CN104753015B - Ice-melting device for transmission line - Google Patents

Abstract

The invention discloses a power transmission line ice-melting device. The device includes a transformer and a diode rectifier bridge, and also includes a three-phase voltage source converter and an AC output filter. The secondary windings of the transformer are respectively connected to the three-phase voltage source converter. The three-phase AC output terminal of the current and AC output filter and the three AC input terminals of the diode rectifier bridge, the three-phase voltage source conversion and AC output filter are mainly composed of a three-phase voltage source conversion circuit and a three-phase filter circuit It is used to convert the three-phase voltage source and compensate the harmonic current generated by the diode rectifier bridge when the ice-melting device is operating in the ice-melting mode. utilization rate.

Description

Transmission line ice melting device

technical field

The invention relates to the technical field of electrical engineering, in particular to an ice-melting device with active reactive power compensation and filtering functions.

Background technique

When a freezing accident occurs in winter, the transmission line needs to use an ice-melting device to inject a certain amount of current into the transmission line to heat the transmission line and then melt the ice. The size of the DC output voltage can adjust the size of the current in the transmission line. In order to ensure the high reliability of the ice-melting device, in the prior art, step-down transformers and diode rectifiers are generally used as the ice-melting device to realize the DC power output of the ice-melting device. However, the ice melting device with this structure has the following defects: defect 1, large harmonic currents are generated during the operation of the ice melting device, and a filtering device with a certain capacity needs to be added to the input side of the device; defect 2, the utilization rate of the ice melting device is low, and the investment within one year The operating time is very little. If the line is not seriously iced, the ice melting device may not be put into real use for a year or even several years, causing the ice melting device to be idle in the substation for many years. Therefore, according to the characteristics of the ice-melting device of this structure and combined with the functional requirements of the substation, it is urgent to develop an ice-melting device with small operating harmonics, simple structure, high operational reliability, and effective improvement of device utilization.

Contents of the invention

The object of the present invention is to provide a power transmission line ice-melting device that can effectively improve the utilization rate of transformers.

The power transmission line melting device provided by the present invention includes a transformer and a diode rectifier bridge, and also includes a three-phase voltage source converter and an AC output filter, and the secondary winding of the transformer is respectively connected to the three-phase voltage source converter and the AC output filter. The three-phase AC output terminal of the device and the three AC input terminals of the diode rectifier bridge. The three-phase voltage source converter and AC output filter are mainly composed of a three-phase voltage source converter circuit and a three-phase filter circuit. The three-phase voltage source converts the current and compensates the harmonic current generated by the diode rectifier bridge when the ice-melting device operates in the ice-melting mode, and operates in dynamic reactive power compensation when the ice-melting device is not melting.

The transformer is a three-winding transformer, one of which is a three-phase primary winding, and the other two windings are three-phase secondary windings. The corresponding three-phase voltage source converter, AC output filter and diode rectifier bridge also have two The first three-phase secondary winding is respectively connected to the three-phase AC output terminals of the first group of voltage source conversion and AC output filters and the three AC input terminals of the first group of diode rectifier bridges, and the second three-phase The secondary windings are respectively connected to the three-phase AC output terminals of the second group of voltage source converters and AC output filters and the three AC input terminals of the second group of diode rectifier bridges, and the negative terminals of the first group of diode rectifier bridges are connected to the second group of diode rectifier bridges. The positive terminals of the two sets of diode rectifier bridges, the positive terminals of the first set of diode rectifier bridges are connected to one end of the ice-melting line as the positive output terminal, and the negative terminals of the second set of diode rectifier bridges are connected to the ice-melting line as the negative output terminal the other end of the The diode rectifier bridge is a three-phase full-bridge diode rectifier bridge. The three-phase voltage source converter and AC output filter is a two-level three-phase voltage source converter and AC output filter, or a three-level three-phase voltage source converter and AC output filter, or a chained multi-voltage filter. Circuit of flat three-phase voltage source converter and AC output filter.

The present invention adds a three-phase voltage source converter and an AC output filter on the basis of the prior art, so that the ice-melting device has active reactive power compensation and filtering functions. When the ice-melting device operates in the ice-melting mode, three The phase voltage source conversion and the AC output filter compensate the harmonic current generated by the diode rectifier bridge, so that these harmonic currents will not flow into the secondary winding of the transformer; when the device does not need to operate in the ice-melting mode, the diode rectifier bridge stops working , the three-phase voltage source converter and the AC output filter operate in the dynamic reactive power compensation mode, thereby improving the utilization rate of the ice-melting transformer.

Description of drawings

Fig. 1 is a circuit block diagram of the present invention.

Fig. 2 is a circuit diagram of the first embodiment of the present invention.

Fig. 3 is a circuit diagram of a second embodiment of the present invention.

