Islanding Detection of Synchronous Distributed Generator Based on the Active and Reactive Power Control Loops

Abstract

There has been a considerable importance for the islanding detection due to the growing integration of distributed generations (DGs) in the modern power grids. This paper proposes a novel active islanding detection scheme for synchronous DGs, considering two additional compensators and a positive feedback for each of active and reactive power control loops. The added blocks are designed using the small gain theorem and stability margins definition considering characteristics of open loop transfer functions of synchronous DG control loops. Islanding can be detected using the proposed method even where there is an exact match between generation and local load without sacrificing power quality. In addition, the performance of the proposed method can be retained even with high penetration of motor loads. The proposed scheme improves the stability and power quality of the grid, when the synchronous DG is subjected to the grid-connected disturbances. Furthermore, this method augments the stability margins of the system in the grid-connected conditions to enhance the disturbances ride-through capability of the system and reduce the negative impact of the active methods on the power quality. Simultaneous advantages of the proposed scheme are demonstrated by modeling a test system in MATLAB software and time-domain simulation achieved by PSCAD.

A Survey on Power System Blackout and Cascading Events: Research Motivations and Challenges

“…In power systems, frequency, voltage and rotor angle of synchronous generating units are the most important quantities that should be properly controlled in order to maintain the power system stability [5]. Power imbalance between demand and generation directly affect the frequency stability, while the voltage is directly affected by the reactive power imbalance [12][13][14][15]. The rotor angle behavior is also a representative of the stability and synchronism in the whole power system.…”

An Effective Passive Islanding Detection Algorithm for Distributed Generations

“…Capability issue of current injection method is investigated in Reference [14] and a solution to solve this problem is also introduced based on considering only certain high frequency components as injected current. Likewise, in References [15][16][17], islanding detection methods for synchronous based generators are presented. In Reference [15], two positive feedback for active and reactive power control loops are presented to make the system unstable in the islanding situation.…”

“…In Reference [15], two positive feedback for active and reactive power control loops are presented to make the system unstable in the islanding situation. Afterwards, in Reference [17], new active and passive power control loops proposed to simultaneously improve the ride-through capability of the synchronous generator, as well as detecting islanding-situation. Integral controllers are added to the governor, and excitation system of the synchronous generator are added in Reference [16] to make the system marginally unstable in the islanding situation.…”

WAMS-Based Online Disturbance Estimation in Interconnected Power Systems Using Disturbance Observer

“…Under frequency load shedding (UFLS) techniques have been used to restore the power system frequency in the event of a large disturbance. Traditional UFLS technique is the most common and in this scheme specific portions of load are shed instantly whenever a frequency threshold is violated [5][6][7][8][9][10][11][12][13]. This technique only relies on local frequency measurements and the magnitude of the disturbance is not estimated.…”