CN214900082U - Voltage source type direct-current ice melting device and flexible interconnection system - Google Patents
Voltage source type direct-current ice melting device and flexible interconnection system Download PDFInfo
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- CN214900082U CN214900082U CN202121133659.6U CN202121133659U CN214900082U CN 214900082 U CN214900082 U CN 214900082U CN 202121133659 U CN202121133659 U CN 202121133659U CN 214900082 U CN214900082 U CN 214900082U
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Abstract
The application discloses voltage source type direct current ice melting device and flexible interconnected system, voltage source type direct current ice melting device includes: the system comprises a starting unit connected with an alternating current power supply end, a modular multilevel converter with an alternating current input end connected with the starting unit, and a measurement control unit connected with the modular multilevel converter, wherein the measurement control unit is connected with the starting unit; the flexible interconnection system comprises two voltage source type direct current ice melting devices with completely same circuit structures, and direct current ends of the two voltage source type direct current ice melting devices are connected in parallel. The starting unit is used for enabling alternating current to flow into the device, and the measurement control unit is used for adjusting the operating state of the modular multilevel converter, so that the modular multilevel converter outputs direct current deicing current to achieve direct current deicing or outputs or absorbs reactive power to achieve reactive power compensation on an alternating current power supply, and the two alternating current power grids can achieve power mutual aid through the flexible interconnection system to achieve flexible interconnection.
Description
Technical Field
The invention relates to the technical field of ice melting of power transmission lines, in particular to a voltage source type direct current ice melting device and a flexible interconnection system.
Background
Among various natural disasters suffered by an electric power system, a freezing disaster is one of the most serious threats, the freezing disaster can cause icing of an electric transmission line, the mechanical and electrical properties of the electric transmission line are seriously influenced, even power supply interruption caused by tower collapse and disconnection occurs, the area where the electric transmission line of the electric power grid passes is complex, meteorological conditions are variable, the serious icing is easy to occur in winter, and the serious threat is caused to the stable and reliable operation of the electric power system. Since 2008, the large-scale freezing disaster in the south causes serious damage to power systems in provinces such as Hunan, Guizhou and Jiangxi, the frequent occurrence of tower collapse and line break accidents caused by the fact that ice cannot be melted in time causes great damage to power transmission lines and power grid structures, and the reliable power supply of users is directly influenced.
At present along with economic technology's development and people's standard of living's improvement, the electric energy has become the essential secondary energy in people's production life, provides endless facility for people's life, consequently, when the transmission line icing condition appears in the electric wire netting, if can't in time clear away the icing, probably lead to the power supply to interrupt to serious influence people's daily life.
Disclosure of Invention
In order to solve the problems, the application provides a voltage source type direct current ice melting device and a flexible interconnection system, which are used for solving the problem that when an ice coating condition occurs on a power grid transmission line, the ice coating cannot be timely removed, so that the ice coating is serious and a tower collapse and disconnection occur. In addition, the invention can also realize reactive compensation to the alternating current power grid and flexible interconnection of the two alternating current power grids, thereby improving the power supply reliability. To achieve the above object, the proposed solution is as follows:
a voltage source type DC ice melting device comprises:
the starting unit is connected with the alternating current power supply end;
the DC output end of the modular multilevel converter is used for connecting a line to be ice-melted when the voltage source type DC ice-melting device is in an ice-melting mode;
the measurement control unit is connected with the modular multilevel converter and is used for controlling the running state of the modular multilevel converter;
the measurement control unit is connected with the starting unit, the measurement control unit sends a switching signal to the starting unit, and the starting unit adjusts the current value of the alternating current flowing into the device based on the switching signal.
Preferably, the starting unit includes: an alternating current breaker, a charging resistor and a bypass switch;
the bypass switch is connected with the charging resistor in parallel, a first public end after the parallel connection is connected with an alternating current power supply end through the alternating current circuit breaker, and a second public end is connected with an alternating current input end of the modular multilevel converter;
the bypass switch is connected with the measurement control unit, and receives the switch signal sent by the measurement control unit to complete the on-off of the bypass switch.
