Search Results (2)

Integrating wind power generators, whose frequency varies in a wide range due to varying wind speeds, into a grid is a formidable problem. At present, the use of permanent magnet synchronous generators (PMSG) and doubly fed induction generators (DFIG) as wind generators with suitable control is the best possible solution. However, a dual-field excited synchronous generator (DESG), which has two windings on the rotor, can also be used for the same purpose with appropriate control. A new control strategy, which essentially employs the d-axis and q-axis components of the alternator terminal voltage, is suggested here. This strategy essentially results in exciting the two field windings with a slip frequency. This eventually holds the stator frequency constant, irrespective of the rotor speed of the wind generator. The difference between the required frequency and the natural frequency, analogous to the rotor speed of the wind power generator, is the slip frequency. The ring modulator automatically adjusts the slip frequency depending on the actual speed of the generator’s rotor. This paper uses the ANSYS MAXWELL 2022 R1 software to design a DESG and uses a ring modulator as the control function generator for feedback with ANSYS TWIN BUILDER 2022 R1. Simulations are carried out using transient–transient co-simulation by combining both of these software tools for cases of both a constant-speed input and of a variable-speed input to the rotor of the machine. Moreover, a mathematical model of the DESG as a wind generator with the proposed controlled strategy is used to perform the stability analysis of a nine-bus three-machine system, and the results are compared with those of conventional wind generators. Full article

Due to an increasing demand for electric power and changes in the typology of loads, stability has become a major concern in power systems. As the system stability is directly related to the response of the connected generator, recent research has focused on enhancing generators’ stability and improving their response to load variations. This study focuses on adding another excitation winding on to the q-axis, perpendicular to the conventional excitation winding on the d-axis, to control both active and reactive power. This paper studies and compares the performance of the dual excitation synchronous generator (DESG) to conventional synchronous generators. The mathematical equations are derived, and a mathematical model is then developed. The experimental tests have been conducted using a laboratory model consisting of a two-phase synchronous generator driven by a DC motor with different loads. The obtained results and radial diagrams for the different loading types are presented and evaluated. Therefore, a new approach has been designed to connect the DESG directly to the power grid without any electronic components using a special coupling that works in one direction. Two perpendicular excitation coils, d and q, were formed from the existing coils, and the tests were carried out on all loads, ensuring that the revolving angle (i.e., the stability angle φ) was fixed. The results show that the proposed method offers significant cost savings, potentially amounting to 15–20% of the unit price. The experimental results confirm that the DESG significantly improves the generator stability by maintaining a constant rotor angle δ, which requires using an automatic angle regulator (AAR) in addition to the conventional automatic voltage regulator (AVR). Full article