Parallel operation of decoupled generation systems

The paper presents adjustable speed generation systems and their parallel operation. The adjustable speed generating set consists of diesel engine, driving permanent magnet axial flux generator and power electronic converter with DSP - FPGA based control unit. The power electronic converter, with intermediate a DC link voltage, converts variable frequency and -amplitude of the voltage, produced by the permanent magnet generator, to standardized AC three phase four wires 400 V voltage. In each unit the engine speed is adjusted to meet power demand. The method of parallel operation control is based on novel modified droop technique. Both steady state and transients are considered. The method provides control of transients of power sharing for connected autonomous adjustable speed generating sets operating initially with different speeds. A method of control of power sharing, during sudden load changes, is described. The paper includes theory of control and presents results of laboratory tests of 40 kVA/400 V/50 Hz units. The advantages of this novel flexible droop method are proven.