CN111668793A - 10kV distribution line uninterrupted alternating current ice melting and voltage and reactive power optimization system and method - Google Patents

Abstract

The invention relates to a 10kV distribution line uninterrupted alternating current ice melting and voltage and reactive power optimization system, which comprises a 10kV distribution line, a movable capacitive reactive power supply, a movable inductive reactive power supply, a plurality of isolation switches pre-installed on the 10kV distribution line and an ice melting and optimization controller installed in a transformer substation, wherein the isolation switches are connected with the power supply and the transformer substation; the mobile capacitive reactive power supply and the mobile inductive reactive power supply form a set of ice melting current generator, and during ice melting, the mobile capacitive reactive power supply and the mobile inductive reactive power supply are respectively connected to two ends of a line section to be melted of a 10kV distribution line through two adjacent isolation switches; the mobile capacitive reactive power source and the mobile inductive reactive power source have equal capacity. The invention has the beneficial effects that: the invention is provided with the movable capacitive reactive power supply, the movable inductive reactive power supply and the ice melting and optimizing controller, and can realize the ice melting without power outage on a 10kV distribution line.

Description

10kV distribution line uninterrupted alternating current ice melting and voltage and reactive power optimization system and method

Technical Field

The invention belongs to the field of safe operation, energy conservation and loss reduction of a 10kV distribution line, and particularly relates to a system and a method for uninterrupted alternating current ice melting and voltage and reactive power optimization of the 10kV distribution line.

Background

With the increasing frequency of extreme climates in recent years, the 10kV overhead distribution line in many mountainous areas of China often has the fault of ice coating and line breaking in winter, the reliability of power supply is reduced, and meanwhile, great property and economic loss are caused. These 10kV circuits also often have small wire diameter, long circuit, and many distribution transformers, resulting in low voltage at the end of the circuit and large line loss. The reduction in power supply reliability and power supply quality due to the above-mentioned reasons seriously affects the quality of life of residents and the development of national economy in power supply areas. Therefore, the work of melting ice and protecting electricity, improving the voltage quality and reducing the loss of the 10kV overhead distribution line in the mountainous area is urgent.

The direct-current ice melting technology developed in recent years can well solve the problem of ice coating and line breaking faults of the power transmission line, and is widely applied to two power grids. Because the redundancy of the power transmission network in China is high, the direct current ice melting can be realized in a way of 'stopping the power supply without stopping the power supply'. However, the 10kV power distribution network in China is weak, the redundancy is low, particularly, the 10kV power distribution network in mountainous areas basically has no redundancy, and once a 10kV power distribution line needs to be shut down, all users on the line lose power. And because under the direct current voltage, the high-voltage winding of the 10kV distribution transformer is a direct-current resistor, and a large number of 10kV distribution transformers are arranged on a 10kV distribution line, if the 10kV distribution transformer is possibly damaged by adopting the direct-current ice melting technology (because larger direct current passes through the high-voltage winding of the distribution transformer), the ice melting effect is also influenced (because part of the direct-current ice melting current is shunted by the 10kV distribution transformer). Therefore, the direct current ice melting technology is not suitable for melting ice of a 10kV distribution line, and the alternating current ice melting technology is needed.

An article published in Zhejiang electric power 2016, 11 th year, "a method for melting ice on a power distribution network line without power outage" aims at solving the problem of ice coating and wire breaking of a 10kV power distribution line, but the voltage of a line section which is melted ice needs to be reduced, so that users in the line section cannot normally use electricity during ice melting; and when the load of the downstream of the line section which is melted with ice is small, the ice melting effect can not be achieved. There are three patents (CN 107658778A; CN 201220619385.6; CN205882638U) for ice melting of distribution lines, which have the common disadvantages: 1) power failure and ice melting are required; 2) at ordinary times, the device is idle when the ice is not melted, and the utilization rate of the equipment is low.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a system and a method for melting ice and optimizing voltage and reactive power of a 10kV distribution line by using uninterrupted alternating current.

