阅读说明：本技术 一种配电网5kHz高频融冰电源电路 (5kHz high-frequency ice-melting power supply circuit of power distribution network ) 是由 周羽生 曾薇 何洋 黄欣超 于 2020-07-27 设计创作，主要内容包括：本发明公开了一种配电网5kHz高频融冰电源电路,它包括：步骤1、整流单元,电网电压经隔离变压器降压后与整流单元连接；步骤2、H桥逆变单元,采用若干个H桥型逆变器串联形成的单相逆变器；步骤3、R-C阻尼型LC滤波器,逆变单元输出端通过R-C阻尼型LC滤波电路后接入覆冰配电线路,滤波电路输出端输出5kHz高压交流电。本发明解决了现有直流短路融冰与工频短路融冰技术不足的缺陷,电源电路结构各单元独立、能够实现大功率输出；串联型拓扑结构在运行时无系统环流；可根据需要融冰线路的长度、线路的电压等级、融冰电源的输出电压或容量决定所需要的H桥逆变器个数,方便了高频电源输出滤波器设计。(The invention discloses a 5kHz high-frequency ice melting power supply circuit of a power distribution network, which comprises: step 1, a rectification unit, wherein the voltage of a power grid is reduced by an isolation transformer and then is connected with the rectification unit; step 2, an H bridge inverter unit adopts a single-phase inverter formed by connecting a plurality of H bridge inverters in series; and 3, the output end of the inversion unit of the R-C damping type LC filter is connected to the ice-coated distribution line after passing through the R-C damping type LC filter circuit, and the output end of the filter circuit outputs 5kHz high-voltage alternating current. The invention overcomes the defects of the prior direct current short-circuit ice melting and power frequency short-circuit ice melting technology, and each unit of the power circuit structure is independent and can realize high-power output; the series topology structure has no system circulation when in operation; the number of the needed H-bridge inverters can be determined according to the length of the ice melting line, the voltage level of the line and the output voltage or capacity of the ice melting power supply, and the design of the high-frequency power supply output filter is facilitated.)

1. A5 kHz high-frequency ice-melting power supply circuit of a power distribution network comprises:

step 1, a rectification unit, wherein the voltage of a power grid is reduced by an isolation transformer and then is connected with the rectification unit;

step 2, an H bridge inverter unit adopts a single-phase inverter formed by connecting a plurality of H bridge inverters in series;

step 3, R-CThe output end of the inversion unit of the damping type LC filter is connected to the ice-coated distribution line after passing through the R-C damping type LC filter circuit, and the output end of the filter circuit outputs 5kHz high-voltage alternating current.

2. The power distribution network 5kHz high-frequency ice melting power supply circuit according to claim 1, characterized in that:

step 1, the PWM controllable rectifying circuit and the voltage type PWM rectifying circuit comprise six insulated gate bipolar transistors S₁～S₆(ii) a Insulated gate bipolar transistor S₁And S₄Series, insulated gate bipolar transistor S₃And S₆Series, insulated gate bipolar transistor S₂And S₅Are connected in series; the three-phase voltage type PWM rectifier network side filter inductor L has the function of filtering higher harmonic components generated in the operation process of the rectifier, and the DC side capacitor C_dcThe energy storage element can reduce ripples in the DC voltage during switching, and can maintain the output DC voltage within a certain range when the load changes.

3. The power distribution network 5kHz high-frequency ice melting power supply circuit according to claim 1, characterized in that:

step 2, the H bridge inverter unit and the inverter output unit circuit are H bridge inverters formed by IGBTs, and a plurality of H bridge inverters are connected in series to form a single-phase inverter, (H bridge inverter)₁～H_N) The high-frequency power supply output filter is a basic H-bridge unit, the topological structure can output multiple levels, reduce harmonic quantity of output waveforms, determine the number of the required H-bridge inverters according to the length of a line needing ice melting, the voltage level of the line and the output voltage or capacity of an ice melting power supply, and facilitate the design of the high-frequency power supply output filter.

4. The power distribution network 5kHz high-frequency ice melting power supply circuit according to claim 1, characterized in that:

step 3, the R-C damping LC filter is provided with a filter inductor L and a filter capacitor C on the inversion side₁、R₂-C₂Damping branch, capacitor C₁And a capacitor C₂Resistance R₂The series branches are connected in parallel, and proper filtering parameters are selected, so that sideband harmonic components of output voltage and current can be effectively filtered, the load capacity of a power supply is enhanced, the dynamic adjustment time of a system is shortened, and the stability of the system is improved.

