Islanded Microgrid Restoration Studies with Graph-Based Analysis

Abstract

The need to restore and keep the grid running or fast restoration during emergencies such as extreme weather conditions is quite apparent given the reliance of other infrastructure on electricity. One promising approach to electricity restoration is the use of locally available energy resources to restore the system to form isolated microgrids. In this paper, we present a black start restoration method that forms islanded microgrids after a blackout. The master DGs in the formed microgrids are coordinated to work together through droop control. Several constraints, including incentive-based demand response (DR) with direct load control (DLC) and distributed generator (DG) operation constraints, were formulated and linearized to realize a mixed-integer linear programming (MILP) restoration model. To improve compactness and to ensure that the model is neither under-sized nor over-sized, a pre-processing graph analysis approach was introduced which helps to characterize the least number of restoration steps needed to optimally restore the microgrid. Studies were performed on a modified IEEE 123 node test feeder to evaluate the effects of demand response, non-dispatchable DGs, and choice of restoration steps on the quality of the restoration solution. When possible, the proposed method yields an interconnected multi-master microgrid with improved redundancy.

A Review on Black-Start Service Restoration of Active Distribution Systems and Microgrids

“…A dynamic objective function for a restoration problem can be typically defined as (5) [4,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

“…In this regard, a time-dependent CLPU model was proposed in [21] to represent the actual dynamic behavior of the loads in the system. In addition to the mentioned dynamic load models, some studies considered the demand response (DR) in the black-start service-restoration problem [12,18,33]. In [18], the authors proposed a time-dependent method to find the minimum and maximum value of each household connected to a bus in order to find the load-demand range in each bus.…”

“…A microgrid can participate in a restoration procedure if and only if its COT is more than the entire outage time of the system. The α-percentile of the COT is defined as (12).…”

“…A similar model was used for mobile emergency generators (MEGs) which were dispatched as DGs to some nodes in the ADNs [19,31], as well as PVs and microturbines (MT) [20,25]. Furthermore, DG output ramp rate [4,6,8,9,[11][12][13][14]18,21,22,24,27,28,30,32,33] and frequency response rate (FRR) [9,11,14,18,30,32] constraints have also been considered in the literature, which can be formulated, respectively, as ( 14) and (15).…”

A Homotopy-Based Approach to Solve the Power Flow Problem in Islanded Microgrid with Droop-Controlled Distributed Generation Units

“…Thus, the islanding phenomenon is one of the greatest challenges for microgrids. Associated with challenges are low-inertia [9]; system stability [10]; power sharing among DGs [11]; the maintenance of voltage and frequency [12,13]; and, predominantly, power flow (PF) studies [14][15][16].…”