外文翻译--svc与statcom在电力系统中应用的效益(编辑修改稿)

外文翻译--svc与statcom在电力系统中应用的效益(编辑修改稿)内容摘要：

major harmonic generation at higher frequencies. The major contributions are at odd multiples of the PWM switch frequency。 at even multiples the levels are lower. The harmonic generation decays with increasing 4 frequency. STATCOMs might also generate harmonics in the same spectra as the conventional SVCs. The magnitudes depend on converter topology and the modulation and switching frequency used. In most cases STATCOMs as well as SVCs require harmonic filters. IX. FOOTPRINT More and more frequently the footprint available for prospective STATCOMs or SVCs is restricted. The trend is, as in many other fields, more capacity on less space. Requirements for extremely tight designs, however, result in higher costs. In general the footprint issue seems not to hinder the utilization of STATCOMs or SVCs, but occasionally, STATCOM has been preferred based on anticipated smaller footprint. When paring SVCs with STATCOMs, it is tempting to assume that the latter will fit within a much smaller footprint, as the passive reactive elements (air core reactors and high voltage capacitor banks) are ―replaced‖ with semiconductor assemblies. In the authors’ opinion, this assumption however remains to be practically proved. The main reason for this is that the voltage sourced converter concepts applied in STATCOMs to date have been built with several (even as many as eight) inverter bridges in parallel. This design philosophy implies many current paths, high fault currents and plex magic interfaces between the converters and the grid. All in all, not all STATCOMs e out as downsized pared to SVCs. Also the higher losses in the STATCOM will require substantially larger cooling equipment. However, as the STATCOM technology evolves, including the use of very pact inverter assemblies with series connected semiconductor devices, and with pulse width modulation, there is a definite potential for downsizing. In the case of SVCs, the industry has a long product development where, when necessary, measures have been taken to downsize the installation. Such measures include elevated design of apparatuses, stacking of ponents (reactors and capacitors), vertical orientation of busbars and use of nonmagic material in nearby structures. In a few extreme cases iron core reactors have been utilized in order to allow installation in very tight premises. In addition the development of much higher power density in high power thyristors and capacitors contributes to physically smaller SVCs. X. LIFE CYCLE OR EVALUATED COSTS It is the authors’ experience that the investment cost of SVCs is today substantially lower than of parable STATCOMs. As STATCOMs provides improved performance, it will be the choice in the cases where this can be justified, such as flicker pensation at large electrical arc furnaces or in bination with active power transfer (backtoback DC schemes). The two different concepts cannot be pared on a subsystem basis but it is clear 5 that the cost of the turnoff semiconductor devices used in VSC schemes must e down significantly for the overall cost to favor the STATCOM. In other industries using high power semiconductors, like electrical traction and drives, the mainstream transition to VSC technology is since long pleted and it is reasonable to believe that transmission applications, benefiting from traction and drive developments, will follow. Although the semiconductor volumes in these fields are relatively small, there is potential for the cost of STATCOMs to e down. Apart from the losses, the life cycle cost for STATCOM and SVCs will be driven by the efforts required for operation and maintenance. Both technologies ca。