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The well-established advantages of resonant converters, including simplicity of circuit configuration, ease of the control scheme, low switching losses, and low electromagnetic interference, among others, have led to their attracting more interest. This work develops a highly efficient battery charger with an improved series-loaded resonant converter for renewable energy applications to improve the performance of traditional switching-mode charger circuits. The switching frequency of the improved series-loaded resonant battery charger was at continuous conduction mode. Circuit operation modes are determined from the conduction profiles. Operating equations and operating theory are also developed. This study utilizes the fundamental wave approximation and a battery equivalent circuit to simplify the circuit analyses. The mean charging efficiency of the proposed topology is as high as 87.5%. Index Terms--Battery charger, series-loaded resonant converter.

This work presents a novel highly efficient and low-stress battery charger with a resonant switch converter--based on resonance and zero-voltage-transition soft-switching theory--that reduces defects associated with high voltage and high current stresses caused by the resonance of traditional resonant circuits. The novel battery charger meets the requirement that all circuit components must operate with zero-voltage switching. Experimental test results indicate that the proposed battery charger reduces the temperature of an active power switch, and switching losses are less than those obtained using a traditional pulsewidth-modulation converter as a battery charger. Index Terms--Battery chargers, soft-switching, zero-voltage-transition (ZVT).

The high-frequency resonant converter has numerous well-known advantages over the traditional hard-switching converters. The most important advantage is that it offers a lower switching loss and a higher power density. Additionally, the softswitching current waveform characterizes a lower electromagnetic interference (EMI). This study presents the circuit configuration with the least components to realize a highly efficient solar energy battery charger with a zero-voltage-switching resonant converter. The optimal values of the resonant components are determined by applying the characteristic curve and the electric functions derived from the circuit configuration. The experiment demonstrates the switching on and off of the main switches in a solar energy battery charger with a zero-voltage-switching resonant converter, wherein the switches are all operated using zero-voltage switching. The circuit efficiency in the overall charging process exceeds 80 %. Index Terms--Battery charger, photovoltaic array, resonant converter, soft-switching, zero-voltage-switching (ZVS).

This paper investigates the power load composition of an isolated power system using a load survey study and estimates wind power generation with a probabilistic network. The typical load pattern of various customer classes is derived, which are then used to derive the total power consumption of all customers within each class. A probabilistic neural network is used to solve the wind power generation based on the wind speed for an offshore island in Taiwan. With the hourly wind speed and load composition, the power generation of diesel generators was obtained. Results of this paper demonstrate that wind power generation can economically and effectively replace the power generation of the island's diesel power plant and provide partial power-supply capability for the net peak load requirement. Index Terms--Load profile synthesis, load survey, probabilistic neural network (PNN), wind-power-generation prediction.

This paper presents a novel inference mechanism to determine appropriate switching operations by the rule-expert knowledge-based Petri net (RKPN) approach. A practical distribution system with 26 feeders is specified to reveal the effectiveness of the developed methodology with computer simulations. The proposed inference mechanism can successfully solve feeder overload/fault contingency based on the load variations resulting from temperature rises. Index Terms--Feeder reconfiguration, load balance, load transfer, rule-expert knowledge-based Petri net (RKPN), service restoration, switching operation, temperature sensitivity.

This paper derives appropriate decisions for load transfer among distribution feeders by switching operations to improve system operating performance by combining the load characteristics and the variations among customers as a result of temperature increases using a switching operation decision inference mechanism based on a colored Petri net (CPN) approach. A practical distribution system with 19 feeders, daily load profiles, and corresponding data on temperature sensitivity (TS) is used to perform computer simulations to demonstrate the effectiveness of the proposed methodology. It is concluded that the proposed CPN inference mechanism can enhance the system operating performance with the proper switching operation by considering the TS of customer power consumption served in each service zone of distribution feeders. Index Terms--Colored Petri net (CPN), feeder reconfiguration, load balance, load transfer, service restoration, switching operation, temperature sensitivity.

This paper presents a novel method of power-factor correction (PFC) using a high-frequency resonant energy tank for the dc-link inverter. The proposed approach has advantages over conventional PFC techniques in terms of a lower current stress and lower switching losses. The developed PFC circuit is implemented on a series-load resonant inverter for illustrative purposes. The experimental results validate the theoretical analyses. The PFC circuit can achieve a power factor of almost one with a very low harmonic distortion. Index Terms--Energy tank, inverter, power-factor correction (PFC), resonant.

