O'Reilly logo

Voltage-Sourced Converters in Power Systems by Reza Iravani, Amirnaser Yazdani

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

7

Grid-Imposed Frequency VSC System: Control in αβ-Frame

7.1 INTRODUCTION

Chapter 5 presented dynamic models of the two-level VSC in αβ-frame and dq-frame and briefly introduced the control of a generic three-phase converter system in those frames. Chapter 6 introduced the three-level NPC as a generalization of the two-level VSC and established that the dynamic model of the three-level NPC is conceptually the same as that of the two-level VSC, except that the three-level NPC requires a DC-side voltage equalizing scheme to maintain the DC capacitor voltages, each at half the net DC-side voltage. Chapter 6 also presented a unified model for the three-level NPC and the two-level VSC which are generically called VSC. In this chapter, we introduce and investigate the control of a grid-imposed frequency VSC system in which the three-phase variables are sinusoidal functions of time with a frequency that is imposed by the AC system, for example, a power utility grid. The methodology is for the VSC and therefore covers the control of both the two-level VSC and the three-level NPC. This class of VSC systems is often adopted for real- and reactive-power control, or for DC voltage control. These functions constitute the main operational functions of electronically-coupled distributed generation (DG) units, VSC-based HVDC systems, and most FACTS controllers.

7.2 STRUCTURE OF GRID-IMPOSED FREQUENCY VSC SYSTEM

Figure 7.1 shows the schematic diagram of a grid-imposed frequency VSC system. The ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required