A Large Power, Low-Switching-Frequency Voltage Source Converter for FACTS Applications With Low Effects on the Transmission Line

Abstract

This paper presents a novel large power voltage source converter for flexible ac transmission systems' applications that employs four three-level, three-phase neutral-point-clamped inverters, combined by means of low volt-ampere rating intermediate magnetic elements. The 12 resulting inverter poles are paralleled up in pairs by using six interphase transformers (IPTs), and their outputs are connected in series by using a simple openwye/delta transformer, rated to 50% of the power throughput. Due to the inherent harmonic cancelation provided by the transformer and the further harmonic mitigation allowed by the IPT connection, the converter is suited for the use of various low-switchingfrequency modulation strategies that obtain a clean output waveform, in some cases comparable to that of a 48-pulse converter. Moreover, the output voltage is doubled by means of the intermediate magnetic elements, which also ensure an equal power sharing between the four inverters. In this paper, the converter components and its operation are explained, and experimental results are provided. Index Terms-FlexibleAC transmission systems (FACTS), integrated gate-commutated transistor (IGCT), interphase transformer (IPT), multipulse, selective harmonic elimination (SHE), static synchronous compensator (STATCOM), static synchronous series compensator (SSSC), voltage source converter (VSC), zero-sequence blocking transformer, 12-pulse, 48-pulse.

Assurance of electromagnetic compatibility of powerful electrotechnical systems

“…Первый вариант в основном используется в качестве системы динамического восстановления напряжения ДВР (DVR -Dynamic Voltage Resorter) или контроля уровня напряжения в точке подключения, в то время как последний -для поддержки напряжения и компенсации реактивной мощности. В качестве альтернативы два компенсатора могут быть объединены в единый регулятор потока мощности (UPFC -Unified Power Flow Controller), чтобы обеспечить и последовательную и параллельную компенсации реактивной мощности [7].…”

“…При U 1 < U 2 (рис. 4, б) ток I 2 опережает напряжение U 1 , поэтому АИН отдает реактивную мощность в сеть [7]. Перевод АИН из режима потребления в режим генерирования реактивной мощности осуществляется изменением напряжения U 2 способом, основанным на принципе широтно-импульсной модуляции (ШИМ).…”

IP-ZSBT Magnetic Configuration for Parallelization–Serialization of Three-Phase High Power Converters

“…In [8] and [17], twelve 3 L-NPC PEBBs are combined too, but using six Inter-Phase Transformers (IPTs) [18]. In [17], the output transformer is connected in open-end configuration and the VA rating of the intermediate magnetic elements that are needed to combine the PEBBs is reduced compared to the topology presented in [8].…”

“…In [17], the output transformer is connected in open-end configuration and the VA rating of the intermediate magnetic elements that are needed to combine the PEBBs is reduced compared to the topology presented in [8].…”

“…The IPTs allow to connect converters in parallel and increase the converter output power [27].By using the IPT, the current is equally shared between the parallelized legs [8]. Fig.…”