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Switching power supply is widely used in industrial equipment, household appliances, and other fields due to the advantages of high integration and lightweight. Voltage sags can seriously affect the output voltage of switching power supply and the working condition of its power supply equipment; at the same time, the working scenarios of power equipment using switching power supply often have different level of harmonic problems. Considering the continuous innovation of switching power supply technology, the previous analysis and test results on the effect of voltage sags and harmonics on switching power supplies may no longer be applicable. The paper reveals the mechanism of the effect of harmonic alone as well as voltage sag superimposed harmonics on the output voltage of the switching power supply. Then the test research program was developed, and four different brands switching power supplies were selected for the test research, with which the effects of different amplitude voltage sags, harmonics with different frequencies and distortion, as well as voltage sag superimposed harmonics on the output voltage of switching power supplies were investigated. The results show that the tolerance ability of switching power supplies to voltage sags has been improved compared with previous switching power supplies, and the harmonic itself has less effect on the output voltage of switching power supply, but the joint action of harmonics and voltage sags will have a greater effect on the output voltage of switching power supply. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper examines the impact of different voltage unbalance definitions on voltage control in unbalanced distribution systems. Traditional voltage regulation methods for unbalanced systems rely on a single voltage unbalance definition with inconsistent adoptions. In such a situation, voltage control performance can vary between definitions, and improper choice leads to control failures. In this study, we perform numerical analysis and simulations to investigate the impact of different definitions. In the numerical analysis, two definitions quantifying negative and zero sequence components are used as reference definitions, and the theoretical error range of the remaining definitions is identified. The results are further verified by the simulations on the IEEE 123 node test system with phase‐by‐phase controlled three‐phase step voltage regulators and smart photovoltaic inverters. The control of the devices is optimized to minimize or limit a specific definition. The results show that the values of each definition at the same voltage condition can differ significantly, and inappropriate definitions may lead to significant uncertainty in the voltage control. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to detect the underground medium with large depth, the transmitter of electromagnetic sounding instrument has higher and higher power and voltage. A novel voltage equalizing strategy for cascaded constant current power supply using in electromagnetic transmitter was proposed in this paper. The cascaded topology of the transmitter has two isolated full‐bridge AC/DC converters, which had same input source and were connected in series on the output side. The mathematical model based on state space average method was analyzed. After simplifying the circuit, the state space equation was used to describe the circuit model. The stability and frequency characteristics of the system were analyzed. Aiming at the constant current output and the output voltage balance of the two converters, the system coupling model was established. The constant current controller and voltage equalizing controller were designed with decoupling method. A 300 W prototype was built and the experimental results verified the performance of the proposed method. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a control method for step voltage regulators (SVRs) to avoid voltage violations in distribution systems with unbalanced voltages due to photovoltaic (PV) generation and electric vehicle (EV) charging. Distribution system operators must effectively address voltage problems resulting from the widespread installation of distributed energy resources under the optimizing the utilization of existing voltage regulators to establish an efficient and rational infrastructure. Therefore, this study focused on advancements in voltage control using SVR based on line‐drop compensator (LDC) control, which is widely used in actual operations. We propose a method that utilizes voltage data from information technology switches to detect and address voltage unbalances in the control section, allowing for the sequential adjustment of the monitoring target in LDC control to maintain appropriate voltage limits under unbalanced conditions. We conducted power flow calculations using a distribution system model that represents an actual distribution system in the Hokuriku area. The effectiveness of the proposed method was evaluated in terms of its impact on PV and EV hosting capacity, as well as the frequency of tap operations. © 2023 The Authors. IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

• RF conditioning of RFQ of IFMIF/EVEDA accelerator (LIPAc) reached stable CW at 80 % of nominal voltage at the end of 2021. • Conditioning towards nominal voltage at CW was stopped in March 2022 because of vacuum leak from one of the O-Ring of the RF windows, damaged by high temperature. • Several coupled RF and thermal simulations of the couplers of the RFQ were performed with FEM codes. Thermal weak point was identified in the contact between the anchor of the RF window and the cooled inner conductor of the coupler. • A solution to improve cooling of the RF window that could be implemented quickly with minor modifications of the RF windows parts of the couplers was found. • After the testing and validation of the modification in a prototype, the couplers with the modified parts were successfully installed in RFQ and RF conditioning of RFQ resumed in June 2023. Under the Broader Approach (BA) agreement, the Accelerator Facility validation activities aim at demonstrating the acceleration of 125 mA D+ beam up to 9 MeV. This is the main goal of the Linear IFMIF Prototype Accelerator (LIPAc) under installation and commissioning in Rokkasho, Japan [ 1 , 2 ]. The LIPAc commissioning by accelerating the beam through the entire line is currently on-going at Rokkasho Fusion Institute [ 3,4 ]. Other than the beam commissioning, in 2021 and 2022 extensive conditioning experimental campaigns have been carried out on the Radio Frequency Power System (RFPS)-RFQ system to reach CW [5]. The RFPS-RFQ is composed of 8 RF-RFQ tetrode based chains injecting RF power into the RFQ by 8 couplers. The target of the RFQ conditioning campaigns is to reach CW operation at nominal vane-voltage of 132 kV. RFQ could achieve CW field of 105 kV at the end of 2021 [ 5,8 ]. During the RFQ conditioning campaigns in 2022, the conditioning was stopped because of abnormal increase of vacuum pressure due to a leak from one O-Ring of the couplers. The 8 couplers are equipped with a ceramic window (vacuum barrier) using O-ring for sealing purposes [ 9 ]. Extensive simulation and design studies have been carried out and an upgraded design of the parts near the RF window of RFQ coupler has been proposed and validated for implementation. This paper will focus on the RFQ couplers technical issue, analysis of the design upgrade, implementation of the upgraded solution and perspective for future improvements of the RFQ couplers designs in view of FNS and DONES application. [ABSTRACT FROM AUTHOR]