gen substation load V ok V/flow limitLines colored by loading; dots show power-flow direction. Click any element to inspect & edit.
Time
—
Frequency
— Hz
ACE
0 MW
Gen / Load
0/0
Op. reserve
0 MW
Marginal price
$0
Bus voltage
— pu
Worst line
0 %
System inertia
0 GW·s
Renewables
0 %
RoCoF
0.0 Hz/s
Status
—
A 12-bus, two-voltage-level system dispatched by economic merit order. Advance the clock, trip a unit or line, edit any unit, and watch frequency, voltages, flows and price respond.
Economic dispatch: cheapest units first to meet net load; marginal unit sets price λ ($/MWh)
Real power (angles): Pij = (θi−θj)/xij · Voltage (Q–V): B″·ΔV = ΔQ
A decoupled load flow: bus angles carry MW, bus voltages follow reactive balance (shunt caps support voltage locally). Only synchronous machines add inertia. Protection trips overloaded lines, sheds load on under-frequency or under-voltage. When a line hits its limit, dispatch is constrained and locational prices separate — congestion.
Teaching notes
Watch a day unfold: load rises to an evening peak while solar fades; the merit order climbs from nuclear/renewables into gas, and the marginal price rises with it.
Contingency (N−1): trip the biggest unit or a key 345 kV line — frequency dips (RoCoF set by inertia), flows reroute and can overload a neighbor, and voltages sag. See if the system rides through.
Voltage control: lower the shunt-capacitor support and voltages sink toward load centers; raise a generator's voltage setpoint to hold its area up.
Inertia & renewables: push wind/solar up and thermal down — system inertia falls (GW·s), so the same contingency produces a steeper RoCoF.
Edit anything: click a unit to change capacity, cost, inertia, droop or voltage setpoint; click a line for its rating and flow; click a bus for its voltage and load.
Click a generator, line, or bus on the network to inspect and edit it.