1、附录 附录一英文资料 Recent advances in var compensators GZA JOOS . Department of Electrical and Computer Engineering, Concordia University 1445, de Maisonneuve W, Montreal, Canada H3G 1M8 e-mail: gezaece.concordia.ca Abstract. Static var compensators have been, for many years, an essential co mponent in the
2、operation of power transmission systems. They are part of a fam- ily of devices known as Flexible AC Transmission System (FACTS) devices. The advent of large capacity force-commutated semiconductor switches allows many developments in power electronic converters to be applied to the implem- entation
3、 of high power compensators. This paper describes the principles of co- ntrolled reactive power compensation, particularly in the context of power syst- ems. It focuses on active static power converter-based compensators and discu- sses issue related to the power circuit topology and control techniq
4、ues including the impact of Pulse Width Modulation (PWM) techniques. Compensators based on current and voltage source converters and on ac controllers, both in the shunt and series configurations, are covered. Methods to enhance power capacity usin -g multi-level and multi-pulse arrangements are dis
5、cussed. Key words. Reactive compensation； power electronic converters； powers ystems. 1. Introduction Reactive power (var) compensation has long been recognized as an essential fun ction in the operation of power systems. At the distribution level, it is used to i- -mprove the power factor and suppo
6、rt the voltage of large industrial loads, such as line commutatedthyristor drives and electric arc furnaces. Reactive power co- mpensation also plays a crucial role at the transmission level in supporting the l- -ine voltage and stabilizing the system. Rotating synchronous condensers and m- echanica
7、lly-switched capacitor and inductor banks have been replaced in the 19 70s by thyristor-based technologies: in typical installations, a thyristor-contro- lled reactor (TCR) provides variable lagging vars, and fixed or thyristorswitched capacitors (TSC) provide the leading vars. The combination of bo
8、th devices in parallel allows continuous control of vars over a wide range of values, from lea -ding to lagging vars (Gyugyi 1979). A large number of units have been succes -sfully installed and operated for many years. At the same time, the potential of var compensators based on static power conver
9、ters have also been recognized an -d a number of configurations proposed and investigated (Gyugyi 1979). However, thyristor technology only allows the implementation of lagging var generators, unless complex force-commutation circuits are used. This drawback has been eliminated with the introduction
10、 of Gate Turn-Off (GTO) thyristors (La -rsen et al 1992). This has allowed the development of a number of configuratio -ns based on the use of synchronous voltage sources (Gyugyi 1993). Prototype GTO-based var compensation units, known as STATCOMs have been installed and tested by utilities (Schaude
11、r etl 1995). The STATCOM and other static var compensators have recently been grouped, together with other types of transmiss -ion system control devices, under the heading of Flexible AC Transmission System (FACTS) devices. Reactive power compensators are typically connected in shunt across transmi
12、s -sion and distribution systems. An alternative connection, the series connection, has recently received much attention from utilities (Gyugyi et al 1996). Techno -logical solutions have been developed to solve problems associated with insula -ting the equipment from ground and the full potential o
13、f series connections can now be exploited. The latest development in var compensation technology has b -een the combination of series and shunt static compensators into one unit, know -n in the area of power systems under the name of Unified Power Flow Controll -er, or UPFC (Gyugyi 1992). Static pow
14、er converters have been successfully applied to a large number of power conversion problems at low and medium power levels. However adapting these solutionsto high power transmission and distribution levels raises special issues. Although the capacity of power semiconductor switching devices has gra
15、 -dually increased, large ratings still require combining devices in series and par -allel. In addition to the large power handling capacity, static compensators must have very high efficiency, since losses have a negative impact on both the initial and operating costs of the power system. Switching
16、 losses are therefore a prima -ry concern and switching frequencies must therefore be kept low. This may res -ult in large harmonic waveform distortion, unless special power circuit configu -rations are used. This paper reviews the various methods available for generating reactive pow -er (var) by means of force-commutated static power converters, taking into acc -ount the above constraints. It discusses topologies suitable for use with devices such as GTOs and the more recently available high power IGBTs and addresses
