Energy Processing and Smart Grid

CHAPTER 6SYNCHRONOUS MACHINES

6.1 INTRODUCTION

Synchronous generators are the main source of bulk power generation at large power stations. They may be driven by prime movers such as hydro turbines, wind turbines, gas turbines, or internal combustion engines. Today's most mature science of power generation rests on synchronous-generator technology. Generators are the largest single unit of electric machines in production, having power of some 1,000 MVA. In a large power system, more than a thousand machines may be interconnected through tie-lines supplying thousands of megawatts of power to consumers dispersed over a wide area. Each machine could be driven by prime movers.

Synchronous generators are scalable and may be built for smaller power-generation applications such as domestic, commercial, and small-scale industrial needs. These could have capacities ranging from 10 kW to 500 kW. Such machines are usually driven by diesel- or gasoline-powered internal combustion engines.

6.2 SYNCHRONOUS-GENERATOR CONSTRUCTION

Synchronous machines operate at 60 or 50 Hz for utility and for larger frequency in large aircraft. Almost all synchronous machines have stationary armatures commonly called the stator and rotating field structures called the rotor. The rotor may be constructed with salient or cylindrical (round with no polar projection) poles, as shown in Figure 6.1 [9]. The prime-mover speed influences the construction of the salient poles rotors. The armature carries three-phase ...