How do you share load and preserve essential services?

P in kW is active power; Q in kvar is reactive power exchanged with electric and magnetic fields. S = √(P² + Q²) in kVA and I = 1,000 S / (√3 U) in amperes, where U is line-to-line voltage. fref and Eref are no-load droop references, so they must exceed loaded bus values. At an equally shared 600 kW / 300 kvar load, fref = 51.2 Hz and Eref = 408 V give 50 Hz and 400 V here. Moving fref alone changes kW sharing; moving Eref alone changes kvar sharing. Both machines are already synchronised initially.

Aggregate model of a balanced lossless islanded bus; machines already synchronised. Governors: target Pm = 250 × (fref − f), bounded by 0 and engine limit; first-order response 0.6 s. Each machine has H = 4 s; df/dt = 50 × (ΣPm − Pload) / (2HΣSrated). Electrical outputs follow mechanical balance and common inertia. Excitation response: 0.5 s; Qi = 18.75 × (Ei − U), with ΣQi = Qload. No rotor-angle dynamics, detailed network, synchronisation, selectivity or automatic protection trips. Calculation stops outside 45–55 Hz or 340–460 V: model envelope, not a vessel protection setting. Losing G2 is irreversible within a trial; restart restores the initial state. This advanced study is not a complete chief-engineer programme and awaits practitioner review.