Operation Control Method of Relay Protection in Flexible DC Distribution Network Compatible with Distributed Power Supply

A novel operation control method for relay protection in flexible DC distribution networks with distributed power supply is proposed to address the issue of inaccurate fault location during relay protection,leading to poor performance.The method combines a fault-tolerant fault location method based on long-term and short-term memory networks to accurately locate the fault section.Then,an operation control method for relay protection based on adaptive weight and whale optimization algorithm(WOA)is used to construct an objective function considering the shortest relay protection action time and the smallest impulse current.The adaptive weight and WOA are employed to obtain the optimal strategy for relay protection operation control,reducing the action time and impulse current.Experimental results demonstrate the effectiveness of the proposed method in accurately locating faults and improving relay protection performance.The longest operation time is reduced by 4.7023 s,and the maximum impulse current is limited to 0.3 A,effectively controlling the impact of large impulse currents and enhancing control efficiency.

A novel testing approach for SSRF digital power supply controllers

Digital power supply controller is one of the key parts of SSRF high resolution high stability magnet power supply system. It is very essential to keep any degradation of these excellent properties by any stages as small as possible via careful testing when the controller is developed. In this study,a novel testing approach was presented,with which a novel closed control loop without actual power converter was constructed,and the new developed SSRF Digital Controller can work well in it.

Generation of Optimal Voltage Reference for Limit Cycle Oscillation in Digital Control-Based Switching Power Supply

Digital control of a general-purpose switching power supply is one of the key technologies to perform the high reliability and the intelligent function demanded for the next generation. The contribution of this paper is the development of a digital control-based switching power supply. In the developed system, the generation method of the optimal voltage reference to eliminate the limit cycle oscillation of output voltage due to the AD/DA resolution is proposed. In the proposed method, the variation of the input power source voltage can be also compensated. The effectiveness of the proposed optimal reference generation method is experimentally verified.

Design of Controller for New EAST Fast Control Power Supply

The effectiveness of the magnetic confinement of plasma can be improved by elongat- ing the plasma cross-section in tokamak devices. But elongated plasma has vertical displacement instability, so a feedback control system is needed to restrain the plasma＇s vertical displacement. A fast control power supply is needed to excite the active feedback coils, which produces a magnetic field to control the plasma＇s displacement. With the development of EAST, the fast control power supply needs to keep on enhancing the fast response and output current. The structure of a new power supply is introduced in this paper. The method of multiple inverters paralleled with the current sharing reactor is presented to meet the need for large current and fast control. According to the design demands of the EAST fast control power supply, the adjuster of the current close loop is applied to the inverter, which can advance its ability to restrain the loop current in low frequency and DC output. The result of the experiment confirms the validity of the proposed scheme and control strategy.

核电厂安全级DCS缺省值设置策略研究

针对数字化仪控系统中无效信号的质量位随意蔓延使系统处于一种不确定状态的问题,结合核电厂运行工况和信号特性,对龙鳞平台故障诊断机制和信号质量位标识进行研究。考虑故障安全准则,系统性地提出缺省值设置原则。从信号执行功能和信号边界两个维度进行分析,确认缺省值的设置范围,并详细给出执行保护功能、报警功能、维护和试验功能信号的缺省值设置策略。同时,针对传统的缺省值验证方式无法全面、有效地进行缺省值验证的问题,提出一种利用全范围模拟机和虚拟数字化控制系统(DCS)进行缺省值验证的新方法。利用该方法可有效地对DCS内设置的缺省值进行系统性的验证。所提出的缺省值设置策略和验证方法可为后续核电厂安全级DCS的缺省值分析和设置提供全面的指导。

Programmable Voltage Regulating Method for 15 kV High Voltage DC Power Supply

In order to solve the disadvantages caused by mechanical slide rheostat that has big errors and low precision,a novel voltage regulation method for high voltage DC power supply was introduced.The key of this method were digital potentiometer MAXIM 5455 and linear photoelectric coupling LOC110,and application programs were compiled using Visual Basic which was graphical compiling language,furthermore the communication between exterior and computer was carried out by ICP7044D module,in consequence the output value of high voltage DC power supply could be regulated with computer.The measured results showed that this method could accurately,conveniently and rapidly regulate the output value of high voltage DC power supply.

Development of Full Automatic Flash Butt Welding with Digital Control

The hardware and software design of two digital control systems based on 80C196KB MCU for flash butt welder is introduced in this paper.The welding power supply is made of six-phase half-wave rectifier.The welding outer characteristic of welding machine is realized by digital PI algorithm with the voltage close-loop feedback.The flashing curve is finished by elec- tric-hydraulic servo valve.The process control system transfers datum with power supply system by a serial communication inter- face.The parameters of the control systems are collected by photoelectrical seclusion to avoid the disturbing of the electromagnetism in welding process.