Preferably, the modular multilevel converter comprises: the three-phase converter comprises three phases with the same structure, wherein each phase is divided into an upper bridge arm and a lower bridge arm, each bridge arm is formed by connecting a bridge arm reactor and a flexible direct current converter valve in series, and the upper bridge arm reactor and the lower bridge arm reactor of each phase are connected in series in the same direction;
the connection point of the upper bridge arm and the lower bridge arm of each phase of the modular multilevel converter is connected with the starting unit;
and the flexible direct current converter valves on each bridge arm in the modular multilevel converter are connected with the measurement control unit.
Preferably, the measurement control unit includes: the control protection subunit, the valve level control subunit and the measurement subunit are connected;
the control protection subunit is respectively connected with the valve level control subunit, the measuring subunit and the starting protection unit;
the valve control subunit is connected with the modular multilevel converter and is used for controlling the operation state of the modular multilevel converter;
the measuring sub-unit is used for measuring the electric parameters of the direct current output end or the alternating current power end of the modular multilevel converter.
Preferably, any one of the aforementioned devices further comprises: a first knife switch and a second knife switch;
and the direct current output end of the modular multilevel converter is connected with the line to be de-iced through the first disconnecting link and the second disconnecting link respectively.
Preferably, the measurement control unit is connected to the starting unit, the measurement control unit sends a signal to the starting unit, and the starting unit receives the signal and releases the limitation on the alternating current flowing into the device.
A flexible interconnect system comprising:
two voltage source type DC ice melting devices as described above;
the measurement control units in the two voltage source type direct current ice melting devices are connected;
the direct current output ends of the modular multilevel converters in the two voltage source type direct current ice melting devices are correspondingly connected, so that the direct current sides of the two voltage source type direct current ice melting devices are connected in parallel.
Preferably, the measurement control units in the two voltage source type dc ice melting devices each include: the control protection subunit, the valve level control subunit and the measurement subunit are connected;
the measurement control units in the two voltage source type direct current ice melting devices are connected, and the measurement control units comprise:
and the control protection subunits in the two voltage source type direct current ice melting devices are connected.
Preferably, the measurement control units in the two voltage source type dc ice melting devices each include: the control protection subunit, the valve level control subunit and the measurement subunit are connected;
the measurement control units in the two voltage source type direct current ice melting devices are connected, and the measurement control units comprise:
the control protection subunits in the two voltage source type direct current ice melting devices are the same subunit.
Preferably, any one of the systems described above further comprises: a third knife switch and a fourth knife switch;
and the third knife switch and the fourth knife switch are used for correspondingly connecting the direct current output ends of the two modular multilevel converters in the flexible interconnection system, so that the direct current sides of the two voltage source type direct current ice melting devices are connected in parallel.
According to the technical scheme, when the voltage source type direct current ice melting device achieves a direct current ice melting mode, two ends of the starting unit are respectively connected with the alternating current power supply and the modular multilevel converter, so that alternating current flows into the modular multilevel converter, and the measuring and controlling unit adjusts the running state of the modular multilevel converter, so that the modular multilevel converter converts alternating current into direct current and outputs the direct current at the direct current output end of the modular multilevel converter. The direct current at the direct current output end of the modular multilevel converter can be regulated to hundreds of amperes or thousands of amperes by regulating the running state of the modular multilevel converter through the measurement control unit, and after the direct current flows into the line to be melted, the line to be melted generates heat, so that ice is covered on the surface of the line and is melted.
Further, the measurement control unit is connected with the starting unit, and based on the connection relation, the measurement control unit can send a switching signal to the starting unit. When the alternating current is too large, the starting unit limits the size of the alternating current based on the switching signal, and damage to the modular multilevel converter caused by the too large alternating current is avoided; when alternating current is stabilized in a device bearable range, the starting unit removes the limitation on the size of the alternating current based on the switching signal, and the starting unit is prevented from being damaged due to the fact that the starting unit limits the current for a long time.