In this paper, the customer information in customer information systems (CIS) and information of customer and distribution transformers in outage management information systems (OMIS) in Taiwan Power Company (Taipower), are used to determine the daily load patterns of service areas, sectionalizing switches, distribution feeders, and main transformers. During system normal operation conditions, the feeder reconfiguration for load balancing among distribution feeders is obtained by the G-Nets inference mechanism to enhance the operation performance of distribution systems. For distribution contingencies, such as feeder overloading and/or short-circuit fault, the G-Nets inference mechanism with operation rules is applied to derive the optimal switching operation decision for service restoration to perform the optimal load transfer among distribution feeders after the fault has been identified and isolated. To determine the effectiveness of the proposed methodology, a practical Taiwan power distribution system with daily load patterns derived by load survey study is selected to perform the computer simulation. It is found that the G-Nets inference mechanism approach can enhance the solution process of fault restoration with proper load transfer and improve feeder load balancing for distribution systems by considering the load characteristics of the service customers. Index Terms--fault detection, feeder reconfiguration, G-Nets, isolation and restoration (FDIR), load balancing, load pattern, service restoration, switching operation.

This study attempts to determine the daily load patterns of service zones, line switches, distribution feeders, and main transformers by using customer information in a customer information system (CIS) and information about distribution transformers in the outage management information system (OMIS) in Taiwan Power Company (Taipower). When a power distribution system is operating under normal conditions, the reconfiguration of feeders for balancing loads among distribution feeders is obtained by the colored Petri nets (CPN) inference mechanism, which improves the operating performance of distribution systems. A practical Taiwan power distribution system, with daily load patterns derived by a load survey, is used for a computer simulation and, thus, determines the effectiveness of the proposed methodology to improve the balancing of the feeder load for distribution systems by considering the load characteristics of the service customers. Index Terms--Colored Petri nets, feeder reconfiguration, load balancing, load patterns, switching operations.

In this paper, the charge and discharge strategies were conducted for a future battery energy storage system (BESS) at the National Penghu University of Science and Technology, Makung, Taiwan. OpenDSS software was used to establish the power distribution system. A probabilistic neural network model was used to predict the daily load and photovoltaic (PV) generation curve for controlling the charge–discharge of the BESS. This study considered both the actual and predicted values of PV generation systems as well as the daily charge–discharge control of the BESS used to balance the peak and off-peak electricity consumption to shave peak loads under the two- and three-phase electricity-pricing methods. The average monthly electric bill and contract capacity were calculated, and the effects of different BESS capacities from the load curve were observed. The results were used to evaluate and determine the capacity required by the BESS. The prediction errors for the load and PV generation of the year were 6.22% and 7.14%, respectively. The electric bills and contract capacities of the actual and predicted values were compared, and the resulting difference was low; this implies that the proposed prediction method is practicable. [ABSTRACT FROM AUTHOR]

This paper develops a novel single-switch resonant power converter for renewable energy generation applications. This circuit topology integrates a novel single-switch resonant inverter with zero-voltage switching (ZVS) with an energy-blocking diode with zero-current switching (ZCS). The energy-blocking diode with a direct-current output filter filters the output stage of the novel single-switch resonant inverter. Only one active power switch is used for power energy conversion to reduce the cost of active power switches and control circuits. The active power switch is controlled by pulsewidth modulation at a fixed switching frequency and a constant duty cycle. When the resonant converter is operated at discontinuous conduction mode, the inductor current through the resonant tank could achieve ZCS of the energy-blocking diode. Accordingly, a high energy conversion efficiency is ensured. Operating principles are derived, and analyses are carried out based on the equivalent circuits for the proposed power converter under different operating modes. The operating principles of the converter were verified using a 32.4-W 70-kHz experimental photovoltaic-powered load system. Given appropriately chosen circuit parameters, the active power switch can be operated with ZVS, and a measured energy conversion efficiency of the proposed topology of 97.3% can be achieved. Experimental results demonstrate a satisfactory performance of the proposed topology, which is particularly suited to the energy conversion applications in renewable energy generation systems. [ABSTRACT FROM PUBLISHER]

In this paper, analysis of circulating currents of paralleled single-phase boost converter systems is presented. The dc loop and ac loop circulating currents are clearly explained. In order to eliminate the dc loop circulating currents and reduce switching losses, a simplified pulsewidth modulation strategy is adopted in a paralleled single-phase boost converter. Based on the analysis of circulating currents, common-mode circulating current (CMCC) and differential-mode circulating current (DMCC) are defined. Then, CMCC and DMCC compensators are proposed in a centralized control scheme to reduce the common-mode and differential-mode circulating currents in a parallel system operated in both rectifier and inverter modes with different power sharing for microgrid applications. Converter-paralleled system stability analysis is also presented. Finally, a prototype system is constructed to facilitate the theoretical results as verification. From the experimental results, the proposed control scheme can indeed reduce the circulating currents under equal and/or different power rating conditions in the parallel system. [ABSTRACT FROM PUBLISHER]

