DAVR-A1A2系列发电机励磁调节器 三.ppt

1 ` 原理框图 应用范围带有永磁机（PMG）供电的同步电动机或同步发电机 应用范围由外部厂用电供电的同步电动机或同步发电机 AVR的改进型，用于带有直流励磁机的同步电动机或同步发电机 应用范围自并励励磁的同步发电机 应用范围带有交流强励系统的自并励同步发电机 带有直流强励系统的自并励同步发电机 Start sequence? If remanence voltage is too low ( 9VAC 3~ or 18 VDC) field flashing or auxiliary supply is required. No over voltage protection? VDR (MOX) in the field is not our standard, since VDRs are quite expensive devices. If required, it can be supplied and connected externally. What’s RS-232 for? Connection to computer for PCTools Software. What’s RS-485 for? Bus communication for VDC (Voltage Droop Compensation) between the AVRs of parallel connected generators. What’s Unet for? Unet will be used for automatic synchronisation (which is a future option). What’s the tact frequence of PWM? It is 1 kHz. How does VDC mode work? VDC is a kind of digital joint control for parallel AVRs. In VDC mode, actually, all AVRs operate in Auto mode with voltage droop. However, each AVR (with own ID number) writes to the RS-485 bus the value of its own amount of reactive power. Each unit reads these values and calculates a common average Mvar setpoint, and compensates the effect of voltage droop. Therefore, voltage level on the busbar is always kept at 100% (not adjustable). More detailed: The VDC function influences the setpoint of the voltage regulator in the same way (but opposite direction) as the reactive power influence does. That is, the actual value of reactive current from the machine in question, is compensated with the average amount of the reactive currents in all machines. Calculated average of reactive current is a correct target value, even if reactive currents are not shared equally in transient situation. This improves system stability. Can generators be added and taken away from the net in VDC mode? Yes. AVRs synchronise themselves automatically to RS-485 communication. RS-485 is hard wired (twisted pair) connection and permanently connected. How can AVRs be divided to separate islands? O