The uninterrupted alternating current ice melting and voltage and reactive power optimization system for the 10kV distribution line comprises the 10kV distribution line, a movable capacitive reactive power supply, a movable inductive reactive power supply, a plurality of isolation disconnecting switches pre-installed on the 10kV distribution line and an ice melting and optimization controller installed in a transformer substation; the mobile capacitive reactive power supply and the mobile inductive reactive power supply form a set of ice melting current generator, when melting ice, the mobile capacitive reactive power supply and the mobile inductive reactive power supply are respectively connected to two ends of a line section to be melted of a 10kV distribution line through two adjacent isolation switches, the mobile capacitive reactive power supply and the mobile inductive reactive power supply respectively output capacitive current and inductive current according to a set value of the ice melting current, and the line section between the two reactive power supplies in the 10kV distribution line is melted with ice without power outage; the capacity of the mobile capacitive reactive power supply is equal to that of the mobile inductive reactive power supply; the mobile capacitive reactive power supply, the mobile inductive reactive power supply and the ice melting and optimizing controller exchange information through a GPRS or a special communication network, and during ice melting, the ice melting current and the ice melting process can be controlled through the ice melting and optimizing controller arranged in a transformer substation, and the ice melting current and the ice melting process can also be controlled through the controller of the mobile reactive power supply on site.

The movable capacitive reactive power supply comprises more than one group of parallel capacitor groups and switching switches thereof, a set of SVG, a voltage transformer, a current transformer and a controller; the parallel capacitor bank and the switching switch thereof are connected with the SVG in parallel, and the parallel capacitor bank and the switching switch thereof are connected with the primary side of the voltage transformer in parallel; the secondary side of the voltage transformer is connected with an A/D sampling circuit in the controller; the primary side of the current transformer is connected in series in the mobile capacitive reactive power supply; the secondary side of the current transformer is connected with an A/D sampling circuit in the controller; the parallel capacitor bank and the switching switch thereof are respectively connected with the controller; the SVG is connected with the controller.

The mobile inductive reactive power supply comprises more than one group of parallel reactor groups and switching switches thereof, a set of SVG, a voltage transformer, a current transformer and a controller; the parallel reactor group and the switching switch thereof are connected with the SVG in parallel, and the parallel reactor group and the switching switch thereof are connected with the primary side of the voltage transformer in parallel; the secondary side of the voltage transformer is connected with an A/D sampling circuit in the controller; the primary side of the current transformer is connected in series in the mobile inductive reactive power supply; the secondary side of the current transformer is connected with an A/D sampling circuit in the controller; the parallel reactor group and the switching switch thereof are respectively connected with the controller; the SVG is connected with the controller.

Preferably, the method comprises the following steps: the ice melting and optimizing controller is also communicated with an SCADA system of the transformer substation.

Preferably, the method comprises the following steps: the isolation disconnecting links are uniformly distributed on the 10kV distribution line and are used for facilitating the uninterrupted access of the mobile reactive power supply.

Preferably, the method comprises the following steps: the movable capacitive reactive power supply increases the number of parallel capacitor banks to replace SVG.

Preferably, the method comprises the following steps: the movable inductive reactive power supply increases the number of parallel reactor groups to replace SVG.

Preferably, the method comprises the following steps: the movable inductive reactive power source is a magnetically controlled reactor.

Preferably, the method comprises the following steps: the capacitor bank in the mobile capacitive reactive power supply is divided into a plurality of capacitor banks with smaller capacity; at ordinary times, the capacitor banks are connected in parallel on the 10kV distribution line through the isolation disconnecting links, each capacitor bank is connected with the ice melting and optimizing controller, and the ice melting and optimizing controller optimizes the voltage and the reactive power of the 10kV distribution line according to the parameters and the real-time operation working condition of the 10kV distribution line.

