Publications
496 results found
Lee ATL, Jin W, Tan SC, et al., 2019, Buck-boost single-inductor multiple-output (SIMO) high-frequency inverters for medium-power wireless power transfer, IEEE Transactions on Power Electronics, Vol: 34, Pages: 3457-3473, ISSN: 0885-8993
In this paper, a non-isolated buck-boost single-inductor multiple-output (SIMO) DC-AC inverter for driving multiple independent high-frequency AC outputs of medium power, is proposed. Compared with traditional bridge-type inverters, the proposed buck-boost SIMO inverter achieves (i) a smaller component count, (ii) fully independent power control of its outputs, (iii) better scalability in increasing the number of AC output channels, and (iv) higher power efficiency. Operating in pseudo-continuous conduction mode (PCCM), the rated power of each output channel of this inverter can be high while attaining zero cross-regulation. The scalability factor of the proposed inverter is formally investigated and the theoretical maximum number of AC outputs is analytically derived. The targeted application of the proposed inverter is for driving multiple transmitter coils to realize versatile multi-device medium-power wireless power transfer. A hardware prototype of a single-inductor three-output (SITO) buck-boost inverter delivering a medium power of 8.4 W per output channel has been constructed. It is experimentally verified that precise and independent current regulation of individual transmitter coil is achievable with the proposed inverter.
Chen H, Tan SC, Hui SYR, 2019, Electrical and thermal effects of light-emitting diodes on signal-to-noise ratio in visible light communication, IEEE Transactions on Industrial Electronics, Vol: 66, Pages: 2785-2794, ISSN: 0278-0046
IEEE Light-emitting diode (LED) based visible light communication (VLC) has recently been promoted by lighting industry for providing services and information for consumers in shopping malls. Communication system designs require well defined signal-to-noise ratio (SNR). Being semiconductor devices, both of LEDs and photo-detectors are highly temperature-sensitive. This research explores the electrical and thermal sensitivities of LED and photo-detector together for VLC applications, and highlights the discoveries that the SNR of LED based VLC could vary substantially over the full operating power range of the LED lighting systems. A new analysis of the SNR based on the photo-electro-thermal theory has been developed. It can be used as the theoretical and design tool to predict such SNR variations. The validity of the new analysis has been confirmed with practical measurements that are consistent with theoretical predictions. The analytic approach can in principle be used as a design tool for LED based VLC.
Wang M, Yang T, Tan SC, et al., 2019, Hybrid electric springs for grid-tied power control and storage reduction in AC microgrids, IEEE Transactions on Power Electronics, Vol: 34, Pages: 3214-3225, ISSN: 0885-8993
The renewable generations (RGs) are conventionally interfaced with the utility grid through battery energy storage systems (BESS). In this cascaded configuration of the grid-connected inverter, battery and RG, the power of the battery is passively governed by the power difference between the RG and the grid. This compromises the state-of-charge (SoC) control of the battery and increases the storage capacity. To address this issue, a hybrid electric spring (HES), which is integrated with the RG and non-critical load (NCL), is proposed in this paper for the grid-tied power control and reduction of battery storage capacity in AC microgrids. Such an integrated configuration enables a flexible control of the power flow among battery, NCL and grid. On top of that, the proposed HES can achieve an extended operating region of grid-tied power control compared with the conventional BESS and the existing electric springs (ES). The operating principle, steady-state analysis and control design of the HES are discussed. The functions of the grid-tied power control and battery SoC control are verified experimentally and through simulations.
Dong Z, Tse CK, Hui R, 2019, Circuit theoretic considerations of LED driving: voltage-source versus current-source driving, IEEE Transactions on Power Electronics, Vol: 34, Pages: 4689-4702, ISSN: 0885-8993
IEEE Light-emitting-diodes (LEDs) are solid-state devices with specific v-i characteristics. In this paper we study the basic requirement of the driving circuits and discuss the proper approach to driving 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 which 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.
