CN114188913B

CN114188913B - Control method and device of direct-current ice melting device and controller

Info

Publication number: CN114188913B
Application number: CN202111516615.6A
Authority: CN
Inventors: 侯丹; 娄彦涛; 任军辉; 李喜喜; 杨帆; 王杉
Original assignee: China XD Electric Co Ltd; Xian XD Power Systems Co Ltd
Current assignee: China XD Electric Co Ltd; Xian XD Power Systems Co Ltd
Priority date: 2021-12-13
Filing date: 2021-12-13
Publication date: 2024-02-02
Anticipated expiration: 2041-12-13
Also published as: CN114188913A

Abstract

The specification provides a control method, a control device and a control device of a direct-current ice melting device, and relates to the technical field of power control, wherein the control method comprises the following steps: acquiring a current working mode of the direct-current ice melting device; under the condition that the current working mode is a STATCOM mode, determining a voltage set value of a target port for accessing an ice melting line as a first numerical value; under the condition that the current working mode is an ice melting mode, acquiring a current set value of an ice melting line connected with the target port, and determining a voltage set value of the target port according to the current set value; determining the number of power modules to be accessed between a target port and an alternating current power grid; and selecting the power modules to be accessed according to the number, and controlling the selected power modules to be accessed between the target port and the alternating current power grid. According to the scheme, the current and ripple of the capacitor flowing in the STATCOM mode are small, so that the capacitor voltage is not too high after being superimposed and disturbed under the fault condition.

Description

Control method and device of direct-current ice melting device and controller

Technical Field

The present disclosure relates to the field of power control technologies, and in particular, to a control method and apparatus for a dc ice melting device, and a controller.

Background

Among natural disasters encountered in various power systems, ice and snow disasters are one of the most serious. The loss of the ice and snow disasters to the power grid is serious, the ice flashes when the ice and snow disasters are light, the tower is broken when the tower is heavy, and even the power network is paralyzed. At present, various methods and devices for deicing and melting ice on a line are provided for improving the capacity of a power grid for resisting ice and snow disasters. Existing ice melting methods are generally divided into four categories: thermal deicing, mechanical deicing, natural passive deicing, and other methods. Mechanical deicing is not easy to operate, natural passive deicing efficiency is low, and the existing methods have the defects of different degrees, so that efficient deicing and deicing of the lines cannot be performed. The thermal ice melting has the advantages of short-time ice melting, simple and convenient operation and easy implementation. Thermal deicing is a deicing technology for converting electric energy into heat energy, and generally, current is introduced into a wire to enable the wire to generate heat so as to achieve the purpose of deicing, and the deicing technology can be divided into alternating current deicing and direct current deicing. Ac ice melting has the problems of unadjustable ac voltage, relatively large impact during ice melting and the like, and compared with the dc ice melting, the ac ice melting becomes a better thermal ice melting mode. In order to improve the utilization rate of the ice melting device, the ice melting device integrating functions of STATCOM, active filtering and the like is provided, and when ice melting is not needed, the equipment can work in a STATCOM mode to provide needed reactive power and harmonic compensation for a system. However, when the dc ice melting device is operated in STATCOM mode, the ac grid faults often cause damage to the capacitance in the dc ice melting device.

Disclosure of Invention

The embodiment of the application aims to provide a control method, a control device and a controller of a direct-current ice melting device, so as to solve the problem that when the direct-current ice melting device operates in a STATCOM mode, the capacitor in the direct-current ice melting device is damaged due to the fault of an alternating-current power grid.

In order to solve the above technical problems, a first aspect of the present disclosure provides a control method of a dc ice melting device, including: acquiring a current working mode of a direct current ice melting device, wherein the working mode comprises a STATCOM mode and an ice melting mode; under the condition that the current working mode is a STATCOM mode, determining a voltage set value of a target port for accessing an ice melting line as a first numerical value; under the condition that the current working mode is an ice melting mode, acquiring a current set value of an ice melting line connected with the target port, and determining a voltage set value of the target port according to the current set value; determining the number of power modules to be connected between the target port and the alternating current power grid according to the voltage set value and the voltage control target value of each phase in the three-phase power of the alternating current power grid; and selecting the power modules to be accessed according to the number, and controlling the selected power modules to be accessed between the target port and the alternating current power grid.

In some embodiments, the direct current ice melting device comprises a direct current bus, the target port is connected with a positive electrode wire and a negative electrode wire on a first side of the direct current bus, three branches are connected between the positive electrode wire and the negative electrode wire on a second side of the direct current bus, and each branch is correspondingly connected with one phase of three phases of three-phase electricity of an alternating current power grid respectively; the method comprises the steps of taking a connection point of a branch and an alternating current power grid as a demarcation point, dividing the branch into a first bridge arm and a second bridge arm, and connecting the first bridge arm and the second bridge arm of each branch in series with at least two power modules.

In some embodiments, controlling the accessing of the selected power module between the target port and the ac power grid includes: and controlling the selected power module to be connected between the target port and the alternating current power grid by controlling a bypass switch connected with each selected power module in parallel to be in an off state.

