UAV data link anti-interference via SLHS-SVM-AdaBoost algorithm:Classification prediction and route planning

The ability to predict the anti-interference communications performance of unmanned aerial vehicle(UAV)data links is critical for intelligent route planning of UAVs in real combat scenarios.Previous research in this area has encountered several limitations:Classifiers exhibit low training efficiency,their precision is notably reduced when dealing with imbalanced samples,and they cannot be applied to the condition where the UAV’s flight altitude and the antenna bearing vary.This paper proposes the sequential Latin hypercube sampling(SLHS)-support vector machine(SVM)-AdaBoost algorithm,which enhances the training efficiency of the base classifier and circumvents local optima during the search process through SLHS optimization.Additionally,it mitigates the bottleneck of sample imbalance by adjusting the sample weight distribution using the AdaBoost algorithm.Through comparison,the modeling efficiency,prediction accuracy on the test set,and macro-averaged values of precision,recall,and F1-score for SLHS-SVM-AdaBoost are improved by 22.7%,5.7%,36.0%,25.0%,and 34.2%,respectively,compared with Grid-SVM.Additionally,these values are improved by 22.2%,2.1%,11.3%,2.8%,and 7.4%,respectively,compared with particle swarm optimization(PSO)-SVM-AdaBoost.Combining Latin hypercube sampling with the SLHS-SVM-AdaBoost algorithm,the classification prediction model of anti-interference performance of UAV data links,which took factors like three-dimensional position of UAV and antenna bearing into consideration,is established and used to assess the safety of the classical flying path and optimize the flying route.It was found that the risk of loss of communications could not be completely avoided by adjusting the flying altitude based on the classical path,whereas intelligent path planning based on the classification prediction model of anti-interference performance can realize complete avoidance of being interfered meanwhile reducing the route length by at least 2.3%,thus benefiting both safety and operation efficiency.

The Research and Application of the Anti-Interference Techniques of Electronic Device in Power System

This paper presents the study and application of the electronic device anti-interference techniques underhigh voltage and/or heavy current electro-magnetic circumstance in power system.[

Anti-interference beam pattern design based on second-order cone programming optimization

When signal-to-interference ratio is low, the energy of strong interference leaked from the side lobe of beam pattern will infect the detection of weak target. Therefore, the beam pattern needs to be optimized. The existing Dolph-Chebyshev weighting method can get the lowest side lobe level under given main lobe width, but for the other non-uniform circular array and nonlinear array, the low side lobe pattern needs to be designed specially. The second order cone programming optimization （SOCP） algorithm proposed in the paper transforms the optimization of the beam pattern into a standard convex optimization problem. Thus there is a paradigm to follow for any array formation, which not only achieves the purpose of Dolph-Chebyshev weighting, but also solves the problem of the increased side lobe when the signal is at end fire direction The simulation proves that the SOCP algorithm can detect the weak target better than the conventional beam forming.

Reconfigurable anti-interference RF transceiver for cognitive radio application

An RF transceiver composed of a zero-IF receiver and a direct up-conversion transmitter for cognitive radio applications is presented. The adjustable channel filter array in the receiver is used to suppress adjacent channel interference in televisions signal coexistence environments. The low noise amplifier （LNA） with wide dynamic range and high linearity is employed to enhance the anti-interference competence of the zero-IF receiver. Meanwhile, the high linearity power amplifier （PA） .is used to promote the adjacent channel power ratio （ACPR） characteristic of the direct up-conversion transmitter. The measured error vector magnitude （EVM） results show that the anti-interference competence of the zero-IF receiver is dramatically enhanced by employing a channel filter array. The measured ACPR of the direct up-conversion transmitter is -47. 98 dBc on the channel centered at 714 MHz when the output power is 27 dBm.

Static-shift suppression and anti-interference signal processing for CSAMT based on Guided Image Filtering

Shallow conductive heterogeneity can lead to static shifts ain the apparent resistivity sounding curve of controlled-source audio-frequency magnetotellurics(CSAMT).The static effect will shift the apparent resistivity curves along with axial log-log coordinates.Such an effect,if not properly processed,can distort the resistivity of rock formation and the depth of interfaces,and even make the geological structures unrecognizable.In this paper,we discuss the reasons and characteristics of the static shift and summarize the previous studies regarding static shift correction.Then,we propose the Guided Image Filtering algorithm to suppress static shifts in CSAMT.In detail,we use the multi-window superposition method to superimpose 1D signals into a 2D matrix image,which is subsequently processed with Guided Image Filtering.In the synthetic model study and field examples,the Guided Image Filtering algorithm has effectively corrected and suppressed static shifts,and finally improved the precision of data interpretation.

