[雙語翻譯]--（節(jié)選）外文翻譯--電力彈簧-一種新型智能電網(wǎng) （原文）

1、1552 IEEE TRANSACTIONS ON SMART GRID, VOL. 3, NO. 3, SEPTEMBER 2012Electric Springs—A New Smart Grid TechnologyShu Yuen (Ron) Hui, Fellow, IEEE, Chi Kwan Lee, Member, IEEE, and Felix F. Wu, Fellow, IEEEAbstract—The scien

2、tific principle of “mechanical springs” was described by the British physicist Robert Hooke in the 1660’s. Since then, there has not been any further development of the Hooke’s law in the electric regime. In this paper,

3、this technological gap is filled by the development of “electric springs.” The scientific prin- ciple, the operating modes, the limitations, and the practical re- alization of the electric springs are reported. It is dis

4、covered that such novel concept has huge potential in stabilizing future power systems with substantial penetration of intermittent renewable en- ergy sources. This concept has been successfully demonstrated in a practic

5、al power system setup fed by an ac power source with a fluc- tuating wind energy source. The electric spring is found to be effec- tive in regulating the mains voltage despite the fluctuation caused by the intermittent n

6、ature of wind power. Electric appliances with the electric springs embedded can be turned into a new genera- tion of smart loads, which have their power demand following the power generation profile. It is envisaged that

7、 electric springs, when distributed over the power grid, will offer a new form of power system stability solution that is independent of information and communication technology.Index Terms—Distributed power systems, sma

8、rt loads, stability.I. INTRODUCTION AMECHANICAL spring is an elastic device that can be used to: i) provide mechanical support; ii) store mechan- ical energy; and iii) damp mechanical oscillations [1]–[4]. When a mechani

9、cal spring is compressed or stretched, the force it ex- erts is proportional to its change in displacement. Potential en- ergy is stored in the mechanical spring when the length of the spring deviates from its natural le

10、ngth. The principle of the me- chanical springs has been described by Robert Hooke in 1678 [5]. The Hooke’s law states that the force of an ideal mechanical spring is:(1)where is the force vector, is the spring constant

11、and is the displacement vector. The potential energy stored in the mechanical spring is(2)Manuscript received January 05, 2012; revised March 26, 2012; accepted May 13, 2012. Date of publication June 19, 2012; date of cu

12、rrent version Au- gust 20, 2012. Paper no. TSG-00004-2012. S. Y. Hui is with the Departments of Electrical r.hui@imperial.ac.uk). C. K. Lee and F. F. Wu are with the Department of Electrical ffwu@eee.hku.hk). This work

13、 was supported by the HK Research Grant Council under the Collaborative Research Fund HKU10/CRF/10, The University of Hong Kong (Seed Projects: 201111159239 ii) store electric energy; and iii) damp electric oscilla- tio

14、ns. Analogous to equation-1, the basic physical relationship of the electric spring is expressed as(3)(4)where is the electric charge stored in a capacitor with capaci- tance , is the electric potential difference across

15、 the capac- itor, and is the current flowing into the capacitor. Equation (3) shows that dynamic voltage regulation (i.e., voltage boosting and reduction) functions of the electric spring can be controlled by the charge

16、stored in the capacitor. Equation (4) indicates that the charge control can be realized by using1949-3053/$31.00 © 2012 IEEE1554 IEEE TRANSACTIONS ON SMART GRID, VOL. 3, NO. 3, SEPTEMBER 2012electromotive force (e.m

17、.f.) with controllable magnitude at the mains frequency can be generated across the capacitor as the electric spring voltage . To ensure that this adjustable ac voltage source is lossless like an ideal mechanical spring,

18、 the vectors of and must be perpendicular. The current vectorcan either lead the voltage vector the by 90 (capacitive mode for voltage boosting) or lag by 90 (inductive mode for voltage reduction).B. Practical Implementa

19、tion and Characteristics of Electric SpringIn electrical engineering term, this electric spring is a spe- cial form of reactive power controller. In the last two decades, power electronics based reactive power controller

20、s (RPC) have been developed in power industry to control power flow in high- voltage transmission lines [8]–[17] and for dimming lighting systems [18], [19]. Their simplified control schematics are illus- trated in Fig.

21、5(a) and 5(b), respectively. In these applications [8]–[19] of series RPC, the input of the RPC is always and the output is regulated to a constant level (i.e., a traditional “output-feedback and output-voltage control”

22、of is adopted). It is important to note that the electric spring differentiates itself from previous use of RPC with the adoption of an “input-feed- back and input-voltage control” as shown in Fig. 5(c). By reg- ulating

23、the input voltage and letting the output voltage to fluctuate dynamically (i.e., a new input-voltage control), such RPC would: i) provide the voltage support as an electric spring and ii) simultaneously shape the load po

24、wer to follow the avail- able power generated by renewable energy source. Such subtle change in the control strategy of a RPC from output control to input control offers new features and functions for power and voltage c

25、ontrol [26]. This new discovery provides the opportu- nity to apply the electric spring for balancing the instantaneous power of the load demand and the generated power [20], [21] for future smart grids with substantial

26、renewable energy sources.III. OPERATIONS AND LIMITATIONS OF ELECTRIC SPRINGSFor a load that can be divided into two parts: a noncritical load and a critical load , as in Fig. 4. By connecting an electric spring in series

27、 with the noncritical load, we can ensure that the voltage and power at the critical load to remain constant when the line voltage feeding the load fluctuates. Such an arrange- ment of load will be called “smart load.” T

28、he aim of the electric spring in the application example of Fig. 4 is to restore to the nominal value of the mains voltage at the location of the device installation. Let be the dynamically-changing input power. The gene

29、ral power balance equation for the system in Fig. 4 is(6)where and are the root-mean-square values of the noncrit- ical load voltage and the ac mains voltage, respectively; is the real part of that represents the resisti

30、ve element is(a)(b)(c)Fig. 5. (a) Simplified control schematic of series reactive power compensator for output voltage support in transmission ( regulated) [9]–[15]. (b) Simpli- fied control schematic of series reactive

31、power compensator as a central dim- ming systems ( regulated) [18], [19]. (c) Simplified control schematic of se- ries reactive power compensator as an electric spring ( regulated).the impedance of the “noncritical” load

32、 and is the impedance of the “critical” load. The vector equation for the electric spring is(7)Equation (6) shows that, if the mains voltage is regulated by the electric spring at the nominal value , the second power ter

33、m should remain constant for the critical load. If the power generated cannot meet the full power for both and , the input-voltage control of the electric spring will generate a voltage vector to keep regulated at . From

34、 (7), the voltage vector across will be reduced and so the power consumption of will also be reduced. Therefore, if the electric spring performs well, for the critical load should re- main constant as expected and for th