Analysis of cascading failures of power cyber-physical systems considering false data injection attacks

This study considers the performance impacts of false data injection attacks on the cascading failures of a power cyber-physical system,and identifies vulnerable nodes.First,considering the monitoring and control functions of a cyber network and power flow characteristics of a power network,a power cyber-physical system model is established.Then,the influences of a false data attack on the decision-making and control processes of the cyber network communication processes are studied,and a cascading failure analysis process is proposed for the cyber-attack environment.In addition,a vulnerability evaluation index is defined from two perspectives,i.e.,the topology integrity and power network operation characteristics.Moreover,the effectiveness of a power flow betweenness assessment for vulnerable nodes in the cyberphysical environment is verified based on comparing the node power flow betweenness and vulnerability assessment index.Finally,an IEEE14-bus power network is selected for constructing a power cyber-physical system.Simulations show that both the uplink communication channel and downlink communication channel suffer from false data attacks,which affect the ability of the cyber network to suppress the propagation of cascading failures,and expand the scale of the cascading failures.The vulnerability evaluation index is calculated for each node,so as to verify the effectiveness of identifying vulnerable nodes based on the power flow betweenness.

Improved direct power injection model of 16-bit microcontroller for electromagnetic immunity prediction

To promote the modeling standardization process of the integrated circuits, an improved electrical simulation model for a direct power injection （DPI） setup which was used to measure the conducted immunity of a 16-bit microcontroller to radio frequency aggression was investigated. Based on the existing model of the same microcontroller, the PDN module was modified by adding the core, PLL and MD network models, which could reflect the actual electric distribution situation within the microcontroller more accurately. By comparing the simulation results with the measurement results, the effectiveness of the modified model can be improved to 500 MHz, and its uncertainty is within ＋1.8 dB （＋2 dB is acceptable）. Then, to improve the simulation accuracy of the complete model in the high frequency range, the I/O model which contained the dynamic and nonlinear characteristics reflecting the variation of the internal impedance of the microcontroller with increasing the frequency of the external noise was introduced. By comparing the simulation results with the measurement results, the effectiveness of the second modified model can be improved up to 1.4 GHz with the uncertainty of ~1.8 dB. Thus, a conclusion can be reached that the proposed model can be applied to a much wider frequency range with a smaller uncertainty than the latest model of the similar type. Furthermore, associated with the electromagnetic emission testing platform model, the PDN module can also be used to predict the electromagnetic conducted and radiated emission characteristics. This modeling method can also be applied to other integrated circuits, which is very helpful to the standardization of the IC electromagnetic compatibility （EMC） modeling process.

Research on the Effect of High Power Microwave on Low Noise Amplifier and Limiter Based on the Injection Method

The reliability of electronic device is threatened in high power microwave (HPM) environment. In accordance with the situation that the emulation is ineffective in evaluating the accuracy and precision of the HPM effect to electronic device, the experimental method is used to resolve the problem. Low Noise Amplifier (LNA) and Limiter are selected as the objects for the experiments, the structural characteristic of the front-end of radar receiver is described, the phenomena and criterion are elaborated and analyzed using injection method due to its ability to get an accurate threshold avoiding the complex coupling, the basic principle of injection experiment is demonstrated, and the method and process of effect experiment about Low Noise Amplifier and Limiter are also explained. The experimental system is established, and the system is composed of low power microwave source such as TWT, test equipment for obtaining the effect parameters, and some of auxiliary equipments as camera, optical microscope or electron microscopy, attenuator, detector, and directional coupler etc. The microwave delivered from source is adjusted to the power infused by attenuator, and pour in the decanting point of effecter via directional coupler, then the couple signal created by directional coupler is input to the recording instrument after detecting by detector, finally the power of effecter is obtained. The value of power, which damages the effecter in the microwave pulse environment, is classified at the index of sensitivity, and the threshold is obtained by power diagnose and wave test. Some regular understandings of the HPM effect to electronic device are obtained based on the results of the experiments. It turns out that the index of electronic device is influenced significantly by the energy via front door coupling, the MOSFET made up of GaAs is the most wearing part to HPM in LNA, the damage threshold of LNA is about 40dBm under single pulse while in repetitive pulse the value is from 33.3dBm to 43.9dBm according to different wave band. The damage threshold of Limiter is about 56dBm to80dBm.