Anti-interference ultra-wideband system based on spreading and interleaving

To suppress the interference in the ultra-wideband （AI-UWB） system is a challenging problem. An anti-interference multiband orthogonal frequency-division multiplexing ultra-wideband （AI-UWB） system, based on spreading and interleaving is addressed. It will exploit the frequency diversity across the subcarriers and provide the robustness to narrow-band interference, by spreading the coded bit streams within each sub-band and interleaving across all sub-bands. Simulating results show that the spreading and interleaving provide about 5 dB to 10 dB advantages over the conventional multiband orthogonal frequency-division multiplexing ultra-wideband system in signal-to-interference ratio. Spreading and interleaving is an effective cure for enhancing the robustness to narrowband interference.

Research on Reverse Recovery Transient of Parallel Thyristors for Fusion Power Supply

In nuclear fusion power supply systems, the thyristors often need to be connected in parallel for sustaining large current. However, research on the reverse recovery transient of parallel thyristors has not been reported yet. When several thyristors are connected in parallel,they cannot turn-off at the same moment, and thus the turn-off model based on a single thyristor is no longer suitable. In this paper, an analysis is presented for the reverse recovery transient of parallel thyristors. Parallel thyristors can be assumed as one virtual thyristor so that the reverse recovery current can be modeled by an exponential function. Through equivalent transformation of the rectifier circuit, the commutating over-voltage can be calculated based on Kirchhoff’s equation. The reverse recovery current and commutation over-voltage waveforms are measured on an experiment platform for a high power rectifier supply. From the measurement results, it is concluded that the modeling method is acceptable.

Study on Heat Dissipater for High-Power Thyristors in Explosion-Proof Shell

A new type water-cooled heat dissipater for multiple high-power thyristors in explosion-proof shell used in coal mine was designed, and then, the numerical computation of the three-dimensional steady-state temperature distributions under different working conditions for cooling core was conducted in order to understand in detail the heat transfer performance. Based on the computation results, the temperature differences and the maximum heat transfer rates were given. These results of the study on the heat dissipater lay a basis for optimising its structure design and guiding its operation.

Anti-interference self-alignment algorithm by attitude optimization estimation for SINS on a rocking base

The performance of a strapdown inertial navigation system(SINS)largely depends on the accuracy and rapidness of the initial alignment.A novel anti-interference self-alignment algorithm by attitude optimization estimation for SINS on a rocking base is presented in this paper.The algorithm transforms the initial alignment into the initial attitude determination problem by using infinite vector observations to remove the angular motions,the SINS alignment is heuristically established as an optimiza-tion problem of finding the minimum eigenvector.In order to further improve the alignment precision,an adaptive recursive weighted least squares(ARWLS)curve fitting algorithm is used to fit the translational motion interference-contaminated reference vectors according to their time domain characteristics.Simulation studies and experimental results favorably demonstrate its rapidness,accuracy and robustness.

Neutron irradiation influence on high-power thyristor device under fusion environment

Because of their economy and applicability,high-power thyristor devices are widely used in the power supply systems for large fusion devices.When high-dose neutrons produced by deuterium–tritium(D–T)fusion reactions are irradiated on a thyristor device for a long time,the electrical characteristics of the device change,which may eventually cause irreversible damage.In this study,with the thyristor switch of the commutation circuit in the quench protection system(QPS)of a fusion device as the study object,the relationship between the internal physical structure and external electrical parameters of the irradiated thyristor is established.Subsequently,a series of targeted thyristor physical simulations and neutron irradiation experiments are conducted to verify the accuracy of the theoretical analysis.In addition,the effect of irradiated thyristor electrical characteristic changes on the entire QPS is studied by accurate simulation,providing valuable guidelines for the maintenance and renovation of the QPS.