Furthermore, the device can be used for performing reactive compensation on the alternating current power supply, and when a reactive compensation mode is realized, the direct current output end of the modular multilevel converter is in a disconnected state and is not connected with a line to be melted with ice. The two ends of the starting unit are respectively connected with the alternating current power supply and the modular multilevel converter, so that alternating current flows into the modular multilevel converter, and the measuring and controlling unit adjusts the running state of the modular multilevel converter, so that the modular multilevel converter absorbs or outputs reactive power to the alternating current power supply. When the measurement control unit measures that the reactive power of the alternating current power supply is excessive, the modular multilevel converter absorbs the reactive power of the alternating current power supply; when the measurement control unit measures that the reactive power of the alternating current power supply is insufficient, the modular multilevel converter outputs the reactive power of the alternating current power supply, and then reactive compensation of an alternating current power supply end is achieved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a voltage source type dc ice melting device according to an embodiment of the present disclosure;
fig. 2 is a circuit structure diagram of a voltage source type dc ice melting device in a dc ice melting mode according to an embodiment of the present application;
fig. 3 is a circuit structure diagram of a voltage source type dc ice melting device provided in the embodiment of the present application when the device is in a reactive compensation mode;
FIG. 4 is a schematic structural diagram of a flexible interconnect system according to an embodiment of the present application;
fig. 5 is a circuit structure diagram of a flexible interconnect system according to an embodiment of the present application in a flexible interconnect mode;
fig. 6 is a circuit structure diagram of a flexible interconnection system in a dc ice melting mode according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Fig. 1 is a schematic structural diagram of a voltage source type dc ice melting device provided in an embodiment of the present application, where the device may include: a starting unit 10 connected with an alternating current power supply end; the modular multilevel converter 20 is connected with the starting unit 10 at an alternating current input end AC1, and a direct current output end of the modular multilevel converter 20 is used for connecting a line to be ice-melted when the voltage source type direct current ice melting device is in an ice melting mode; a measurement control unit 30 connected to the modular multilevel converter 20 for controlling an operation state of the modular multilevel converter 20, wherein the measurement control unit 30 is connected to the starting unit 10, the measurement control unit 30 sends a switching signal to the starting unit 10, and the starting unit 10 adjusts a current value of an ac current flowing into the device based on the switching signal.
In this embodiment, the voltage source type dc ice melting apparatus can melt ice in dc, when entering a dc ice melting mode, an ac current flows into the modular multilevel converter 20 through the starting unit 10, and the measurement control unit 30 controls the operating state of the modular multilevel converter 20, so that the modular multilevel converter 20 converts ac current into dc current with a set value, and after the dc current flows into a line to be melted, the line to be melted generates heat, and ice is further coated on the line to be melted.
Further, the measurement control unit is connected with the starting unit, and based on the connection relation, the measurement control unit can send a switching signal to the starting unit. When the alternating current is too large, the starting unit limits the size of the alternating current based on the switching signal, and damage to the modular multilevel converter caused by the too large alternating current is avoided; when alternating current is stabilized in a device bearable range, the starting unit removes the limitation on the size of the alternating current based on the switching signal, and the starting unit is prevented from being damaged due to the fact that the starting unit limits the current for a long time.
Furthermore, the voltage source type dc ice melting device may also be used to perform reactive compensation on the AC power supply AC1, and when the reactive compensation mode is implemented, the dc output terminal of the modular multilevel converter 20 is in a disconnected state and is not connected to the line to be melted with ice. The start unit 10 controls the flow of AC current into the modular multilevel converter 20 and the measurement control unit 30 controls the operation state of the modular multilevel converter 20 such that the modular multilevel converter 20 absorbs or outputs reactive power to the AC power source AC 1. When the measurement control unit 30 measures that the reactive power of the AC power source AC1 is excessive, the measurement control unit 30 controls the modular multilevel converter 20 to absorb the reactive power of the AC power source AC 1; when the measurement control unit 30 measures that the reactive power of the AC power source AC1 is insufficient, the measurement control unit 30 controls the modular multilevel converter 20 to output the reactive power to the AC power source AC1, thereby implementing the reactive power compensation on the AC power source AC 1.
