微机化功率因数补偿器的研制

介绍一种用８０９８单片机控制的功率因数补偿器。该功率因数补偿器上仍各相负载分别补偿，补偿电容在电压过零时投切，各相功率因数和电流值分时显示等特点。     

Performance characteristics around the TDC of linear compressor based on whole-process simulation

A whole-process simulation platform is established for linear compressor to analyze the performance characteristics on different piston displacement conditions from small oscillation without pumping till to rushing out of the top dead center (TDC). The measuring methods of the related parameters in the model are presented and the values of these parameters are obtained from an actual test. The simulated results agreed well with the experimental results under the same working conditions. The errors of the effective voltage, the effective current, the compression efficiency and the phase angle between the current and the displacement were within ±6.9%, ±8.5%, ±6.2% and ±13.4%, respectively. Based on this simulation platform, the performance characteristic around the TDC of the linear compressor on different working conditions is analyzed. The performance comparison on 60 Hz shows that the compression efficiency near to the TDC on 0.7 MPa is higher than that on 0.5 MPa because the phase angle α under that condition is around 90°, but the operation reliability on 0.7 MPa is worse than that on 0.5 MPa because the jump phenomenon happens when the piston displacement goes near to the TDC. The jump phenomenon results in unstable operation as the piston displacement jumps from the position before the TDC to the position after the TDC. According to the simulation on different power frequency, two important performance characteristics are inferred. One is that there is an inflection point in the curve of the phase angle α versus the displacement at the TDC. This characteristic is a good choice for the TDC detection. The other is that the jump phenomenon is prone to happening when there exist different displacement responses on the same voltage value, becoming inconspicuous when the power frequency is decreased and disappearing when the power frequency is increased. Based on this characteristic, the jump phenomenon can be avoided through suitable system configuration and frequency adjustment.     

基于RLS算法的有源滤波器自适应基波检测方法

揭示了有源电力滤波器中谐波补偿指令相位的微小变化都将对谐波控制效果产生很大的负面影响，并导致新的谐波产生。而谐波补偿指令相位偏差主要是由谐波检测算法产生。针对电力系统中信号波形的局部周期性，提出和研究了基于递推最小二乘算法（RLS）的自适应谐波能量最小化基波检测算法，给出了均方意义下的收敛性分析结果。研究表明，在电力系统中出现过渡带及基波信号发生时变时，采用FFT算法的估计结果存在较大的相位偏移。RLS谐波检测方案较Kalman滤波器尤其是FFT方法计算量小，适时跟踪性能好，是有源滤波器中补偿指令检测的有效方法。     

67 GHz宽带谐波相位参考及其定标技术

作为非线性矢量网络分析仪的重要参考测量通道,谐波相位参考能够提供多频点、多波量以及复频率下的绝对相位测量能力。设计了基于共面波导非线性传输线方案的原型谐波相位参考样机,并提出了基于EOS光电采样系统的完整谐波相位参考定标技术,主要包括时基失配、平均去噪、相位对准、连接器失配与示波器复频率响应修正等流程。定标实验结果表明,原型样机能够在1 GHz功率27 d Bm信号激励下输出半峰值脉宽为22 ps的周期脉冲序列,其频带覆盖范围超过67 GHz,并在超高次谐波频点上拥有小于±10°的相位精度与小于±5°的相位可重复性。最后将原型样机装配到非线性矢网中,通过测量2 GHz信号激励下超窄时域脉冲发生器的输出时域信号,并将之与采样示波器测量结果进行比对,结果证实了谐波相位参考设计与定标技术的有效性与正确性。     

一种低压有源电力滤波器设计

面向电网谐波的治理,研发了一种基于瞬时无功功率理论的有源电力滤波器。采用TMS320F2812作为控制核心,使用IGBT作为开关器件,通过产生与负载谐波电流次数相等、幅值相等但相位相反的补偿电流注入电网,降低电网侧的谐波含量,并减少谐波源负载对相邻设备的高频电磁干扰,同时补偿一定的无功功率。配电系统实测表明,所研发的基于瞬时无功功率理论的有源电力滤波器投运后,大幅度减少了配电系统中的谐波含量,并有效修正了电压波形。     

矿热炉短网补偿双闭环控制系统的研究

由于矿热炉内部工况变化的随机性,电极与矿料放电拉弧经常处于动态起伏状态,使短网存在大量的谐波电流和功率因数品质偏低等严重问题,本文提出了一种基于电流分解、倍频变换的软测量方法,在不增加硬件和免除常规坐标变换等复杂运算的基础上,较好地实现了对短网基波电流、谐波电流以及功率因数的检测。同时设计了以功率因数为控制目标,融合无功补偿和谐波电流抑制功能的双闭环控制系统,经过仿真和实际测试较好地验证了该电流预测方法及补偿控制规律的可行性,为其它电力变换设备等实施无功功率补偿、谐波抑制以及故障诊断和保护等方案提供了可参考的模型。     