As the consciousness of human beings in preserving the world increases, the demand of alternative energy resources has been expanding exponentially in recent years, and wind power is one of the most promising renewable energy resources. Taiwan, with its abundant coastal wind resources and good geographical conditions, is very suitable for developing wind farms. The development and implementation of renewable energy regulations have defined a direction for future renewable energy development in Taiwan. This also shows Taiwan's determination to follow the footsteps of the developed countries and the commitment to environmental protection. Therefore, the decision making of wind farms has become the most important link for the construction of wind farms in the future. This paper proposed a fuzzy analytic network process with benefit–opportunity–cost–risk approach to systemize the complicated decision making of wind farm site selection. A case study is carried out to examine the proposed approach and to evaluate the performance of several existing wind farms in Taiwan. By adopting the systematic analysis method, the most suitable wind farm can be determined, and the results can be references for planning and development of wind power industry in the future. [ABSTRACT FROM AUTHOR]

This paper presents a battery float charge technique based on a parallel-loaded resonant converter. The main purpose of the float charge is to ensure that the battery remains fully charged indefinitely. With a simple circuit configuration and few components, low switching loss and high efficiency are achieved. The proposed parallel-loaded resonant converter is operated in discontinuous current mode to achieve high efficiency at a fixed switching frequency. With carefully designed circuit parameters, the power switches can support zero voltage switching and zero current switching. The operating principles and equivalent circuit are analyzed in detail. Experimental results are obtained using a 12-V 150-Ah rechargeable battery to confirm the feasibility of the proposed scheme. The maximum charging efficiency of the proposed topology during the overall float charge period is 97.6%. The measurements yield satisfactory performance. [ABSTRACT FROM PUBLISHER]

Among the many advantages that resonant power conversion has over conventionally adopted pulse-width modulation include a low electromagnetic interference, low switching losses, small volume, and light weight of components due to a high switching frequency, high efficiency, and low reverse-recovery losses in diodes owing to a low di/dt at switching instant. This work presents a novel loaded-resonant converter for direct currennt (dc)-to-dc energy conversion applications. The proposed topology comprises a half-bridge inductor-capacitor-inductor (L-C-L) resonant inverter and a bridge rectifier. Output stage of the proposed loaded-resonant converter is filtered by a low-pass filter. A prototype dc-to-dc energy converter circuit with the novel loaded-resonant converter designed for a load is developed and tested to verify its analytical predictions. The measured energy conversion efficiency of the proposed novel loaded-resonant topology reaches up to 88.3%. Moreover, test results demonstrate a satisfactory performance of the proposed topology. Furthermore, the proposed topology is highly promising for applications of power electronic productions such as switching power supplies, battery chargers, uninterruptible power systems, renewable energy generation systems, and telecom power supplies. [ABSTRACT FROM AUTHOR]

A novel microprocessor-controlled electronic ballast with a class-E resonant inverter for illumination applications is employed to link a photovoltaic (PV)-powered battery energy storage system (BESS) as a main power source with a utility ac power as a complementary source. The proposed strategy aims to control power flow either from the PV-powered BESS or from the utility ac power line to the electronic ballast. This novel design has lower loss, easier control, and higher efficiency than traditional PV panel has. A 27-W fluorescent lamp is ignited by electronic ballast with a class-E topology to validate the proposed theoretical analyses. When the electronic ballast is driven by the PV-powered BESS and the utility ac power, overall efficiency of the proposed system is 94.2% and 91.1%, respectively. Experimental results demonstrate the functionality of the overall system, indicating that it is a good solution for several hybrid-source applications. [ABSTRACT FROM PUBLISHER]

This paper presents a novel application of half-bridge series–parallel resonant converter (HBSPRC) for dc source and secondary battery interface. The converter practically eliminates both low- and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger circuit. Moreover, operation above resonance is preferred, because the power switches turn on at zero current and zero voltage; thus, the freewheeling diodes do not need to have very fast reverse-recovery characteristics. The proposed battery charger circuit has few components and low-energy conversion loss, which enhance the system's overall efficiency. Circuit operation modes are determined from the conduction profiles. Operating equations and an operating theory are also developed. Experimental results based on a 12-V 48-Ah battery charger are proposed to validate the analysis and to demonstrate the performance of the proposed approach. The maximum charging efficiency of the proposed topology during the overall charging period is 93.98%. Satisfactory performance is obtained from the measured results. [ABSTRACT FROM AUTHOR]