Models For Stability Analysis Of Power System Containing AC Excited Generators And Their Applications

Compared with the traditional synchronous generator, ASG (Asynchronized Synchronous Generator) can implement VSCF (Variable Speed Constant Frequency) generation, has better static and transient stability and deep condensive operation capability. It can not only improve the operating efficiency of hydroelectric generating unit and wind generating unit by variable speed operation, but also be very useful for solving the reactive surplus problem caused by EHV (Extra High Voltage) long distance trasmission line and enhance the power system stability as well. However, for ACEG (AC Excited Generator), the most widely used ASG, there is no proper and effective mathematical model of ACEG for stability analysis. Based on the power system stability perspective, modeling, control strategy and stability analysis of ACEG have been studied, main achievements are as follows:Based on the proposed rotor magnetic field dq0 coordinates, a new mathematical model of ACEG is established and the corresponding 5th order practical model is derived too. It can be easily degraded to the model of traditional synchronous generator, thus, it reveals the differences and relations between ACEG and ordinary synchronous generator. A more simplified 3rd order practical model for ACEG (round pole) used only is also derived. Simulation results of several typical experiments show that the above models are correct.Based on the ACEG 5th order practical model, a linearized model with K₁～K₁₄ real coefficients for ACEG SMIB system is derived for small signal stability analysis. It can be degraded to the K₁～K₆, model of traditional synchronous generator conveniently. Meanwhile, a linearized model with K₁～K₁₁ real coefficients for ACEG is obtained based on the above ACEG 3rd order practical model. Eigenvalues and simulation results of small disturbances in an ACEG SMIB testing system have verified the above linearized models.Presents a new kind of Stator Voltage Oriented Vector Control Excitation Strategy for ACEG, the corresponding linearized model is also derived. Simulations with the nonlinear model and small signal analysis of testing systems have proved that the strategy system can achieve perfect decoupled control of active and reactive power (or voltage), and has good characteristics of stability as well.A linearized model of multi-machine power system containing ACEGs with regulation system concerned is derived. For a testing system containing an ACEG and the other with synchronous machines only, simulations and eigenvalues of the two system have been compared. The comparison indicates that the introduction of ACEG(s) can significantly improve the stability of multi-machine power system.