In-situ measurement of the current transformer burden in a current transformer testing system using a shunt resistor

Both the ratio error and phase angle error of a current transformer (CT) are significantly affected by the CT burden connected in series to the secondary terminal of the CT. Thus, the precise measurement of this CT burden is required for the evaluation of the CT errors. A method for measuring the CT burden in-situ in a CT testing system (CTTS) has been developed by employing the non-reactive type shunt resistor. For the measurement of the CT burden, the shunt resistor was connected in parallel to the secondary terminal of the CT under test in the CTTS. The burden values represented by the apparent power and the power factor can be calculated from the resistance (and reactance), which was obtained by measuring the ratio error (and phase angle error) as a function of the resistance of the shunt resistor. The uncertainties in the measurements of the apparent power and the power factor for the rated burdens studied were found to be less than 2.1%. The CT burden values obtained using our method were consistent with those measured using a digital multimeter within the corresponding uncertainties.     

大功率CO2激光器薄膜λ/4波片的制备及薄膜位相延迟的初步研究

作为光束均值器,λ/4波片是大功率CO₂激光加工机中的关键部件。多层膜反射镜（包括内反射和外反射）,在倾斜入射时,两个偏振分量会产生不同的相移,因此可用计算机优化设计出特定位相差的膜系。本文的目的是设计10.6μm的90°相位膜,它的作用就象四分之一波片。与传统的波片相比,它的优点是可以适用于任何波长,具有高的位相精度和大的孔径。文中提出了两种设计方法,并报告了制备技术、实验结果及误差分析。     

静止无功发生器SVG的VF-DPC控制策略

针对静止无功发生器(SVG)传统电流控制方式输出谐波较多、电流响应速度慢的问题,介绍了静止无功发生器的工作原理及运行特性,提出了一种基于虚拟磁链定向的直接功率控制策略(VF-DPC),以瞬时功率与给定功率的计算差值为依据,在设计中采用双滞环结构的思路对电压矢量扇区内开关表进行改进,将差值送入开关表选取矢量,并以整流器开关的模式实现了系统控制。同时运用Matlab/Simulink工具,基于TSM320LF2812D型DSP的平台,对VF-DPC的补偿方案进行了仿真调试,将实验室搭建系统应用于冶金电网。研究结果表明,基于虚拟磁链定向的直接功率控制的静止无功发生器能够缩短补偿电流全动态响应时间,减小输出电流畸变量,且现场测试系统电网功率因数得到大幅提高,输出电压电流相位相同,完全满足系统无功补偿控制要求。     

The development of simplified ultrasonic CT system and its application to the evaluation of weld metal

In this paper, as a new measurement method to estimate the change of material condition, the simplified ultrasonic CT system, which uses the information of three directions, that is, 90°, + 45° and −45° about inspection plane is proposed. Use of simplified CT system has two merits: Firstly, the measurement time is very short compared with general CT. Secondly, it can detect sensitively small defect in vertical or slant direction about inspection plane because the obtained image is CT image calculated from three directions. From these merits, this method can be considered as an effective method to evaluate material conditions. The basic performance of the proposed method was confirmed through several specimens with several simple defects. In order to confirm the applicability of actual NDT, several kinds of welded specimens are investigated. The result showed that the CT image obtained had good agreement with actual defect of specimens.     

有源电力滤波器数字控制系统的研究

对有源电力滤波器全数字化控制系统的总体方案进行了设计,并联电压型三相有源电力滤波器主电路直流侧电容电压保持恒定,同时输出电流跟踪指令电流信号,详细设计了过零同步信号产生电路,并且利用PWM控制信号直接控制开关器件的导通与关断.谐波电流检测采用了瞬时无功功率理论的检测方法.最后用Matlab对有源电力系统搭建了模型并且进行了仿真,仿真结果验证了谐波电流检测方法的有效性及控制方案的可行性,可以更好地实现动态抑制谐波和无功补偿,并且整体设计精简了外设,能实现更多的控制算法.     

粗光栅信号全数字化处理法实现高倍数细分

针对在粗光栅软件细分中的信号误差影响细分数的问题,提出了按细分的主要误差来源分类进行数字滤波和补偿的全数字化处理法,以达到粗光栅高精度测量的要求。首先对光栅测量信号进行有针对性的数字滤波,使其波形接近于理想状态。然后根据误差来源进行数字补偿,通过对软件数字细分原理的分析,推导出了原始信号不正交、幅值不等、谐波失真等误差影响细分结果的表达式,并提出了与此相对应的数字补偿方法。最后用软件细分法对测量信号进行高倍数数字细分。滤波前后波形信号的仿真比较结果验证了基于严格线性相位的FIR数字带通滤波器可以有效地屏蔽光栅信号频谱中的高低频干扰和噪声。研究结果表明,在粗光栅满足一定质量的前提下,利用全数字化处理法能够满足500细分的精度要求。     

