Tham khảo tài liệu 'electrical generation and distribution systems and power quality disturbances part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Modeling of Photovoltaic Grid Connected Inverters Based on Nonlinear System Identification for Power Quality Analysis 67 The system identification scheme is shown in . Good accuracy of models are achieved by selecting model structures and adjusting the model order of linear terms and nonlinear estimators of nonlinear systems. Finally output voltage and current waveforms for any type of loads and operating conditions are then constructed from the models. This allows us to study power quality as required. Steady state conditions To emulate working conditions of PVGCS systems under environment changes irradiance and temperature affecting voltage and current inputs of inverters six conditions of DC voltage variations and DC current variations. The six conditions are listed as Table 1. They are 3 conditions of a fixed DC current with DC low medium and high voltage . FCLV Fixed Current Low Voltage FCMV Fixed Current Medium Voltage and FCHV Fixed Current High Voltage which shown in Fig. 16. The other three corresponding conditions are a DC fixed voltage with DC low medium and high current . FVLC Fixed Voltage Low Current FVMC Fixed Voltage Medium Current and FVHC Fixed Voltage High Current as shown in . 400 300 200 100 0 -100 -200 -300 -400 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Time msec Time msec Fig. 16. AC voltage and current waveforms corresponding to FCLV FCMV and FCHV conditions Fig. 17. AC voltage and current waveforms corresponding to FVLC FVMC and FVHC conditions Time msec 68 Electrical Generation and Distribution Systems and Power Quality Disturbances No. Case Idc A Vdc V Pdc W lac A Vac A Pac VA 1 FCLV 12 210 2520 11 220 2420 2 FCMV 12 240 2880 13 220 2860 3 FCHV 12 280 3360 15 220 3300 4 FVLC 2 235 470 2 220 440 5 FVMC 10 240 2 400 10 220 2 200 6 FVHC 21 245 5 145 23 220 5 060 Table 1. DC and AC parameters of an inverter under changing operating conditions Transient conditions Transient conditions are studied under two
