The possibilities of selectively providing inertial and primary frequency support as an emergency support service to asynchronous AC areas through Multiterminal Direct Current (MTDC) grid with minimal-communication are explored. Under nominal condition, only voltage droop is considered to allow the AC systems operate asynchronously as they are meant to. When an AC system needs support, the corresponding converter transmits basic information via a distress signal through the DC lines or existing communication channels used for common DC voltage droop control. Following AC-side disturbances, the frequency droop is activated with values that are predetermined based on our proposed design procedure, which ensures primary frequency support through selective converter participation. Model predictive control, which aims to achieve the best possible frequency dynamics with a single-point actuation is also implemented at the converter station connected to the affected area to provide inertial support. Following a converter outage, MTDC power references are modified to ensure minimal impact on the AC side frequencies. Simulation studies showing the effectiveness of the proposed strategies are presented.

Provision of inertial and primary frequency support in a controlled manner through Multiterminal Direct Current (MTDC) grid connecting asynchronous AC areas and offshore wind farms (OWFs) is explored. Under nominal condition, only voltage droop is considered to allow the AC systems operate asynchronously as they are meant to. Following an AC-side disturbance, the corresponding converter transmits basic information via a distress signal through the DC lines or existing communication channels used for common DC voltage-droop control. Upon receiving the distress signal, a new decentralized inertial-droop based controller and the traditional decentralized frequency-droop controller are activated in preselected participating converters with values that are predetermined based on our proposed design procedure. The procedure ensures a new ratio-based performance while providing frequency support. The proposed scheme is based on an Nth-order model of N-asynchronous-area MTDC system. Furthermore, to extract frequency support from an OWF connected to AC-MTDC system, its power reference is modified such that the whole of AC-MTDC system with OWF is emulated as an N-asynchronous-area MTDC system. The proposed strategies are first implemented in the Nth- order model for theoretical validation and later, in full order models of study systems (with and without OWF) for a more rigorous verification.

The interdependency of multiple networks makes today's infrastructures more vulnerable to failures. Prior works mainly focused on robust network design and recovery strategies after failures, given complete knowledge of failure location. Nevertheless, in real-world scenarios, the location of failures might be unknown or only partially known. In this work, we focus on cascading failures involving the power grid and its communication network with imprecision in failure assessment. We consider a model where functionality of the power grid and its failure assessment rely on the operation of a monitoring system and vice versa. We address ongoing cascading failures with a twofold approach: 1) Once a cascading failure is detected, we limit further propagation by re-dispatching generation and shedding loads, 2) We formulate a recovery plan to maximize the total amount of load served during the recovery intervention. We performed extensive simulations on real network topologies showing the effectiveness of the proposed approach in terms of number of disrupted power lines and total served load.

In this article, a novel soft switched interleaved boost structure with a simple auxiliary circuit is proposed which is suitable for stand-alone loads or ac grid applications. In this topology, coupled inductors and switched capacitor cells of parallel modules are merged to obtain high voltage conversion ratio. The converter also has the capability of adding extra switched capacitor cells to attain very high voltage gain. To provide soft-switching condition in the wide range of output power, a new zero-voltage transition auxiliary circuit is employed which is responsible for soft switching of both phases and benefits from low conduction losses, the minimum number of semiconductor elements, and only one auxiliary gate-driver. These merits provide very high efficiency at both full-load and light loads. More importantly, no auxiliary magnetic components are utilized by taking advantage of the leakage inductance of coupled inductors for the resonant network. All semiconductor components operate under soft switching alleviating the reverse recovery problem and switching losses. Besides, the converter benefits from common ground between input and output which simplify voltage feedback. The experimental results of the interleaved converter prototype with 400-V output voltage at 400 W and 100 kHz switching frequency are provided. The full load efficiency of 98% was achieved and the power density was observed 1.9 W/Cm ³ .

Data dropouts in communication network can have a significant impact on wide-area oscillation damping control of a smart power grid with large-scale deployment of distributed and networked phasor measurement units and wind energy resources. Remote feedback signals sent through communication channels encounter data dropout, which is represented by the Gilbert-Elliott model. An observer-driven reduced copy (ORC) approach is presented, which uses the knowledge of the nominal system dynamics during data dropouts to improve the damping performance where conventional feedback would suffer. An expression for the expectation of the bound on the error norm between the actual and the estimated states relating uncertainties in the cyber system due to data dropout and physical system due to change in operating conditions is also derived. The key contribution comes from the analytical derivation of the impact of coupling between the cyber and the physical layer on ORC performance. Monte Carlo simulation is performed to calculate the dispersion of the error bound. Nonlinear time-domain simulations demonstrate that the ORC produces significantly better performance compared to conventional feedback under higher data drop situations.