The working method of the uninterrupted alternating current ice melting and voltage and reactive power optimization system for the 10kV distribution line comprises the following steps:

1) when ice needs to be melted on a certain section of line in a 10kV distribution line, a mobile inductive reactive power supply and a mobile capacitive reactive power supply are respectively connected to two ends of the section of line through pre-installed isolation switches, corresponding inductive current and capacitive current are output according to the required ice melting current, and the amplitude of the output inductive current is equal to that of the output capacitive current; at the moment, the current flowing through the 10kV distribution line is the superposition of the pre-ice-melting load current and the reactive power supply output current, so that the purpose of melting ice is remarkably increased; because the currents of the mobile inductive reactive power supply and the mobile capacitive reactive power supply are mutually offset, except the ice-melted line section, the currents of other sections of the 10kV distribution line are basically kept unchanged (namely the load current before ice melting), so the voltage distribution change along the line is very small, and a user can still use electricity normally in the ice melting process;

2) in normal times, a capacitor bank in the movable capacitive reactive power supply is divided into a plurality of capacitor banks with smaller capacity, and the capacitor banks are connected in parallel to a 10kV distribution line through an isolation switch pre-installed on the 10kV distribution line; the ice melting and optimizing controller controls the switching and cutting of the capacitor groups according to line parameters and real-time load working conditions so as to realize comprehensive optimization control over the voltage and the reactive power of the 10kV distribution line.

The invention has the beneficial effects that:

1. the invention is provided with the movable capacitive reactive power supply, the movable inductive reactive power supply and the ice melting and optimizing controller, and can realize the ice melting without power outage on a 10kV distribution line.

2. At ordinary times (when the ice is not melted), the capacitor bank in the movable capacitive reactive power supply can be split into a plurality of capacitor banks with smaller capacities, the voltage and reactive power optimization control can be performed on the 10kV distribution line through the ice melting and optimization controller, the voltage quality is improved, the line loss is reduced, and the energy-saving effect is good.

Drawings

FIG. 1 is a schematic diagram of a system configuration during ice melting according to the present invention;

FIG. 2 is a schematic diagram of the system configuration during voltage and reactive power optimization according to the present invention;

FIG. 3 is a schematic diagram of a mobile capacitive reactive power supply of the present invention;

fig. 4 is a schematic diagram of a mobile inductive reactive power supply according to the present invention.

Detailed Description

The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

The utility model adopts the reactive power supply to provide the alternating current ice melting current, and carries out the uninterrupted alternating current ice melting on the 10kV distribution line section needing ice melting. The problem of high voltage or low voltage of a line caused by ice melting reactive current during ice melting is solved by adopting a method of mutually matching a capacitive reactive power supply and an inductive reactive power supply. At ordinary times, the reactive power of the 10kV distribution line is compensated in a distributed mode by utilizing the capacitor group in the capacitive reactive power supply, so that the voltage quality of the 10kV distribution line can be improved, and the line loss can be reduced.

Example one

The embodiment of the application provides a system configuration structure during ice melting. As shown in fig. 1, the 110KV bus is connected to the 10KV bus through the main transformer of the substation, and the 10KV bus is connected to the 10KV distribution line. A plurality of isolation disconnecting links are uniformly installed on a 10kV distribution line. A mobile capacitive reactive power supply and a mobile inductive reactive power supply are matched to form a set of ice melting current generator. During ice melting, the two reactive power supplies are connected to two ends of the ice melting line section through the isolation disconnecting link, an ice melting and optimizing controller installed in the transformer substation coordinately controls the two reactive power supplies to generate required ice melting current, and ice melting is carried out on the line section between the two reactive power supplies without power outage. As the currents of the capacitive reactive power source and the inductive reactive power source are mutually offset, except the ice-melted line section, the currents in other sections of the 10kV distribution line are basically kept unchanged (namely the load current before ice melting), so that the voltage distribution change along the line is small, and a user can still use electricity normally in the ice melting process. The ice melting and optimizing controller, the mobile capacitive reactive power supply and the mobile capacitive reactive power supply perform information interaction through a GPRS or a special communication network.