Anti-interference Strategy of 20-Hi Cold Mill Automatic Gauge Control

Automatic gauge control(AGC in the article)is the key technology of product thickness accuracy and flatness quality in modern cold rolling mill.Most traditional AGC control algorithms need stable external system conditions and hard to stabilize under complex interference that meets coverage requirements.This paper presents a new anti-interference strategy for AGC control of 20-Hi cold reversing mill.The proposed algorithm introduces a united dynamic weights algorithm of feed forward-mass flow to avoid the complex interference problem in AGC control,the relevant control strategy is provided to eliminate the adverse effects.At the same time,the D-value between feed forward-mass flow pre-computation and thickness measurement deviation is dynamic compared,the final gap position regulation is calculated by developing a set of united dynamic weights between feed forward control and mass flow control.Finally,the output of controllers is sent to actuator though a constant rate smoothing.The proposed strategy is compared with conventional AGC control on Experimental platform and project application,the results show that the proposed strategy is more stable than comparison method and majority of system uncertainty produced by mentioned interference is significantly eliminated.

Coordinated Design of Thyristors Controlled Braking Resistors and Power System Stabilizer for Damping

This paper presents a new concept for damping electro-mechanical oscillations in large turbo generator. The proposed concept is based on coordination between Power System Stabilizer （PSS） and Thyristor Controlled Braking Resistor （TCBR）. This coordination will enhance the stability of the inertial and torsional oscillatory modes. The study is performed on system-I of the second IEEE benchmark for simulation of Sub-Synchronous Oscillations, using eigenvalue analysis and verified by detailed digital simulation. A dynamic fundamental frequency model for TCBR is developed. The pole placement technique is used to design the control system of TCBR and PSS. The shaft torque＇s following a disturbance is computed and analyzed. The obtained results indicate that substantial damping is achieved by the proposed coordination.

新一代高韧性直流输电技术(二):高倍载模块化换向式换流器

针对高韧性直流输电技术对高倍载、高经济性直流换流器的需求,提出一种高倍载模块化换向式换流器(high-overload modular commutated converter,MCC)。首先,对MCC的拓扑构造和运行原理进行详细分析,指出其器件软开关特性、桥臂能量脉动优化和高倍载潜力;针对MCC的宽范围电压变比调节、串联模块电压均衡控制、架空线应用中的直流故障自清除等关键问题,给出解决方案;以±500 kV/2000 MW直流输电系统为例,分析MCC的元件用量、体积、效率、成本等技术特性,并与常规模块化多电平IGBT换流器进行综合对比;最后,研制基于IGCT-Plus器件的±15 kV/60 MVA MCC产品,开展综合性测试验证。结果表明,提出的MCC有望将现有换流器技术方案的体积、成本、损耗率分别减小达50%,在电能变换与传输中具有广阔的应用前景。

可控关断逆阻型IGCT换流阀研制

基于大功率晶闸管构成的电流源型换流器在HVDC工程中得到广泛应用,由于晶闸管的固有关断特性,当交流系统电压跌落时会引发换相失败问题,这将导致直流功率波动、甚至直流闭锁,威胁电网安全稳定运行。为了解决换相失败问题,首先基于逆阻型集成门极换流晶闸管(RB-IGCT)构建了新型换流器,提出了这种换流器的两种运行模式,设计了可控关断RB-IGCT换流器控制系统,并基于所设计的控制系统提出了换流器换相工作时序。其次采用6英寸RB-IGCT设计了换流阀,并提出了IGCT驱动单元的设计方案。最后搭建了换流阀运行试验系统,完成了RB-IGCT换流阀样机研制和验证,通过试验验证了换流阀设计的合理性。所提成果可为后续RB-IGCT在HVDC工程中的应用提供有力支撑。

Analysis and Optimization of the Characteristics of a New IEC-GTO Thyristor

Based on a short anode GTO structure （SA-GTO）,a novel GTO structure called an injection efficiency controlled gate turn off thyristor （IEC-GTO） is proposed,in which the injection efficiency can be controlled via an additional thin oxide layer located in the short anode contact region. The forward blocking, conducting, and switching characteristics are analyzed and compared with an SA-GTO and conventional GTO. The results show that the IEC-GTO can obtain a better trade-off relation between on-state and turn-off characteristics. Additionally,the width of the oxide layer covering the anode region and the doping concentration of the anode region are optimized, the process feasibility is analyzed, and a realization scheme is given. The results show that the introduction of an oxide layer would not increase the complexity of process of the IEC-GTO.

