DS-CDMA system outer loop power control and improvement for multi-service

When a new user accesses the CDMA system, the load will change drastically, and therefore, the advanced outer loop power control （OLPC） technology has to be adopted to enrich the target signal interference ratio （Silt） and improve the system performance. The existing problems about DS-CDMA outer loop power control for multi-service are introduced and the power control theoretical model is analyzed. System simulation is adopted on how to obtain the theoretical performance and parameter optimization of the power control algorithm. The OLPC algorithm is improved and the performance comparisons between the old algorithm and the improved algorithm are given. The results show good performance of the improved OLPC algorithm and prove the validity of the improved method for multi-service.

Outer Loop Power Control Algorithm Based on T-norms Information Fusion Technology in TD-SCDMA

An outer loop power control algorithm based on triangle norm(t-norm) information fusion technology is proposed in this paper.According to the difference between block error rate and bit error rate with target values,the membership function calculation and level dividing of the two differences are dealt with.And then t-norm operator is used to fuse the two membership function values to determine the adjustment step-size.The algorithm can acquire the optimal adjustment step-size in the light of the channel status and avoid the overshoot phenomenon of the existing outer power control methods.As a result,the block error rate can converge to the target value quickly.Experiment results verify the excellent property of the algorithm.

Interference Management for DS-CDMA Systems through Closed-Loop Power Control, Base Station Assignment, and Beamforming

In this paper, we propose a smart step closed-loop power control (SSPC) algorithm and a base station assignment method based on minimizing the transmitter power (BSA-MTP) technique in a direct sequence-code division multiple access (DS-CDMA) receiver with frequency-selective Rayleigh fading. This receiver consists of three stages. In the first stage, with constrained least mean squared (CLMS) algorithm, the desired users’ signal in an arbitrary path is passed and the inter-path interference (IPI) is reduced in other paths in each RAKE finger. Also in this stage, the multiple access interference (MAI) from other users is reduced. Thus, the matched filter (MF) can use for more reduction of the IPI and MAI in each RAKE finger in the second stage. Also in the third stage, the output signals from the matched filters are combined according to the conventional maximal ratio combining (MRC) principle and then are fed into the decision circuit of the desired user. The simulation results indicate that the SSPC algorithm and the BSA-MTP technique can significantly reduce the network bit error rate (BER) compared to the other methods. Also, we observe that significant savings in total transmit power (TTP) are possible with our methods.

Joint Closed-Loop Power Control and Adaptive Beamforming for Wireless Networks with Antenna Arrays in a 2D Urban Environment

The interference reduction capability of antenna arrays and the power control algorithms have been considered separately as means to decrease the interference in wireless communication networks. In this paper, we propose smart step closed-loop power control (SSPC) algorithm in wireless networks in a 2D urban environment with constrained least mean squared (CLMS) algorithm. This algorithm is capable of efficiently adapting according to the environment and able to permanently maintain the chosen frequency response in the look direction while minimizing the output power of the array. Also, we present switched-beam (SB) technique for enhancing signal to interference plus noise ratio (SINR) in wireless networks. Also, we study an analytical approach for the evaluation of the impact of power control error (PCE) on wireless networks in a 2D urban environment. The simulation results indicate that the convergence speed of the SSPC algorithm is faster than other algorithms. Also, we observe that significant saving in total transmit power (TTP) are possible with our proposed algorithm. Finally, we discuss three parameters of the PCE, number of antenna elements, and path-loss exponent and their effects on capacity of the system via some computer simulations.