In some embodiments of the present application, another circuit structure of a voltage source dc ice melting device is provided, and with reference to fig. 2, a starting unit 10 in the voltage source dc ice melting device may include: an alternating current breaker K11, a charging resistor R11 and a bypass switch K12.
The bypass switch K12 and the charging resistor R11 are connected in parallel, the first common terminal after parallel connection is connected with an alternating current power supply AC1 through an alternating current breaker K11, and the second common terminal is connected with the connection point of the upper and lower bridge arms of each phase in the modular multilevel converter 20.
The bypass switch K12 is connected to the measurement control unit 30, and the bypass switch K12 receives the switch signal sent by the measurement control unit 30 to complete the closing and opening of the bypass switch K12.
And the alternating current breaker K11 is used for controlling the alternating current to flow into the voltage source type direct current ice melting device.
And the charging resistor R11 is used for limiting the current when the device is started, so that the modular multilevel converter 20 is prevented from being damaged due to the generation of large current at the power-on moment. When the charging resistor R11 is selected, factors such as the maximum current allowed by the device, the starting speed and the resistor volume need to be comprehensively considered.
The bypass switch K12 is used to cut off the charging resistor R11 and to release the limitation of the ac current flowing into the device. It can be understood that, since the current flowing through the charging circuit in the device is large, the power consumed by the charging resistor R11 is also large, and the charging resistor R11 is connected in series in the charging circuit for a long time and may be damaged due to too large heat generation, after the device is powered on, when the internal capacitance voltage of the flexible dc converter valve (K101, K102, K103, K104, K105, K106) reaches a set threshold, it is necessary to close the bypass switch K12 so that the ac current flows through the bypass switch K12 and no longer flows through the charging resistor R11, so as to cut off the charging resistor R11, protect the charging resistor R11, and the bypass switch K12 may complete the operations of closing and opening by receiving the switching signal sent by the measurement control unit 30.
Further, as shown in fig. 2, the modular multilevel converter 20 in the voltage source type dc ice melting apparatus may include: the three-phase converter comprises three phases with the same structure, each phase is divided into an upper bridge arm and a lower bridge arm, each bridge arm is formed by connecting a bridge arm reactor and a flexible direct current converter valve in series, and the upper bridge arm reactor and the lower bridge arm reactor of each phase are connected in series in the same direction.
The flexible dc converter valves (K101, K102, K103, K104, K105, and K106) on each bridge arm of the modular multilevel converter 20 are all connected to the valve stage control subunit 302 in the measurement control unit 30. It should be noted that, in fig. 2, for the sake of simplicity of the drawing, only the connection relationship between the valve stage control subunit 302 and the flexible dc converter valve K102 is illustrated, and the connection relationship between the remaining flexible dc converter valves (K101, K103, K104, K105, K106) and the valve stage control subunit 302 is not illustrated in the drawing.
The bridge arm reactors (L11, L12, L13, L14, L15 and L16) are used for restraining the bridge arm current from rapidly rising when the modular multilevel converter 20 outputs current harmonic waves, and bridge arm circulation and short circuit occur.
And the flexible direct current converter valves (K101, K102, K103, K104, K105 and K106) are used for realizing flexible conversion of alternating current and direct current and outputting and absorbing reactive power. Each flexible direct current converter valve is formed by connecting a plurality of power modules in series, and each power module is a full-bridge or half-bridge module formed on the basis of IGBTs.
The IGBT is an Insulated Gate Bipolar Transistor, is a composite fully-controlled voltage-driven power semiconductor device consisting of a BJT (Bipolar junction Transistor) and an MOS (Insulated Gate field effect Transistor), and has small driving power and reduced saturation voltage.
Still further, as shown in fig. 2, the measurement control unit 30 in the voltage source type dc thawing apparatus may include: a control protection subunit 301, a valve level control subunit 302 and a measurement subunit (not shown in fig. 2).
