Power Flow Control Solutions for a Modern Grid Using SMART Power Flow Controllers. Kalyan K. Sen
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СКАЧАТЬ plant input bus voltage (vplant) and plant current (i), drawn by a typical electric arc furnace."/>

      The voltage (Vcomp) at the compensation bus is regulated to maintain the voltage flicker at an acceptable level. The control philosophy in this project is given by the following equations:

      (1‐6)equation

Schematic illustration of the use of a STATCOM, combined with a Fixed Capacitor (FC) as an arc furnace compensator. Schematic illustration of instantaneous reactive power drawn by the furnace and supplied by the compensator.

      where

       Putil is the active power supplied by the utility

       Pfurn is the active power used by the arc furnace

       Pcomp is the active power exchanged by the compensator

      and

      (1‐7)equation

      where

       Qfurn is the reactive power used by the arc furnace

       Qcomp is the reactive power exchanged by the compensator.

      As shown in Figure 1-18, the compensation scheme supplies nearly all the instantaneous reactive power (q) drawn by the furnace.

      This preferred solution for a utility application is to use a larger‐than‐usual‐sized DC capacitor, which provides a sink and a source of fluctuating active power for the load, thereby leveling off the active power drawn from the utility source. The instantaneous active power (p) drawn by the compensator, which is composed of a STATCOM and a FC, and the furnace and supplied by the utility are shown in Figure 1-19. The negative active power drawn by the compensator indicates that a part of the furnace power is supplied by the compensator. If the size of the DC capacitor was further increased to support a larger amount of fluctuating active power, the active power drawn from the utility could be made equivalent to a fixed resistive load.

Schematic illustration of instantaneous active power drawn by a compensator and a furnace and supplied by a utility. Schematic illustration of flicker measurements without and with a compensation provided by a STATCOM.

      The first generation of FACTS Controllers consisted of GTO‐based VSCs. Since the commissioning of the world’s first commercial STATCON at TVA in 1995, nine GTO‐based VSCs were built. During the same time, several IGBT‐based VSCs were also built. During the past two decades, the IGBT technology has advanced by several generations. So, what about the GTO technology? Unfortunately, it is no longer manufactured. While the IGBT is the industry workhorse at the present time, the future trend is to develop wide bandgap‐type Silicon Carbide (SiC)‐ and Gallium Nitride (GaN)‐based switches due to the several attractive attributes: higher‐temperature operation, smaller turn‐on and turn‐off times that result in a lower switching loss, smaller gate‐drive circuit, smaller snubber circuit, lower cooling requirement, and so on. So how can one source spare parts for the GTO‐based FACTS Controllers? That is not an easy question to answer. Most of the installations with GTO‐based VSCs were dismantled after a short life span, which was unforeseen at the inception of FACTS development. Based on the facts about FACTS Controllers of the last three decades, component obsolescence is the primary reason for a 10–15 years of life span of power electronics‐based VSCs.

      In this context, one might ask why not use the latest high‐power СКАЧАТЬ