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About 2MW PV system was constructed in Hokuto city of Yamanashi Prefecture in Japan for verifying grid-stabilization control methods and evaluation of various kinds of PV module characteristics for construction of future large-scale PV systems. Five-year tests were finished in March last year. The test results are summarized in this paper and discussed.
This paper describes a molded-cased circuit breaker (MCCB) for higher voltage direct current (HVDC) power feeding systems. To protect circuits from fault current, such as an overcurrent or a short circuit current, an overcurrent circuit breaker is installed in power feeding systems. When a large-scale overcurrent circuit breaker is required, the case which uses MCCBs in HVDC power feeding system can...
Design considerations and performance evaluations of the recently introduced three-phase, two-switch, zero-voltage-switching (ZVS), power-factor-correction (PFC), discontinuous-conduction-mode (DCM) boost rectifier, named the Taipei rectifier, are presented. The performance evaluation was done on a 3-kW, 400-V-output prototype designed to operate with a line-to-line RMS input voltage from 180 V to...
Sodium Nickel Chloride Batteries for stationary applications have demonstrated to be effectively used for high energy density deployment in telecom facilities. This paper reviews the characteristics of Sodium-Chloride batteries and describes the installations in telecom facilities.
This paper presents the novel driving technique of synchronous rectifier (SR) for the LLC converter. The unique characteristic of “Vo*D=constant” of LLC converter is utilized to predict optimal duty ratio D, where D is the conduction period of secondary diode. This technique does not need the sensing of SR current neither SR voltage. The technique is confirmed by experimentally.
A new architecture using multi-level lows voltage DC/DC cells with super high power density is presented in this paper. The new class inverter topology is based on cascaded low-voltage DC/DC converter cells that will benefit from the hyper-competitive DC/DC computer/telecom converter global supply chain and manufacturing infrastructures. Furthermore, the switching frequency of each DC/DC cell can...
Data centers (DCs) are considered critical loads that require premium power from utilities to ensure reliability at all times. Microturbine (MT) generation systems are becoming important in DCs, not only as distributed generation (DG) for supplying electricity, but also for providing cooling and heating functions, which is known as combined cooling, heat and power (CCHP) or tri-generation. This paper...
This paper discusses the operating characteristics of push-pull type series resonant converter. The AC equivalent model and AC analysis of push-pull type series resonant converter are confirmed by analytically and experimentally. Moreover, the operating characteristics of push-pull type series resonant converter including SR are also investigated.
Battery and DC power system assets management is a critical and important part of any operating Telco's service reliability and availability plans. This needs to be addressed within tighter constraints on CAPEX for assets that don't directly generate revenue and in an environment of an aging infrastructure.
While the speed of operation of conventional circuit breakers for equipment (CBE) is suitable for the majority of modern day equipment applications, ultra-sensitive solidstate circuitry typically found in telecom power distribution applications will often require faster switching protection under overcurrent conditions than electromechanical CBEs can achieve.
The power consumption of portable devices such as smartphones and notebook PCs has increased in recent years. Therefore, these devices require a high energy density power supply. Direct methanol fuel cells (DMFCs), for which the theoretical energy density is 10 or more times greater than that of current lithium ion batteries, are expected to be the future power sources for such devices. We have previously...
Digital control is becoming more and more popular in Power Supply Unit (PSU) applications. Hardware-oriented power supply designers typically need more understanding on the optimum way to implement a digital control. This paper presents different possibilities and approaches on implementing digital control for a telecom AC-input PSU. Multiple challenges affecting the control partitioning are presented...
This paper presents a reconfigurable solar photovoltaic (PV) battery charger. A traditional PV charger either utilizes a DC/DC converter between the PV array and load, or it connects the battery directly to the PV array without any power conversion. Different from these approaches, our proposed PV charger avoids conventional DC/DC converters by using a reconfigurable switch matrix. This switch matrix...
This paper describes the configurations of semiconductor circuit breakers we developed for higher-voltage direct-current (HVDC) power feeding systems. Semiconductor breakers have some merits. The shutdown parts of the breakers are compact and can be controlled remotely. In addition, they do not need to be replaced after shutting down a short circuit. When semiconductor breaker shutdown overcurrent...
The aim of a new site solution concept (i-Site) has been to optimize energy costs, speed of deployment, and site equipment such as number of PV modules. The present study provides the first example of a Life Cycle Assessment (LCA) quantifying the future environmental benefit of i-Site for support of a radio base station in South African Vodafone network. This study will moreover show the business...
This paper deals with bidirectional AC-DC converter with high power efficiency and high power factor, in which the novel FPGA control strategy is applied. The prototype bidirectional AC-DC converter of the rated power of 2kW is made and tested. As a result, in both forward operation mode and regenerative one, the power efficiency is at 97.0% at the rated output power of 2kW, is over 98.0% at 25% output...
The principle of full-bridge DC-DC converter is briefly expounded, including the two typical control methods, named limited dual polarity hard-switch control and phase-shifted soft-switch control. Then the common mode noise equivalent circuits of full-bridge DC-DC converter are deduced, taking the common mode noise of the bridge leg's midpoint into account, and the difference between the two typical...
In some environments, such as among mountains, the installation of power supply systems is difficult. In such cases, a power supply independent of the Communication Bureau is necessary. Solar cells can be used as an independent power supply that requires little maintenance. To make most effective use of sunlight, this paper proposes the use of a three-dimensional photovoltaic module whose configuration...
After a stationary battery has reached end-of-life or is no longer required for use, it must be carefully managed and steered through a mandated disposal and reclamation process. The failure to do this, can cause the owner to fall foul of several regulatory requirements that may result in various legal actions resulting in heavy fines or even imprisonment. In most cases, the owner is deemed to be...
In this paper harmonic current control in a power electronic based load emulation system is presented. Purpose of the load emulation system is to carry out full load tests of power electronic systems under realistic conditions, while the energy yield of the device under test is fed back the power grid. Harmonic currents drawn by the device under test from the power grid need to be compensated by the...
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