单相AC AC变换器补偿电压骤降和骤升外文翻译.doc
《单相AC AC变换器补偿电压骤降和骤升外文翻译.doc》由会员分享,可在线阅读,更多相关《单相AC AC变换器补偿电压骤降和骤升外文翻译.doc(29页珍藏版)》请在三一办公上搜索。
1、外文文献翻译Compensation of Voltage Sags and Swells usinga Single-Phase AC-AC ConverterAbstract-In this paper, a topology to compensate voltage sags and swells simultaneously in critical loads is proposed. It consists in a single-phase AC-AC converter in a matrix arrangement, which keeps a continuous regu
2、lation in the output voltage. The proposed scheme has the capability to compensate up to 25% voltage sags and 50% voltage swells.Energy storage devices are not required by the AC-AC converter and it is connected between the AC mains and the load by using a series transformer. One of the advantages o
3、f this topology is that taps for the coupling transformer are no necessary to change the polarity of the compensation voltage. A four step switching technique is used to drive the AC-AC converter switches, executing snubber-less operation. The reference signal is generated using single-phase d-q the
4、ory, obtaining a fast response time and high regulation.Simulation and experimental results of a 5kW capacity, 127V, 60Hz equipment are presented.I.INTRODUCTIONThe quality of the AC mains has been affected by the use of new semiconductor-devices technologies. Nowadays, it is common to find disturban
5、ces in the amplitude or waveform shape of current and voltage in the electric systems. These conditions could produce fails in the equipments, raising the possibility of an energy interruption. The voltage fast variations that appear in the AC mains during 10 seconds or less are commonly known as vo
6、ltage sags and swells. These variations are produced by normal operation of high power loads as well as theirs connection and disconnection; the voltage fast variation effects are function of the amplitude and the duration of the event. Some studies show that 92% of all disturbances in the electrica
7、l power distribution systems are produced by voltage sags 1.It is important to eliminate the voltage fast variations because they are the most frequently cause of disrupted operations for many industrial processes, particularly those using modern electronic equipment, which are highly sensitive to s
8、hort duration source variations 2.Dynamic Voltage Restorer(DVR) and Uninterrupted Power Supply (UPS) systems had been researched and developed along the last decades and they are capable to compensate voltage sags and swells. Nevertheless, they depend on devices to store energy, like large capacitor
9、s or batteries bank. The nominal power operation is a function of size and capacity of those devices; if the power is increased, the size of the devices will increase. In spite of the above, the UPS systems are capable to support energy interruptions.Other option developed, which is able to compensa
10、te voltage sags is based on PWM AC-AC converter3,4.This solution uses an autotransformer composed by one primary side and two secondary windings presenting a good performance. The system compensates until 50% voltage sags and swells and can continuously shape the output voltage to be sinusoidal (wit
11、h low THD). Nevertheless, the autotransformer drives all the load power due to it is connected between the load and the AC mains.In this paper a PWM AC-AC converter is presented, in order to compensate voltage sags and swells simultaneously in critical loads, and to maintain a continuous regulation
12、in the output voltage. The system consists in a single-phase AC-AC converter in a matrix arrangement, and energy storage devices are not required. A four step switching technique is used to drive AC-AC converter switches, executing snubber-less operations. The reference signal is generated using sin
13、gle-phase d-q theory, obtaining a fast response time and continue regulation, with a high efficiency.One of the advantages in this structure is that the taps of the coupling transformer are not required to change the polarity of the compensation voltage, and the converter drives only a percent of th
14、e load power.Design, construction and performance are detailed, and several simulations and experimental results obtained with a laboratory prototype are showed to validate the approach. II.CONVERTER ANALYSISThe structure of the proposed approach is shown in Fig. 1.Fig.l Conceptual design of the pro
15、posed approach Its principal objective consists in supply a compensation voltage in order to keep always the nominal value of the AC mains. When voltage sag occurs, the converter supplies the necessary voltage to maintain regulation in the output voltage. In the same way, when voltage swell occurs,
16、the converter reproduces the necessary voltage to cancel out theovervoltage.The topology of the single-phase AC-AC converter is shown in Fig. 2.Fig.2 Single-Phase AC-AC converter The converter has the following elements: Four current and voltage bi-directional switching devices connected to the AC m
17、ains 5,6,7. Two low-pass filters to reduce the high frequency associated to switching in input current and output voltage8. The AC-AC converter generates a PWM AC voltage to cancel the variations in the AC mains and to compensate the voltage sags and swells.S1,S2,S3 and S4 are used to generate the P
18、WM voltage with the polarityrequired. The adequate operation of the switches allows producing anoutput voltage Vout on phase or 180phase-shifted with respect to Vin. When the utility voltage is at normal level, the switches S3 andS4 are closed (or S1 and S2) and the output voltage is equal to zero.
19、Whenthere is a voltage sag, the switch S4 is closed, and S1 and S3 are operatedwith a duty cycle D, generating a Vout, for compensation. When there isa voltage swell, the switch S3 is closed, and S2 and S3 generate a Vout,with a polarity inverted for compensation. Switches S1-S3 and S2-S4never shoul
20、d be closed at the same time in order to avoid a short-circuitin the AC mains side. The switches are driven using a signal pattern which incorporate afour-step switching strategy, reducing the switching losses andeliminating the use of snubbers circuits. III.MODULATION TECHNIQUEThe function of the s
21、ingle-phase AC-AC converter is to reproduce avoltage with a peak amplitude lower or equal than the AC mains value. To achieve this, the voltage of the AC mains is modulated by using a switching pattern. The amplitude of the fundamental voltage will depend on themodulation index of the switching patt
22、ern. Fig.3 shows the scheme used to obtain a pulsed pattern. In thiscase, it is used a Digital Signal Processor(DSP) to generate the duty cycle D and to control the PWM of the switching devices. The operation mode of the scheme consists in to obtain a referencesignal that represents the compensation
23、 voltage Vc. In this case, it isused the d-q theory to transform the AC mains voltage in a DC signal. Thed component is compared with the nominal peak voltage of the AC mainsVnom, to obtain the Vc. (The d-q theory is explained in section IV).Fig.3 Scheme to generate the control pulsesThe C(s)control
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 单相AC AC变换器补偿电压骤降和骤升外文翻译 单相 AC 变换器 补偿 电压 骤降 外文 翻译
链接地址:https://www.31ppt.com/p-2926766.html