The control protection subunit 301 is connected to the valve level control subunit 302, the measurement subunit, and the start unit, and is configured to send a control signal to the valve level control subunit 302 to control the operating state of the flexible dc converter valve (K101, K102, K103, K104, K105, K106) and receive a measured value of a relevant electrical parameter sent by the measurement subunit in real time.
The control protection subunit 301 is configured to obtain a set value input by a user, obtain and send a signal to the valve level control subunit 302 based on the set value and the obtained measured values of the relevant electrical parameters sent by each measurement subunit in the device in real time, and adjust a current value of an ac current flowing into the device by sending a switching signal to the start unit. In addition, the control protection subunit 301 also monitors various electrical parameters of the device during operation, and controls corresponding devices to adjust relevant electrical parameters or cut off the power supply of the device when the measured electrical parameters are abnormal, so as to protect the device.
The valve control subunit 302 is configured to detect a capacitor voltage of a flexible dc converter valve (K101, K102, K103, K104, K105, K106) in the modular multilevel converter 20 after the ac power is input into the modular multilevel converter 20, and after the capacitor voltage reaches a set unlocking threshold, the valve control subunit 302 sends a signal to the flexible dc converter valve (K101, K102, K103, K104, K105, K106) in the modular multilevel converter 20, so that the flexible dc converter valve (K101, K102, K103, K104, K105, K106) is unlocked. Besides, after the flexible dc converter valves (K101, K102, K103, K104, K105, K106) are unlocked, the valve stage control subunit 302 determines and sends signals that the flexible dc converter valves can receive and recognize based on the content sent by the control protection subunit 301, and the signals can adjust the operating states of the flexible dc converter valves (K101, K102, K103, K104, K105, K106), so as to realize the functions of adjusting the dc current values and dc voltage values output by the flexible dc converter valves (K101, K102, K103, K104, K105, K106), and outputting or absorbing reactive power.
And the measuring sub-unit is used for measuring the electrical parameters of the direct current output end and the alternating current power end of the modular multilevel converter 20. It can be understood that there are multiple measurement subunits in the device, and the measurement subunits are required to be installed at the dc output terminal and the ac power terminal of the modular multilevel converter 20, and the measurement subunits can measure the electrical parameters required by the device and send the measured electrical parameters to the control protection subunit 301 in real time. It should be noted that, for the sake of simplicity of the drawings, the installation positions of the measurement subunits and the connection lines with the control protection subunit 301 are not illustrated in the drawings, and the specific installation positions are subject to the positions capable of accurately measuring the required electrical parameters.
In some embodiments of the present application, as shown in fig. 2, the voltage source type dc ice melting apparatus may further include: knife switches K13, K14. When the voltage source type dc ice melting device realizes the dc ice melting mode, the dc input terminal of the modular multilevel converter 20 may be connected to the line to be melted through the knife switches K13 and K14, respectively.
In some embodiments of the present application, the measurement and protection unit 30 may also be connected to the starting unit 10 for controlling the starting unit 10 to adjust the current value of the alternating current flowing into the device. Referring to fig. 2, the measurement protection unit 30 is connected to the start unit 10, specifically, the control protection subunit 301 is connected to the bypass switch K12, and when the internal capacitance voltage of the flexible dc converter valve (K101, K102, K103, K104, K105, K106) reaches a set threshold, the control protection subunit 301 sends a switching signal to the bypass switch K12, so that the bypass switch K12 is closed based on the switching signal, so that the ac current does not flow into the charging resistor R11 any more, and the limitation on the ac current flowing into the apparatus is removed. It should be noted that, for the sake of simplicity of the drawing, the connection relationship between the control protection subunit 301 and the bypass switch K12 is not shown in the drawing.
Referring to fig. 2, when the voltage source type dc ice melting apparatus implements a dc ice melting mode, a dc output terminal of the modular multilevel converter 20 is connected to a line to be melted, an ac current flows into the modular multilevel converter 20 through the ac breaker K11 and the charging resistor R11, the valve control subunit 302 sends a signal to the flexible dc converter valves (K101, K102, K103, K104, K105, K106) in the modular multilevel converter 20, and the flexible dc converter valves (K101, K102, K103, K104, K105, K106) receive the signal, convert the flowing ac current into a dc current, and output the dc current through the dc output terminal of the modular multilevel converter 20, where the current generates heat after flowing into the line to be melted, thereby implementing line ice melting.
