Application Of Dynamic Phasor Theory In Simulation And Research Of Flexible AC Transmission System

In the 21 st century, large-scale interconnected power system has many advantages, it has become one important trend of modern power system, but it also makes modern power system becoming larger, its structure and operation mode becoming increasingly complex. At the same time, Flexible AC Transmission Systems (FACTS) has made a great progress, and significantly improved controllability, flexibility and reliability of power system. A large number of power electronic devices used in power systems make it include not only continuous events but also discrete events, so the system analysis becomes more complicated. The traditional quasi-steady model can not reflect the rapid changes in the electromagnetic transient process. Although the electromagnetic transient model can accurately reflect the electromagnetic transient process, however, the calculation speed is too slow to complete large-scale power system simulation. These new features of power system modeling and simulation need a higher requirement.STATCOM is an important compensation device in FACTS family which has fast response, big transmission capacity, and good control characteristic, it represents a new direction of reactive power compensation technology. This dissertation choose STATCOM to study has theoretical and practical significance.Dynamic phasor theory was proposed in 1991, it is a new method which based on averaging theory. The theoretical breakthrough the traditional sinusoidal quasi-steady state power system model assumption, it has made a great development in power system modeling and simulation.This dissertation expanding research from two aspects, time-domain model and the dynamic phasor model of STATCOM.First, the summary reflects overview of the reactive power compensation technology and FACTS devices modeling and simulation technology. Based on introducing the principle of STATCOM, propose optimization measures of the main circuit, study the indirect current control strategy, build and analyze the time domain mathematical model. Complete STATCOM time domain model system simulation on MATLAB/Simulink platform under changing working conditions, and validates its feasibility and effectiveness.Second, compare the dynamic phasor method with the traditional phasor method. Dynamic phasor model comes from average time-domain differential equation computation, so it has large signal, time-invariant features. In the steady state, the dynamic phasor model is transformed into the circuit theory phasor model, it reflects the physical nature of the power system. The Buck-boost converter, for example, based on time domain model derived its corresponding dynamic phasor model, compared simulation waveforms and consuming time of time domain model with dynamic phasor model, highlights advantages of dynamic phasor method, built the foundation for the study of STATCOM by using dynamic phasor.Finally, deriving STATCOM dynamic phasor model rely on its time-domain model, meanwhile complete power, transmission lines and components dynamic phasor model derivation and modeling. Compared the simulation results between the dynamic phasor model and the domain model, the results show that the STATCOM dynamic phasor model can get high precision and fast speed.