Design of digital controller for HEPS corrector power supply

Purpose In order to realize the control of current closed loop in HEPS corrector power supply,a digital control board is designed.Methods The control board uses the latest FPGA to realize digital processing and uses two different AD chips to realize current and voltage sampling,respectively.In order to achieve high-precision closed-loop control,an effective closed-loop control program is designed.Results The controller has been widely used in HEPS projects,and its control effect has been proved.Conclusions In order to realize control and reduce power cost,the controller is designed.The testing experiments show that the controller has excellent performance,reliable operation and low cost.

基于VSC-HVDC的电力系统频率稳定控制策略

针对电力系统在典型故障与扰动下表现出的“暂态失稳”现象,提出了一种基于VSC-HVDC的电力系统频率稳定控制方法。考虑某大规模发电厂通过VSC-HVDC连接至交流电网,该方法允许此发电厂向交流电网提供频率控制服务。该控制策略包含整流器对直流电压的控制以及逆变器对频率的控制,即逆变器通过交流电网频率的变化来调节直流电压的变化,而整流器通过直流电压的变化来控制发电厂有功的投放,以补偿交流电网有功的短缺,使电网在故障恢复的初始阶段更好地提高系统稳定性。通过在Power Factory Digsilent上进行仿真,验证了该控制策略能显著增强系统的稳定性。

Identification of the Worst-case Static Voltage Stability Margin Interval of AC/DC Power System Considering Uncertainty of Renewables

Calculation of static voltage stability margin(SVSM)of AC/DC power systems with lots of renewable energy sources(RESs)integration requires consideration of uncertain load growth and renewable energy generation output.This paper presents a bi-level optimal power flow(BLOPF)model to identify the worst-case SVSM of an AC/DC power system with line commutation converter-based HVDC and multi-terminal voltage sourced converter-based HVDC transmission lines.Constraints of uncertain load growth’s hypercone model and control mode switching of DC converter stations are considered in the BLOPF model.Moreover,uncertain RES output fluctuations are described as intervals,and two three-level optimal power flow(TLOPF)models are established to identify interval bounds of the system worst-case SVSM.The two TLOPF models are both transformed into max–min bi-level optimization models according to independent characteristics of different uncertain variables.Then,transforming the inner level model into its dual form,max–min BLOPF models are simplified to single-level optimization models for direct solution.Calculation results on the modified IEEE-39 bus AC/DC case and an actual large-scale AC/DC case in China indicate correctness and efficiency of the proposed identification method.

数字控制DC-DC变换器改进离散迭代建模和稳定性分析

离散迭代模型是一种能精确描述数字控制变换器特性的工具,然而传统的离散模型通常计算复杂而且不够直观,不利于控制器的设计。该文对离散迭代模型进行合理近似,推导出数字控制DC-DC变换器在前沿和后沿调制下的二阶全局等效电路模型,解决了传统模型直观性和精确性之间的矛盾。该模型可以反映具有不同脉冲宽度调制方法的DC-DC变换器的稳态和动态行为。在等效电路的基础上,分析了数字控制的特性,推导出了z域传递函数,从而得到了不同调制方式下控制-输出的频率响应,并且分析了两种调制方式对系统稳定性的影响。此外,等效电路模型可以准确地跟踪详细开关电路的工作波形,并且对系统参数变化时系统的稳定边界做出精确预测。最后,搭建了DC-DC变换器的样机,验证了模型和理论分析的有效性。

A comparative study of digital low dropout regulators

Granular power management in a power-efficient system on a chip(SoC)requires multiple integrated voltage regulators with a small area,process scalability,and low supply voltage.Conventional on-chip analog low-dropout regulators(ALDOs)can hardly meet these requirements,while digital LDOs(DLDOs)are good alternatives.However,the conventional DLDO,with synchronous control,has inherently slow transient response limited by the power-speed trade-off.Meanwhile,it has a poor power supply rejection(PSR),because the fully turned-on power switches in DLDO are vulnerable to power supply ripples.In this comparative study on DLDOs,first,we compare the pros and cons between ALDO and DLDO in general.Then,we summarize the recent DLDO advanced techniques for fast transient response and PSR enhancement.Finally,we discuss the design trends and possible directions of DLDO.

Study of Sliding Mode Control of DC-DC Buck Converter

In this paper, a robust sliding mode controller for the control of dc-dc buck converter is designed and analyzed. Dynamic equations describing the buck converter are derived and sliding mode controller is designed. A two-loop control is employed for a buck converter. The robustness of the sliding mode controlled buck converter system is tested for step load changes and input voltage variations. The theoretical predictions are validated by means of simulations. Matlab/Simulink is used for the simulations. The simulation results are presented. The buck converter is tested with operating point changes and parameter uncertainties. Fast dynamic response of the output voltage and robustness to load and input voltage variations are obtained.

Fusion power supply advances by the J-TEXT engineering team

To meet the stringent requirements of the fusion power supply for large-scale fusion devices,the J-TEXT engineering team has carried out key technology research and applications in several important directions of fusion power supply.This article presents the advances made by the J-TEXT engineering team in recent years in the following areas:(1) a high-voltage power supply for an auxiliary heating system;(2) a breakdown protection device for an auxiliary heating power supply;(3) magnetic field compatibility;(4) a high-voltage pulsed power supply for a fieldreversed configuration;(5) a large physics experimental facility control system.The research backgrounds,technical progress,test results,applications,summaries and prospects are described in detail in each part.These innovative research results and valuable engineering experience can promote the progress of fusion power supply technology,and also lay a foundation for the development of power supplies with higher parameters in the future.