As shown in fig. 3, the mobile capacitive reactive power source includes: at least one or more groups of parallel capacitor groups and the fling-cut switches thereof, a set of SVG, a group of voltage and current transformers and a controller. The mobile capacitive reactive power supply also can not comprise the SVG, but needs to increase the number of the parallel capacitor banks. The capacitor bank and the corresponding fling-cut switch thereof are connected with the SVG in parallel, and the capacitor bank and the corresponding fling-cut switch thereof are connected with the primary side of the voltage transformer in parallel. And the secondary side of the voltage transformer is connected with an A/D sampling circuit in the controller. The primary side of the current transformer is connected in series in the reactive power supply. And the secondary side of the current transformer is connected with the A/D sampling circuit of the controller. The controller samples local voltage and current signals and monitors the state of the controller (such as the capacitance value of a capacitor, the running state of the SVG and the like); and during ice melting, the controller controls the output of the reactive current according to the set ice melting current.

As shown in fig. 4, the mobile inductive reactive power supply comprises: at least one or more groups of parallel reactor groups and the fling-cut switches thereof, a set of SVG, a group of voltage and current transformers and a controller. The movable inductive reactive power supply also can not comprise the SVG, but needs to increase the number of the parallel reactor groups. The reactor group and the corresponding fling-cut switch thereof are connected with the SVG in parallel, and the reactor group and the corresponding fling-cut switch thereof are connected with the primary side of the voltage transformer in parallel. And the secondary side of the voltage transformer is connected with an A/D sampling circuit in the controller. The primary side of the current transformer is connected in series in the mobile inductive reactive power supply. And the secondary side of the current transformer is connected with the A/D sampling circuit of the controller. The controller samples local voltage and current signals and monitors the state (such as the capacitance value of the reactor, the SVG running state and the like) of the controller; and during ice melting, the controller controls the output of the reactive current according to the set ice melting current. The mobile inductive reactive power supply may also be just a Magnetically Controlled Reactor (MCR).

Example two

The second embodiment of the application provides a system configuration structure during voltage and reactive power optimization. As shown in fig. 2, at ordinary times, the capacitor bank in the mobile capacitive reactive power source is divided into a plurality of capacitor banks with smaller capacity, the 10kV distribution line is accessed in parallel through the isolation switch pre-installed on the 10kV distribution line, and the voltage and reactive optimal control function of the 10kV distribution line is realized through the real-time control of the ice melting and optimization controller. The ice melting and optimizing controller controls the switching and cutting of the capacitor sets according to the parameters and the real-time operation working conditions of the 10kV distribution line, so that the voltage and reactive power optimization of the 10kV distribution line is realized. The goals of the voltage and reactive power optimization control are: 1) the voltage along the 10kV distribution line is qualified; 2) the loss of the 10kV distribution line is minimum.

Claims (8)

1. The utility model provides a 10kV distribution lines alternating current ice-melt concurrently voltage and reactive power optimization system that does not have a power failure which characterized in that: the system comprises a 10kV power distribution line, a movable capacitive reactive power supply, a movable inductive reactive power supply, a plurality of isolation disconnecting switches pre-installed on the 10kV power distribution line and an ice melting and optimizing controller installed in a transformer substation; the mobile capacitive reactive power supply and the mobile inductive reactive power supply form a set of ice melting current generator, and during ice melting, the mobile capacitive reactive power supply and the mobile inductive reactive power supply are respectively connected to two ends of a line section to be melted of a 10kV distribution line through two adjacent isolation switches; the capacity of the mobile capacitive reactive power supply is equal to that of the mobile inductive reactive power supply; the mobile capacitive reactive power supply, the mobile inductive reactive power supply and the ice melting and optimizing controller exchange information through a GPRS or a special communication network;