In some embodiments, according to the voltage set value and the voltage control target value of each phase in the three-phase power of the ac power grid, determining the number of power modules to be connected between the target port and the ac power grid, and selecting the power modules to be connected according to the number, including: respectively solving the difference value between the voltage set value and the voltage control target value of each phase to obtain each corresponding difference value; determining the number of power modules to be respectively connected between the target port and each phase of the alternating current power grid according to each corresponding difference value; selecting power modules to be accessed from the first bridge arm of the corresponding branch according to the number; and/or respectively summing the voltage set value and the voltage control target value of each phase to obtain each corresponding added value; determining the number of power modules to be respectively connected between the target port and each phase of the alternating current power grid according to each corresponding superposition value; and selecting the power modules to be accessed from the second bridge arms of the corresponding branches of each phase according to the quantity.

In some embodiments, determining a voltage set point from the current set point comprises: converting the current set point into a first voltage value; the first voltage value is multiplied by a predetermined coefficient to obtain a voltage set point.

In some embodiments, before determining the number of power modules to be connected between the target port and the ac power grid according to the voltage set value and the voltage control target value of each phase in the three-phase power of the ac power grid, the method further includes: determining a voltage compensation value of the power module according to the current set value and the current measured value; determining a d-axis voltage reference value of the three-phase alternating current according to the voltage compensation value of the power module and the voltage measurement value of each power module; and converting the d-axis voltage reference value of the three-phase alternating current into a voltage control target value of each phase in the three-phase power of the alternating current power grid.

A second aspect of the present specification provides a control method of a direct current ice melting apparatus, including: acquiring a current working mode of a direct current ice melting device, wherein the working mode comprises a STATCOM mode and an ice melting mode; under the condition that the current working mode is an ice melting mode, acquiring a voltage compensation value of the power module; according to the voltage compensation value of the power module and the voltage measurement value of each power module, determining a voltage control target value of each phase in three-phase power of an alternating current power grid; determining the number of power modules to be connected between the ice melting line and the alternating current power grid according to the voltage control target value of each phase in the three-phase power of the alternating current power grid; and selecting the power modules to be connected according to the quantity, and controlling the selected power modules to be connected between the ice melting line and the alternating current power grid.

A third aspect of the present specification provides a control device for a direct current ice melting apparatus, comprising: the first acquisition unit is used for acquiring a current working mode of the direct-current ice melting device, wherein the working mode comprises a STATCOM mode and an ice melting mode; the first determining unit is used for determining a voltage set value of a target port for accessing the ice melting line to be a first value under the condition that the current working mode is a STATCOM mode; under the condition that the current working mode is an ice melting mode, acquiring a current set value of an ice melting line connected with the target port, and determining a voltage set value of the target port according to the current set value; the second determining unit is used for determining the number of power modules to be connected between the target port and the alternating current power grid according to the voltage set value and the voltage control target value of each phase in the three-phase power of the alternating current power grid; and the selection control unit is used for selecting the power modules to be accessed according to the number and controlling the selected power modules to be accessed between the target port and the alternating current power grid.

In some embodiments, controlling the accessing of the selected power module between the target port and the ac power grid includes: the selecting control module controls the selected power module to be connected between the target port and the alternating current power grid by controlling a bypass switch connected with each selected power module in parallel to be in an off state.

In some embodiments, according to the voltage set value and the voltage control target value of each phase in the three-phase power of the ac power grid, determining the number of power modules to be connected between the target port and the ac power grid, and selecting the power modules to be connected according to the number, including: the second determination unit includes: a first calculating subunit, configured to calculate difference values respectively from the voltage set value and the voltage control target value of each phase, so as to obtain each corresponding difference value; the first determining subunit is used for determining the number of power modules to be respectively connected between the target port and each phase of the alternating current power grid according to each corresponding difference value; correspondingly, the selection control unit comprises: the first selecting subunit is used for selecting the power module to be accessed from the first bridge arm of the corresponding branch according to the number; and/or, the second determining unit includes: a second calculating subunit, configured to sum the voltage set value and the voltage control target value of each phase respectively, so as to obtain each corresponding added value; the second determining subunit is used for determining the number of power modules to be respectively connected between the target port and each phase of the alternating current power grid according to each corresponding superposition value; correspondingly, the selection control unit comprises: and the second selecting subunit is used for selecting the power modules to be accessed from the second bridge arms of the corresponding branches of each phase according to the number.

In some embodiments, the first determining unit comprises: a conversion subunit for converting the current set value into a first voltage value; and the coefficient subunit is used for multiplying the first voltage value by a preset coefficient to obtain a voltage set value.

In some embodiments, the apparatus further comprises: the third determining unit is used for determining a voltage compensation value of the power module according to the current set value and the current measured value; a fourth determining unit, configured to determine a d-axis voltage reference value of the three-phase alternating current according to the voltage compensation value of the power module and the voltage measurement value of each power module; and the conversion unit is used for converting the d-axis voltage reference value of the three-phase alternating current into a voltage control target value of each phase in the three-phase power of the alternating current power grid.

A third aspect of the present specification provides a control device for a direct current ice melting apparatus, comprising: the second acquisition unit is used for acquiring a current working mode of the direct-current ice melting device, wherein the working mode comprises a STATCOM mode and an ice melting mode; the third acquisition unit is used for acquiring a voltage compensation value of the power module under the condition that the current working mode is an ice melting mode; a fifth determining unit, configured to determine a voltage control target value of each phase in the three-phase power of the ac power grid according to the voltage compensation value of the power module and the voltage measurement value of each power module; the sixth determining unit is used for determining the number of power modules to be connected between the ice melting line and the alternating current power grid according to the voltage control target value of each phase in the three-phase power of the alternating current power grid; and the selection control unit is used for selecting the power modules to be accessed according to the number and controlling the selected power modules to be accessed between the ice melting line and the alternating current power grid.