Nielsen C, Hui R, Lui W-Y, et al., 2019, Towards predicting intracellular radiofrequency radiation effects, PLOS ONE, Vol: 14, ISSN: 1932-6203
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- Citations: 5
Chakravorty D, Guo J, Chaudhuri B, et al., 2019, Small Signal Stability Analysis of Distribution Networks with Electric Springs, IEEE Transactions on Power Systems, Vol: 10, Pages: 1543-1552, ISSN: 0885-8950
This paper presents small signal stability analysis of distribution networks with electric springs (ESs) installed at the customer supply points. The focus is on ESs with reactive compensation only. Vector control of ES with reactive compensation is reported for the first time to ensure compatibility with the standard stability models of other components such as the interface inverter of distributed generators (DGs). A linearized state-space model of the distribution network with multiple ESs is developed which is extendible to include inverter-interfaced DGs, energy storage, active loads etc. The impact of distance of an ES from the substation, proximity between adjacent ESs and the R/X ratio of the network on the small signal stability of the system is analyzed and compared against the case with equivalent DG inverters. The collective operation of ESs is validated through simulation study on a standard distribution network.
Yan S, Wang MH, Chen J, et al., 2019, Smart Loads for Improving the Fault-Ride-Through Capability of Fixed-Speed Wind Generators in Microgrids, IEEE Transactions on Smart Grid, Vol: 10, Pages: 661-669, ISSN: 1949-3061
In this paper, the smart load formed by the back-to-back electric springs (ES-B2B) is evaluated for improving the fault-ride through (FRT) capability of the wind turbine generation system (WTGS) with fixed speed induction generator (FSIG) for the first time. The characteristic of the ES-B2B in providing fast reactive power compensation is found to be highly useful in recovering the rotor speed of FSIGs when a fault event occurs. This is a new function in addition to the original function of stabilizing mains voltage against renewable generations. A simple and yet effective controller is then developed for the ES-B2B in order to ensure fast response. The ES-B2B based smart load and the proposed control have been tested in Matlab/Simulink and Real-Time Digital Simulator (RTDS) for the evaluation of i) the reactive power compensation capability of ES-B2B, ii) the effectiveness of the proposed control of ES-B2B for FRT support, and iii) a comparison of distributed ES-B2Bs with centralized STATCOM in providing distributed FRT support in different grid topologies.
Li K, Yang Y, Tan S-C, et al., 2019, Sliding-Mode-Based Direct Power Control of Dual-Active-Bridge DC-DC Converters, 34th Annual IEEE Applied Power Electronics Conference and Exposition (APEC), Publisher: IEEE, Pages: 188-192, ISSN: 1048-2334
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- Citations: 20
Yang Y, Tan S-C, Hui SYR, 2019, Communication-Free Control Scheme for Qi-Compliant Wireless Power Transfer Systems, 11th Annual IEEE Energy Conversion Congress and Exposition (ECCE), Publisher: IEEE, Pages: 4955-4960, ISSN: 2329-3721
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- Citations: 7
Jin W, Lee ATL, Tan S-C, et al., 2019, Power Loss Analysis of a Back-to-Back Switching Single-Inductor Multiple-Output Inverter, 34th Annual IEEE Applied Power Electronics Conference and Exposition (APEC), Publisher: IEEE, Pages: 689-694, ISSN: 1048-2334
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- Citations: 1
Yang T, Liu T, Chen J, et al., 2018, Dynamic modular modeling of smart loads associated with electric springs and control, IEEE Transactions on Power Electronics, Vol: 33, Pages: 10071-10085, ISSN: 0885-8993
IEEE Smart loads associated with electric springs (ES) have been used for fast demand-side management for smart grid. While simplified dynamic ES models have been used for power system simulation, these models do not include the dynamics of the power electronic circuits and control of the ES. This paper presents a dynamic and modular ES model that can incorporate controller design and the dynamics of the power electronic circuits. Based on experimental measurements, the order of this dynamic model has been reduced so that the model suits both circuit and system simulations. The model is demonstrated with the radial chordal decomposition controller for both voltage and frequency regulation. The modular approach allows the circuit and controller of the ES model and the load module to be combined in the d-q frame. Experimental results based on single and multiple smart loads setup are provided to verify the results obtained from the model simulation. Then the ES model is incorporated into power system simulations including an IEEE 13 node power system and a three-phase balanced microgrid system.
