The Development Of Control System For Synchronous Compensator Integrated With Distribution Transformer

With the continuous deepening of the research of modern power electronicstechnology and control technology, more and more FACTS devices are put into actualoperation of the power system.As one of the important members in the FACTS family,STATCOM is the best reactive power compensation device in use, with comprehensivecompensation ability, good control performance, fast response characteristics,and has animportant role in reactive power compensation, dynamic voltage support, harmonicsuppression and improve system stability.Therefore, the research of principles andapplication of STATCOM has become a hot spot.Basing on the characteristics of the lowload rate in distribution network,our group proposed DT-STATCOM integrated with thedistribution transformer. DT-STATCOM not only has good compensation performance, butalso effectively reduces the cost of the device.This paper focus on the research of a controlsystem for DT-STATCOM.Firstly, the principle and control strategy of DT-STATCOM was studied. Afteranalyzing the DT-STATCOM feasibility and economics, this paper introduced the existingtarget current detection methods of STATCOM.Because DT-STATCOM spans both sides ofthe transformer, the target current detection point is inconsistent with the compensationpoint, so this paper improved the original ip-iq algorithm.The hysteresis current control method based on variable ring width, thathysteresis-band is calculated by means of system voltage and instruction current, overcamethe shortcoming of large scale of switching frequency in the traditional hysteresis currentcontrol method.Then this paper build a DT-STATCOM simulation model and verified theimproved algorithm by simulation.Then, the paper selected and designed the control system hardware platform. Based onthe significant features of DT-STATCOM,this paper proposed the configurationrequirements and design principles of the hardware platform design.To meet therequirements of computing speed and the accuracy of PWM output,the paper proposedDSP+FPGA-based dual-core processing hardware architecture.And,the DSP is responsible for the major part of STATCOM control.FPGA is responsible for the PWM modulationcapabilities.After hardware platform design is completed,the programs of DSP and FPGA werewriting and debugging. Procedures are designed in the light of the modular principle, sothe program’s versatility and readability is greatly improved.Then,the analysis and definition of function requirements for each module is carriedon. And in accordance with the functional requirements,this paper introduced detaileddesign for each module.Finally, the control system is simulated and tested to verify that the design of controlsystem hardware and software meet the needs of the system.