Referring to fig. 3, when the voltage source type dc ice melting device implements the reactive compensation mode, the dc output terminal of the modular multilevel converter 20 is in a disconnected state. Further, when the dc output terminals of the modular multilevel converter 20 are connected to the switches K13 and K14, respectively, the other ends of the switches K13 and K14 are not connected to the line; if the reactive compensation mode needs to be started when the ice melting line is connected, at least one of the knife switches K13 and K14 needs to be in a disconnected state all the time.
Referring to fig. 3, when the voltage source type dc ice melting apparatus implements the reactive compensation mode, ac current flows into the modular multilevel converter 20 through the ac breaker K11 and the charging resistor R11, the valve stage control subunit 302 sends a signal to the flexible dc converter valves (K101, K102, K103, K104, K105, K106) in the modular multilevel converter 20, and the flexible dc converter valves (K101, K102, K103, K104, K105, K106) receive the signal, so that the flexible dc converter valves (K101, K102, K103, K104, K105, K106) absorb or output reactive power. When the reactive power of the alternating current power supply is insufficient, the flexible direct current converter valves (K101, K102, K103, K104, K105 and K106) output the reactive power to the alternating current power supply; when the reactive power of the alternating current power supply is excessive, the flexible direct current converter valves (K101, K102, K103, K104, K105 and K106) absorb the reactive power of the alternating current power supply.
An embodiment of the present application further provides a flexible interconnection system, and referring to fig. 4, fig. 4 is a block diagram of a flexible interconnection system provided in an embodiment of the present application.
As shown in fig. 4, the system includes two voltage source type dc ice melting devices as shown in fig. 1, where the two voltage source type dc ice melting device measurement control units are connected to each other, and the dc output terminals of the device modularized multi-level converters are correspondingly connected to realize parallel connection of the dc sides of the two voltage source type dc ice melting devices.
When the flexible interconnection system enters a flexible interconnection mode, the starting unit 10 and the starting unit 40 respectively control alternating current to flow into the modular multilevel converter 20 and the modular multilevel converter 50, the measurement control unit 30 and the measurement control unit 60 respectively send signals to the modular multilevel converter 20 and the modular multilevel converter 50, and the operating states of the modular multilevel converter 20 and the modular multilevel converter 50 are adjusted, so that the modular multilevel converter realizes the conversion between alternating current and direct current. By adjusting the operation state of the modular multilevel converter 20, flexible interconnection can be realized between the alternating current power supplies corresponding to the two voltage source type direct current ice melting devices in the system. It can be understood that the flexible interconnection mode is to connect two disconnected alternating current power supplies through a flexible interconnection system, and the two alternating current power supplies can realize mutual energy transfer through the flexible interconnection system.
Assuming that two alternating current power supplies are respectively connected A, B at two ends of the flexible interconnection system, the absorption or output of active power is realized through the modular multilevel converter at the A end. When the active power of the AC power supply at the A end is insufficient and the active power of the AC power supply at the B end is sufficient, the modular multilevel converter at the A end absorbs the active power of the AC power supply at the B end; when the active power of the A-end alternating current power supply is sufficient and the active power of the B-end alternating current power supply is insufficient, the modularized multi-level converter at the A end outputs the active power to the B-end alternating current power supply, and then flexible interconnection between the two alternating current power supplies is achieved.
Furthermore, when the flexible interconnection system enters a flexible interconnection mode, the two voltage source type direct current ice melting devices in the system can also adjust the running state of the modular multilevel converter in the device through the measurement control unit in the device, so that the modular multilevel converter absorbs or outputs reactive power to the alternating current power supply, and reactive power compensation of the alternating current power supply corresponding to each voltage source type direct current ice melting device is realized.