A fifth aspect of the present specification provides a controller comprising: the system comprises a memory and a processor, wherein the processor and the memory are in communication connection, the memory stores computer instructions, and the processor realizes the steps of the method in the first aspect or the second aspect by executing the computer instructions.

A sixth aspect of the present description provides a computer storage medium storing computer program instructions which, when executed, implement the steps of the method of any one of the first or second aspects.

According to the control method and device for the direct current ice melting device and the electronic equipment, a new determination basis (namely a direct current control unit part in fig. 4) is added on the basis of determining the number of power modules to be connected between a target port and an alternating current power grid according to the voltage control target value of each phase in the three-phase power of the alternating current power grid in the prior art, namely, the voltage set value of the target port is also based on the determination of the number of the power modules to be connected. In the ice melting mode, the voltage set value of the target port is determined according to the input current set value of the ice melting line, in the STATCOM mode, the voltage set value of the target port is determined to be a preset constant, and therefore, the voltage set value sources of the target port in the two modes are different, the actual voltages of the target port obtained by control in the two modes are different, decoupling of control signals in the two modes is achieved, and therefore the voltage set value of the target port in the STATCOM mode can be set to be a small value such as 0, and the current flowing through the capacitor in the STATCOM mode is small and ripple is small. When disturbance acts on the capacitor of the power module under the condition of AC power grid fault, the original partial pressure of the capacitor is not too high after normal ripple and fault disturbance are overlapped. For example, the current flowing through the capacitor in the ice melting mode is 200a, and the current flowing through the capacitor in the statcom mode is 1A. Then, when a disturbance of 50A occurs in the fault to act on the capacitor, the maximum current value required to be borne by the capacitor is 51A, which is much smaller than 200A, thereby improving the capability of the capacitor to withstand voltage in the direct current ice melting device.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic view showing the general structure of a direct current ice melting apparatus provided in the present specification;

fig. 2 shows a circuit configuration diagram of the power module provided in the present specification;

FIG. 3 is a circuit block diagram of a power module group portion of the DC ice melting apparatus provided in the present specification;

FIG. 4 shows a schematic diagram of the control principle provided in the present specification;

fig. 5 shows a flowchart of a control method of the direct current ice melting apparatus provided in the present specification;

fig. 6 shows a flowchart of a method for selecting a power module to be accessed provided in the present specification;

FIG. 7 is a flow chart illustrating another method of controlling a DC ice melting apparatus provided herein;

fig. 8 shows a schematic block diagram of a control device of a dc ice melting apparatus provided in the present specification;

Fig. 9 shows a schematic block diagram of a control device of another dc ice melting apparatus provided in the present specification;

fig. 10 shows a schematic structural diagram of the controller provided in the present specification.

Detailed Description

In order to make the technical solutions in the present application better understood by those skilled in the art, 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 some embodiments of the present application, but not all embodiments. All other embodiments, based on the embodiments herein, which would be apparent to one of ordinary skill in the art without undue burden are intended to be within the scope of the present application.

The inventor finds that in the prior art, the capacitor in the direct-current ice melting device is often damaged due to the fault of the alternating-current power grid, and mainly because the same direct-current voltage control instruction is adopted in the direct-current ice melting mode and the STATCOM mode, the capacitor voltage and ripple wave in the STATCOM mode are larger, and disturbance is further generated to act on the capacitor voltage when the alternating-current power grid breaks down.

Based on the finding, the embodiment of the specification provides a control method of a direct current ice melting device, so as to solve the problem that in the prior art, when the direct current ice melting device operates in a STATCOM mode, the capacitor in the direct current ice melting device is damaged due to the fault of an alternating current power grid.

Fig. 1 shows a schematic structural diagram of a dc ice melting apparatus, and fig. 3 shows a schematic structural diagram of a power module group portion of the dc ice melting apparatus. As shown in fig. 1, the direct current ice melting device comprises a power module group, a direct current bus and an ice melting line.

In fig. 1, a dc bus M is a positive line, a dc bus N is a negative line, a first side of the positive and negative lines of the dc bus is connected to an ice melting line, and a second side is connected to a power module group. The target port is arranged on the first side of the direct current bus and is used for being connected with the ice melting line. The destination port includes a positive terminal and a negative terminal. In the ice melting mode, the positive electrode end and the negative electrode end of the target port are connected with an ice melting circuit; in the STATCOM mode, the target port is not connected with the ice melting line, i.e. the target port is suspended.

The three-phase alternating current circuit of the alternating current power grid is connected with the power module group, and alternating current is converted into direct current through the power module group. In the power module group, a plurality of power modules for AC-DC conversion and reactive power adjustment are arranged corresponding to each phase of the AC power grid, and each power module is connected or not connected between the ice melting line and the AC power grid (namely, between the target port and the AC power grid) according to the control instruction.