Yang Y, Tan SC, Hui SYR, 2018, Mitigating distribution power loss of DC microgrids with DC electric springs, IEEE Transactions on Smart Grid, Vol: 9, Pages: 5897-5906, ISSN: 1949-3053
DC microgrids fed with substantial intermittent renewable energy sources face the immediate problem of power imbalance and the subsequent dc bus voltage fluctuation problem (that can easily breach power system standards). It has recently been demonstrated that dc electric springs (DCES), when connected with series non-critical loads, are capable of stabilizing the voltage of local nodes and improving the power quality of dc microgrids without large energy storage. In this paper, two centralized model predictive control (CMPC) schemes with: 1) non-adaptive weighting factors and 2) adaptive weighting factors are proposed to extend the existing functions of the DCES in the microgrid. The control schemes coordinate the DCES to mitigate the distribution power loss in the dc microgrids, while simultaneously providing their original function of dc bus voltage regulation. Using the DCES model that was previously validated with experiments, simulations based on MATLAB/Simulink platform are conducted to validate the control schemes. The results show that with the proposed CMPC schemes, the DCES are capable of eliminating the bus voltage offsets as well as reducing the distribution power loss of the dc microgrid.
Chen B, Pin G, Ng WM, et al., 2018, Online detection of fundamental and interharmonics in AC mains for parallel operation of multiple grid-connected power converters, IEEE Transactions on Power Electronics, Vol: 33, Pages: 9318-9330, ISSN: 0885-8993
Parallel operation of multiple grid-connected power converters through LCL filters is known to have the potential problem of triggering oscillations in the ac mains. Such oscillatory frequencies are not integral multiples of the fundamental frequency and hence form a new source of interharmonics. Early detection of such oscillations is essential for the parallel power converters to move out of the unstable zone. This paper presents an online observer-based algorithm that can perform fast detection of interharmonics within a specified frequency band. The algorithm has been adopted in a specific and reduced form from an integral observer algorithm for detection of fundamental and interharmonic voltage components in the ac mains. A new method based on the kernel signal for fast interharmonic detection is proposed and practically verified. It has been implemented in a digital controller to detect oscillations such as those occurring between two grid-connected power converters. The practical results indicate that the algorithm can locate such frequency within the specific frequency band within 1 mains cycle.
Dong Z, Tse CK, Hui SYR, 2018, Current-source-mode single-inductor multiple-output LED driver with single closed-loop control achieving independent dimming function, IEEE Journal of Emerging and Selected Topics in Power Electronics, Vol: 6, Pages: 1198-1209, ISSN: 2168-6777
Single-inductor multiple-output (SIMO) LED drivers have the advantages of being compact, efficient and low cost. However, the voltage-to-current transfer function of each output of the SIMO converter is not independent, with significant cross regulation issues that necessitate the use of complex closed-loop control for achieving independent dimming function. This paper proposes a current-source-mode (CSM) SIMO dc-dc converter from duality principle, which is shown to be more suited for LED driving due to widened control range of the duty cycle and inherently inductor-less LED driving topology. The outputs of the CSM SIMO dc-dc converter are inherently independent, resulting in very simple control requirement involving only one closed-loop controller for providing the constant current feeder, and several simple open-loop controllers for independent dimmable driving of LEDs. Simultaneous voltage step-up and step-down of multiple outputs is an added feature that simplifies the input power source requirement especially for portable applications. The whole system is simple, reliable and low cost. Taking the CSM single-inductor dual-output (SIDO) dc-dc converter as an example, we illustrate the circuit operation and establish a small-signal model for facilitating the design of the feedback control. A direct duty-cycle dimming method is described. Experimental tests are presented for verification.
