Ron Hui

Smart Grids with Intelligent Periphery: An Architecture for the Energy Internet

ABSTRACT A future smart grid must fulfill the vision of the Energy Internet in which millions of people produce their own energy from renewables in their homes, offices, and factories and share it with each other. Electric vehicles and local energy storage will be widely deployed. Internet technology will be utilized to transform the power grid into an energy-sharing inter-grid. To prepare for the future, a smart grid with intelligent periphery, or smart GRIP, is proposed. The building blocks of GRIP architecture are called clusters and include an energy-management system (EMS)-controlled transmission grid in the core and distribution grids, micro-grids, and smart buildings and homes on the periphery; all of which are hierarchically structured. The layered architecture of GRIP allows a seamless transition from the present to the future and plug-and-play interoperability. The basic functions of a cluster consist of ① dispatch, ② smoothing, and ③ mitigation. A risk-limiting dispatch methodology is presented; a new device, called the electric spring, is developed for smoothing out fluctuations in periphery clusters; and means to mitigate failures are discussed.

Virtual inertia with PV inverters using DC-link capacitors

Soon, virtual inertia for grid control must be covered by photovoltaic inverters. It is suggested to use DC link capacitors for this task. This requires 5 W, 50 J and a capacitor size of about 200 cm3 per installed kW, corresponding to the size of single phase DC link capacitors. It is shown that the additional power ripple (and thus current ripple) is in the order of 0.1% and the voltage ripple of the intermediate voltage will typically remain between +/-3.6%. The related control can be easily extended by adding a voltage signal to the control voltage, which is proportional to the frequency deviation. Then, the existing controller inherently sets the required additional power fluctuation required for the virtual inertia function.

A new energy harvesting and wireless power transfer system for Smart Grid

The increasing use of online monitoring systems for power transmission and distribution networks has led to new challenges for (i) a reliable energy source and (ii) new techniques for satisfying the simultaneous requirements of high-voltage isolation and high energy efficiency in mid-range power transfer. This paper presents a novel concept of insulation strings with simultaneous functions of high-voltage insulation (HVI) and wireless power transfer (WPT) capability. Resonator coils are embedded in insulation discs, which are connected in series to form the new insulation strings with the HVI and WPT functions. Simulation study on this structure suggests that the proposal is not only feasible but also enjoy high energy efficiency.

LLC resonant converter design for bendable power converter

In this paper, a design approach of LLC resonant converter with bendable transformer is presented. First, the electrical parameters of the LLC resonant converter are calculated based on the first-harmonic-approximation (FHA) equivalent circuit. Second, the bendable transformer design approach based on bendable transformer model gives the physical structure of transformer from the electrical parameters calculated. This design approach is adopted in an LLC resonant converter with an isolated output with ratings of 5 V and 2 A for a USB power supply. The design approach is described in details and experimental measurements of a hardware prototype are included to confirm the design approached.

Bendable transformer for wearable electronics

This paper proposes a bendable transformer for wearable electronics. This transformer is bendable to wrap around the forearm. A model using partial equivalent circuit theory (PEEC) is established to analyze the characteristic of the bendable transformer. The bendable transformer is then applied to an LLC DCDC converter. A prototype is built and tested to verify the mode. This LLC resonant converter provides a 5 V, 500 mA (USB) output. Simulation and experimental results are included to confirm the usefulness of the transformer and the validity of the model.

Circuit Theoretic Considerations of LED Driving:Voltage-Source Versus Current-Source Driving

Light-emitting diodes (LEDs) are solid-state devices with specific

Printed circuit board planar current transformer for GaN active diode

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Capability analysis and design considerations of Electric Springs

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A unified converter topology for Electric Spring

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Investigating the scope for electroplated magnetic alloys in shielding of PCBs

characteristics. In this paper, we study the basic requirement of the driving circuits and discuss the proper approach to drive LEDs in view of their characteristics. We compare voltage source driving and current source driving, and discuss their relative advantages and constraints. We specifically introduce the use of circuit duality principle for developing new current-source-mode (CSM) drivers that are less known but are theoretically more versatile compared to their conventional voltage-source-mode counterparts. The study highlights the effects of the choice of driving circuits in terms of the number and size of circuit components used, duty cycle variation, sensitivity of control, nonlinearity and control complexity of LED drivers. We propose a CSM single-inductor multiple-output (SIMO) converter, which demonstrates the advantage of having inductorless and easily controlled current-source drivers, and present a comparison of the CSM SIMO converter with the existing SIMO converters. We further illustrate that a high-voltage-step-down ratio can be naturally achieved by the CSM high-voltage-step-down converter without the use of transformers. This paper presents a systematic and comparative exposition of the circuit theory of driving LEDs, with experimental evidence supporting the major conclusions.