Architecture Design for Integrated Wide Area Protection and Control Systems

This paper firstly reviews the recent development in power system protection and control, with special attention paid to the wide-area and integrated protection, in order to look into future development of integration of protection and control for smart grids. This paper mainly reports on the development of integrated wide area protection and control for power systems. The concept of integrated wide area protection and control is introduced, in which a hierarchical protection and control system provides the protection and control of wide area or regional power substations/ plants and their associated power network. The system is mainly divided into three levels, the local, the substation/plant and the wide area/regional protection and control. The integrated functions at each level are described in details with an aim to develop an optimal coordination mechanism between the levels. One of the core elements in the system is the synchronised wide area communication network between the substations and the protection and control system, in which latest communication technology is employed. Another important player in the system is the wide area synchronized protection and control information platform, which not only enables the fusion three line of defence for power system protection and control, but also provides a perfect tool for the application of cloud computing to substations and power networks.

Simulation Studies of an Integrated Overcurrent Relay Protection Scheme for Distribution Systems

This paper presents an integrated protection technique for power distribution systems. A novel integrated protection scheme based on overcurrent protection technique for distribution system is described, in which a specially designed protection relay is installed at each substation of a network and responsible for the protection of every line sections connected to the substation busbar The conventional directional overcurrent and the new adaptive accelerated protection algorithms with multiple settings are implemented into the relay to cover all the protected line sections. The paper includes studies of a typical multi section distribution network to demonstrate the principle of the scheme. Studies show that the new scheme not only offer the new protection features for individual power line section, but also provide the characteristics of integrated protection.

Music Protection Based on Digital Watermarking and Encryption

Two fast and robust digital watermarking schemes for compressed music format and MIDI format are put forward, which are suitable for on-line distribution through the Internet. For compressed music, the watermark is embedded in partially uncompressed domain and the embedding scheme is closely related to music content. For MIDI, the watermark is embedded in virtual notes that are generated and randomly hide among the MIDI notes. This paper also presents a method for controlling usage and protecting against copying of digital music contents and their associated players. The digital music contents and their players installed in one computer cannot be used if they are copied to another computer. Even in the same computer, the duplicated digital music contents are not usable. The usage associated to the music content will restrict the running time and times. Also the music can be played and it will be automatically updated after each playing. The digital music cannot be accessible if its permitted usage expires.

Comparative Analysis of Analog and Digital Controllers for Negative Output Superlift Luo Converter (NOSLC)

This paper focuses on the comparative study of analog and digital control techniques for Negative Output Superlift Luo converter (NOSLC). NOSLC is a high gain converter in which the positive source voltage is converted into a negative load voltage. Though the negative load voltage is produced effectively, there is lot of non-linearities that affects the voltage level. To overcome this, analog controllers like Proportional-integral (PI), fuzzy PI and a sliding mode controller (SMC) were proposed for NOSLC. However PI controller does not respond to changes in operating point, fuzzy PI is based on the systematic approach and proved to be a trial and error oriented method and SMC brings an oscillation in the duty cycle. Therefore, to overcome these drawbacks, a digital control technique using PIC microcontroller is proposed in this paper which provides high versatility and programmability approach. Simulation studies are carried out in MATLAB and the performances of these controllers have been investigated for the proposed DC-DC converter. A prototype of the NOSLC converter is built by employing digital control and the results are verified experimentally.

Digital Servo Control of a Robotic Excavator

An electro-hydraulic control system is designed and implemented for a robotic excavator known as the Lancaster University Computerised and Intelligent Excavator （LUCIE）. The excavator is being developed to autonomously dig trenches without human intervention. Since the behavior of the excavator arm is dominated by the nonlinear dynamics of the hydraulic actuators and by the large and unpredictable external disturbances when digging, it is difficult to provide adequate accurate, quick and smooth movement under traditional control methodology, e.g., PI/PID, which is comparable with that of an average human operator. The data-based dynamic models are developed utilizing the simplified refined instrumental variable （SRIV） identification algorithm to precisely describe the nonlinear dynamical behaviour of the electro-hydraulic actuation system. Based on data-based model and proportional-integral-plus （PIP） methodology, which is a non-minimal state space method of control system design based on the true digital control （TDC） system design philosophy, a novel control system is introduced to drive the excavator arm accurately, quickly and smoothly along the desired path. The performance of simulation and field tests which drive the bucket along straight lines both demonstrate the feasibility and validity of the proposed control scheme.

