Đang chuẩn bị liên kết để tải về tài liệu:
YNCHRONOUS MACHINES

Máy móc đồng bộ đến trong một loạt các công trình xây dựng khác nhau và thiết kế. Sự khác biệt xảy ra trong kinh phí vật lý của các cánh quạt và trong cách thức mà thông lượng kích thích được cung cấp (nếu nó được cung cấp tại tất cả) trong máy. Bất kể loại Tuy nhiên, tất cả các máy đồng bộ, có cùng xây dựng stator. Stator là của crosssection hình trụ, sản xuất từ tấm dát mỏng thép, và nó mang một ba pha cuộn dây đó là cung cấp (trong trường hợp động cơ). | ENGNG 2024 Electrical Engineering SYNCHRONOUS MACHINES 1. INTRODUCTION Synchronous machines come in a variety of different constructions and designs. The differences occur in the physical outlay of the rotor and in the way in which excitation flux is provided if it is provided at all in the machine. Regardless of the type however all the synchronous machines have the same construction of the stator. Stator is of cylindrical crosssection manufactured from laminated sheets of steel and it carries a three-phase winding that is supplied with in the motor case or that produces in the generator case a system of three-phase voltages. The three windings that constitute the stator three-phase winding are displaced in space by 120 degrees around the circumference of the machine. Three-phase voltages have the phase displacement of 120 degrees. Synchronous machines are the main work-horse of the electricity generation industry. They are used as generators in all the hydro nuclear coal-fired gas-fired and oil-fired power plants. This means that a synchronous generator is a standard machine used for conversion of mechanical energy into electric energy in all the power plants that rely on conventional energy sources. Rated powers of synchronous generators are typically from a few megawatts up to a few tens of megawatts or even a several hundreds of megawatts. Synchronous machines are used as motors as well. In this case rated power of a synchronous motor is either relatively very low up to few kilowatts or is in the high power region from around 150 kW to 15 MW. In between induction motors are used as a rule due to their numerous advantages in this power region. The two types of synchronous machines that are relevant for the discussion that follows are 1. Machines with uniform air-gap and excitation winding on rotor. 2. Machines with non-uniform air-gap and excitation winding on rotor. Rotor cross-section in these two types differs and leads to different mechanisms of torque .