Patent ID: 7710729

Claim:
A method of filtering invalid measurements, comprising the steps of: (a) receiving measurements from a first phasor measurement unit at a sending bus i of a transmission line, and a second phasor measurement unit at a receiving bus j of said transmission line; (b) calculating charging reactive powers at said sending bus and said receiving bus; a reactive power flow excluding charging reactive power at said sending bus, a reactive power flow excluding charging reactive power at said receiving bus, and a reactive power loss of said line, using said measurements; (c) calculating a grounding admittance Y(new) using the following equation: Y ⁡ ( new ) = Q ij - Q i + Δ ⁢ ⁢ Q V i 2 + V j 2 wherein V i is a voltage magnitude at said sending bus, V j is a voltage magnitude at said receiving bus, Q i , is a reactive power flow including charging reactive power at said sending bus, and Q ij is a reactive power flow including charging reactive power at said receiving bus; and ΔQ is a power loss of said transmission line; (d) using said grounding admittance Y(new) to recalculate said charging reactive power at said receiving bus, and said reactive power flow excluding charging reactive power at said receiving bus; (e) calculating a resistance R ij and a reactance X ij using the following equation: R ij ⁡ ( new ) = aP ij + bQ ij * P ij 2 + ( Q ij * ) 2 ⁢ ⁢ and ⁢ ⁢ ⁢ X ij ⁡ ( new ) = aQ ij * - bP ij P ij 2 + ( Q ij * ) 2 wherein P ij is a real power flow at said receiving bus, Q* ij is a reactive power flow excluding said charging reactive power at said receiving bus; and a and b are calculated using the following equations: − V j 2 +V i V j Cos θ ji =a V i V j Sin θ ji =b wherein θ ji =θ j −θ i wherein θ i is a voltage angle at said sending bus and θ j is a voltage angle at said receiving bus.