基于DSP的低压无功自动补偿控制器的研究与设计

提出一种采用DSP芯片作为控制核心的控制器，它能自动跟踪检测电网的无功功率和电压，实现无功功率的动态快速补偿，同时，完成对低压电网的配电监测，谐波治理和电能计量等多种功能。     

A power supply for a technological installation

A voltage changer for the power supply of an ultrasonic piezoelectric transducer is designed on the basis of a resonance inverter. The output filter designed on the basis of a series-resonant circuit with parallel and series compensation ensures matching of the changer to the load. The changer ensures a load current of 0.5A±10% within a wide range of the load resistance (from 50 to 400 Ω) at an input voltage of 220 V±15% with automatic tuning to the frequency of the load mechanical resonance. The changer output power is 100 W, and the output current is a sinusoid with a frequency of 22±2 kHz.     

High-accuracy ultrasonic temperature measurement based on MLS-modulated continuous wave

Ultrasonic temperature measurement has the potential to improve measurement accuracy by increasing the length of a received signal due to its excellent performance with noise resistance. However, when the distance between the transmitter and receiver is limited, the received signal can be polluted by strong multiple echoes, which can significantly degrade temperature accuracy. This paper proposes a method for high-resolution ultrasonic temperature measurement. With the use of a maximum length sequence (MLS)-modulated continuous wave, the obstructive effect of echoes is effectively suppressed. A hybrid method is employed for accurate time-of-flight (TOF) estimation by incorporating both cross-correlation and phase shift (PS), which is the basis of highly accurate temperature measurement. The experimental results in distilled water show that the proposed method estimates TOF with a standard deviation of less than 0.3 ns, and temperature errors consistently remain within ±0.04 °C.     

对称式微波功率传感器的设计

为了克服传统微波功率传感由于失配和热损耗带来的微波功率测量误差,提出了一种基于MEMS技术的对称式微波功率传感器,对该微波功率传感器的微波损耗、温度分布以及微波功率的精确测量进行了研究.首先,根据提出的损耗模型推导了微波损耗功率和损耗电压的表达式,并建立了该传感器的传热解析模型;接着,设计并制作了该微波功率传感器;最后...     

大口径光学元件斜入射反射波前误差测量和计算

针对测量高功率激光驱动装置中大口径矩形反射光学元件的波前误差时测量角度和使用角度不完全相同引入的测量误差,提出了将测量角度下的反射波前转换到使用角度的反射波前的换算及恢复方法。首先分析了将斜入射测量角度下的波前转换到使用角度下波前的余弦换算方法,得到了实际测量角度与实际使用角度下的波前误差计算关系;然后计算并分析了双三次插值算法本身引起的中频PSD1(功率谱密度)误差,指出在满足有效口径测量的情况下,选择的入射角度应该与实际使用的角度尽可能的相接近。最后,基于410mm×410mm的熔石英反射镜开展了误差分析和实验验证。利用该方法将0°反射波前换算到45°反射波前,并将得到的测试结果与45°直接测量得到的测试结果进行了比较。结果显示上述结果的PV值相差0.01λ,RMS值相差0.003λ,PSD1值相差0.08nm;表明该换算方法不仅能够准确计算出使用角度下反射波前的低频误差,而且能获得相对准确的中频段PSD1误差。     

A microwave interferometer with increased stability for diagnostics of steady-state plasma

The schematic and results of studying an interferometer for a wavelength of 8 mm with homodyne frequency conversion for measuring the electron density of a steady-state plasma are described. The design of its waveguide system allows the drift of the indicated initial phase to be reduced to a level of ±0.1°/h. The maximum phase shift measured is 360°, the tolerable signal-power decay in plasma is 16 dB, and the maximum phase measurement error is ～5%.     

动态无功补偿装置在煤矿供电系统中的设计

介绍了煤矿供电系统中对频繁启动谐波源设备采取的无功补偿和抑制谐波的方法,提出了SVG无功补偿装置系统的方案,能有效提高电网的电能品质、功率因数和节约电能,给矿井带来了明显的经济效益。     

激光外差干涉的非线性误差补偿

为了补偿用激光外差干涉法进行纳米测量产生的非线性误差,进行了非线性误差补偿的实验研究。根据镀膜实体角锥棱镜反射光的偏振特性,推导出当激光器出射光束存在偏振椭圆化时,测量角锥棱镜以运动方向为轴线的轴向旋转对非线性误差一次谐波的影响模型。分析表明,测量角锥棱镜以其运动方向为轴线的轴向旋转会减小非线性误差一次谐波。实验显示,当测量角锥棱镜轴向旋转角从0°增加到100°时,非线性误差从3.48 nm减小到1.39 nm,实现了非线性误差一次谐波减小为原来的40%。该方法避免了现有的非线性误差补偿方法光路系统和电路系统复杂的缺点,系统实现很简单。