功

By adding an equivalent harmonic impedance in the branch circuit of power grid, this HAPF could force all the harmonic currents flow into passive power filters, which resulting in eliminating harmonic contamination more effective. And using the capacitive feature of PPF in the fundamental frequency, this HAPF could compensate fixed-capacity reactive power without increasing APF's burden. Moreover, in order to decrease APF's cost, the fundamental voltage will largely be endured by capacitor in view of the series resonance circuit tuned at the fundamental frequency, so the APF just bears little harmonic voltages.

其基本工作原理是：有源部分等效于在电网支路中串联了一个谐波阻抗，该谐波阻抗对基波电流不起作用，而对谐波电流产生很大阻碍作用，迫使谐波电流流入无源滤波器，从而达到滤除谐波的目的；同时新型注入式混合有源滤波器还充分利用了无源滤波器的无功补偿功能，在不增加有源部分容量的前提下，可以提供一定容量的无功功率；由于有源部分承受的电网基波电压不大，也没有基波电流流入，因此逆变器容量小，初期投资较小。

The basic principles and evolution process of Active Power Filter are first introduced. The scheme and structure of single-phase hybrid filter system is then illustrated and quantitative analysis is made based on the harmonic and reactive compensation principles. Through theoretical derivation, the said system has been proved to have the function of harmonic and reactive compensation.

本文首先介绍了有源电力滤波器(Active Power Filter，简称APF)的基本原理及发展历程，阐述了单相混合型滤波系统的方案和结构原理，对其进行了谐波和无功补偿原理的定量分析，通过理论推导证明了该系统具有谐波和无功补偿的功能。

Based on the theory of instantaneous reactive power, the multiple frequency rotate transform theory is put forward. It overcomes the defect of that the theory of instantaneous reactive power can only measure the harmonic total amount. The positive sequence and negative sequence k-multiple frequency rotate coordinate is respectively put forward in detail.

倍频旋转变换理论是基于瞬时无功功率理论提出的，它克服了瞬时无功功率理论测量方法只能测量谐波总量的缺陷，该理论分别针对正序谐波和负序谐波，提出正向和负向倍频旋转坐标，通过k—倍频旋转坐标可将k次谐波分离出来。

The commonly used real time detecting theory of instaneous reactive and harmonic current based on vector transform has the shortcomings of complexity of vector transform and illegibility of physics meanings.

针对建立在瞬时无功功率理论的基础上的瞬时无功和谐波电流检测算法存在的矢量变换复杂，物理意义不明确的缺陷。

Especially, the inductive load and impactive load of electrical equipments bring much Var and harmoniousness to the power system. They lead to low power factor, vast harmonious component and lead to other electrical equipment deviant work.

特别是用电设备中的感性负荷和冲击负荷给电网带来了大量的无功和谐波，造成电网功率因数降低，谐波成分增大，引起本身和其它用电设备不能正常高效的工作，为此，补偿电网的无功和谐波就成为人们及其关注的课题。

Now compare the work done lifting the cart with the work done pulling it up inclined plane.

现在将提升车子所作的功和沿着斜面拉车上来所作的功进行比较。

The infeasibility degree was introduced into the mathematical model of voltage regulation, which can deal with the constraints of the model. In addition, an improved genetic algorithm was used to solve the voltage regulation problem.

在电压无功调整的数学模型中引入了不可行度概念，用于处理模型中的约束条件，并结合改进遗传机制的遗传算法对系统进行电压无功调整。

The cylinder pressure and the cylinder head instantaneous temperature of acceleration process in 492Q gasoline engine were measured.

针对492Q汽油机，测取了加速过程的示功图和燃烧室表面瞬态温度；并对加速过程进行了示功图与燃烧分析。

Harmonic current; reactive current; instantaneous reactive power theory; matlab simulation

谐波电流；无功电流；瞬时无功功率理论；Matlab仿真

A closed-loop detecting circuit of harmonic and reactive current based on instantaneous reactive power theory has been analyzed and used in this APF system. It can achieve the accurate and real-time detection, and make the system stable.

本文将基于瞬时无功功率理论的自适应闭环检测方法应用于有源电力滤波器，使系统在快速、准确检测谐波及无功电流的同时，具有良好的鲁棒性。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。