核电DCS网络安全防护技术研究

核电数字化控制系统(DCS)属于国家关键信息基础设施(CII),亟需为其建立综合防御、积极防范、本质安全的网络安全保障体系。基于国家标准法规技术要求,结合核电DCS业务特点、安全现状,对DCS网络安全防护技术进行了深入研究,形成了满足核电DCS业务需求和网络安全等级保护四级技术要求的整体防护技术方案。防护技术方案以“一个中心、三重防护”为设计核心,基于自主研发的网络安全产品,创新应用多项保障DCS业务安全的关键技术,采用安全区域划分、分布控制、集中管控等安全措施构建了网络安全综合防御体系,有效提升了核电DCS防护能力。相关技术已在多个核电工程项目落地,应用效果良好,为其他领域的国家CII系统网络安全建设提供了良好的示范和借鉴。

Practice and Prospect of AC/DC Hybrid Power Grid in Southern China

China Southern Power Grid is a unique EHV AC/DC hybrid transmission network that operates in China. In its service area, the distribution of energy resources and the development of economy are extremely unbalanced, so long-distance and bulk power transmission are needed; besides, the geography and climate conditions are serious, rains, fogs, lightning and typhoon as well as high temperature are common all the year round. Facing these challenges, the power grid enhanced stability control, improved the equipment and strengthen the network structure. In the future, the power grid plans to optimize the disposition of power sources and build digitalized power system.

Research on the application of digital power supply based on domestic FPGA

Purpose The digital controller for the accelerator magnet power supply typically employs a field-programmable gate array(FPGA)as the signal processing chip for executing digital processing of closed-loop control.Currently,FPGA chips are predominantly utilized in Intel or Xilinx products.To address the“key areas and stranglehold”issue pertaining to FPGA chips in accelerator power supply,we have devised a digital power supply prototype using a domestic FPGA chip and validated its feasibility in the upgrade project’s magnet power supply digital transformation plan for the Beijing Electron Positron Collider(BEPCII).Method A domestic FPGA chip from the Seal5000 SA5Z-30-D1 series by Xi’an ZhiDuoJing Microelectronics Co.serves as the core component for the design of a digital corrector magnet power supply to replace the existing analog controlled corrector power supply at BEPCII.The power supply’s digital control of the closed loop is achieved through the use of a hardware description language,and the digital controller hardware is constructed based on the original power supply power topology.Results and conclusions After conducting experiments and tests on the power supply prototype,we have successfully met the current operational requirements of the BEPCII corrector power supply,thus confirming the feasibility of utilizing domestic FPGA for digital application on accelerator power supply.

新型混合式贯通牵引供电系统及其复合控制策略

电分相与负序等电能质量问题是制约电气化铁路向高速化、重载化发展的桎梏。贯通牵引供电系统为消弭上述问题提供了契机,但既有贯通方案依然存在所需器件数目多、改造成本高、可靠性差等弊端。为此,在充分利用既有牵引变压器基础上,该文设计一种新型混合式贯通牵引供电装置。该装置通过共直流侧与功率均分手段有效抵消输入侧纹波功率,降低有源/无源器件数目与电容容量。同时,针对直流侧二次纹波与负荷功率冲击,提出一种输入端口复合控制策略,有效解决纹波传递与冲击波动问题。最后通过仿真与实验验证所提装置及其控制策略的可行性与可靠性。

智能型DCS控制电源的研究与应用

在我国工业快速发展的过程中,智能化科技也获得了普遍的应用,其中集散控制系统(DCS)的应用最为广泛。该系统的核心之一在于电源的应用,从传统的开关电源到冗余电源技术再到如今的智能型电源,都对DCS系统有着巨大推进作用。文章将主要针对智能型DCS控制电源进行研究与应用,论述DCS控制系统及其电源的发展,并介绍其应用实例,进一步通过对智能化技术的合理应用,以达到增强系统设备可靠性与安全性的目的,以期能够进一步促进DCS控制和电源控制的技术发展。

面向低压大容量直流供电的混合型AC/DC接口变流器解耦控制

为解决传统基于电流源型整流器(currentsourcerectifier,CSR)的两级式高降压比电力电子变换设备中存在的多控制目标之间的耦合问题,在所提出的相控电流源型整流器和输入串联输出并联LLC-DC/DC变换器相结合的混合型拓扑结构基础上,通过建立考虑系统直流环节电感电容的小信号模型,提出了一种在较低自由度下可同时实现交流侧功率因数和输出直流电压调节的解耦控制方法。通过绘制系统的根轨迹,分析了系统解耦前后控制参数对系统稳定性的影响。最后,通过RT-Lab半实物仿真验证了所提方法的有效性。