مد کنترلی مورد استفاده چیست؟ ظاهراً مشکل سیستم مورد نظر، یک Reactive load sharing ناموفق ناشی از تغییر AVRمی باشد که موجب جریانهای گردشی نوسانی بین ژنراتورها شده است. برخی از مدهای کنترلی نظیر Cross current compensation for kVAR load sharing نسبت به این تغییرات حساس تر می باشند، بنابراین باید ضمن چک مجدد ستینگ تجهیزات با توجه به مد کنترلی انتخابی، با سازنده سیستم کنترل جدید مشورت نمود. پارامترهای متنوعی ممکن است در بروز این اختلال سهیم باشند. In a paralleled arrangement, the voltage and frequency outputs of the generator sets are forced to exactly the same values when they are connected to the same bus. Consequently, generator set control systems cannot simply monitor bus voltage and speed as a reference for maintaining equal output levels. If, for example, one set operates at a higher excitation level than the other sets, the reactive load will not be shared equally. Similarly, if a generator set is regulated to a different speed than the others, it will not share kW load properly with other generator sets in the system. Each generator set in the system has two active control systems always in operation: the excitation control system regulating voltage and the fuel control system regulating engine speed. Generators can be sharing kW load and have problems sharing kVAR load, and vice versa. So real power sharing (expressed as kW) depends on speed matching between the generator sets and fuel rate control; reactive power (expressed as kVAR) is primarily dependent upon voltage matching and excitation system control between the generator sets. Although it is sometimes possible to integrate systems of different manufacturers, generator set governors and load sharing controls should be of the same manufacturer to avoid conflicts in responsibility for proper system operation. Several types of load sharing control are available: -Droop governing and voltage regulation (reactivedroop compensation) -Isochronous kW load sharing -Cross current compensation for kVAR load sharing -Isochronous Voltage kVAR load sharing. Cross current is a flow of electrical current between generator sets that is caused by dissimilar excitation levels in those sets. Cross current compensation is a term describing operation of paralleled generator sets without intentional voltage droop. This is achieved by insertion of a droop current transformer (CT), usually on
