High-voltage network high-capacity powerfree compensation continuous regulation method

Abstract

Provided total reactive power Q requested by system is supplied by n pieces of reactive compensation branch. A fixed capacitor is connected to a variable voltage source in one piece of compensation branch to supply 0-Q / n continuous controlled reactive power. Other n-1 pieces of compensation branch connect fixed capacitor to power source to supply fixed reactive powers. System reactive power is continuous controlled from 0-Q by continuous controlling reactive power in first piece of compensation branch and switching to other compensation branches. The capacity Qv of variable voltage source is only 1 / 4n of Q. Switching operation is implemented at time of zero current of all capacitors in n pieces of reactive compensation branch in order to avoid impulsion from electric network. Features are: low cost to realize reactive continuous control for electric network in high voltage, and prolonging service life of capacitor and switches.

Description

technical field [0001] The invention relates to a large-capacity reactive power compensation continuous adjustment method for a high-voltage power grid, which can be used for reactive power compensation of a 6KV and above power grid, and belongs to the technical field of electric power systems. Background technique: [0002] At present, the main methods of reactive power compensation for 6KV and above power grids at home and abroad are as follows: [0003] 1) Provide capacitive reactive power for the power system through capacitor switching to improve the power factor of the power supply system. [0004] 2) By adjusting the conduction angle of the thyristor, the magnitude of the current passing through the inductor can be changed, and the size of the inductive reactive power can be adjusted to maintain the stability of the grid voltage. [0005] But this traditional method has the following outstanding problems: [0006] 1) Capacitor switching of large-capacity reactive po...

AI Technical Summary

Problems solved by technology

[0006] 1) Capacitor cut-off of large-capacity reactive power compensation device of high-voltage power grid is carried out in stages. Since the cost of switch-over switch in high-voltage system is very high, the number of stages cannot be too many, and the steps are all above 1000kVar. It is necessary to increase or decrease more than 1000kVar, so that the power system is still often in the state of overcompensation or undercompensation

Due to the inability to continuously adjust the reactive power of many enterprises, the economic loss of fines due to reactive power exceeding the standard is very large

[0007] 2) When the capacitor is switched on, the impact current is very large, which not only causes an impact on the power grid, but also greatly affects the life of the capacitor and the switching switch

[0008] 3) In places where reactive power changes frequently, the service life of the cut-and-throw switch is far from meeting the actual needs

Taking an electrified railway as an example, whenever a locomotive passes a certain section, reactive power compensation must be carried out, so that the number of capacitor cut-offs can be as high as 600 times / day, and a large current passes through the switch when switching, so that the switch lifespan has become a problem that cannot be solved for a long time

[0009] 4) Although the use of solid-state switches can solve the impact of current, it has high cost and large power consumption in high-voltage systems. Although the adjustment of its conduction angle can continuously adjust the reactive power, it brings serious harmonics to the power system. wave pollution

[0014] In the high-voltage power grid, the capacity of the reactive power compensation device required by the system is very large, generally at the Mvar level, for example, if Q=6Mvar, the capacity of the variable voltage source Qv=1500KVA, and the corresponding device cost is very high.

Images