Huang Y, Xiong S, Tan SC, et al., 2018, Nonisolated harmonics-boosted resonant DC/DC converter with high-step-up gain, IEEE Transactions on Power Electronics, Vol: 33, Pages: 7770-7781, ISSN: 0885-8993
High-step-up dc/dc converters are widely required in grid-connected applications with renewable energy sources. An extremely high-ratio step-up nonisolated dc/dc converter, in the form of a harmonics-boosted resonant converter, is proposed in this paper. This proposed converter consists of a high-frequency dc/ac inverter stage that is followed by a passive ac/dc rectifier stage connected in cascade. Conventionally, such a dc/ac inverter is designed to output a pure sinusoidal ac voltage with an amplitude several times the amplitude of the input voltage. However, for the proposed converter, the harmonics-boosted inverter stage is designed to contain selected voltage harmonics that significantly boost the amplitude of its output voltage. This greatly increases the overall gain of the converter. The adopted ac/dc stage is a diode-capacitor rectifier, which is of high efficiency and easily extendable to increase the voltage gain. Importantly, the proposed converter involves only one active switch. With only one active switch, the driver's loss is minimized and the converter's control is simplified. Zero-voltage switching is applied to reduce the switching loss, which also allows the converter to operate efficiently at high frequency, and thus can be designed for high power density. The optimal design of the two converter stages and their combined voltage gain is investigated and reported. Besides, a design guideline of the proposed converter is provided. A prototype of a 57-time harmonics-boosted resonant converter with 3.3 V input voltage, 500 kHz switching frequency, and 21 W output power, is built. The experimental result shows that the achieved converter's efficiency is as high as 88.6%.
Chakravorty D, Chaudhuri B, Hui S, 2018, Estimation of aggregate reserve with point-of-load voltage control, IEEE Transactions on Smart Grid, Vol: 9, Pages: 4649-4658, ISSN: 1949-3053
Voltage dependent loads can collectively provide a certain amount of power reserve (by virtue of the ability to change their power consumption within the stipulated voltage tolerance) which could be exploited for grid frequency regulation through voltage control at the substation/feeder or at the point ofload. The amount of such power reserve would vary with time of the day depending on the incidence of different types of voltage dependent loads and also the voltage profile across the feeders. It is important for the grid operators to know the aggregate power reserve from the voltage dependent loads during different times of the day in order to schedule other forms of reserves accordingly. This paper presents a methodology to estimate such power reserve from the measured power and voltage at the bulk supply points without knowing the actual distribution network topology and/or load profile of individual customers. The proposed method is applied to estimate the time variation of the aggregate reserve offered by the voltage dependent loads within the domestic sector in Great Britain (GB). Studies on astandard IEEE distribution network are presented to validate the estimated reserve margins under typical voltage profiles across the distribution feeders.
Yang Y, Zhong W, Kiratipongvoot S, et al., 2018, Dynamic improvement of series-series compensated wireless power transfer systems using discrete sliding mode control, IEEE Transactions on Power Electronics, Vol: 33, Pages: 6351-6360, ISSN: 0885-8993
This paper presents a discrete sliding mode control (DSMC) scheme for a series-series compensated wireless power transfer (WPT) system to achieve fast maximum energy efficiency (MEE) tracking and output voltage regulation. The power transmitter of the adopted WPT system comprises a dc/ac converter, which incorporates the hill-climbing-search-based phase angle control in achieving minimum input current injection from its dc source, thereby attaining minimum input power operation. The power receiver comprises a buck-boost converter that emulates an optimal load value, following the MEE point determined by the DSMC scheme. With this WPT system, no direct communication means is required between the transmitter and the receiver. Therefore, the implementation cost of this system is potentially lower and annoying communication delays, which deteriorate control performance, are absent. Both the simulation and experiment results show that this WPT system displays better dynamic regulation of the output voltage during MEE tracking when it is controlled by DSMC, as compared to that controlled by the conventional discrete proportional-integral (PI) control. Such an improvement prevents the load from sustaining undesirable overshoot/undershoot during transient states.
