and Ref [107] which uses the same methodology. It is assumed the natural frequency of the system to be equal to the damping frequency of the injected current which is not true and also ignored the damping co-efficient of current in calculation; whereas, Ref [107] tried to consider all the dynamics and variables of the system under fault conditions.…”

“…This is further elaborated and explained by comparing different research works carried out in Ref [24] and Ref [107] which uses the same methodology. It is assumed the natural frequency of the system to be equal to the damping frequency of the injected current which is not true and also ignored the damping co-efficient of current in calculation; whereas, Ref [107] tried to consider all the dynamics and variables of the system under fault conditions. Table 2 compares and analyse the variations in fault distance estimation error by both the methods when a pole-to-pole is created, where E1 and E2 represents the percentage estimation error by the methodologies adopted by [24,107], respectively.…”

Development of a Voltage Compensation Type Active SFCL and Its Application for Transient Performance Enhancement of a PMSG-Based Wind Turbine System

“…The simulation conditions of a symmetrical fault are defined as follows: a three-phase line-toground fault is supposed to happen on the main network at = 2 s; the fault resistance is = 1 Ω [32,33]; the fault duration is 170 ms. Figure 13 shows the three-phase voltage characteristics of the wind generation system. During the process of the fault feeding, the wind generation system's output voltage coupled to the AC side will decrease from 200 V to 36 V (peak value).…”

Development of fault section identification technique for low voltage DC distribution systems by using capacitive discharge current

“…Therefore, it is impossible to analyze current by using Prony's method due to the lack of data with respect to capacitive discharge current. In order to overcome this challenge, an additional back-up capacitor [3] or probe power unit [14][15][16][17] are installed.…”