As shown in fig. 3, three branches are connected between the positive and negative lines on the second side of the dc bus, and each branch is correspondingly connected to one phase of the three-phase power of the ac power grid. The method comprises the steps of dividing a branch into a first bridge arm and a second bridge arm by taking a connection point of the branch and an alternating current power grid as a demarcation point, wherein at least one power module is arranged on the first bridge arm and the second bridge arm of each branch in series.

In some embodiments, a power module is serially connected to the first bridge arm and the second bridge arm of each branch, so that the function of ac-dc conversion can be achieved.

In some embodiments, two or more power modules are connected in series on the first bridge arm and the second bridge arm of each branch, so that in addition to the function of realizing ac-dc conversion, the current of the ice melting line, that is, the bus current, can be adjusted by adjusting the number of the power modules connected to each bridge arm in the ice melting mode. Under the condition that the resistance of the ice melting line is certain, if the voltage division is different, the current is different, so that the current of the ice melting line can be adjusted by controlling the number of the connected power modules.

Power modules, such as module HA1, module HB1, module HC1, etc. in fig. 3. Each power module includes at least one controllable switching device and at least one capacitor. The controllable switch device can be IGBT, and is used for controlling whether the power module is put into or not, and further realizing conversion of direct current and alternating current. The direct current side of the direct current ice melting device can provide direct current according to requirements, so that an ice melting function is realized; the alternating current side can also provide reactive power according to requirements, namely realize a STATCOM function. Thus, the DC ice melting device can have a STATCOM function.

The number of controllable switching devices in each power module is four or more. Each power module is also provided with a controllable bypass switch in parallel. For example, fig. 2 shows a specific structure of the module HA1 in fig. 3, where the specific structure includes a capacitor C and bypass switches K, X and Y are two connection terminals of the module HA1, respectively. It should be noted that, in fig. 3, the connection structure of the power module group is shown for brevity, but the bypass switch is not illustrated, but in reality, two ends of the power module in fig. 3 are connected in parallel to a controllable bypass switch.

The bypass switch connected in parallel with the power module can be used for controlling whether the power module is connected between the alternating current power grid and the ice melting line, namely, whether the power module is connected between the alternating current power grid and the target port, namely, whether the power module is connected between the positive electrode line and the negative electrode line of the direct current bus. Specifically, when the bypass switch is controlled to be closed, current flows through the bypass switch but not through the power module, so that the power module is not connected; when the bypass switch is controlled to be closed, current can only flow through the power module, so that the power module is connected.

In some embodiments, as shown in fig. 2, four controllable switching devices and capacitors are included in each power module. Specifically, each power module is used for being connected in series (the series connection refers to a branch circuit formed by the series connection), two branches are included between two connecting ends X, Y, and two anti-series controllable switching devices are arranged on each branch circuit; a capacitor is further arranged in parallel between the two connecting ends X, Y of each power module, which are connected in series, and the capacitor is connected with the two branches in parallel. The flow direction of current can be controlled by controlling the on-off sequence of four controllable switching devices of the power module, so that the conversion of direct current and alternating current is realized. The specific method of controlling the current flow is known to those skilled in the art and will not be described in detail.

Fig. 4 shows a control schematic diagram of the inside of a controller of the direct current ice-melting apparatus according to an embodiment of the present specification.

Before describing the control principle shown in fig. 4 specifically, it should be noted that, since the capacitor is connected between two connection ends of the power module and is connected in parallel with other devices in the power module, the voltage across the capacitor in this specification (abbreviated as capacitor voltage) is the voltage across the power module where the capacitor is located (abbreviated as power module voltage).

In addition, the average capacitance voltage refers to an average value of capacitance voltages in all power modules on each bridge arm that is not cut off, that is, an average voltage of power modules, that is, an average value of voltages of all power modules on each bridge arm that is not cut off. In one control period, some power modules on the bridge arm which are not cut off are connected between the alternating current power grid and the direct current bus, and some power modules which are not connected are connected, but the current value of the direct current bus and the voltage value between the target ports can be determined through control of a plurality of periods in the following period, so that in the embodiment of the specification, the power modules which are currently connected or not connected are all counted into calculation of the average voltage value in one control period. For example, in the current period, there are 8 power modules on the bridge arm that is not cut off, only 4 power modules are connected, the voltage of each power module is 2kV, and the remaining 4 power modules are not connected, so that the capacitance average voltage (i.e., the average voltage of the power modules) is 8×2kv≡8=2 kV.

As shown in fig. 4, at the outer ring control unit, given a capacitance average voltage initial value uc_avg_ref, the third regulator PI (3) calculates a d-axis voltage reference value Idref of the three-phase alternating current based on the capacitance average voltage initial value uc_avg_ref and a measured value uc_avg of the capacitance average voltage. In the outer loop control unit, the user can select a reactive power control mode, wherein the control mode comprises an alternating current control mode and a reactive power control mode. The ac control mode is reactive power outputted by setting ac voltage control, and the reactive control mode is reactive power outputted by setting reactive power control. In an alternating current control mode, calculating to obtain a q-axis voltage reference value Iqref of the three-phase alternating current according to an alternating current voltage set value Uacref and an alternating current voltage measured value Uac; in the reactive power control mode, a Q-axis voltage reference value Iqref of the three-phase alternating current is calculated according to the reactive power set value Qref and the reactive power measured value Q.