Loop-Shaping Based Control for Switch Mode DC-DC Power Converters

Renewable energy sources require switching regulators as an interface to a load with high efficiency, small size, proper output regulation, and fast transient response. Moreover, due to the nonlinear behavior and switching nature of DC-DC power electronic converters, there is a need for high-performance control strategies. This work summarized the dynamic behavior for the three basic switch-mode DC-DC power converters operating in continuous conduction mode, i.e. buck, boost, and buck-boost. A controller was designed using loop-shaping based on current-mode control that consists of two feedback loops. A high-gain compensator with wide bandwidth was used in the inner current loop for fast transient response. A proportional-integral controller was used in the outer voltage loop for regulation purposes. A procedure was proposed for the parameters of the controller that ensures closed-loop stability and output voltage regulation. The design-oriented analysis was applied to the three basic switch-mode DC-DC power converters. Experimental results were obtained for a switching regulator with a boost converter of 150 W, which exhibits non-minimum phase behavior. The performance of the controller was tested for voltage regulation by applying large load changes.

Novel Control Strategy for Multi-Level Active Power Filter without Phase-Locked-Loop

Active power filter (APF) using novel virtual line-flux-linkage oriented control strategy can not only realizes no phase-locked-loop (PLL) control, but also achieves a good inhibitory effect to interfere. However, there are some problems in the conventional method, such as the error of amplitude, the shift of phase angle and the non-determinacy of initial oriented angle. In this paper, two one-order low-pass filters are adopted instead of the pure integrator in the virtual line-flux-linkage observer, which can steady the phase and amplitude. Furthermore, an original scheme of harmonics detection under the rotating coordinate is advanced based on the simplified space vector pulse width modulation (SVPWM) strategy. Meanwhile, by using the new SVPWM algorithm, the voltage space vector diagram of the three-level inverter can be simplified and applied into that of two-level inverter, and this makes the control for Neutral Point potential easier.

Power Control Based on State Space Strategies for Grid⁃Oriented Inverters with LCL Filters

Through a third⁃order mathematical model of grid⁃oriented LCL⁃type converters,this paper analyzes the complicated dynamic characteristics and resonance problems which may influence the system stability.To realize active damping for LCL filters and improve dynamic performance of current regulators,a state space current PI controller is proposed whose parameters can be tuned based on the polynomial equations approach.An extended state observer is integrated with the regulation scheme,where additional sensors are not necessary in contrast with conventional active damping strategies.Synchronous reference frame PLL(SRF⁃PLL)equipped with filter technology is proposed for grid voltage disturbance suppression.This method is then applied to establish a double⁃closed⁃loop power regulator that demonstrates improved performance compared with other controllers.The simulation results are displayed to illustrate the efficiency of the regulation methods.

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.

PD Power-Level Control Design for MHTGRs

Due to its inherent safety feature, the modular high temperature gas-cooled reactor (MHTGR) has been seen as one of the best candidates in building next generation nuclear plants (NGNPs). Since the MHTGR dynamics has high nonlinearity, it is necessary to develop nonlinear power-level controller which is not only beneficial to the safe, stable, efficient and autonomous operation of the MHTGR but also easy to be implemented practically. In this paper, based on the concept of shiftedectropy and the physically-based control design approach, it is proved theoretically that the simple proportional-differential (PD) output-feedback power-level control can provide globally asymptotic closed-loop stability. Numerical simulation results verify the theoretical results and show the influence of the controller parameters to the dynamic response.

基于分数阶滑模控制的光伏并网模型预测直接功率控制

针对外界扰动情况下的光伏并网模型预测直接功率控制(model predictive direct power control,MPDPC)系统中存在系统抖振、功率跟踪速度慢、并网电流总谐波失真率较高等问题,提出一种改进分数阶滑模电压控制器,该策略在直流侧母线电压外环采用了分数阶微积分理论.首先,构造分数阶非奇异快速终端滑模面函数,削弱系统抖振,提高系统动态性能;然后,构造分数阶双幂次指数趋近律,引入加权积分型增益和饱和函数,有效避免系统在非滑动模态阶段时切换增益的增大,提高系统控制精度;最后,设计新型分数阶电压环控制器并运用于光伏并网系统中.研究结果表明,改进后的分数阶滑模电压控制器能够满足光伏并网MPDPC系统的各项基本需求,抑制系统抖振,提高功率跟踪性能,降低并网电流总谐波失真率,有效解决可再生能源和公共电网电能转化的关键难题,对光伏并网系统高性能控制的理论研究具有重要意义.

