Low-voltage current limit and PI control unit coordination optimization method for high-voltage direct-current transmission

Abstract

The invention discloses a low-voltage current limit and PI control unit coordination optimization method for high-voltage direct-current transmission. The low-voltage current limit and PI control unit coordination optimization method for the high-voltage direct-current transmission includes steps that 1, designing objective functions capable of reflecting the dynamic reactive power change rate of converter consumption of a direct current system, the active power change rate of transmission and the reactive power peak value; 2, confirming optimization parameters of the low-voltage current limit and PI control unit of a direct-current control system, confirming decision variables of the low-voltage current limit control unit as optimization parameters, and forming an optimizing feasible region; 3, designing an electromagnetic transient time domain simulation optimization method according to an optimization object, wherein the electromagnetic transient time domain simulation optimization method has strong adaptability to the variable optimizing feasible region of the object; 4, comparing the reactive power consumption and active power restoration effects of the converter before and after optimization, if the result is reasonable, returning to the step 3, resetting initial optimization values, otherwise, returning to the step 2, and correcting the optimizing feasible region. The low-voltage current limit and PI control unit coordination optimization method for the high-voltage direct-current transmission accelerates the reactive power demand reduction at the reactive power demand faltering stage and always fastens the active power restoring in the restoring process.

Description

technical field [0001] The invention relates to a power system control operation protection technology, in particular to a method for coordinating and optimizing low-voltage current limiting and PI control links of high-voltage direct current transmission. Background technique [0002] In the AC-DC transmission system, the low-voltage current limiting unit and the PI link control unit are introduced in the DC transmission control and protection to limit the excessive DC current in the recovery stage after the fault, the minimum arc-extinguishing angle, and control the triggering angle. Reduce the reactive power to reactive power consumption of the converter, and promote the active power recovery of the transmission. [0003] The adaptability of the parameters of the low-voltage current limiting unit and the PI control unit to the DC system directly affects the recovery performance of the DC system after a fault. In the past, the optimization of the parameters of the two con...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and provide a coordinated optimization method for low-voltage direct current transmission, low-voltage current limiting and PI control links. The problem of too fast recovery of active power at the same time; it is characterized by the minimum voltage threshold value of the low-voltage current limiting link, the highest voltage threshold value, the minimum limiting current, the gain of the PI control link, and the inertia time of the integral link as variables; When the derivative of time is zero, the corresponding time point is used as the boundary to divide the optimization into two stages; the optimal objective function is designed with the derivatives of the reactive power consumption and active power recovery of the converter as factors; the embedded optimization algorithm is used to search for coordinated optimization parameters

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