the movable capacitive reactive power supply comprises more than one group of parallel capacitor groups and switching switches thereof, a set of SVG, a voltage transformer, a current transformer and a controller; the parallel capacitor bank and the switching switch thereof are connected with the SVG in parallel, and the parallel capacitor bank and the switching switch thereof are connected with the primary side of the voltage transformer in parallel; the secondary side of the voltage transformer is connected with an A/D sampling circuit in the controller; the primary side of the current transformer is connected in series in the mobile capacitive reactive power supply; the secondary side of the current transformer is connected with an A/D sampling circuit in the controller; the parallel capacitor bank and the switching switch thereof are respectively connected with the controller; the SVG is connected with the controller;

the mobile inductive reactive power supply comprises more than one group of parallel reactor groups and switching switches thereof, a set of SVG, a voltage transformer, a current transformer and a controller; the parallel reactor group and the switching switch thereof are connected with the SVG in parallel, and the parallel reactor group and the switching switch thereof are connected with the primary side of the voltage transformer in parallel; the secondary side of the voltage transformer is connected with an A/D sampling circuit in the controller; the primary side of the current transformer is connected in series in the mobile inductive reactive power supply; the secondary side of the current transformer is connected with an A/D sampling circuit in the controller; the parallel reactor group and the switching switch thereof are respectively connected with the controller; the SVG is connected with the controller.

2. The uninterruptible alternating current deicing and voltage and reactive power optimization system for the 10kV distribution line according to claim 1, characterized in that: and the ice melting and optimizing controller is communicated with the SCADA system of the transformer substation.

3. The uninterruptible alternating current deicing and voltage and reactive power optimization system for the 10kV distribution line according to claim 1, characterized in that: the isolation switches are uniformly distributed on the 10kV distribution line.

4. The uninterruptible alternating current deicing and voltage and reactive power optimization system for the 10kV distribution line according to claim 1, characterized in that: the movable capacitive reactive power supply increases the number of parallel capacitor banks to replace SVG.

5. The uninterruptible alternating current deicing and voltage and reactive power optimization system for the 10kV distribution line according to claim 1, characterized in that: the movable inductive reactive power supply increases the number of parallel reactor groups to replace SVG.

6. The uninterruptible alternating current deicing and voltage and reactive power optimization system for the 10kV distribution line according to claim 1, characterized in that: the movable inductive reactive power source is a magnetically controlled reactor.

7. The uninterruptible alternating current deicing and voltage and reactive power optimization system for the 10kV distribution line according to claim 1, characterized in that: the capacitor bank in the mobile capacitive reactive power supply is divided into a plurality of capacitor banks with smaller capacity; at ordinary times, the capacitor banks are connected in parallel on a 10kV distribution line through isolation switches, and each capacitor bank is connected with the ice melting and optimizing controller.

8. The method for operating the uninterruptible alternating current deicing and voltage and reactive power optimization system for the 10kV distribution line according to claim 1, comprising the following steps:

1) when a certain section of a 10kV distribution line is subjected to ice melting, a mobile inductive reactive power supply and a mobile capacitive reactive power supply are respectively connected to two ends of the section of the line through pre-installed isolation switches, corresponding inductive current and capacitive current are output according to the required ice melting current, and the amplitude of the output inductive current is equal to that of the output capacitive current; at the moment, the current flowing through the 10kV distribution line is the superposition of the load current before ice melting and the output current of the reactive power supply; the currents of the mobile inductive reactive power supply and the mobile capacitive reactive power supply are mutually offset, except for the ice melting line section, the currents in other sections of the 10kV distribution line are kept unchanged, so that the voltage distribution change along the line is small, and a user still uses electricity normally in the ice melting process;

2) in normal times, a capacitor bank in the movable capacitive reactive power supply is divided into a plurality of capacitor banks with smaller capacity, and the capacitor banks are connected in parallel to a 10kV distribution line through an isolation switch pre-installed on the 10kV distribution line; the ice melting and optimizing controller controls the switching and cutting of the capacitor groups according to line parameters and real-time load working conditions so as to realize comprehensive optimization control over the voltage and the reactive power of the 10kV distribution line.

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