The d-axis voltage and the q-axis voltage are voltage components in the dq0 rotation coordinate system, and can be converted into each phase voltage component in the abc coordinate system by inverse park transformation. This is known in the art and will not be described in detail.

The control target value of each phase voltage in the three-phase power of the alternating current power grid is sent to a decision unit, and the decision unit determines the number and the positions of the power modules to be connected in a sequencing voltage-sharing method so as to achieve the control target and enable the voltages of the connected power modules to be basically the same.

Based on the above dc ice melting device, the embodiment of the present disclosure provides a control method of the dc ice melting device. The method can be used for the direct current ice melting device and can also be used for a direct current ice melting device different from the direct current ice melting device, and the specific different points can be determined according to the description of the steps in the method. As shown in fig. 5, the method comprises the steps of:

s510: the method comprises the steps of obtaining a current working mode of the direct-current ice melting device, wherein the working mode comprises a STATCOM mode and an ice melting mode.

STATCOM mode means that the direct current de-icing device is able to absorb or emit reactive power, the output of which can be varied to control specific parameters in the alternating current network. In STATCOM mode, the ice melting line is not connected (i.e., the ice melting line is not connected to the target port), and the current in the dc bus is approximately 0.

The ice melting mode is that the direct current ice melting device is used for generating large current by adopting an ice melting line so as to melt ice and snow. In the ice melting mode, an ice melting line is connected (i.e. the ice melting line is connected with a target port), and in order to prevent the direct current ice melting device from absorbing or emitting reactive power to influence the parameters of the alternating current power grid, the voltages at the two ends of each power module need to be controlled to be 0, i.e. the voltages at the two ends of the capacitor are 0, or the voltages at the two ends of the capacitor are smaller enough to influence the parameters of the alternating current power grid.

S520: under the condition that the current working mode is a STATCOM mode, determining a voltage set value of a target port for accessing an ice melting line as a first numerical value; and under the condition that the current working mode is the ice melting mode, acquiring a current set value of an ice melting line connected with the target port, and determining a voltage set value of the target port according to the current set value.

In a STATCOM mode, the voltage set value of a target port connected with the ice melting line in the ice melting mode is adopted to control the direct-current ice melting device due to the characteristic that the ice melting line is not connected; in the ice melting mode, the current in the ice melting line is needed to melt ice, so that the direct-current ice melting device is controlled by adopting the current set value.

For example, in STATCOM mode, the voltage set point for the target port may be determined to be 0, or a smaller value greater than 0, such as 0.15; in the ice melting mode, the current set value of the ice melting line can be determined according to the heat required by ice melting.

In the ice melting mode, the method for determining the voltage set point according to the current set point may be: the current set point is converted into a first voltage value, and then the first voltage value is multiplied by a preset coefficient to obtain a voltage set point. The predetermined coefficient may be 0.5. The method of converting the current set point into the first voltage value may be to employ the first regulator PI (1) shown in fig. 3.

S530: and determining the number of power modules to be connected between the target port and the alternating current power grid according to the voltage set value and the voltage control target value of each phase in the three-phase power of the alternating current power grid.

In the direct current ice melting device, the power modules connected between the target port and one phase of the alternating current power grid are in series connection, and the decision module controls the voltages of the connected power modules to be balanced, so that each power module can be used as a voltage unit, and the voltage value of the target port and the voltage value of an ice melting line can be adjusted by increasing or decreasing the voltage units connected in series. That is, the decision module controls the current of the ice melting line and the voltage value of the target port in a voltage approximation mode. Therefore, in this embodiment, in order to control the voltage value of the target port and the current value of the ice melting line, the number of power modules connected in series between the target port and each phase of the ac power grid needs to be determined.

The voltage approximation type control method is different from a PWM control method, and the PWM control method achieves the purpose of controlling current by adjusting the duty ratio of square wave control signals of IGBT in a circuit.

S540: and selecting the power modules to be accessed according to the number, and controlling the selected power modules to be accessed between the target port and the alternating current power grid.

As shown in fig. 4, before the decision unit determines the power modules to be connected according to the voltage control target values of the phases in the three-phase power, the output value of the direct current control unit is obtained, and the number of the power modules to be connected is determined by combining the voltage control target values of the phases in the three-phase power and the output value of the direct current control unit.

For example, the sum of the voltage control target value of each phase in the three-phase power and the output value of the direct current control unit may be used, or a difference value may be calculated, the sum/difference value may be used as a new control target value, and the number of power modules to be connected may be determined according to the new control target value.

As a specific example, the voltage control target value of the a phase is 120kV, the output value of the dc control unit is 10kV, and 130kV of the sum of the two or 110kV of the difference of the two may be used as a new voltage control target value, and the number of power modules to be connected may be determined according to the new control target value.

In some embodiments, each branch is divided into the first leg and the second leg, and since the boundary points of the first leg and the second leg are connection points of the branches and the ac power grid, and the first leg and the second leg are respectively connected with polar lines of different polarities of the current bus (for example, the first leg is connected with a positive line of the dc bus and the second leg is connected with a negative line of the dc bus in fig. 3), current flow directions of the first leg and the second leg are opposite, and actions on the ac power are different, and when the decision unit selects the power module for access, different selection methods need to be adopted for the first leg and the second leg.