基于大创项目的应用技术开发实践——以数字电源教具设计为例

针对教学环节中的难点和重点内容,基于dsPIC33CK256MP505数字信号控制器芯片,为开发新型的数字电源教具,在降压转换器的电路拓扑结构基础上,利用MplabPowerSmart开发软件,完成了电压控制型数字环路补偿器的设计,实现3P3Z数字补偿器的实时算法功能。

电网故障下含直驱风电机组的电力系统频率动态响应分析

电网受扰后基于模型解析的频率响应分析对电力系统安全评估与紧急控制具有重要意义。电网发生故障时,直驱风电机组(DDWT)并网点电压幅值跌落引发控制器暂态响应,同时电压相位突变引发锁相暂态响应,锁相暂态响应又通过变流器控制传导产生功率控制误差,可能导致现有以负荷突变场景为对象的频率特性分析产生较大偏差。为此,提出了电网故障下DDWT锁相偏差的量化方法;解析了锁相偏差经DDWT变流器控制的传导路径,提出了锁相暂态响应导致DDWT功率控制误差的机理及其计算方法;建立了电网故障下含DDWT的电力系统频率响应模型,提出了锁相暂态响应影响下系统频率变化率和最大频率偏差的计算方法,解析了电网故障下考虑DDWT功率控制误差的电力系统频率动态响应特性,并通过算例分析验证了所提方法的有效性。

基于模糊平均电流控制的电池电源控制器研究

为保障控制器输出电压的稳定性,引进模拟控制理论,对电池电源控制器展开全面的设计研究。建立电池电源控制推挽式拓扑结构,划分电路工作过程;根据作业需求,设计内环和外环的控制器,内环控制器主要实现对系统内部细节的精确控制,而外环控制器用于调整内环的控制参数;参照PD控制器,开发模糊控制器,设计模糊推理规则,描述输入电压与输出电压之间的模糊关系,实现电压模糊化处理。仿真结果表明:提出的控制器在应用中的效果良好,此控制器可以实现对其运行中扰动的控制,以此种方式,保证电压的输出精度。

基于功率转速双闭环的增程器发电功率动态控制策略

针对电动汽车内燃发电增程器发电功率动态控制存在的控制精度不高、响应滞后和反向超调等问题,提出并设计了一种结合功率/转速双闭环的增程器发电功率动态控制策略。该策略基于高效运行曲线进行发电功率的转矩/转速解耦,同时考虑了基于实际发电功率反馈的内燃机目标发电转矩修正、发电转矩转速动态协调修正。变工况发电试验结果表明,增程器发电过程中的发电功率最大正向超调为1.37 kW,最大反向超调为1.89 kW,稳态误差均小于0.01 kW,功率上升响应时间约为2.5 s,功率下降响应时间约为2.8 s,且工作点均在高效运行曲线附近。该增程器发电功率动态控制策略能够减少瞬态发电功率的响应滞后和反向超调的问题,在工程实践中具备可行性。

稠油电加热嵌入式控制装置设计及其试验

为提高稠油井电加热系统的加热效率,解决油田中频电源加热运行控制主要依靠人工经验设置和低效的自动控制造成电能浪费的现状,本文设计了稠油电加热嵌入式控制装置。基于非嵌入式获取的油井生产电信号,以稠油开采电机的电功率为闭环反馈信号,获取油液最优温度的参考输入。在此基础之上,通过井口油液温度的微分反馈环节,改善温度迟滞效应,实现中频电源的节能优化控制。通过对嵌入式硬件核心电路模块的设计和主要软件功能的开发,不仅实现了稠油井电加热过程的动态控制,还实现了各项运行指标的现场及云端的实时监测。稠油井场试验分析表明,所设计的稠油电加热嵌入式控制装置符合井场节能安全的生产需求,节约能耗可达20%。

