Study On Reactive Power Compensation Devices Based On Dsp

The rapid development of power system increases the size and complexity of grid, and reactive power and harmonic current from nonlinear equipments seriously affect the quality of power energy, which bring a great challenge to grid's security, reliability and quality. The new advanced static var generator (ASVG) as an effective technology to change the quality of power system has been developed rapidly. It is becoming the hot spots of Flexible AC Transmission System because of its advanced performance on control and good compensation effect. This paper sets the ASVG as the object of study, and makes in-deep discussion about its control method, hardware and software.Specific summarized as follows.Firstly,the commonly used circuit's topologies of Var generator are introduced in this paper. The operation principle of voltage ASVG is also discussed. The two control modes of ASVG including indirect control and direct control are analyzed and compared, and elaborate their shortcoming. The commonly used reactive current detection method founded on instantaneous reactive power theory is studied in detail,and the effect of grid voltage to reactive current and harmonic detection is analyzed too. At last, a novel reactive current detection method based on ip-iq method is proposed.Mathematical model of voltage ASVG system is founded concerning its circuit topology, and we analyze the coupling relationship between the active current ip and reactive current iq in the Rotating coordinate system. And to solve this problem,we take a method of feed-forward decoupling ,which fulfills the independent control of three-phase active current and reactive current. By studying space vector control stragey of the ASVG, the system's vector control program is determined. So the model of double loop control system is established based on analyzing the DC voltage of the system. And the simulation model of main circuit is established and simulated in MatLAB. The result of simulation verifies the correctness of control method and system's feasibility.Based on theoretical analysis, the platform of hardware test platform is built. And the system hardware is designed with the TMS320LF2407A DSP as core, including sampling circuit, PLL circuit, the main circuit of compensation, the drive circuit and protection circuit. In the base of hardware, the system's software has been developed using the CCS3.1, and the main program and each module subroutine are completed. The debugging of ASVG system is carried basing on the platform of hardware and software. The correctness of the hardware circuit is verified. The results show that the system can swiftly and accurately sample the voltage on the load current, complete reactive current detection, to complete the sending SVPWM and various protection functions. And experiments verify that the control strategy is correct and the development of system's hardware and software is right and reasonable. All those lay a foundation for further debugging.