Specifically, as shown in fig. 6, the power module to be accessed may be selected by the following method:

s601: and respectively obtaining the difference value between the voltage set value and the voltage control target value of each phase to obtain each corresponding difference value.

In some embodiments, before the difference is obtained, the current set value of the ice melting line is converted into a first voltage value, and then the first voltage value is multiplied by a predetermined coefficient to obtain a second voltage value. Accordingly, S601 obtains a difference between the second voltage value and the voltage control target value of each phase.

For example, as shown in fig. 4, in the ice melting mode, the current set value of the ice melting line is IDc-ref, IDc is a current measured value of the ice melting line, and the current measured value is converted into the voltage Udc between the positive and negative lines of the direct current bus after passing through the first regulator PI (1), multiplied by the coefficient 0.5, and sent to the decision unit, so that the decision unit selects the power module to be connected according to the 0.5 Udc.

As shown in fig. 4, in the STATCOM mode, the current set value of the ice melting line is 0, and the ice melting line is directly sent to the decision unit without processing, so as to be used for the decision unit to select the power module to be connected according to the current set value. It should be noted that, when the current set value of the ice melting line in the STATCOM mode is not 0, the current set value of the ice melting line may be converted into the voltage Udc between the positive and negative lines of the direct current, multiplied by the coefficient 0.5, and sent to the decision unit, so that the decision unit may select the power module to be connected according to the 0.5 Udc.

S602: and determining the number of power modules to be respectively connected between the target port and each phase of the alternating current power grid according to the corresponding difference values.

S603: and selecting the power modules to be accessed from the first bridge arms of the corresponding branches of each phase according to the number.

For example, in the ice melting mode, the current set value of the ice melting line is a, the voltage set value X can be obtained according to the current set value X1, and the voltage control target value of each phase is A, B, C, then a ', B ', C ' are obtained by calculation, and the power module to be connected is selected from the first bridge arm according to a ', B ', C ', wherein a ' =a-X, B ' =b-X, C ' =c-X.

S604: and summing the voltage set value and the voltage control target value of each phase respectively to obtain each corresponding superposition value.

In some embodiments, the current set point of the ice-melting line is converted into a first voltage value before summing, and the first voltage value is multiplied by a predetermined coefficient to obtain a second voltage value. Accordingly, S603 is to sum the second voltage value and the voltage control target value of each phase, respectively.

Other content may be found in the description of S601.

S605: and determining the number of power modules to be respectively connected between the target port and each phase of the alternating current power grid according to each corresponding superposition value.

S606: and selecting the power modules to be accessed from the second bridge arms of the corresponding branches of each phase according to the number.

For example, in the STATCOM mode, the voltage set value of the target port is X, and the voltage control target value of each phase is A, B, C, a ', B ', C ' are calculated, and the power module to be connected is selected from the second bridge arm according to a ', B ', C ', where a ' =a+ X, B ' =b+ X, C ' =c+x.

In some embodiments, the first bridge arm and the second bridge arm are both put into use, that is, may be selected as the power modules to be accessed, and when determining the number of the power modules to be accessed, each corresponding superposition value and each corresponding difference value are considered at the same time, and the number of the power modules to be accessed is determined based on the two.

It should be noted that, in the case where the power module group adopts the circuit shown in fig. 3, the first bridge arm of each branch should be cut off when the first bridge arm of one branch is cut off; in the case where the second leg of one leg is cut, the second leg of each leg should be cut.

According to the control method of the direct current ice melting device, a new determination basis (namely the direct current control unit part in fig. 4) is added on the basis of determining the number of power modules to be connected between the target port and the alternating current power grid according to the voltage control target value of each phase in the three-phase power of the alternating current power grid in the prior art, namely, the voltage set value of the target port is also based on when the number of the power modules to be connected is determined. In the ice melting mode, the voltage set value of the target port is determined according to the input current set value of the ice melting line, in the STATCOM mode, the voltage set value of the target port is determined to be a preset constant, and therefore, the voltage set value sources of the target port in the two modes are different, the actual voltages of the target port obtained by control in the two modes are different, decoupling of control signals in the two modes is achieved, and therefore the voltage set value of the target port in the STATCOM mode can be set to be a small value such as 0, and the current flowing through the capacitor in the STATCOM mode is small and ripple is small. When disturbance acts on the capacitor of the power module under the condition of AC power grid fault, the original partial pressure of the capacitor is not too high after normal ripple and fault disturbance are overlapped. For example, the current flowing through the capacitor in the ice melting mode is 200a, and the current flowing through the capacitor in the statcom mode is 1A. Then, when a disturbance of 50A occurs in the fault to act on the capacitor, the maximum current value required to be borne by the capacitor is 51A, which is much smaller than 200A, thereby improving the capability of the capacitor to withstand voltage in the direct current ice melting device.