Furthermore, the flexible interconnection system can also realize direct-current ice melting, and when the flexible interconnection system enters a direct-current ice melting mode, two public ends of the parallel connection of the direct-current output ends of the two modular multilevel converters in the flexible interconnection system are respectively connected with two ends of a line to be melted with ice. The start unit 10 and the start unit 40 control the alternating current to flow into the modular multilevel converter 20 and the modular multilevel converter 50, respectively, and the measurement control unit 30 and the measurement control unit 60 control the operation states of the modular multilevel converter 20 and the modular multilevel converter 50, respectively, and output the direct current at the direct current output terminal of the modular multilevel converter (20, 50). By controlling the operating states of the modular multilevel converter 20 and the modular multilevel converter 50 through the measurement control unit 30 and the measurement control unit 60, respectively, the direct current at the direct current output end of the modular multilevel converter (20, 50) can be adjusted to be hundreds of amperes or thousands of amperes, and after flowing into the line to be melted, the line to be melted will generate enough heat to melt the ice on the surface of the line.
Based on the circuit structure diagram of the device introduced in the foregoing embodiment, the embodiment of the present application discloses a circuit structure diagram of a system, as shown in fig. 5.
The measurement control unit in the two voltage source type dc ice melting devices in the flexible interconnection system may include: the control protection subunit, the valve level control subunit and the measurement subunit. The connection relationship between the measurement control units in the two devices can be the connection relationship between the control protection subunits. In addition, the control protection subunits in the two devices can be the same unit. Fig. 5 merely illustrates the interconnection between the control protection subunits of the measurement control units in both devices.
As further shown in fig. 5, the flexible interconnect system provided in the embodiment of the present application may further include: knife switches K31, K32. The direct current output ends of two modular multilevel converters in the flexible interconnection system are correspondingly connected through the disconnecting links K31 and K32 respectively, so that the direct current sides of the two voltage source type direct current ice melting devices are connected in parallel. Specifically, the connection relationship is as follows: one end of the knife switch K31 is connected with a first output end of the modular multilevel converter in the first device, and the other end is connected with a first output end of the modular multilevel converter in the second device; one end of the knife switch K32 is connected with the second output end of the modular multilevel converter in the first device, and the other end of the knife switch K32 is connected with the second output end of the modular multilevel converter in the second device, so that the direct-current sides of the two voltage source type direct-current ice melting devices are connected in parallel.
The embodiment of the application provides a flexible interconnection system, can be on the basis of realizing flexible interconnection mode, through increasing the set value that sets up reactive power in two voltage source type direct current ice-melt devices to the realization realizes reactive compensation to the reactive power of alternating current power supply in the device separately, reactive compensation and flexible interconnection can go on simultaneously, and when the system realized flexible interconnection function, each device in the flexible interconnection system realized the reactive compensation to device separately.
The flexible interconnection system provided by the embodiment of the application can also realize the function of direct-current ice melting, and as shown in fig. 6, when the flexible interconnection system realizes the direct-current ice melting mode, two common ends of the flexible interconnection system, which are connected in parallel with the direct-current output ends of the two modular multilevel converters, need to be connected to two ends of a line to be melted respectively.
Further, as shown in fig. 6, the flexible dc system may further include: knife switches K33, K34. The first public end of the system after the modularized multi-level converters of the two voltage source type direct current ice melting devices are connected in parallel is connected with a line to be melted with ice through a disconnecting link K33, and the first public end after the parallel connection is connected with the line to be melted with ice through a disconnecting link K34.
When the flexible interconnection system realizes the direct-current ice melting mode, the flexible interconnection system is the same as the voltage source type direct-current ice melting device for realizing the direct-current ice melting mode, two voltage source type direct-current ice melting devices in the system are not interfered with each other, alternating current is converted into direct current through a modular multilevel converter in the device, direct current of hundreds of amperes or thousands of amperes is output through a direct-current output end and flows into a line to be melted together, so that the line to be melted generates heat enough for coating ice on the surface of the line to be melted, and then the ice coating of the line is melted.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, article, or apparatus that comprises the element.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, the embodiments may be combined as needed, and the same and similar parts may be referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A voltage source type direct current ice melting device is characterized by comprising:
the starting unit is connected with the alternating current power supply end;
the DC output end of the modular multilevel converter is used for connecting a line to be ice-melted when the voltage source type DC ice-melting device is in an ice-melting mode;
the measurement control unit is connected with the modular multilevel converter and is used for controlling the running state of the modular multilevel converter;
the measurement control unit is connected with the starting unit, the measurement control unit sends a switching signal to the starting unit, and the starting unit adjusts the current value of the alternating current flowing into the device based on the switching signal.