Zhong W, Hui SYR, 2018, Reconfigurable wireless power transfer systems with high energy efficiency over wide load range, IEEE Transactions on Power Electronics, Vol: 33, Pages: 6379-6390, ISSN: 0885-8993
Optimum energy efficiency in a wireless power transfer (WPT) system usually occurs only at a specific load value while the load such as a battery is normally not constant. A major challenge in WPT is therefore to achieve high energy efficiency over a wide load range. Previously, impedance transformation methods such as DC-DC converters and use of a relay coil, have been used to transform the practical load resistance to the optimum (or near optimum) value. In this paper, a new approach based on re-configurable magnetic resonant structures is proposed to achieve high energy efficiency and low volt-amp ratings. This basic principle is to create more than one efficiency-load curve. The WPT system is controlled to be operated within the top regions of the energy efficiency curves of the reconfigurable circuits so that high energy efficiency can be achieved over a very wide load range. The principle of this new approach is explained with an analysis and verified with practical measurements.
Yan S, Wang MH, Yang TB, et al., 2018, Achieving multiple functions of 3-phase electric springs in unbalanced 3-phase power systems using the instantaneous power theory, IEEE Transactions on Power Electronics, Vol: 33, Pages: 5784-5795, ISSN: 0885-8993
IEEE Three-phase electric spring (3-ph ES) has recently been proposed as a fast demand response technology for applications in unbalanced power systems fed with a mixture of conventional and renewable power generation. Using the Instantaneous Power Theory as the theoretical framework, this paper presents the criteria and conditions for minimizing the average and oscillating power of the 3-ph ES for the first time. A detailed analysis of the use of 3-ph ES is included for providing multiple control objectives of voltage regulation and power balancing of the 3-ph power system, and minimization of the average and oscillating ac power of the ES. A corresponding control scheme implementable in a single controller is included and explained. The control scheme has been practically verified with experiments.
Wu H, Wong SC, Tse CK, et al., 2018, Single-phase LED drivers with minimal power processing, constant output current, input power factor correction, and without electrolytic capacitor, IEEE Transactions on Power Electronics, Vol: 33, Pages: 6159-6170, ISSN: 0885-8993
High-power light-emitting diodes (LEDs) having properties of high luminous efficacy and long life span are becoming a major light source for general illumination. To fully utilize the advantages of LED in lighting applications, the offline power supply that drives the LED should possess the following features: high efficiency, long life span, high input power factor, and (COC). In this paper, high efficiency is achieved by using a minimal power processing (MPP) configuration. Near perfect power factor correction (PFC) is achieved by a simple dual-output disc-ontinuous-conduction-mode (DCM) pulse-width-modulated (PWM) front-end converter. One output of the front-end converter is connected to the LED load using a control switch. The other output is connected directly to a dc storage capacitor cascaded with a downstream DCM PWM converter driving the same LED load to achieve COC driving. The power flow is controlled to achieve the required MPP that can also reduce the storage capacitance by balancing only the ac input ripple power and the dc output power without power recycling. Thus, the design requires no electrolytic capacitor, hence extending the system life span. The achievement of input PFC, MPP, and COC requires design tradeoff among design freedom, ease of control and component count. LED drivers having all these properties are developed, designed, and tested.
Jin W, Lee ATL, Li S, et al., 2018, Low-Power Multichannel Wireless Transmitter, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 33, Pages: 5016-5028, ISSN: 0885-8993
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- Citations: 12
Chen B, Pin G, Ng WM, et al., 2018, An Adaptive-Observer-Based Robust Estimator of Multi-sinusoidal Signals, IEEE TRANSACTIONS ON AUTOMATIC CONTROL, Vol: 63, Pages: 1618-1631, ISSN: 0018-9286
This paper presents an adaptive observer-based robust estimation methodology of the amplitudes, frequencies and phases of biased multi-sinusoidal signals in presence of bounded perturbations on the measurement. The parameters of the sinusoidal components are estimated on-line and the update laws are individually controlled by an excitation-based switching logic enabling the update of a parameter only when the measured signal is sufficiently informative. This way doing, the algorithm is able to tackle the problem of over-parametrization (i.e., when the internal model accounts for a number of sinusoids that is larger than the true spectral content) or temporarily fading sinusoidal components. The stability analysis proves the existence of a tuning parameter set for which the estimator's dynamics are input-to-state stable with respect to bounded measurement disturbances. The performance of the proposed estimation approach is evaluated and compared with other existing tools by extensive simulation trials and real-time experiments.
