Abstract
Traditional distribution networks are transforming into active distribution networks (ADNs) with the advancement of distributed generators (DGs). Break faults that lead to voltage and current imbalances and fluctuations threat the safety of sensitive power electronic equipment in ADNs. However, locating break faults in ADNs remains a challenge under the influence of DG fault polymorphism. This paper proposes a new method to locate break faults by monitoring information of DG current based on the observability of ADNs. The DG equivalent model is established based on the DG output characteristics under the presence of a single-phase break fault. The characteristics of the fault current contributed by DG are analyzed. An identification method of break faults is proposed based on the variations in DG current. Thus, a fault-locating matrix algorithm is proposed combined with current information and location information of DGs. The simulation results demonstrate that the proposed method can locate break faults quickly and accurately. The method is not affected by topology and changes of DG output and load.
Highlights
E existing fault location methods for distribution networks mainly include the impedance method [3], traveling wave method [4], active injection method [5], matrix algorithm [6], and artificial intelligence algorithm [7]
Many scholars have recently examined these methods while considering the influence of distributed generators (DGs). e study in [8] proposed a method that compensates for fault impedance and errors associated with DGs for distance relays yet requires a multipoint simultaneous measurement. e work in [9] proposed a fault location method based on voltage sag measurements that reduces voltage measurement requirements and is proven suitable for various types of DGs. e study in [10] proposed a heuristic algorithm based on bus currents and voltages that employs a pattern search method to estimate the optimal fault point
active distribution networks (ADNs) contain many sensitive power electronic equipment, which can be damaged by severe voltage and current fluctuations caused by break faults [12]
Summary
Distribution lines are susceptible to lightning strikes, external forces, electrical effects, etc., resulting in break faults. E study in [18] proposed a break fault location method based on the correlation coefficient of the negative sequence voltage and current. The doubly fed wind turbine output tracks the reference values and the d- and q-axis components of the stator current can be expressed as. According to the mathematical model of a doubly fed wind turbine [26], the d- and q-axis positive sequence components of the rotor current in the case of a steady-state break fault are formulated as idr+. Equations (2)–(5) show that the DG output current is determined by the terminal voltage and the active and reactive power reference values in the break fault steady state. Combining (10), (13), and (15) reveals that when a break fault occurs upstream of DG, the variation in DG current relative to that under normal operations is formulated as
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