Empirical Scaling Laws of Neutral Beam Injection Power in HL-2A Tokamak

We present an experimental method to obtain neutral beam injection （NBI） power scaling laws with operating parameters of the NBI system on HL-2A, including the beam divergence angle, the beam power transmission efficiency, the neutralization efficiency and so on. With the empirical scaling laws, the estimating power can be obtained in every shot of experiment on time, therefore the important parameters such as the energy confinement time can be obtained precisely. The simulation results by the tokamak simulation code （TSC） show that the evolution of the plasma parameters is in good agreement with the experimental results by using the NBI power from the empirical scaling law.

Development of SA-533 Type B CL. 1+SA-240 Type 304L roll-bonded clad steel plate for safety injection tank of CAP1400 nuclear power plant

Aiming to meet the demand of the country＇ s nuclear demonstration project on the CAP1400 nuclear power plant, Baosteel uses the roll-bonding technology and develops the SA-533 Type B CL. 1 ＋ SA-240 Type 304L high-strength and high-toughness clad steel plate with a shear strength of over 310 MPa for the nuclear power plant＇ s safety injection tank. The properties of the quenched and tempered and the simulated post-weld heat treatment states are systematically studied herein through a comprehensive inspection and evaluation of the composition,microstructure,and properties of the clad steel plate. The results show that the bonding interface has high shear strength and that the base metal has high strength and good toughness at low temperatures. Hence, the performance fully meets the technical requirements of the CAP1400 nuclear power plant＇ s safety injection tank in the country＇ s nuclear demonstration project. The roll-bonded clad steel plate can be used to manufacture the safety injection tank of the CAP1400 nuclear power plant.

Grid-connected inverter for wind power generation system

In wind power generation system the grid-connected inverter is an important section for energy conversion and transmission, of which the performance has a direct influence on the entire wind power generation system. The mathematical model of the grid-connected inverter is deduced firstly. Then, the space vector pulse width modulation （SVPWM） is analyzed. The power factor can be controlled close to unity, leading or lagging, which is realized based on H-type current controller and grid voltage vector-oriented control. The control strategy is verified by the simulation and experimental results with a good sinusoidal current, a small harmonic component and a fast dynamic response.

High-Power Simultaneous Wireless Information and Power Transfer: Injection-Locked Magnetron Technology

Applications using simultaneous wireless information and power transfer(SWIPT)have increased significantly.Wireless communication technologies can be combined with the Internet of Things to develop many innovative applications using SWIPT,which is mainly based on wireless energy harvesting from electromagnetic waves used in communications.Wireless power transfer that uses magnetrons has been developed for communication technologies.Injection-locked magnetrons that can be used to facilitate high-power SWIPT for several devices are reviewed in this paper.This new technology is expected to pave the way for promoting the application of SWIPT in a wide range of fields.

Forecast of Power Generation for Grid-Connected Photo-voltaic System Based on Grey Theory and Verification Model

Being photovoltaic power generation affected by radiation strength, wind speed, clouds cover and environment temperature, the generating in each moment is fluctuating. The operational characteristics of grid-connected PV systems are coincided with gray theory application conditions. A gray theory model has been applied in short-term forecast of grid-connected photovoltaic system. The verification model of the probability of small error will help to check the accuracy of the gray forecast results. The calculated result shows that the ?model accuracy has been greatly enhanced.

Influence of Control Modes of Grid-Connected Solar Photovoltaic Generation on Grid Power Flow

Integration of Solar Photovoltaic (PV) generation into an existing distribution system has many impacts on the system, with the power flow being one of the major issues. This impact is not generic for any network, but it may manifest itself either positively or negatively, depending on the grid configuration, interface control modes, operation mode, and load profile. Grid-connected PV systems have three control options of the local voltage controller of the interface DC-AC converter. These control modes are Power Factor control, voltage control, and Droop Voltage control. This paper aims at evaluating and comparing the impacts of those control modes on the grid power flow. A set of evaluation criteria and indices is defined and mathematically formulated. Based on the requirements of the used program (Power Factory Dig Silent V14.1.3), a computation plan (algorithm) has been proposed. The algorithm has been applied to a typical weak network and a wide range of simulations has been carried out. Simulation results have been thoroughly discussed and important findings have been concluded.

