Parameter design method for series passive impedance adapter applicable to voltage source converter based high voltage direct current (vsc-hvdc) transmission system

A parameter design method for a series passive impedance adapter applicable to a voltage source converter based high voltage direct current (VSC-HVDC) transmission system, wherein the series passive impedance adapter comprises a capacitor, a resistor, and an inductor, and the capacitor and the resistor are connected to the inductor in parallel after being connected in series;

• and
• the parameter design method comprises the following steps:
• step 1:
• obtaining alternating current (AC) impedance of a VSC-HVDC transmission system within a specified frequency range;
• and
• calculating an AC impedance evaluation index of the VSC-HVDC transmission system based on the AC impedance of the VSC-HVDC transmission system;
• step 2:
• setting parameters A, B, and C;
• calculating an initial parameter of the inductor based on a premise that a rated current only flows through a branch of the inductor and reactive power consumed by the series passive impedance adapter is A times rated power of a converter;
• determining an initial parameter of the resistor based on a premise that a resistance value of the resistor is equal to a maximum value of the AC impedance evaluation index of the VSC-HVDC transmission system within the specified frequency range;
• determining an initial parameter of the capacitor based on a premise that capacitive reactance of the capacitor is C times inductive reactance of the inductor;
• determining a parameter change range of the inductor based on the initial parameter of the inductor and a preset multiple change range of the initial parameter of the inductor;
• determining a parameter change range of the resistor based on the initial parameter of the resistor and a preset multiple change range of the initial parameter of the resistor;
• determining a parameter change range of the capacitor based on the initial parameter of the capacitor and a preset multiple change range of the initial parameter of the capacitor;
• determining a parameter combination change range based on the parameter change range of the inductor, the parameter change range of the resistor, and the parameter change range of the capacitor;
• calculating a reactive power consumption and an active power loss of the series passive impedance adapter under each parameter combination within the parameter combination change range;
• wherein for any parameter combination, if the reactive power consumption of the series passive impedance adapter is greater than A times the rated power of the converter, or Re{Zadapter(f)}>X(f) is not always satisfied within the specified frequency range, the active power loss is denoted as N*B times the rated power of the converter, wherein Re{Zadapter(f)} represents a real part of an impedance transfer function of the series passive impedance adapter, and X(f) represents the AC impedance evaluation index of the VSC-HVDC transmission system;
• and
• obtaining a parameter combination with a lowest active power loss based on the active power loss of each parameter combination;
• and
• step 3:
• if the parameter combination with the lowest active power loss satisfies a condition that Re{Zadapter(f)}>X(f) is always satisfied within the specified frequency range, reducing a value of A or B, and returning to step 2 until the parameter combination with the lowest active power loss does not satisfy the condition that Re{Zadapter(f)}>X(f) is always satisfied within the specified frequency range, to obtain a global optimal parameter combination;
• or if none of parameter combinations within the parameter combination change range satisfies the condition that Re{Zadapter(f)}>X(f) is always satisfied within the specified frequency range, increasing a value of A or B, and returning to step 2 until a global optimal parameter is obtained.