Patent ID: 7321834
Filing Date: 2008-01-22
Classification: H02J,Y02E,Y04S

Abstract:
1. A method for calculating power flow solution of a power transmission network that includes the interline power flow controllers (IPFCs), said IPFC having a plurality of voltage source converters (VSCs), wherein the DC sides of said VSCs are linked together to a DC coupling capacitor and the AC sides are linked to the transmission lines of said power transmission network through coupling transformers; said VSCs being modeled by a plurality of series branches, each series branch comprising a voltage source in series with an impedance; the first series branch being able to adjust the active or reactive power of a transmission line of said power transmission network; each of the remaining series branches being able to adjust simultaneously the active and reactive power of a transmission line of said power transmission network; said power flow solution including the voltage at each bus of said power transmission network and the equivalent voltages of the VSCs; said method comprising: A) calculating an original mismatch vector without considering the IPFC; B) establishing a Jacobian matrix corresponding to the original mismatch vector in A); C) obtaining d-q components of a receiving-end bus voltage of the IPFC by a d-q axis decomposition; D) calculating equivalent active and reactive loading at sending-end and receiving-end buses of a first branch of the IPFC; E) calculating equivalent active and reactive loading at sending-end and receiving-end buses of remaining series branches; F) calculating active power flowing from a DC coupling capacitor; G) modifying the original mismatch vector and the Jacobian matrix; H) updating an unknown vector by an iteration formula; I) judging convergence of the power flow solution; if the solution converges within a specified tolerance, going to J); otherwise, going to A); J) calculating the equivalent voltage of a converter; and k) using the result in J in setting up a steady state model of IPFC.