Wang MH, Mok KT, Tan SC, et al., 2018, Multifunctional DC Electric Springs for Improving Voltage Quality of DC Grids, IEEE Transactions on Smart Grid, Vol: 9, Pages: 2248-2258, ISSN: 1949-3053
© 2016 IEEE. Electric springs (ESs) have been proposed as a distributed demand-response technology for mitigating voltage and frequency fluctuations of ac power systems fed by substantial intermittent renewable energy. This paper extends this concept to the development of DCESs for voltage regulation of emerging dc power grids. The configurations of series and shunt DCES and their respective operating modes are explained. Both types of ES and their functionalities for dc bus voltage regulation, double-line frequency harmonic compensation, and providing fault-ride-through support are discussed. The proposed DCES has been successfully applied to a 48 V dc microgrid system for experimental verification. The results show a good agreement with the theoretical analysis, confirming that the DCES can be an effective solution to provide simultaneous functions of dc microgrid bus voltage regulation.
Yang T, Mok KT, Tan SC, et al., 2018, Electric springs with coordinated battery management for reducing voltage and frequency fluctuations in microgrids, IEEE Transactions on Smart Grid, Vol: 9, Pages: 1943-1952, ISSN: 1949-3053
Electric springs based on power electronics have been proposed as a demand response method for stabilizing power grid fed by substantial intermittent renewable energy sources. Associated with energy storage, they can provide both active and reactive power compensation. Due to the limited storage capacity of the battery, this project explores a new control scheme for the third version of the electric springs (ES-3) to operate under the physical constraints of the state-of-charge of the battery for microgrid stability applications. The ES-3 is based on a bi-directional grid-connected power converter with a battery bank. Unlike the traditional control of grid-connected power inverters for injecting renewable power to the power grid, the proposed control scheme puts the stability of the power grid as a high priority while maintaining its normal bi-directional power flow functions. Such a scheme has been tested in an experimental prototype and a power grid simulator. Results are presented in this paper to illustrate the use of the scheme in battery's monitoring, charging/discharging management, and output power control.
Ron Hui SY, 2018, Technical and safety challenges in emerging trends of near-field wireless power transfer industrial guidelines, IEEE Electromagnetic Compatibility Magazine, Vol: 7, Pages: 78-86, ISSN: 2162-2264
Wireless power transfer (WPT) has reached commercialization stage in consumer electronics and manufacturing industry. New initiatives by industry for expanding the scope of wireless charging in extended short-range and mid-range applications for portable electronics and electric vehicles and are actively underway. In this article, the author addresses some technical challenges in near-field WPT applications on consumer electronics and electric vehicles. In addition, he shares his views on some of the emerging topics about recently proposed industrial guidelines. It is hoped that this article will arouse more interests and discussions on these emerging guidelines among the research and industrial communities so that future industrial standards will cater for all key aspects of user friendliness, health and safety.
Yang Y, Ho SS, Tan SC, et al., 2018, Small-signal model and stability of electric springs in power grids, IEEE Transactions on Smart Grid, Vol: 9, Pages: 857-865, ISSN: 1949-3053
When multiple stable systems are combined into one system, the newly formed hybrid system has a certain possibility to be unstable. Such a natural phenomenon has been verified in the fields of chemistry and biology over the last century. The implementation of electric springs (ESs) in large quantity over the power grids can also suffer from the same issue if specified design are not performed. As an initial feasibility study of multiple ES in smart grids, in this paper, based on the concept of relative stability, a method of tuning Kpand Kiof the proportional-integral controllers of the ES to ensure the overall system stability of a weak grid is investigated and is achieved through the aid of simulation on an extended low-voltage (LV) network of IEEE 13-node test feeder. Both simulation and experimental results validate that as the number of ES in the isolated LV network (weak grid) increases, more stringent values of Kpand Kiare required to achieve system stability. Besides, a hypothesis that if the optimal values of Kp and Kiare adopted, a maximum number of ES can be stably installed over the grid is proposed. It is also shown experimentally that by eliminating the instability of voltage fluctuation in the distribution line, the subsequent frequency fluctuation of the power generation can also be eliminated.