Digital Control Design for the Boiler Drum BDT921

A boiler drum BDT921 that is installed in the Control Laboratory, Department of Mechatronics and Robotics Engineering, Faculty of Electric and Electronic Engineering, Universiti Tun Hussein Onn Malaysia （UTHM） is being used as a model plant to achieve the digital control system since its analog. Implementing a digital system to boiler quite a though work. This paper covers analysis from the experiment done to match with digital design that will be implemented to the real system. The digital control design will come up with the mathematical model and will be analyzed with MATLAB and SIMULINK software named as ＂Discrete Analysis ofBDT921 Simulation＂. A proportional integral and derivative （PID） controller is being chosen as the control element in discrete form as the real system is using the same control element. The output responses behave as the second order system with a bit difference in rise times and peak times compared with data obtained from experiment. With regarding to the analysis done, the digital control can be implemented and for further viewing, to be controlled digitally with computer in the control room.

Analysis of thermal management and anti-mechanical abuse of multi-functional battery modules based on magneto-sensitive shear thickening fluid

Electric vehicles(EVs)have garnered significant attention as a vital driver of economic growth and environmental sustainability.Nevertheless,ensuring the safety of high-energy batteries is now a top priority that cannot be overlooked during large-scale applications.This paper proposes an innovative active protection and cooling integrated battery module using smart materials,magneto-sensitive shear thickening fluid(MSTF),which is specifically designed to address safety threats posed by lithium-ion batteries(LIBs)exposed to harsh mechanical and environmental conditions.The theoretical framework introduces a novel approach for harnessing the smoothed-particle hydrodynamics(SPH)methodology that incorporates the intricate interplay of non-Newtonian fluid behavior,capturing the fluid-structure coupling inherent to the MSTF.This approach is further advanced by adopting an enhanced Herschel-Bulkley(H-B)model to encapsulate the intricate rheology of the MSTF under the influence of the magnetorheological effect(MRE)and shear thickening(ST)behavior.Numerical simulation results show that in the case of cooling,the MSTF is an effective cooling medium for rapidly reducing the temperature.In terms of mechanical abuse,the MSTF solidifies through actively applying the magnetic field during mechanical compression and impact within the battery module,resulting in 66%and 61.7%reductions in the maximum stress within the battery jellyroll,and 31.1%and 23%reductions in the reaction force,respectively.This mechanism effectively lowers the risk of short-circuit failure.The groundbreaking concepts unveiled in this paper for active protection battery modules are anticipated to be a valuable technological breakthrough in the areas of EV safety and lightweight/integrated design.

An Integrated Control and Protection System for Photovoltaic Microgrids

The microgrid has shown to be a promising solution for the integration and management of intermittent renewable energy generation.This paper looks at critical issues surrounding microgrid control and protection.It proposes an integrated control and protection system with a hierarchical coordination control strategy consisting of a stand-alone operation mode,a grid-connected operation mode,and transitions between these two modes for a microgrid.To enhance the fault ride-through capability of the system,a comprehensive three-layer hierarchical protection system is also proposed,which fully adopts different protection schemes,such as relay protection,a hybrid energy storage system(HESS)regulation,and an emergency control.The effectiveness,feasibility,and practicality of the proposed systems are validated on a practical photovoltaic(PV)microgrid.This study is expected to provide some theoretical guidance and engineering construction experience for microgrids in general.

