Optimal Coordination of Overcurrent Relays in Radial System with Distributed Generation Using Modified Firefly Algorithm

Abstract

Overcurrent relays (OCRs) play a vital role in operating the protection of power distribution system. In the presence of distributed generation (DG), OCR coordination is used to ensure reliability and speed of relay operation to avoid unintentional DG disconnection during fault conditions. Therefore, this paper presents an optimal OCR coordination in radial system under the presence of DG. An optimal OCR coordination can be obtained by selecting time dial setting (TDS) and plug setting (PS). A modified firefly algorithm (MFA) is proposed to finds the optimal OCR coordination. The proposed method is applied to four different case studies with DG. The proposed method is compared to both the firefly algorithm (FA) and conventional method. The results show that the proposed method can significantly improve the result of the FA and reduce all cases operating time of the OCR coordination, which reaches 38.38 %.

Optimization Techniques for Directional Overcurrent Relay Coordination: A Comprehensive Review

“…The primary limitation of this OF is that it only decreases the operating time of the primary relay, which could lead to a longer discrimination time between the primary and backup relays. [15], [17], [18], [21], [23], [26], [27], [36], [37], [41], [42], [48], [51], [55], [57], [59], [61], [64], [66], [70], [76], [79], [80], [86], [87], [92], [95], [97]- [100], [103], [104], [111], [113], [116], [118], [125]- [127], [131]- [136], [138], [141], [143], [144], [174]- [179] 𝑚𝑖𝑛 𝑊 𝑖 ′ 𝑇 𝑖𝑘 Where 𝑇 𝑖𝑘 the operating time of i-th relay for a fault in zone k and 𝑊 𝑖 ′ is a coefficient that represents the probability of the occurrence of the fault on a line.…”

“…Other objective functions are presented in Table I, including the minimization of the summation of relay operating times for near-end faults. It aims to reduce the overall time of the protection system when dealing with faults that occur close to the relay location [15], [17], [18], [21], [23], [26], [27], [36], [37], [41], [42], [48], [51], [55], [57], [59], [61], [64], [66], [70], [76], [79], [80], [86], [87], [92], [95], [97]- [100], [103], [104], [111], [113], [116], [118], [125]- [127], [131]- [136], [138], [141], [143], [144], [174]- [179]. Additionally, it includes the minimization of the total operating time of all primary relays for both near-end and f...…”

“…In [61], Rao-1 was used to find the optimal settings of the DOCRs in the presence and absence of distributed generators for a 4-bus distribution system. The results were compared to PSO [57], GSA [97], FA [79], [94], MFA [79], AMFA [80], RTO [94], CPSO [94], and CGA [94]. It was found that the Rao-1 approach produced superior results than other algorithms and had a convergence rate that was significantly faster than the other algorithms.…”

“…In [79], the standard FA was modified to eliminate its weakness by improving randomness of the fireflies because it influences the fireflies in exploration of the optimal solution. The modified Firefly Algorithm (MFA) reduced the randomness of fireflies by modifying the randomization parameter.…”

“…called (AMFA), which aims to find the optimal coordination of DOCRs by exploring the search space and increasing the convergence rate. The proposed algorithm was tested on the same system in [79].…”