| Symbol | Meaning | Unit |
| ΔPmi | Conventional turbine mechanical power deviation | p.u. |
| ΔPwind | Wind turbine mechanical power deviation | p.u. |
| ΔPd | Disturbance power | p.u. |
| Δf | Deviation of system frequency | p.u. |
| PED | Instruction power | w |
| Tgi | Speed governor time constant | sec |
| Fri | Reheat time constant | sec |
| Tri | Turbine time constant | sec |
| D | Load-damping constant | - |
| K1 | Integral gain of secondary frequency control | - |
| R1 | Regulation coefficient of primary control | - |
| H | Inertia of generators and motors | - |
| s | Laplace operator | - |