面向MMC应用的大功率IGCT器件加速老化试验拓扑研究

集成门极换流晶闸管(integrated gate commutated thyristor, IGCT)具有阻断电压高、通流能力强等特点,在柔性直流输电等领域具有广阔的应用潜力,但其在高电压、大通流应力下的可靠性问题,成为限制应用的潜在因素,如何针对不同工况开展加速老化等效测试成为开展可靠性研究的关键瓶颈。文中以模块化多电平换流器(modular multilevel converter,MMC)工况为代表,针对IGCT器件可靠性等效测试难题开展研究。首先分析MMC工况下IGCT器件的暂态电气应力和长期电热应力,分别采用TCAD仿真软件与平均值等效计算模型定量获得IGCT器件在实际工况下的应力大小;其次,基于应力分析结果,提出一种三半桥式两级电流应力加速老化试验拓扑,设计并搭建2 500 V/4 000 A/150 Hz参数的IGCT加速老化试验平台;最后,开展约100 h高压、大电流老化运行试验,验证平台具备长时运行的能力,且等效测试应力达到设计要求。所提出的等效拓扑及其构建方法,不仅解决了MMC工况下IGCT器件的加速老化测试问题,对其他交直流变换工况、其他类型功率半导体亦有很好的参考价值。

Trench MOS Controlled Thyristor

A new structure of power MOS-gated thyristor named Trench MOS Controlled Thyristor (TMCT) is presented.The MOSFETs used to turn on and turn off the thrysitor are formed with UMOS technology.No parasitic transistors exist in this structure,so the problems created by the parasitic transistors can be eliminated.So,the TMCT is expected to be of better performance.The experimental results of the multicellular 600V TMCT with the active area of 02mm2 show that the on-state drop is 125V at 300A/cm2,and the maximum controllable current reaches 296A/cm2 at the gate voltage of -20V and with an inductive load.

一种新型IGCT门极驱动单元设计

门极驱动单元(GU)是集成门极晶闸管(IGCT)的重要组成部分,GU需具备主驱动控制(强触发开通、维持导通、门极换流关断)、状态检测、逻辑监测等功能。为了满足大功率等级IGCT器件开关性能的要求以及电网特殊应用工况,本文优化门极电流续流拓扑、改进铜皮硬压搭接的分离式方案、优化关断电容组合,提出了一种具备快速响应、黑启动、可拆卸、高可靠性的新型IGCT门极驱动单元。本文搭建了开通能力测试平台、脉冲测试平台和功率对推测试平台,对所提GU的高性能和可靠性进行了验证,研究结果可为非对称IGCT(AS-IGCT)在后续的柔性直流电网中的工程应用提供参考。

故障期间交流电压和直流电流暂态特性作用下的换流阀晶闸管关断机理研究

传统直流输电逆变侧交流母线故障后,交流电压的跌落和直流电流的上升是导致换相失败的主要原因。为了得到交流电压与直流电流暂态特性综合作用下换流阀晶闸管的关断特性,提出受端交流系统故障后不同交流电压跌落下最大直流电流的近似解析方法;然后,在SABER平台建立换流阀晶闸管换相及关断等效电路,研究故障后综合考虑交流电压和直流电流变化的晶闸管关断特性,并通过载流子迁移恢复特性解析模型对各阶段晶闸管内部的剩余电荷进行计算,定量评估晶闸管关断特征;最后,对比分析仅考虑交流电压跌落、仅考虑直流电流上升、考虑二者综合作用的晶闸管关断特性。结果表明,随着故障严重程度增加,晶闸管的阻断能力恢复时间(即临界关断角)呈现减小趋势,但是换相时间及总关断时间大幅增加,可能导致换流阀换相失败;故障后仅考虑交流电压跌落或直流电流上升,所得到的临界关断角偏大,一方面会对系统提出更高的关断要求,另一方面很可能将原本未发生换相失败的场景误判为换相失败,而综合考虑交流电压和直流电流动态变化可得到更为准确的晶闸管关断特性。

非理想条件下晶闸管整流器多重化的数学分析

本文作者在计及整流变压器漏感的情况下,根据三相可控硅整流器功率器件的换流规律,利用移相整流变压器原副边电流关系矩阵,得到多重化整流器输入电流及输出电压的波形。对输入电流波形和输出电压波形进行Fourier级数分解,得到交流输入电流、直流侧电压的Fourier级数表达式,进而完成了非理想情况下多重化可控硅整流器的数学分析,给出了输入电流基波成分、谐波含量、功率因数以及直流输出电压的平均值、换相压降、谐波电压含量等的计算公式,为多重化可控硅整流器的设计和分析提供了理论依据。