中英文翻译-基于瞬时无功功率理论谐波检测的建模与仿真.doc

毕业设计（论文）中英文资料题目 基于瞬时无功功率理论检测 的建模与仿真专 业 名 称 自动化班 级 学 号 108202216学 生 姓 名 黄绿强指 导 教 师 李俊填 表 日 期 2014 年 3 月 9 日基于瞬时无功功率理论的谐波和无功电流检测 引言 20世纪80年代后，电力电子技术迅速发展。各种变频器、变流器、开关电源和电抗器的应用日益增多。随之产生的谐波污染也日益严重，造成电力系统电压、电流严重畸变。影响仪器仪表正常工作，增加电力器件损耗，危及电力系统安全运行。目前，谐波污染已经成为电力系统的严重公害之一解决电力系统谐波问题显得尤为迫切。电力系统谐波问题涉及面很广，包括谐波检测、谐波分析、谐波源分析、电网谐波潮计算、谐波抑制、谐波标准等。谐波检测是谐波问题中的一个重要分支，是解决其他谐波问题的基础。电力系统的谐波由于受随机性、分布性、非平稳性等因素影响，对其进行准确检测并非易事。随着电力电子装置的广泛应用，使得谐波和无功问题成为了研究的热点。日本学者赤木泰文于1983年提出了三相电路瞬时无功功率理论，又称为p q理论，为三相电路谐波和无功检测提出了新的方法。1.基于一的三相瞬时无功功率理论 为了克服p q理论检测时受电压质量影响的不足之处，p q理论经过不断的发展和完善，形成一为基础的三相瞬时无功功率理论。该理论的核心思想在于把满足+=0的三相电流经过不含零序分量的Park变换得到，。即： 可以看出，此时电流的检测只与A相电压的电角度t有关，而电压波的畸变对检测结果没有影响其中是三相到两相的坐标变换阵；是旋转坐标变换阵。 式中，k为整数，是角频率，和为各次电流的幅值和初相。 当k=l、7、13时取上符号；k=5、11、17时取下符号。若滤去(3)式中的交流分量可得： 由(4)式可知，与传统意义上的基波分量的有功电流和无功电流相对应。因为和可经LPF分离而得到直流分量,若将同时反变换，可得到基波分量，如下式： 式中C23是两相到三相的坐标变换阵。进而可得谐波电流，为： 对谐波电流，进一步分析，可得出三相交流电中所含的高次谐波的具体情况，从而可实现对高次谐波实时检测和有针对性的滤波控制。如果只将作(1)式的反变换，得到无功电流分量的瞬时值，如下式： 由式(7)可无延时地分离出三相交流电中的瞬时无功电流，在实践中可根据该电流值设计控制系统，实现快速的无功补偿。可以看出，三相电路瞬时无功功率理论的提出，为快速的检测无功电流和高次谐波电流提供了理论基础。2.基于无功功率理论的谐波和无功电流检测 三相瞬时无功功率理论提出后，由于其在检测电流时的实时性，很快被用于电力系统谐波和无功电流的检测。并随着该理论的进一步发展，派生出各种检测方法。其中具有代表性的有：p一q检测法、-检测法。下面讨论pq的检测方法： 该方法根据定义算出pg，当电压波无畸变时(即为标准正弦波)，而电流中含有无功分量和谐波分量： 式中，k为整数表示谐波次数，是角频率；和为各次电流的幅值和初相。将(8)式变换到坐标系中并代入(5)式中得： 式中，n=3k+1。当n=3k+1时，计算式(9)中取上符号；当n=3k一1时，计算式(9)取下符号。可以看出，(9)式可以分成两部分，其中前半部分为直流分量对应n=1时，即功率中的基波有功和基波无功。后半部分为交流部分的功率对应nl时，即功率中的高次谐波有功和无功。用该检测方法检测谐波时的计算框图如图1所示。 该检测方法简述如下，首先对采样得到的三相电压、电流值、和、进行变换，得到、和，；再由定义算出p，q；通过低通滤波器得到p，q中的直流分量p,q；将p，q互进行反变换得到三相电流中的基波电流分量、。用三相电流、减去基波电流分量、得到电流中的高次谐波分量、当电网电压无畸变时，从上面的推导可以看出基波电流分量、的检测是准确的，从而高次谐波分量、的检测值也是准确的。下面讨论当电网电压有畸变时的检测情况。设电网电压为： 由上式可以看出，直流分量p，q不仅含有基波有功功率(无功功率)还含有高次谐波产生的有功功率(无功功率)，因此由该式算出的三相电流中的基波电流分量、必然存在误差，从而使检测到的高次谐波分量、也必然出现误差。这也是p-q检测算法最大的不足之处。要检测谐波电流和无功电流的和电流，从而进行综合补偿，可采用图2。 在该检测检测框图中，只对p进行了低通滤波处理，而q不进行滤波。将p，q进行反变换得到三相电流中的基波电流分量、，此时、中只含有基波有功电流分量；用三相电流、和减去基波电流分量，、得到电流中的高次谐波和无功电流的和电流+q、+q和+q。3.结语 准确、实时地检测出电网中的谐波电流和无功电流是抑制谐波和无功补偿的关键。依据瞬时无功功率理论，对三相谐波电流进行了检测。证明了基于瞬时无功功率理论的谐波检测方法的可行性及有效性，为抑制谐波和无功补偿提供准确、实时的谐波及无功分量。Based on instantaneous reactive power theory of harmonic and reactive current detection Introduction After the 1980s, the rapid development of power electronics technology. Various inverter, converter, switching power supply and reactor applications is increasing. Consequent harmonic pollution has become increasingly severe, resulting in the power system voltage and current severe distortion. Impact of instrumentation work, increased power consumption devices, endangering the safe operation of the power system. Currently, harmonic pollution has become one of the serious pollution of the power system. Solve the problem of power system harmonics is particularly urgent. Power system harmonics problems involving a wide range, including harmonic detection, harmonic analysis, harmonic source analysis, harmonic tidal calculations, harmonic suppression, harmonic standards. Harmonic harmonic detection is an important branch in question is the basis for solving other harmonic problems. Power system harmonics due to the randomness of the distribution of non-stationary and other factors, its accurate detection is not easy. With the extensive application of power electronic devices, making the harmonic and reactive issue became the focus of research. Thai Akagi Japanese scholars put forward in 1983 a three-phase circuit instantaneous reactive power theory, also known as the p q theory, a new method for three-phase circuit harmonics and reactive detection. 