As shown in fig. 4, the dc current control unit controls the dc current by controlling the total number of modules connected between the positive and negative lines of the dc bus to control the dc voltage. The control requirements for the dc voltage are different for the ice melting mode and the STATCOM mode. Specifically, in the ice melting mode, the voltage between the positive electrode line and the negative electrode line of the direct current bus is carried out by the number of the power modules connected between the positive electrode line and the negative electrode line of the direct current bus, which is obtained through the direct current control loop, and because the average value of the capacitor voltage is controlled through the outer ring of the active branch, the decision unit generally adopts a sequencing and voltage equalizing mode to carry out balanced control on the voltage of the power modules, so that the voltage of the power modules can be considered to be balanced, and then the voltage between the positive electrode line and the negative electrode line of the direct current bus is controlled by the number of the connected power modules. In the STATCOM mode, the voltage between the anode and the cathode of the direct current bus can be controlled to be any value within a rated range, and the influence factors on the capacitor voltage are considered, so that the voltage between the anode and the cathode of the direct current bus is controlled to be 0, the current flowing through the power module when the power module operates in the STATCOM mode can be minimized, and correspondingly ripple waves are smaller. When disturbance acts on the capacitor of the power module under the condition of AC power grid fault, the original partial pressure of the capacitor is not too high after normal ripple and fault disturbance are overlapped.

In some embodiments, a plurality of power modules are disposed in series on each leg. The plurality of power modules are arranged on the branch in series, so that on one hand, the voltage application range of the direct-current ice melting device can be improved, and the application range of the direct-current ice melting device is not limited to the middle-low voltage application field, for example, the voltage of each power module is 2kV, the voltage between the positive electrode wire and the negative electrode wire of the direct-current bus can reach 20kV under the condition of 10 power modules, and the voltage between the positive electrode wire and the negative electrode wire of the direct-current bus can reach 100kV under the condition of 50 power modules; on the other hand, the control precision of the middle-low voltage application field can be improved, for example, the number of the accessible power modules is 10, the control precision is V/10, the number of the accessible power modules is 100, the control precision is V/100, and V can be a set value, such as a current set value of an ice melting line.

The inventor also finds that when the direct-current ice melting device provided by the specification works in an ice melting mode, the steady-state performance of the system is poor, and the current fluctuation of the direct-current bus or the ice melting line is easy to generate continuous fluctuation.

In this regard, the inventors have further studied and found that, in the case of poor steady-state performance of the system, the number of power modules connected between the dc buses is switched back and forth between adjacent integers, mainly because the current in the ice melting line is not high when the existing dc ice melting device works in the ice melting mode, and therefore, the number of power modules connected in series in the existing dc ice melting device is also not high, so that the control accuracy is not high, and the value obtained by dividing the voltage at both ends of the ice melting line (i.e., the voltage of the target port) by the voltage of a single power module is not an integer.

For example, when the resistance of the ice melting line is 4.1 Ω and the ice melting current is required to be 5kA, the dc voltage needs 20.5kV, the voltage initial setting value of the power module is 2.0kV, and the number of modules connected between the positive and negative lines of the dc bus can be switched back and forth between 10 and 11, so that the steady state performance of the dc voltage and the dc current of the whole dc ice melting device is poor, and the control precision is not high.

In contrast, the embodiment of the present specification provides a control method of a direct current ice melting apparatus. The method can be used for the direct current ice melting device and can also be used for a direct current ice melting device different from the direct current ice melting device, and the specific different points can be determined according to the description of the steps in the method. This method can also be used simultaneously with the control method shown in fig. 5.

As shown in fig. 7, the method includes the steps of:

s710: the method comprises the steps of obtaining a current working mode of the direct-current ice melting device, wherein the working mode comprises a STATCOM mode and an ice melting mode.

Please refer to the description of step S510.

S720: and under the condition that the current working mode is the ice melting mode, acquiring a voltage compensation value of the power module.

Since the voltage across the power module is equal to the voltage across the capacitor, the voltage compensation value of the power module is the capacitor voltage compensation value.

Since the voltages of the power modules are balanced, the voltage values of the power modules described in this specification may be understood as voltage "average" values of the power modules, and the voltage compensation values of the power modules may be understood as voltage "average" compensation values of the power modules.

The voltage compensation value of the power module may be a given specific value or may be calculated according to other values.

For example, the voltage compensation value of the power module may be obtained by: and obtaining a current set value and a current measured value of the ice melting line, and calculating a voltage compensation value of the power module according to the current set value and the current measured value, wherein the voltage compensation value of the power module can be calculated by adopting a PI or PID regulator.

S730: and determining a voltage control target value of each phase in the three-phase power of the alternating current power grid according to the voltage compensation value of the power module and the voltage measurement value of each power module.

In some embodiments, the d-axis voltage reference value of the three-phase alternating current may be determined according to the voltage compensation value of the power module and the voltage measurement value of each power module, and then the d-axis voltage reference value of the three-phase alternating current is converted into the voltage control target value of each phase in the alternating current power grid.

As shown in fig. 4, in the capacitor voltage compensation control module, the current set value idc_ref and the current measured value IDc of the ice melting line are obtained, and the purpose of the "delay enabling" subunit is to make the whole device system of the dc ice melting device operate for a period of time, after the system is stabilized, the obtained value is input into the second regulator PI (2), and the capacitor voltage compensation value uc_comp, that is, the voltage compensation value of the power module is output. The voltage compensation value uc_comp is input to the outer ring control unit, and is used for being input to the third regulator PI (3) together with the capacitance voltage measurement value uc_avg (i.e. the voltage measurement value of the power module), and the d-axis voltage reference value Idref is obtained by output, and the inner ring control unit converts the d-axis voltage reference value Idref into a voltage control target value uref_abc of each phase in three-phase electricity of the ac power grid, i.e. a voltage control target value of A, B, C phases.