知识溢出视角下企业数字化转型与全球价值链融入

企业数字化转型能够诱发知识溢出,是促进企业融入全球价值链的有效路径。本文利用2007~2016年中国制造业上市企业数据,探讨知识溢出视角下企业数字化转型对全球价值链融入的影响。结果表明:相较于非数字化转型的企业,数字化转型企业的知识溢出显著促进了企业融入全球价值链,在克服内生性问题和稳健性检验后,结论依然成立;异质性分析表明,数字化转型企业的知识溢出对国有企业、低IT投资企业和技术资本密集型企业融入全球价值链有显著正向影响;进一步讨论发现,知识产权保护的加强、融资约束的缓解强化了数字化转型企业知识溢出对企业融入全球价值链的积极作用。

基于控保协同的三端混合直流输电系统线路保护

灵敏可靠的保护原理对多端混合直流输电系统的安全运行具有重要意义。现有多端混合直流输电系统线路保护原理易受过渡电阻、噪声等因素干扰,且多忽略与换流器控制环节之间的协调配合。为此,提出一种基于控制特征量的多端混合直流线路单端保护方案。首先,利用故障电流变化方向进行故障区域识别;然后,基于不同故障情况下等效阻抗回路中电感的差异,分析不同位置故障时控制信号积分值的大小差异,以此构造区内、外故障识别判据,并利用正、负极控制信号积分值比值进行故障选极;最后,通过PSCAD/EMTDC进行仿真验证,结果表明所提保护方案能够可靠、灵敏地识别各种故障,且具有较强的抗干扰和抗过渡电阻能力。

数字新质生产力、农村三产融合与农业高质量发展

文章利用2012—2022年中国30个省份的面板数据,对数字新质生产力、农村三产融合与农业高质量发展之间的逻辑关系进行实证分析。结果显示,数字新质生产力对农业高质量发展具有积极的促进作用,且经过稳健性检验和内生性处理后,这一结论仍然成立。中介效应检验结果显示,数字新质生产力通过农村三产融合推动农业高质量发展。调节效应检验结果显示,知识产权保护在数字新质生产力推动农业高质量发展的过程中发挥正向调节效应。异质性检验结果表明,数字新质生产力对数字化水平较高地区与东部地区农业高质量发展的推动作用更为显著。

网络空间中数字身份认同与个人隐私保护

本文基于对10000名网民数字身份行为数据进行的统计分析,探讨了网络空间中数字身份认同的技术实现方式及其存在的隐私安全问题。研究发现,62.5%的用户在多个网络平台采用同一数字身份,75.3%的用户遭遇过不同程度的隐私信息泄露。针对上述问题,本文从密码学、访问控制、可信计算、隐私保护数据挖掘等技术层面,提出了一种基于联邦学习的隐私保护数字身份认同方案。仿真实验表明,该方案能够有效平衡数字身份的可用性与隐私安全性。

Control and protection strategy for MMC MTDC system under converter-side AC fault during converter blocking failure

This paper investigates a control and protection strategy for a four-terminal modular multilevel converter(MMC)based high-voltage direct current(HVDC)system under a converter-side AC fault.Based on the system operating condition,a control and protection strategy against the fault with normal blocking of the converter is proposed.In practical,applications encountering such a fault,the MMC at the fault side may experience different conditions of blocking failure.The blocking failures may occur on:①the whole converter;②one converter arm;③one sub-module(SM)/several SMs of one converter arm;④other conditions.The phenomenon of the multi-terminal HVDC(MTDC)system following the fault is analyzed under the first three conditions with real-time simulations using the real-time digital simulator(RTDS).Based on the impact of different conditions on the MTDC system,the necessity of utilizing special control and protection is discussed.A special control and protection strategy is proposed for emergency conditions,and its effectiveness is verified by real-time simulation results.

Developments of power system protection and control

Synchronized wide area communication has become a mature technology,which makes the real-time interaction between the substations and the wide area protection and control system possible.However,the present protection and control system to handle this real-time data has been recognized to be deficient.This paper begins by reviewing the development history of power system protection,with special attention paid to the recent development in the field of wide-area and integrated protections,in order to look into the future development of protection and control systems.Then the concept of integrated wide area protection and control is introduced,where it can be shown that a hierarchical protection and control system provides the protection and control for wide area or regional power substations/plants and their associated power networks.The system is mainly divided into three levels:the local,the substation/plant,and the wide area/regional.The integrated functions at each level are described in details with an aim to develop an optimal coordination mechanism between each level.The key element in the proposed system is the wide area real-time protection and control information platform,which not only enables the merger of three lines of defence for power system protection and control,but also provides a perfect tool for the application of cloud computing in substations and power networks.