Technical Field

The invention belongs to the ice melting technology of a power transmission line; in particular to a 5kHz high-frequency ice melting power supply circuit of a power distribution network.

Background

The ice coating of the power transmission line seriously threatens the safe and stable operation of the power system and causes great harm to national economic production and people life. The ice melting technology of the power transmission line is always an important subject of disaster prevention and reduction research of a power system, and at present, an ice melting scheme which mainly uses thermal ice melting and assists mechanical ice melting is applied to most ice removing projects. The application of the direct-current short-circuit ice melting technology and the power-frequency alternating-current short-circuit ice melting technology is mature, but the direct-current short-circuit ice melting technology and the power-frequency alternating-current short-circuit ice melting technology have certain limitations, ice can be melted after a line is shut down, a power-frequency alternating-current ice melting power supply needs to emit large reactive power, the device is large in size, and the applicability to high-voltage-class lines is not strong.

Under a high-frequency electric field, ice serves as a dielectric medium, medium loss heat is generated due to steering polarization, and equivalent resistance of unit length is increased due to a skin effect when high-frequency current passes through a lead, so that the ice-coated medium loss heat and the skin effect Joule heat act simultaneously, and uniform heating is obtained on the lead. Compared with the traditional thermal ice melting method, the high-frequency ice melting method has the advantages of small ice melting current, high ice melting uniformity, high ice melting efficiency and the like, is matched with a wave trap and a wave trap special for ice melting, has a technical development prospect of realizing ice melting without power outage, and has the core technology of researching and developing a high-frequency large-current ice melting power supply.

The invention content is as follows:

the technical problems to be solved by the invention are as follows: the high-frequency ice-melting power supply circuit of the 5kHz power distribution network is provided, ice-melting is carried out under the combined action of ice-coating medium loss heat and skin loss heat, the ice-melting time can be greatly shortened, the working efficiency is improved, the problem that the existing direct-current short-circuit ice-melting and power-frequency short-circuit ice-melting technologies are not enough is solved, the high-frequency ice-melting power supply circuit can be applied to distribution lines with the voltage level of 35kV or below, the technical development prospect of realizing the ice-melting of the lines without power outage is realized, and the economic.

The technical scheme of the invention is as follows:

a5 kHz high-frequency ice-melting power supply circuit of a power distribution network comprises:

step 1, a rectification unit, wherein the voltage of a power grid is reduced by an isolation transformer and then is connected with the rectification unit;

step 2, an H bridge inverter unit adopts a single-phase inverter formed by connecting a plurality of H bridge inverters in series;

and 3, the output end of the inversion unit of the R-C damping type LC filter is connected to the ice-coated distribution line after passing through the R-C damping type LC filter circuit, and the output end of the filter circuit outputs 5kHz high-voltage alternating current.

Step 1, the PWM controllable rectifying circuit and the voltage type PWM rectifying circuit comprise six insulated gate bipolar transistors S₁～S₆(ii) a Insulated gate bipolar transistor S₁And S₄Series, insulated gate bipolar transistor S₃And S₆Series, insulated gate bipolar transistor S₂And S₅Are connected in series. The three-phase voltage type PWM rectifier network side filter inductor L has the function of filtering higher harmonic components generated in the operation process of the rectifier, and the DC side capacitor C_dcThe energy storage element can reduce ripples in the DC voltage during switching, and can maintain the output DC voltage within a certain range when the load changes.

Step 2, the H bridge inverter unit and the inverter output unit circuit are H bridge inverters formed by IGBTs, and a plurality of H bridge inverters are connected in series to form a single-phase inverter, (H bridge inverter)₁～H_N) Is a basic H-bridge unit. The topological structure can output multiple levels, reduce harmonic quantity of output waveforms, determine the number of the needed H-bridge inverters according to the length of the ice melting line, the voltage level of the line and the output voltage or capacity of the ice melting power supply, and facilitate the design of a high-frequency power supply output filter.

