Today's power grids are facing tremendous challenges because of the ever-increasing power demand, system complexity, infrastructure cost, knowledge base, and policy and regulatory issues to achieve supply-demand power balance and resiliency with respect to more frequent extreme weather events and cyber-attacks. It is particularly challenging when the transition toward 100% intermittent renewable energy sources is considered. Many countries are calling for building up more transmission and distribution lines to increase power delivery capacities. This paper is an attempt to answer two urgent questions: Is more transmission and distribution infrastructure really needed to meet the increasing power demand? What kind of future grid infrastructure should we envision and build? This paper attempts to answer these questions and proposes the concept of community-centric asynchronous renewable and resilient energy grids. By clearly differentiating the concepts of grid resilience and reliability, the importance of building resilient power electronics devices and robust system level control algorithms to achieve 100% renewable energy integrated resilient grids is presented. To identify the shortcomings and propose advancements, power electronics technologies are categorized using the proposed concepts of Natural Source frequencies (NSf), energy storage, Direct energy Conversion/Control and Fault protection (DeCaFp), and high efficiency Energy Consumption and Buffering ( he ECaB) technology. The ability of networked microgrids to greatly reduce power outages and power system restoration time is demonstrated by leveraging robust de-centralized and centralized control algorithms, identified through a comprehensive literature review. Future research areas are proposed to further enhance grid stability, controllability, cybersecurity and protection against faults in the presence of 100% renewable sources by leveraging the advanced capabilities of NSf, DeCaFp and he ECaB devices and system level control algorithms.

This paper demonstrates the potential of inverter-based loads to support grid reliability during power system transients thereby enabling reliable integration of renewable energy in power systems. Such loads are referred to in this paper as grid-supportive loads (GSLs). A new GSL model is developed that simulates the transient response capabilities that can be programmed in electronic loads. The model’s design enables it to be easily integrated in widely used commercial power system transient analysis software. Theoretical expressions are derived that explain the workings of the GSL model. The performance, numerical stability, and impact of the GSL model is validated on 9-bus and 2000-bus synthetic power system models using generator tripping and bus fault disturbances. Results on the 2000 bus system show that in the absence of frequency support from wind/solar generation resources, just 20% of loads with grid-supportive capabilities can improve frequency response by up to 2000 MW/0.1 Hz and reduce deviation in frequency at nadir by up to 60% compared to the situation when GSLs are absent. Power system reliability also improves under fault events. It is further shown that GSLs can aid in integrating more renewable generation without degrading the overall transient response of the power system.

For power grids with high penetration of distributed energy resources (DERs), microgrids can provide operation and control capabilities for clusters of DERs and load. Furthermore, microgrids enhance resilience of the hosting bulk power grid if they are enabled to serve critical load beyond the jurisdiction of the microgrids. For widespread deployment of microgrids, a modular and standardized Microgrid Building Block (MBB) is essential to help reduce the cost and increase reliability. This paper proposes the conceptual design of an MBB with integrated features of power conversion, control, and communications, resulting in a systemwide controller for the entire microgrid. The results of a feasibility study indicate that, in a utility-connected mode, MBB-based microgrids can exchange power with the hosting power grid while serving regulation and optimal dispatch functions. In a resiliency (islanded) mode when the microgrid is disconnected from the utility system, the MBB control system acts to stabilize the system frequency and voltage under small or large disturbances. The microgrid controller is supported by a communication system that meets the latency requirements imposed by the microgrid dynamics as well as data acquisition time. The extended IEEE 13-node system is used as a microgrid model to validate the proposed MBB design and functionality.

Distributed energy resource management systems (DERMS) are increasingly deployed to manage potential adverse impacts of DERs on distribution feeder voltages. However, communication channels used by DERMS controllers, along with the unmanned substations where they are deployed, provide a target for cyber attackers to cause severe voltage disturbances. The voltage problems can damage equipment, trip inverters, and cause undesirable operations of voltage regulating devices. In this paper, using detailed cyber-physical models, the various cyberattack paths an adversary may use to conduct falsified control command cyberattacks are presented. Robust and fast acting centralized cyber layer and de-centralized inverter intrusion detection are also proposed. This two-tiered system can detect and mitigate these cyberattacks before the power system layer is impacted, even if the DERMS controller itself has been compromised. The cyberattack models and proposed intrusion detection techniques have been validated using IEEE test feeders.

Islanded microgrids may experience voltage and frequency instability due to uncontrolled state changes of voltage regulation devices and inaccurate demand forecasts. Uncontrolled state changes can occur if optimal microgrid restoration and dispatch algorithms, used for generating control commands for distributed energy resources, do not incorporate the behavior of automatic controllers of voltage regulation devices. Inaccurate demand forecasts may be encountered since post-outage demand of behind-the-meter net metered (NM) loads can vary significantly from their historical NM profiles. This paper proposes an optimization formulation which allows optimal control of voltage regulators and capacitor banks without remote control and communication capabilities. A generalized demand model for NM loads is proposed which incorporates the cold load pickup phenomenon and their time varying post-outage demand in accordance with the IEEE 1547 standard. The time dependent optimal control formulation and the NM demand model are integrated in a sequential microgrid restoration algorithm by linearization of the involved logic propositions. A detailed case study on the unbalanced IEEE 123-node test system in OpenDSS validates the effectiveness of the proposed approach.