1.Based on an -phase instantaneous reactive power theory In order to overcome the p q theory is detected by the inadequacies of the voltage quality impacts, p q theory through continuous development and improvement, the formation of an -based three-phase instantaneous reactive power theory. The core idea of this theory is that the meet + + = 0 does not contain zero-phase-sequence component of current through the Park transform,. Namely: As can be seen,only the detected current and the electrical angle A phase voltage, whereas the voltage wave distortion does not affect the test results.Where is a three-phase to two-phase coordinate transformation matrix;is rotating coordinate transformation matrix. When a symmetrical three-phase current is detected current is:Where, k is an integer, is the angular frequency,andis the second current amplitude and initial phase. The (2) into (1), we obtain the following formula:Remove the symbol k = 5,11,17 . when; When k = l, 7,13 . when to take the sign. If filtered (3) of the AC component can be obtained: From (4) shows that And the fundamental component in the traditional sense of the active current and reactive current correspond. Because ip and iq can be obtained by separating the DC component LPF , If While the inverse transform, the fundamental component is obtained,following formula: Whereis a two-phase to three-phase coordinate transformation matrix. Furthermore harmonic current can be obtained , , is:Harmonic current , , further analysis, three-phase alternating current can be drawn from the circumstances contained in higher harmonics, enabling real-time detection of high harmonics and targeted filtering control. If only thefor (1) the inverse transform, get instantaneous reactive current component value, the following formula: Can be separated out without delay by the formula (7) in a three-phase alternating current instantaneous reactive current, which in practice may be based on the current value of the control system design for fast reactive power compensation. As can be seen, proposed a three-phase circuit instantaneous reactive power theory for the rapid detection of reactive current and harmonic current to provide a theoretical basis. 3 Based on the theory of harmonic reactive power and reactive current detection After a three-phase instantaneous reactive power theory suggests, because of its real-time detection of current and soon to be used to detect power system harmonics and reactive currents.And with the further development of the theory, derived from a variety of detection methods. Where a representative has: p a q assay, -detection method. Detection methods discussed below p-q is: The method as defined by the calculated p-g, when the voltage wave without distortion (i.e., standard sine wave), which contains the reactive current component and a harmonic component: Where in, k represents an integer number of harmonics, is the angular frequency; and is the second current amplitude and initial phase. (8) is converted to the formula and the coordinate system is substituted into (5) have the formula:Wherein, n = 3k +1. When n = 3k +1, the formula (9) to take the symbol; when n = 3k-1, the formula (9) Remove symbol. As can be seen, (9) can be divided into two parts, the first part of the DC component corresponding to n = 1, i.e. the power of the fundamental wave and the fundamental wave reactive active. The latter part of the exchange for the power part of the corresponding n l, that the power of the higher harmonic active and reactive power. The testing methods used to calculate harmonics block diagram shown in Figure 1. The detection method outlined below, firstly sampled three-phase voltage and current values , and ,carried transformation, , and ,; then calculated by the definition of p, q; a low-pass filter obtained by p, q DC component p, q; the p, q mutually inverse transform of the fundamental phase current current component ,. Three-phase currents,minus the fundamental current component , get current in high harmonics, when the grid voltage without distortion, can be seen from the above derivation of the fundamental current component,detection is accurate, so the harmonic component, detection value is also accurate. Discussed below, when the grid voltage distortion of the testing situation. Let the grid voltage is: As can be seen from the above equation, the DC component of p, q only contains fundamental active power (reactive power) also contains higher harmonics generated by the active power (reactive power), so the formula is calculated by the three-phase currents fundamental current component ,errors are bound to exist, so that the detected high harmonics,errors are bound to occur. It is also the biggest s