“电力电子技术基础”闭环型教学控制模型分析与实践

自动控制原理中的反馈闭环控制结构可以消除设定值与输出值之间的误差,使输出值跟随设定值或输入值。本文给出几种单闭环或双闭环反馈型教学控制结构,在与自动控制原理中反馈闭环控制结构进行对比分析后,分析了反馈型教学控制结构的工作原理,并给出了过去反馈型教学控制获得的经验,表明反馈型教学控制结构概念清晰,互操作性强,执行效率高,可扩展性强,易于推广应用。

面向稳控系统E1通道的网络靶场实验台的设计与实现

随着智能电网和跨区稳定控制技术的发展,信息通信与电力系统的耦合更加紧密,网络攻击带来的安全风险也越来越高。稳控系统E1通道作为重要的测控通道,其安全性对稳控系统起到重要的作用,因此,开展面向稳控系统E1通道的半实物仿真和攻防演练,对发现E1通道的安全漏洞有重要意义。首先,基于半实物仿真技术设计了面向稳控系统E1通道的网络靶场实验台,介绍基于该实验台的攻防演练方案;然后,通过该实验台对一个典型的在运稳控系统E1通道开展仿真和攻击模拟实验,测试了稳控系统的安全隐患,并验证了实验台的有效性;最后,提出几种提升E1通道安全性的方法,并展望了实验台的应用前景。

基于MATLAB的功率因数可控的AC-DC变换电路研究

为解决谐波信号过多可能会导致电网的传输效率降低的问题,对功率因数可控的AC-DC变换电路进行了研究.基于Boost型单级有源功率因数校正变换器,控制电路中采用了外电压环和内电流环双闭环控制系统,利用滞环电流控制提高交流端功率因数,电压环稳定输出电压.采取小信号分析法,建立小信号模型并设计了控制电路.通过MATLAB仿真实验可得,双环控制的功率因数校正电路能够实现高功率因数,同时能够稳定输出电压.

探究无功控制回路对构网型并网逆变器暂态稳定性的影响

随着全球能源结构的转型和环境保护意识的提升,作为一种高效、环保的能源利用方式,基于新能源的分布式发电系统正逐渐在电力系统中占据重要地位。而随着分布式发电系统渗透率的不断提高,电网的等效惯性不断降低,严重影响电力系统的频率稳定。因此,虚拟同步控制应运而生,其通过模拟传统旋转同步发电机的动态特性,能够对电网补偿惯性和等效阻尼。虽然虚拟同步机(Virtual Synchronous Generators, VSG)的小信号稳定控制已经得到广泛的研究,但其无功回路对系统的大信号暂态稳定性的影响仍需进一步研究。文中首先对构网型并网逆变器无功回路对其暂态稳定性的影响进行了理论分析,在此基础上列举了三种能够有效改善并网逆变器暂态稳定性的方法;最后,通过MATLAB/Simulink平台对其进行了仿真验证。

基于STM32的SWISS整流器研究与设计

SWISS整流器具有输出功率高、输出电压可调、易高频化等特点,十分适合用于电动汽车大功率充电、数据中心、通信基站等大功率变换场合。文中提出一种采用STM32F334单片机控制的SWISS整流器设计方案,利用电压电流PI双闭环控制策略实现对输出电压的精确控制,并进行控制算法的设计,实现系统功率因数校正的功能。设计SWISS整流器的硬件电路方案,并给出元件参数计算及选型方法。制作400 V/1 000 W样机对所提出的方案进行实验验证。结果表明:系统功率因数在额定功率下可达0.998,转换效率可达97.37%,并具有较快的响应速度;在半载满载切换时,动态调节时间小于70 ms,且电压超调量最大为10%。验证了所提方案的可行性。