Grid-Connected PV Solar Energy Converter with Active and Reactive Power Control

This work proposes a 12 kW three-phase grid-connected single stage PWM DC-AC converter destined to process the energy provided by a photovoltaic array composed of 57 KC200GT PV modules with high power factor for any solar radiation. The PWM inverter modeling and the control strategy, using dqO transformation, are proposed in order to also allow the system operation as an active power filter, capable to compensate harmonic components and react power generated by the non-linear loads connected to the mains grid. An input voltage clamping technique is proposed to impose the photovoltaic operation on the maximum power point. Simulation and experimental results are presented to validate the proposed methodology for grid connected photovoltaic generation system.

MHD flow of power-law fluid on moving surface with power-law velocity and special injection/blowing

The problem of magnetohydrodynamic （MHD） flow on a moving surface with the power-law velocity and special injection/blowing is investigated. A scaling group transformation is used to reduce the governing equations to a system of ordinary differen- tial equations. The skin friction coefficients of the MHD boundary layer flow are derived, and the approximate solutions of the flow characteristics are obtained with the homotopy analysis method （HAM）. The approximate solutions are easily computed by use of a high order iterative procedure, and the effects of the power-law index, the magnetic parameter, and the special suction/blowing parameter on the dynamics are analyzed. The obtained results are compared with the numerical results published in the literature, verifying the reliability of the approximate solutions.

Power-combining based on master-slave injection-locking magnetron

A microwave power-combining system composed of two Panasonic 2M244-M1 magnetrons based on master–slave injection-locking is demonstrated in this paper. The principle of master–slave injection-locking and the locking condition are theoretical analyzed. Experimental results are consistent with the theoretical analysis and the experimental combined efficiency is higher than 96%. Compared with the external-injection-locked system, the power-combining based on the master–slave injection-locking magnetron is superior by taking out the external solid-state driver and the real-time phase control system. Thus, this power-combining system has great potential for obtaining a high efficiency, high stability, low cost, and high power microwave source.

Norton equivalent circuit for current control loop of grid-connected system

Modeling method for the current control loop of a grid-connected PWM inverter with the LCL output filter was discussed.Firstly,the current control loop with the LCL inverter-side current as feedback was established.Then,parameters of PI controller were calculated on the basis of an equivalent controlled object.Finally,Norton equivalent circuit for the current control loop of grid-connected system was derived by integrating one control equation,which connected the PWM inverter output voltage and the LCL inverter-side current,with two circuit equations,separately using the LCL inverter-side current and the injected current as loop currents.With the induced Norton equivalent circuit,system-level resonant and unstable issues on real grid-connected system applied in weak distributed power systems can be easily analyzed.The validity of substituting Norton equivalent circuit for grid-connected system is verified by simulation and experiment.

Research on the Method of Calculating Node Injected Reactive Power Based on L Indicator

With the power grid load increasing, the problem of grid voltage stability is increasingly prominent, and the possibility of voltage instability is also growing. In order to improve the voltage stability, this paper analyzed how the voltage stability was influenced by different reactive power injection based on the simplified L-indicator of on-line voltage stability monitoring. According to the basic differential property of the simplified L-indicator, a general and normative analytical algorithm about reactive power optimization was deduced. The analytical algorithm can calculate the load node injected reactive power, and then the network can run in the optimal steady state on the basis of the calculation results. According to the simulation results of IEEE-14, IEEE-30, IEEE-57 and IEEE-118, the feasibility and effectiveness of the proposed algorithm to improve voltage stability and reduce the risk of grid collapse were verified.

A Modified-Simplified MPPT Technique for Three-Phase Single-State Grid-Connected PV Systems

Nowadays,the single state inverter for the grid-connected photovoltaic(PV)systems is becoming more and more popular as they can reduce circuit complexity resulting in less power losses of the inverter.This paper focuses on the use of model predictive control(MPC)to control a 3-phase and 2-level single-state grid-connected inverter in order to regulate the PV maximum power point(MPP).The algorithm of MPC scheme was done to measure the simultaneous current signal including predicting the next sampling current flow.The reference current(Id∗)was used to control the distribution of electrical power from the solar cell to the grid.To be able to control the maximum power point tracking(MPPT)when the sunlight suddenly changes,so that a developing MPPT based on estimation current perturbation and observation(ECP&O-MPPT)technique was used to control the reference current.This concept was experimented by using MATLAB/Simulink software package.The proposed technique was tested and compared with the old technique.The simulation results showed that the developed MPPT technique can track the MPP faster when the light changes rapidly under 1,000W/m2,25℃ standard climatic conditions.The MPPT time was 0.015 s.The total harmonic distortion(THD)was 2.17%and the power factor was 1.

