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The structure and connections in networked microgrids consisting of two or more interconnected microgrids is influenced by the dynamic behaviors of power markets, the demand and supply interactions between market participants, and the possibility of operating in the grid-connected or islanded modes. Protection zones in the above-mentioned scenarios are dynamic and should not be determined a priori. Also, fault currents will vary depending on the operating modes, online or offline status of Distributed Energy Resources (DERs), variation of solar irradiation or wind speed, etc. This paper proposes a Centralized Intelligent Station-Level Protection (CISP) approach for the protection of various electric power equipment technologies in networked (interconnected) microgrids using adaptive protective relaying algorithms and a network theory-based zone selection algorithm. The proposed CISP approach utilizes wide area IEC 61869-9 Sampled Values (SVs) measurements and IEC 61850 Generic Object-Oriented Substation Events (GOOSE) messages, intelligently determines the protection zones, and automatically selects the protection algorithms to use in each of the protection zones based on the prevailing system topology and operating conditions. The effectiveness of the proposed CISP approach is demonstrated through real-time simulations using the RTDS®. The results obtained were promising for the various system configurations, operating conditions, and fault conditions considered. [ABSTRACT FROM AUTHOR]

The rising demand for electricity, economic benefits, and environmental pressures related to the use of fossil fuels are driving electricity generation mostly from renewable energy sources. One of the main challenges in renewable energy generation is uncertainty involved in forecasting because of the intermittent nature of renewable sources. The demand also varies according to the time of day, the season, the location, the climate, and the availability of resources. Microgrids offer a potential solution for the integration of small-scale renewable energy sources and loads along with energy storage systems and other non-renewable sources. However, intermittent generation and varying demand need to be matched to provide stable power to consumers. Therefore, it is crucial to design an energy management system to effectively manage the energy sources and supply loads for reliable and efficient operation. This paper reviews different techniques proposed in the literature to achieve the objectives of a microgrid energy management system. The benefits of existing energy management systems and their challenges are also discussed. The challenges associated with uncertainties and methods to overcome them are critically reviewed. [ABSTRACT FROM AUTHOR]

• A novel hybridization scheme using both stochastic and deterministic techniques. • Achieves an optimum operational trajectory under forecast uncertainties. • Simplified and computationally efficient problem formulation. • Reduced dependence on frequently updated forecasts. • Proof-of-concept is depicted on a remote off-grid PV-Diesel-Battery power system. With the precipitated integration of intermittent renewable sources, operation optimization employed with uncertainty management strategies is imperative to ensure a reliable, cost-effective, and secure energy supply for the remote off-grid power systems. This paper presents a two-stage operation optimization process embedded in a model predictive control framework. The first stage decision variables are derived in a deterministic optimization framework to achieve minimum operational costs and emissions. The second stage uses a stochastic optimization framework to refine the first stage decision variables to achieve a feasible operation considering several candidate scenarios in a computationally inexpensive manner. Several measures are integrated to the proposed framework in order to address the operational requirements pertaining to remote off-grid power systems. The effectiveness of the proposed framework is demonstrated through numerical experiments for an isolated remote power system in Northern Canada for both summer and winter seasons. Quality of the obtained results as well as the computation efficiency of the overall framework has been verified compared to the existing energy management techniques. The overall result confirms the applicability of the proposed method in achieving a cost-effective and environmentally friendly operational trajectory while effectively accounting for the underlying uncertainties with a reduced computational burden. [ABSTRACT FROM AUTHOR]

The protection of active distribution networks incorporating microgrids with high penetration of Distributed Energy Resources (DERs) can be challenging if traditional protective relays are used. This is mainly due to the changes in the power flow, fault current level, difficulty in protection coordination, changes in system topology, and system operating conditions. This paper proposes three new protection algorithms for active distribution networks with large penetration level of inverter-based DERs. These protection algorithms comprise of an adaptive differential protection algorithm, incremental transient energy-based directional protection, and a rate-of-change of current protection. The proposed protection algorithms were tested with a distribution network integrated with wind, solar, diesel generator, and battery storage DERs which are capable of operating in islanded mode forming local microgrids. The distribution system and the proposed protection functions modelled and simulated using the Real-Time Digital Simulator (RTDS®). The results obtained from tests validate the proposed algorithms; and their capability to correctly detect and timely isolate faults without resulting in nuisance tripping of the DERs. [ABSTRACT FROM AUTHOR]

• A three-level hierarchical controller is proposed in a centralized architecture. • Both logical and quantitatively optimized power system operation is ensured. • Improved situational awareness through simulation-based operation evaluation. • Proof-of-concept is shown on a remote off-grid PV-Diesel-Battery power system. Integration of locally available renewable energy sources and energy storage have proven to be a cost-effective and eco-friendly retrofit for the primarily diesel-based remote off-grid power systems. However, in the presence of multiple sources and energy storage, the energy management and power management mechanisms must be properly designed to enhance their envisioned benefits while assuring stability, availability, and security of power supply. This paper presents a hierarchical controller equipped with both energy management and power management strategies to obtain an optimum and stable system operation subjecting remote off-grid power systems. An operation evaluation framework is deployed to assess the applicability of the derived optimum operational routines as well as to verify the competence of the low-level controls. Results are demonstrated for a remote off-grid PV-Diesel-Battery power system under different diurnal and seasonal variations. Results revealed the competence of incorporated power management strategies as well as the use of proposed operation evaluation mechanism in identifying certain risks associated with optimum operational routines derived through energy management systems. The overall study confirmed that a coordinated control and operation evaluation platform is required to achieve a logical and quantitatively optimized operational trajectory. [ABSTRACT FROM AUTHOR]