Reactive compensation method for electrified railway V/V transformer

Abstract

The invention discloses a reactive compensation method for an electrified railway V / V transformer. A reactive compensation device for the electrified railway V / V transformer is adopted. The reactive compensation method comprises the specific steps that a bus voltage, a bus current and the current of a compensation network are detected; the bus voltage, the bus current and fundamental signals of the compensation network are extracted and converted into digital signals through an ADC circuit to be transmitted to a controller; the controller processes the digit value bus voltage, the digit value bus current and the digit value fundamental signals of the compensation network through a symmetrical component method and a balance compensation method in sequence, and all phase compensation admittance of the compensation network is obtained; a fuzzy PI regulator is used for obtaining a thyristor firing angle of the compensation network according to the relation of the compensation admittance and the thyristor firing angle; the controller sends out trigger pulses which are sent to the gate pole of a thyristor through a driving circuit. By means of the reactive compensation method for the electrified railway V / V transformer, reactive power can be completely compensated for, negative-sequence currents are thoroughly eliminated, and the compensation capacity is not limited.

Description

technical field [0001] The invention belongs to the technical field of electrical engineering, and relates to a reactive power compensation method for a V / V transformer of an electrified railway. Background technique [0002] Electrified railway transportation is an important mode of transportation in various countries. Electric locomotive traction has many advantages such as strong transportation capacity, low pollution and driving safety, which improves the railway transportation capacity, and is also conducive to the rational allocation of resources, reduction of operating costs, and protection of the ecological environment. etc., become the development direction of the future railway, but due to the characteristics of the electric locomotive load itself, it will cause power quality problems such as low power factor, unbalanced three-phase, high harmonic content of the electrified railway grid, and this situation will not only affect the electrified railway The power qual...

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Problems solved by technology

In the three-phase compensation of the secondary side of the STATCOM traction substation, each H-bridge needs a cascaded transformer and voltage support capacitor, resulting in complex system structure, difficult control, and high cost; the method of two-phase compensation on the secondary side of the APF traction substation uses APF eliminates the harmonics and reactive current of the system, but due to the limitation of the applicable voltage level of the fully-controlled device, this method requires two compensation transformers for voltage conversion and sends the compensation current to the secondary side of the traction transformer, resulting in a very large system size. Large, the compensation capacity is greatly limited, and the transformer needs to have the transmission capacity of higher harmonics, so the application of this method is limited; the two-phase compensation method on the secondary side of the SVC traction substation can completely eliminate the reactive power and harmonics of the system current, but the negative sequence current cannot be eliminated. When the capacity of the power supply system is not sufficient, the asymmetric operation of the secondary side will generate voltage asymmetry on the primary side

The three-phase compensation method on the primary side of the SVC traction substation is a direct compensation scheme on the primary side, which can completely eliminate the reactive power, harmonics and negative sequence current of the primary side (high voltage side) system, and can balance the asymmetry of the primary side grid, although The harmonic components on the secondary side of the transformer can be filtered out after passing through the transformer and flowing into the fixed capacitor filter bank on the primary side, but the harmonics passing through the transformer will seriously affect the performance of the transformer

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