Yang Y, Tan SC, Hui SYR, 2018, Adaptive reference model predictive control with improved performance for voltage-source inverters, IEEE Transactions on Control Systems Technology, Vol: 26, Pages: 724-731, ISSN: 1063-6536
Power converters under the model predictive control (MPC) inherently suffer from nonignorable steady-state residuals in its control outputs when it exists a mismatch in the parameters between the actual system in control and the system's model adopted in the control. In this brief, an adaptive reference MPC (ARMPC) is proposed in response to this issue. Unlike those conventional derivatives of MPC, the ARMPC is designed to track the so-called virtual references instead of the actual references. The virtual references are generated by a flexibly modeled virtual multiple input multiple output system. Consequently, additional tuning is not required for different operating conditions. ARMPC has been applied to a single-phase full-bridge voltage-source inverter with both resistive and resistive-inductive loads. It is experimentally verified that the proposed ARMPC can significantly attenuate the steady-state offsets in the environment of model mismatch (which is an inherent problem of MPC without significantly sacrifice transient performance). Also, a demonstration that ARMPC renders a consistent attenuation of steady-state errors than the conventional MPC with integrator is provided. More importantly, ARMPC shows better transient performance than the MPC with integrator for some cases.
Huang Y, Mei Y, Xiong S, et al., 2018, Reverse electrodialysis energy harvesting system using high-gain step-up DC/DC converter, IEEE Transactions on Sustainable Energy, Vol: 9, Pages: 1578-1587, ISSN: 1949-3029
Salinity gradient power (SGP) between fresh river water and sea water is a form of renewable energy with huge potential but not well explored. This paper presents a feasibility study on energy harvesting of SGP based on: 1) the use of reverse electrodialysis (RED) stack, and 2) the combined use of harmonicsboosted resonant inverter and multistage diode-capacitor step-up converter. The properties of an RED stack have been characterized into steady-state ac and dc equivalent circuit models for power converter design for the first time. The gains of the resonant inverter and diode-capacitor step-up converter are also optimized for maximizing the energy efficiency. An RED stack prototype comprising multiple alternating anion and cation exchange membranes with an area of 0.01 m 2 each has been constructed. The dc output voltage of 2-3 V from the RED stack has been stepped up to be over 155 V. This study has confirmed that energy can be harvested with a membrane power density of at least 1.4 W/m 2 , a power converter's efficiency exceeding 85%, and a voltage gain of 67.3 times.
Li S, Lee ATL, Tan SC, et al., 2018, Plug-and-play voltage ripple mitigator for DC links in hybrid AC-DC power grids with local bus-voltage control, IEEE Transactions on Industrial Electronics, Vol: 65, Pages: 687-698, ISSN: 0278-0046
In this paper, a straightforward plug-and-play voltage ripple mitigator (RM) is proposed. Unlike existing voltage ripple reduction methods, the proposed device can be attached to the dc link of a hybrid ac-dc power system without modifying the host system itself. In particular, a local bus-voltage control scheme is employed to achieve the plug-and-play operation. With the requirement of the dc-link voltage measurement only, this device can be operated as a standalone module. Theoretical analysis and experimental work on a boost-type power factor correction rectification system have been successfully performed to validate the effectiveness of the ripple-mitigating function, the hot-swap operation and the nonintrusive property of the RM. Practical results obtained from a 110-W miniature hybrid ac-dc power system comprising an ac/dc converter and two resistive loads are included to demonstrate some of the functions of the RM.
Qi W, Li S, Tan S-C, et al., 2018, Parabolic-Modulated Sliding-Mode Voltage Control of a Buck Converter, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 65, Pages: 844-854, ISSN: 0278-0046
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- Citations: 32
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