Integrated Wide Area Protection and Control for Power Grid Security

The traditional“three defense lines”for power systems are based on local information and static protection&control strategy,which are not suitable to modern large-scale power systems.In order to improve the security of UHV hybrid power grids,the Integrated Wide Area Protection&Control(IWAPC)is proposed in this paper by applying the new technologies of synchronized high-speed communication,which integrates“three defense lines”and promotes existing wide area protection only for security control.The IWAPC is the hierarchical protection and control system which provides the protection and control for wide area power networks to improve their reliability and security.It is divided into three levels,the local bay level,the substation integrated protection level and the wide area protection level.The wide area real-time protection and control information platform is the most important part of the IWAPC,which is based on a synchronized wide area communication network.The key technologies and new development trends include network topology analysis,wide area backup protection,wide area intelligent reclosing,wide area load shedding,wide area auto-switching,overload cutoff and transfer,transmission section protection,intelligent system splitting and dynamic stability control.It cannot only integrate three lines of defense for power system protection and control,but also improve security of the power grid.

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.

Fault component integrated impedance-based pilot protection scheme for EHV/UHV transmission line with thyristor controlled series capacitor(TCSC) and controllable shunt reactor(CSR)

This paper analyzes the fundamental frequency impedance presents a novel transmission line pilot protection scheme characteristic of a thyristor controlled series capacitor （TCSC） and based on fault component integrated impedance （FCII） calculated for a transmission line with TCSC and controllable shunt reactor （CSR）. The FCII is defined as the ratio of the sum of the fault component voltage phasors of a transmission line with TCSC and CSR to the sum of the fault component current phasors where all the phasors are determined at both line＇s terminals. It can be used to distinguish internal faults occurring on the line from external ones. If the fault is an external one the FCII reflects the line＇s capacitive impedance and has large value. If the fault is an internal one on the line the FCII reflects the impedance of the equivalent system and the line and is relatively small. The new pilot protection scheme can be easily set and has the fault phase selection ability and also it is not affected by the capacitive current and the fault transition resistance. It is not sensitive to compensation level and dynamics of TCSC and CSR. The effectiveness of the new scheme is validated against data obtained in ATP simulations and Northwest China 750 kV Project.

设施黄瓜主要病害发生及综合防控

从病害发生特点、为害症状、侵染循环、流行因素及防控技术等方面对我国设施黄瓜主要病害发生情况及其综合防控技术进行总结、分析和展望,以期为黄瓜主要病害监测和防控技术研究提供参考。

数字化转型对制造业企业风险承担水平的影响

数字化转型背景下,提高风险承担水平对制造业企业可持续发展具有重要的影响作用。文章以2012—2022年中国A股制造业上市公司为研究样本,通过构建过程机制模型,考察数字化转型对制造业企业风险承担水平的影响。结果表明:数字化转型显著提高了制造业企业风险承担水平;外部交易成本和内部控制质量在数字化转型影响制造业企业风险承担水平过程中发挥中介作用;供应链集成对数字化转型影响制造业企业风险承担水平起正向调节作用;数字化转型对制造业企业风险承担水平的提升作用在非国有制造业企业中显著,而在国有制造业企业中不显著。

风电场参与电网调频的多机协同控制策略

【目的】考虑风电场中不同风况下风电机组参与一次调频能力的差异,在下垂控制和惯量控制策略的基础上,对机组的调频能力评估方法进行优化。【方法】提出了一种改进的多机组调频参考功率协同控制策略。【结果】引入多机组协同控制方法能够有效改善机组之间调频参考功率的分配,从而有效调节各机组参与系统一次调频的程度。在惯量控制和下垂控制的基础上引入改进的协同控制策略,依据机组在实际风况下运行的状态,评估机组能够有效参与一次调频的参考功率。引入调频能力系数能够实现调频功率参考值在各机组之间按能分配。【结论】协同控制策略能够有效保护风电机组转速,同时能够有效改善电网频率响应。