Nondetection zone computation and analytics for unintentional islanding in a distribution grid. (September 2022)

• Record Type: Journal Article
• Authors: Wu, Yuqi; Ma, Xiao; Feng, Zhongnan; Cao, Shankang; Wei, Fanrong; Li, Zhengtian; Lin, Xiangning; Zhang, Fengge; Xiong, Xiaoping; Xu, Haibo
• Is Part Of: International journal of electrical power & energy systems. Volume 140(2022)
• Publication Date: 2022-09
• Subjects: Distribution grid -- Islanding detection -- Nondetection zone -- Over/under voltage -- Over/under frequency; Electrical engineering -- Periodicals; Electric power systems -- Periodicals; Électrotechnique -- Périodiques; Réseaux électriques (Énergie) -- Périodiques; Electric power systems; Electrical engineering; Periodicals; 621.3
• DOI: 10.1016/j.ijepes.2022.107986
• Languages: English
• ISSNs: 0142-0615

Abstract

Highlights: Difficulties to balance the demands of accuracy, rapidity, and practicality for NDZ computation. Establish the mathematical model and uncertainty model of NDZ to obtain robust NDZ results. Indicate the impacts of factors on NDZ and design the islanding defensive countermeasures. Fast compute and apply in real time-based on the existed central monitoring control system. Abstract: With the integration rate of distributed energy resources (DERs) increasing rapidly, the significance of unintentional islanding hazard evaluation has become progressively prominent for distribution network planning and operations. The nondetection zone (NDZ) could serve as an effective metric for evaluating the hazards of unintentional islanding, but the existing research is still not able to balance the engineering demands of accuracy, rapidity, and practicality for NDZ computation. In this paper, a new method for fast online computation of NDZ is proposed aiming at the inverter-based microgrid. First, the mathematical model and the uncertainty model of the NDZ are analyzed and established. Then, Newton's downhill method is implemented to iteratively compute the model above. Numerical results demonstrate that the proposed method can obtain the NDZ quickly, effectively, and robustly. The characteristics of NDZ when different control strategies coexist are revealed, and the influences of different load types on NDZ are indicated. Additionally, investigations of the impacts of unbalanced loads on NDZ are covered. Based on NDZ, this paper further calculates the unintentional islanding frequencies and designs precautionary islanding defensive countermeasures.