Optimized Load Shedding Approach for Grid-Connected DC Microgrid Systems under Realistic Constraints

Abstract

Abstract:The microgrid system is an answer to the necessity of increasing renewable energy penetration and also works as a bridge for the future smart grid. Considering the microgrid system applied to commercial building equipped with photovoltaic sources, the usage of a DC microgrid architecture can improve the efficiency of the system, while ensuring robustness and reducing the overall energy cost. Given the power grid stress and the intermittency of the DC microgrid power production, backup power provision and load shedding operations may occur to stabilize the DC bus voltage. Based on the knapsack problem formulation, this paper presents a realistic optimization approach to shedding a building's appliances, considering the priority of each appliance, and also considering a minimum amount of load that must be attended. The problem is solved by mixed integer linear programming and the CPLEX solver. The proposed architecture ensures critical load supply and voltage stabilization through the real-time operation of the operational algorithm allowing the load shedding optimization approach to be applied without compromising the robustness of the system. The results obtained by simulation prove that the DC microgrid is able to supply the building power network by applying the load shedding optimization program to overcome, mainly, the renewable energy intermittency.

A review: compatibility of fuel cells as promising technology for DC-microgrids

“…As shown in Figure 1, DC microgrid is a power distribution system which consists of one or more interconnected DC power sources which then supply to DC loads or DC to DC converters or AC loads via nverters [12]. DC microgrids create an easy and economical platform to deliver DC power to DC loads from DC power sources.…”

DC Microgrid System Modeling and Simulation Based on a Specific Algorithm for Grid-Connected and Islanded Modes with Real-Time Demand-Side Management Optimization

“…Therefore, in order to operate the demand-side management, i.e., to allow load shedding optimization, it is necessary to assign the priority of each electrical appliance, to define the time duration of load shedding, and to define the power based on the real electrical appliances and critical loads. The purpose is to define the load power closing to the real load power by applying a load shedding real-time optimization [22], which is described in detail in [23] and is formulated to the load optimization problem based on the knapsack problem and solved using mixed-integer linear programming with IBM CPLEX [24]. The load power p L and the load shedding power p L_S are given respectively by Equations (14) and (15), where p L_OPT is the load power after the load real-time optimization, p AVAIL is the total DC microgrid available power, and p L_D is the load demand power.…”

“…The DG used in this simulation was SDMO Technic 6500 E AVR. Regarding the SC, its capacity C SC is 94 F and the v SC_Rated is 75 V. The load power curve is scaled according to a real daily consumption profile of our university building during the weekdays, which consists of 49 appliances, as stated in [23].…”

Simulation of Power Router-Based DC Distribution Systems with Distributed Generation and Energy Storage Units

“…Smart grids can incorporate individual clusters (microgrids) [9,10] consisting of electricity consumers, power grids, and distributed generation (DG) units [11,12], including those using renewable energy sources (RES) in their operation [13,14]. To improve the energy efficiency of smart grids, DC microgrids can be integrated into them [15][16][17] to serve power to consumers within a building (or several buildings) and at the sites of C&I facilities [18]. DC power grids have the following advantages [19]:…”