Step 3, the R-C damping LC filter is provided with a filter inductor L and a filter capacitor C on the inversion side₁、R₂-C₂Damping branch, capacitor C₁And a capacitor C₂Resistance R₂Are connected in parallel. By selecting proper filtering parameters, the sideband harmonic components of output voltage and current can be effectively filtered, the load capacity of a power supply is enhanced, the dynamic adjustment time of a system is shortened, and the stability of the system is improved. The invention has the beneficial effects that:

the invention adopts an AC-DC-AC frequency conversion technology, the power frequency AC current is converted by electric energy and then outputs 5kHz high-frequency AC current, the front stage is a three-phase PWM rectifier, and the rear stage is a series H-bridge inverter unit. The H bridge inversion units are connected in series to improve output voltage and power, and a series topology structure has no system circulation when in operation, and measures are not needed to eliminate the influence of circulation. The high voltage of input alternating current is reduced into low voltage available for a rectifier by a transformer, the low voltage is converted into direct current through the rectifier of a power unit, the output of each inversion unit is connected in series, a plurality of inversion units are superposed to form multi-level high voltage, and then high-frequency sinusoidal alternating current is output through a filter device;

the invention overcomes the defects of the prior direct current short-circuit ice melting and power frequency short-circuit ice melting technology, can be applied to distribution lines with the voltage class of 35kV or below, and has the technical development prospect of realizing ice melting of the lines without power outage.

Description of the drawings:

FIG. 1 is a schematic diagram of a topological circuit configuration of the present invention;

FIG. 2 is a schematic diagram of a three-phase PWM rectification unit topology circuit structure according to the present invention;

fig. 3 is a schematic diagram of an inverter unit topology circuit structure according to the present invention.

The specific implementation scheme is as follows:

the power distribution network 5kHz high-frequency ice-melting power supply circuit is explained in the following with the attached drawings.

A5 kHz high-frequency ice-melting power supply circuit of a power distribution network is shown in figure 1, wherein the voltage of the power grid is reduced by an isolation transformer and then is connected with a rectifying unit, inversion units are connected in series, and the output ends of the inversion units are connected into an ice-coating power distribution line after passing through an R-C damping type LC filter circuit.

The power unit comprises a PWM controllable rectifying circuit, as shown in figure 2, the PWM controllable rectifying circuit is connected with a series H bridge inversion output unit circuit, the inversion output unit circuit is connected with an R-C damping type LC filter circuit, and the output end of the filter circuit outputs 5kHz high-voltage alternating current. The R-C damping LC filter circuit comprises an inductor L and a capacitor C₁Damping resistance R₂Damping capacitance C₂. By selecting proper filtering parameters, sideband harmonic components of output voltage and current can be effectively filtered, the load capacity of a power supply is enhanced, the dynamic adjustment time of a system is shortened, and the stability of the system is improved.

The PWM controllable rectifying circuit comprises six insulated gate bipolar transistors S₁～S₆(ii) a Insulated gate bipolar transistor S₁And S₄Series, S₃And S₆Series, S₂And S₅The series network side filter inductor L has the function of filtering higher harmonics in the operation process of the rectifier, and the value is 8.5 × 10^-4H. The capacitor C is used as an output direct current filter capacitor of the rectifier, so that output direct current pulsation is reduced, and the value of the output direct current pulsation is 0.05F.

The inversion output adopts an H-bridge inverter formed by a series unit circuit IGBT. The main characteristic is that the inversion power units are connected in series, each H-bridge module is composed of two groups of bridge arms and a direct current voltage source, and the direct current voltage is the output voltage of the PWM rectification unit. Each bridge arm is composed of an upper IGBT switching tube and a lower IGBT switching tube, and each IGBT is reversely connected with a diode in parallel.

The 5kHz ice melting power supply provided by the invention is formed by cascading a plurality of H-bridge inverter power units, has certain redundancy, and can increase the output voltage so as to increase the capacity of the ice melting power supply. Each power unit of the rectifier is provided with electric energy by a group of secondary sides of a transformer, and the transformer mainly plays a role in isolating a power grid and a de-icing device. The primary side of the transformer is connected into a 10kV power grid, and the secondary side voltage passes through a PWM rectification unit and then passes through a direct current capacitor C_dcStable direct current voltage is obtained after filtering, and the problem of low power factor of a network side is solved. Each H-bridge inverter power unit is a voltage type single-phase inverter circuit, and the control mode of the H-bridge inverter power unit adopts a series carrier phase shift modulation (CPS-SPWM) technology. Wherein H_i(i 1-N) is a single-phase H-bridge inverter module, L is a filter inductor, C₁Is a filter capacitor, C₂-R₂For parallel damping branches u₁For the inverter module output voltage u_oOutput voltage for de-icing the device, I_LFor filtering the inductor current, I_oIs the current of the ice coated wire.