2. The apparatus of claim 1,
the starting unit includes: an alternating current breaker, a charging resistor and a bypass switch;
the bypass switch is connected with the charging resistor in parallel, a first public end after the parallel connection is connected with an alternating current power supply end through the alternating current circuit breaker, and a second public end is connected with an alternating current input end of the modular multilevel converter;
the bypass switch is connected with the measurement control unit, and receives the switch signal sent by the measurement control unit to complete the on-off of the bypass switch.
3. The apparatus of claim 1,
the modular multilevel converter comprises: the three-phase converter comprises three phases with the same structure, wherein each phase is divided into an upper bridge arm and a lower bridge arm, each bridge arm is formed by connecting a bridge arm reactor and a flexible direct current converter valve in series, and the upper bridge arm reactor and the lower bridge arm reactor of each phase are connected in series in the same direction;
the connection point of the upper bridge arm and the lower bridge arm of each phase of the modular multilevel converter is connected with the starting unit;
and the flexible direct current converter valves on each bridge arm in the modular multilevel converter are connected with the measurement control unit.
4. The apparatus of claim 1,
the measurement control unit includes: the control protection subunit, the valve level control subunit and the measurement subunit are connected;
the control protection subunit is respectively connected with the valve level control subunit, the measuring subunit and the starting protection unit;
the valve control subunit is connected with the modular multilevel converter and is used for controlling the operation state of the modular multilevel converter;
the measuring sub-unit is used for measuring the electric parameters of the direct current output end or the alternating current power end of the modular multilevel converter.
5. The apparatus of claim 1, further comprising:
a first knife switch and a second knife switch;
and the direct current output end of the modular multilevel converter is connected with the line to be de-iced through the first disconnecting link and the second disconnecting link respectively.
6. A flexible interconnect system, comprising:
two voltage source dc ice melting devices according to any of claims 1-5;
the measurement control units in the two voltage source type direct current ice melting devices are connected;
the direct current output ends of the modular multilevel converters in the two voltage source type direct current ice melting devices are correspondingly connected, so that the direct current sides of the two voltage source type direct current ice melting devices are connected in parallel.
7. The system of claim 6,
the measurement control units in the two voltage source type direct current ice melting devices respectively comprise: the control protection subunit, the valve level control subunit and the measurement subunit are connected;
the measurement control units in the two voltage source type direct current ice melting devices are connected, and the measurement control units comprise:
and the control protection subunits in the two voltage source type direct current ice melting devices are connected.
8. The system of claim 6,
the measurement control units in the two voltage source type direct current ice melting devices respectively comprise: the control protection subunit, the valve level control subunit and the measurement subunit are connected;
the measurement control units in the two voltage source type direct current ice melting devices are connected, and the measurement control units comprise:
the control protection sub-units in the two voltage source type direct current ice melting devices are the same unit.
9. The system of claim 6, further comprising:
a third knife switch and a fourth knife switch;
and the third knife switch and the fourth knife switch are used for correspondingly connecting the direct current output ends of the two modular multilevel converters in the flexible interconnection system, so that the direct current sides of the two voltage source type direct current ice melting devices are connected in parallel.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2022247100A1 (en) * | 2021-05-25 | 2022-12-01 | 南方电网科学研究院有限责任公司 | Voltage source type direct-current ice melting apparatus, flexible interconnection system and control method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2022247100A1 (en) * | 2021-05-25 | 2022-12-01 | 南方电网科学研究院有限责任公司 | Voltage source type direct-current ice melting apparatus, flexible interconnection system and control method |
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