A Simulation Research on the Grid-Connected Control Technology of Single-Phase Inverters Based on MATLAB

This paper primarily discusses the main circuit of single-phase inverter circuits.It begins by introducing the research context and the significance of the subject,then discusses the topology of grid-connected single-phase inverter circuits,continues by discussing the control strategy for grid-connected single-phase inverter circuits,realizes a sinusoidal pulse width modulation(SPWM)signal generation circuit and an inverse control algorithm program,and finally ensures good output waveform and fast dynamic response.In view of the hysteresis feature of the grid voltage’s synchronous signal sampling circuit,the acquisition function in digital signal processing(DSP)control chips is applied,and the reasons for the hysteresis phenomenon are thoroughly investigated.The reliability of the SPWM control algorithm is revealed through the results.

Analysis and experiments of self-injection magnetron

Magnetrons are widely used in microwave-based industrial applications, which are rapidly developing. However, the coupling between their output frequency and power as well as their wideband spectra restricts their further application. In this work, the output frequency and power of a magnetron are decoupled by self-injection. Moreover, the spectral bandwidth is narrowed, and the phase noise is reduced for most loop phase values. In order to predict the frequency variation with loop phase and injection ratio, a theoretical model based on a circuit equivalent to the magnetron is developed. Furthermore, the developed model also shows that the self-injection magnetron is stabler than the free-running magnetron and that the magnetron＇s phase noise can be reduced significantly for most loop phase values. Experimental results confirm the conclusions obtained using the proposed model.

海上桩基础注水加压拆除法的研究

近年来,全球海上风电发展势头迅猛.单桩基础作为最早应用于海上风电的基础类型,在全球风场中占据主导地位.现有风机的寿命一般约为20年,预计未来10年将迎来大量风机退役,这使得海上桩基础的回收问题变得愈发重要.为更好地解决海上桩基础退役拆除问题,本文通过物理模型实验的方式对注水加压拆除法进行了研究.实验结果显示:大直径桩基础拆除时所需压强更小,更易通过注水加压拆除法进行拆除;桩基础初始倾角对注水加压拆除所需压强影响较小,但初始倾角越大基础越易倾倒;拆除过程中桩基础单位位移引起的舱内压强下降幅度始终相同,不受基础直径、入泥深度以及倾角的影响.根据物理模型实验数据,结合土力学、水力学相关理论,建立了注水加压拆除法全过程理论模型,可大致预测不同桩径、不同入泥深度桩基础的启动舱内压强与舱内压强-位移曲线,并且在此基础上,结合渗流计算,利用有限元模型对水泵在注水回收过程中可产生的最大舱内压强进行了预测,对比最大舱内压强与基础拆除所需的启动舱内压强即可判断此水泵能否用于注水加压拆除.本文所得结论可为海上风电桩基础的退役处理提供参考,有助于保障风场海床资源的可持续利用,具有一定的工程价值.

基于自适应生成对抗网络的智能电网状态重构的虚假数据攻击检测

考虑到电力系统与能源互联网的深度耦合,虚假数据注入攻击对电力系统的威胁不断提升。文章针对虚假数据注入攻击(false data injection attack,FDIA)设计自适应生成对抗网络(adaptive generative adversarial networks,AGAN)状态重构的虚假数据注入攻击检测方法。该方法在生成对抗网络(generative adversarial networks,GAN)基础上融入卷积神经网络(convolutional neural network,CNN)以及自适应约束下的自注意力机制(self-attention,SA),实现节点间全局参考性,从而实现状态的有效重构和异常状态的准确预测;根据AGAN的异常数据预测结果设计结合网络判别值的检测逻辑。最后,在IEEE14节点的电力系统上验证所提方法的有效性,且对比GAN、CNN,AGAN重构的平均绝对百分比误差为0.0001%,检测准确率可达到98%。

励磁系统交流侧接地对转子接地保护的影响

励磁系统交流侧接地将引起注入式转子接地保护、乒乓切换式转子接地保护误动作。本文介绍了一起相关案例,并对引起误动的基本原理进行了深入分析和定量计算,总结了励磁系统交流侧接地引起采样数据变化的典型特征,提出了关于缩小转子接地保护定位范围的思考。当转子一点接地保护动作后,应首先根据采样数据的变化,对故障点位于励磁系统交流侧还是直流侧做出初步判断,缩小故障定位范围,为快速查找故障提供决策依据。