Fig. 4 is a circuit diagram of a third embodiment of the present invention.

detailed description

Embodiment 1: It can be seen from Fig. 1 that the present invention includes a transformer 1 and a diode rectifier bridge (4, 5), and also includes a three-phase voltage source converter and an AC output filter (2, 3), and a diode rectifier bridge (4, 5). 5) A three-phase full-bridge diode rectifier bridge is adopted. Transformer 1 adopts a three-winding transformer, in which one winding in the three-winding transformer is a three-phase primary winding, and the other two windings are three-phase secondary windings. The corresponding three-phase voltage source There are also two groups of converter and AC output filters (2, 3) and diode rectifier bridges (4, 5). A three-phase secondary winding is respectively connected to the three-phase AC output terminals U1/V1/W1 of the first group of three-phase voltage source conversion and AC output filter 2 and the three AC input terminals of the first group of diode rectifier bridge 4 A1/B1/C1, the second three-phase secondary winding of transformer 1 is respectively connected to the three-phase AC output terminal U2/V2/W2 of the second group of three-phase voltage source converter and AC output filter 3 and the second group The three AC input terminals A2/B2/C2 of the diode rectifier bridge 5, the negative terminal of the first group of three-phase full-bridge diode rectifier bridge 4 is connected to the positive terminal of the second group of diode rectifier bridge 5, the first group of diode rectifier bridge 4 The positive end DC1+ of the ice-melting device of the present invention is connected to one end of the ice-melting circuit as the positive output end DC+ of the ice-melting device of the present invention, and the negative end DC2- of the second group of diode rectifier bridge 5 is connected as the negative output end DC- of the ice-melting device of the present invention The other end of the melted line.

For the two groups of the filters (2, 3) and the diode rectifier bridges (4, 5) used in the same embodiment, the configuration is the same, except that they are respectively connected to the two secondary windings. The following uses one of the circuit diagrams of the three-phase voltage source converter and AC output filter 2 and the diode rectifier bridge 4 to illustrate their composition, see FIG. 2 . It can be seen from the figure that the three-phase voltage source converter and the AC output filter of this embodiment are two-level, and the two-level structure is simple in structure, and the required power electronic components (such as insulated gate bipolar transistor- IGBT) and other characteristics, but because a single power electronic device needs to withstand high voltage, it cannot directly achieve high voltage output. When the output voltage of the transformer is high (greater than 1000V), it is necessary to introduce a step-down transformer and a step-up transformer, resulting in Equipment is complicated. This structure should be adopted when the output voltage is low.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that its three-phase voltage source converter and AC output filter are three-level. Compared with Embodiment 1, it can realize high voltage by connecting power electronic devices in series. Output, without additional step-down transformers and step-up transformers, but when the output reactive power capacity is large (greater than 1000kvar), it is necessary to introduce power electronic components in parallel to achieve high current output, and at the same time connect power electronic components in series and in parallel It is a difficult point, and it is easy to reduce the reliability of device operation. This structure should be adopted when the output voltage is high and the capacity is small.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that its three-phase voltage source converter and AC output filter are chained multi-level, and low-voltage power electronic devices are used to form power modules, and the power modules can be connected in series. Realize high voltage and large reactive capacity output. This structure should be adopted when the output voltage is high and the capacity is large.

Claims (3)

1. a kind of ice-melting device for transmission line, including transformator (1) and diode rectifier bridge（4、5）, it is characterised in that also include Two groups of three-phase voltage source unsteady flows and exchange output filter (2,3), the vice-side winding of the transformator are coupled with the three-phase Voltage source unsteady flow and the three-phase alternating current outfan and diode rectifier bridge of exchange output filter (2,3)（4、5）Three exchange Input, the diode rectifier bridge are two three phase full bridge diode rectifier bridges, for realizing DC ice melting, the three-phase electricity Potential source unsteady flow and exchange output filter be mainly made up of three-phase voltage source convertor circuit, for three-phase voltage source unsteady flow and Filter action is played in ice-melt, is compensated the harmonic current that diode rectifier bridge is produced, is run on dynamic passive compensation in not ice-melt.

2. ice-melting device for transmission line according to claim 1, it is characterised in that the transformator is three-winding transformer, its In winding be three-phase primary side winding, another two winding is three-phase vice-side winding, corresponding three-phase voltage source unsteady flow and friendship Stream output filter (2,3) and diode rectifier bridge（4、5）Also there are two groups respectively, first three-phase vice-side winding is coupled with First group of voltage source unsteady flow and exchange output filter（2）Three-phase alternating current outfan and first group of diode rectifier bridge（4）'s Three ac input ends, second three-phase vice-side winding are coupled with second group of voltage source unsteady flow and exchange output filter（3） Three-phase alternating current outfan and second group of diode rectifier bridge（5）Three ac input ends, first group of diode rectifier bridge（4） Negative pole terminate to second group of diode rectifier bridge（5）Positive terminal, first group of diode rectifier bridge（4）Positive terminal as just Output is terminated to by one end of DC ice-melting, second group of diode rectifier bridge（5）Negative pole end be connected to as negative output terminal and melted The other end of ice circuit.

3. ice-melting device for transmission line according to claim 1 or claim 2, it is characterised in that the three-phase voltage source unsteady flow and exchange Output filter be two level three-phase voltage source unsteady flows and exchange output filter or for three-level three-phase voltage source unsteady flow and Exchange output filter or for many level three-phase voltage source unsteady flows of chain type and exchange output filter circuit.