Power system dynamic state estimation (DSE) remains an active research area. This is driven by the absence of accurate models, the increasing availability of fast-sampled, timesynchronized measurements, and the advances in the capability, scalability, and affordability of computing and communications. This paper discusses the advantages of DSE as compared to static state estimation, and the implementation differences between the two, including the measurement configuration, modeling framework and support software features. The important roles of DSE are discussed from modeling, monitoring and operation aspects for today's synchronous machine dominated systems and the future power electronics-interfaced generation systems. Several examples are presented to demonstrate the benefits of DSE on enhancing the operational robustness and resilience of 21st century power system through time critical applications. Future research directions are identified and discussed, paving This work was partially supported by US Department of Energy under Advanced Grid Modernization Program.
Owing to the advantages of high efficiency, high energy density, electrical isolation, low electromagnetic interference (EMI) and harmonic pollution, magnetic integration, wide output ranges, low voltage stress, and high operation frequency, the LLC resonant converters are widely used in various sectors of the electronics-based industries. The history and development of the LLC resonant converters are presented, their advantages are analyzed, three of the most popular LLC resonant converter topologies with detailed assessments of their strengths and drawbacks are elaborated. Furthermore, an important piece of research on the industrial applications of the LLC resonant converters is conducted, mainly including electric vehicle (EV) charging, photovoltaic systems, and light emitting diode (LED) lighting drivers and liquid crystal display (LCD) TV power supplies. Finally, the future evolution of the LLC resonant converter technology is discussed.
This study proposes a novel non-inverting buck-boost converter topology with extra-wide operational zones under both continuous current mode (CCM) and discontinuous current mode (DCM), by introducing a four-mode modulation (4MM) strategy. The proposed 4MM method is able to eliminate the operation dead zone, thus extending the operation zones of the buck-boost converter to contain boost mode, extended boost mode, extended buck mode, and buck mode. Rigorous analyses and design principles are presented in detail to demonstrate the four-mode function through CCM and DCM operational investigations and illustrations. Theoretical analyses and parameter design are verified by software simulation and hardware experimentation in this study, which validates the proposed 4MM method and the functionality of the proposed 4MM-based buck-boost converter. They clearly indicate the superiority of the proposed 4MM-based four-switch non-inverting buck-boost converter over its conventional counterparts, posing wide applicability in industrial practices.
Crosstalk phenomena taking place between synapses can influence signal transmission and, in some cases, brain functions. It is thus important to discover the dynamic behaviors of the neural network infected by synaptic crosstalk. To achieve this, in this paper, a new circuit is structured to emulate the Coupled Hyperbolic Memristors, which is then utilized to simulate the synaptic crosstalk of a Hopfield Neural Network (HNN). Thereafter, the HNN’s multi-stability, asymmetry attractors, and anti-monotonicity are observed with various crosstalk strengths. The dynamic behaviors of the HNN are presented using bifurcation diagrams, dynamic maps, and Lyapunov exponent spectrums, considering different levels of crosstalk strengths. Simulation results also reveal that different crosstalk strengths can lead to wide-ranging nonlinear behaviors in the HNN systems.
This paper presents and analyzes an AC-DC power converter structure, which is comprised of a Power Factor Correction (PFC) module and a LLC resonant DC-DC converter module. This converter only uses two switches, and requires three less diodes and one less switch compared to popular LLC resonant converter solutions. Compared to its conventional counterpart, the rectifier of interest has high energy efficiency while a smaller size, owing to the soft-switching in the LLC resonant converter. Detailed theoretical analyses are conducted in this study, followed by software simulation and hardware experimentation, which demonstrate that the single stage double-switched (DS)-LLC rectifier is able to realize unity power factor and a wide output range, indicating its effectiveness and applicability.
This paper proposes a novel high-efficiency generation technique for photovoltaic (PV) system, named maximum power point capturing (MPPC) technique. This is an aperiodic perturbation MPPC technique compared to the conventional periodic perturbation maximum power point tracking technique. Firstly, under a closed-loop circuit and an open-loop circuit, the complete I-V curves and P-V curves are defined. Secondly, the proposed MPPC technique is based on the complete I-V curves and a practical model of solar PV systems. The proposed method realizes that maximum power point (MPP) is captured online, and its control strategy is designed to set a steady operating area around MPP. The duty cycle keeps constant when the operating point is within the steady operating area, i.e., aperiodic perturbation, and when the operating point is outside the steady operating area, MPPC is triggered to capture a new MPP with an updated steady operating area. Simulation results demonstrate that no oscillations exist in steady-state; dynamic performances are improved; and only two perturbations are required to capture the new MPP. Using the proposed MPPC method, low voltage ride through and high voltage ride through can be prevented.
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