Variables ∆e Error between the normalized frequency,ω, and the normalized DC voltage,V dc δ(b, t, c) Voltage angle of AC bus b at time t for contingency c δ(p, t, c) Voltage angle of AC bus p at time t for contingency c δ bp (t, c) Voltage angle difference between buses b, p at time t for contingency ĉ ω Normalized value of frequency ω V dc Normalized value of DC voltage ω Measured value of frequency ω at at time t C P V Capital cost of PV arrays C W T Capital cost of WT ES AC (b, t, c) Energy content in AC storage in bus b at the end of the current time step for contingency c P ex (b, t, c) Active power exchange between considered bus b and other buses at time t for contingency c P AC (g, t, c) Active power generation of AC generator g at time t for contingency c P ic (t, c) Active power flow through the interlinking converter at time t for contingency c P l AC (b, t, c) Active AC load at bus b at time t for contingency c P ls AC (b, t, c) Involuntary loss of active AC load at bus b at time t for contingency c P os AC (b, t, c) AC overslack for active power at bus b at time t for contingency c Q ex (b, t, c) Reactive power exchange between considered bus b and other buses at time t for contingency c Q AC (g, t, c) Reactive power generation of AC generator g at time t for contingency c Q ic (t, c) Reactive power flow through the interlinking converter at time t for contingency c Q l AC (b, t, c) Reactive AC load at bus b at time t for contingency c Q ls AC (b, t, c) Involuntary loss of reactive AC load at bus b at time t for contingency c Q os AC (b, t, c) AC overslack for reactive power at bus b at time t for contingency c S c AC (b, t, c) AC Storage charging into bus b at time t for contingency c S d AC (b, t, c) AC Storage discharging from bus b at time t for contingency c S AC (i, t, c) Apparent power of AC branch i at time t for contingency c V AC (b, t, c) Voltage at AC bus b at time t for contingency c V AC (p, t, c) Voltage at AC bus p at time t for contingency c V dc Measured value of DC voltage at time t