S740: and determining the number of power modules to be connected between the ice melting line and the alternating current power grid according to the voltage control target value of each phase in the three-phase power of the alternating current power grid.

This step may be understood with reference to step S530.

S750: and selecting power modules to be connected according to the number, and controlling the selected power modules to be connected between the ice melting line and the alternating current power grid.

This step can be understood with reference to step S540.

According to the control method of the direct current ice melting device, on the basis of determining the voltage control target value of each phase in the three-phase electricity of the alternating current power grid according to the voltage measurement value of the power module in the prior art, a new determination basis (namely, a capacitor voltage compensation control unit part in fig. 4) is added, namely, the voltage control target value of each phase in the three-phase electricity of the alternating current power grid is determined, and the voltage compensation value of the power module is also based. The method can be used for carrying out micro adjustment on the voltage of the power modules on the basis of the existing method, so that when the number of the power modules to be connected is determined, the voltage between the original direct current buses is divided by the voltage of the power modules, and the obtained value is not an integer, the voltage can be adjusted to the integer or very close to the integer, and then the number of the connected power modules can be determined to be an integer for a long time without switching back and forth.

For example, when the resistance of the ice melting line is 4.1 Ω and the ice melting current is required to be 5kA, the direct current voltage needs to be 20.5kV, the voltage initial set value of the power module is 2.0kV, the number of modules connected between the positive electrode line and the negative electrode line of the direct current bus in the existing mode can be switched back and forth between 10 and 11, after the voltage compensation value is adopted for adjustment, the voltage of the power module is adjusted to be 2.05kV, and the number of modules between the direct current buses can be stabilized at 10.

In some embodiments, a branch switch (e.g., the switch shown as U1, U2, V1, V2, W1, W2 in fig. 2) and at least one power module are disposed on each of the first leg and the second leg of each branch.

Correspondingly, the control method provided by the embodiment of the specification further comprises the following steps: performing fault monitoring on the first bridge arm and the second bridge arm of each branch; under the condition that faults occur in the target bridge arms of the target branches, the controllable switches on the target bridge arms of the branches are controlled to be disconnected, so that the target bridge arms of the branches are cut off, namely the fault bridge arms are cut off. The target bridge arm may be a first bridge arm or a second bridge arm.

For example, when the power module HBn on the first leg in fig. 1 fails, the switches U1, V1, W1 may be controlled to open, and the switches U2, V2, W2 may be controlled to close, so that only the power module of the second leg on each leg operates. By arranging the branch switch, the problem that the whole direct-current ice melting device cannot work due to the failure of part of the power modules can be avoided.

The embodiment of the specification provides a control device of a direct current ice melting device, which can be used for realizing the control method of the direct current ice melting device shown in fig. 5. As shown in fig. 8, the apparatus includes a first acquisition unit 810, a first determination unit 820, a second determination unit 830, and a selection control unit 840.

The first obtaining unit 810 is configured to obtain a current working mode of the dc ice melting device, where the working mode includes a STATCOM mode and an ice melting mode.

The first determining unit 820 is configured to determine, when the current working mode is a STATCOM mode, a voltage set value of a target port for accessing the ice melting line to be a first value; and under the condition that the current working mode is the ice melting mode, acquiring a current set value of an ice melting line connected with the target port, and determining a voltage set value of the target port according to the current set value.

The second determining unit 830 is configured to determine, according to the voltage set value and the voltage control target value of each phase in the three phases of the ac power grid, the number of power modules to be connected between the target port and the ac power grid.

The selection control unit 840 is configured to select a power module to be accessed according to the number, and control the selected power module to be accessed between the target port and the ac power grid.

In some embodiments, the direct-current ice melting device comprises a direct-current bus, a target port is connected with a positive electrode wire and a negative electrode wire on a first side of the direct-current bus, three branches are connected between the positive electrode wire and the negative electrode wire on a second side of the direct-current bus, and each branch is correspondingly connected with one phase of three-phase electricity of an alternating-current power grid; the method comprises the steps of taking a connection point of a branch and an alternating current power grid as a demarcation point, dividing the branch into a first bridge arm and a second bridge arm, and connecting the first bridge arm and the second bridge arm of each branch in series with at least two power modules.

In some embodiments, the selection control module 840 controls the access of the selected power module between the target port and the ac power grid by controlling the bypass switch in parallel with each selected power module to be in an off state.

In some embodiments, the second determining unit 830 includes a first deriving subunit 831 and a first determining subunit 832.

The first calculating subunit 831 is configured to calculate the difference between the voltage set value and the voltage control target value of each phase, so as to obtain each corresponding difference. The first determining subunit 832 is configured to determine, according to each corresponding difference value, the number of power modules to be connected between the target port and each phase of the ac power grid.

Accordingly, the selection control unit 840 includes: a first selecting subunit 841, configured to select, according to the number, a power module to be accessed from a first bridge arm of a corresponding branch of each phase;

the second determination unit 830 includes a second determination subunit 833 and a second determination subunit 834.

The second calculating subunit 833 is configured to sum the voltage set value and the voltage control target value of each phase to obtain each corresponding added value. The second determining subunit 834 is configured to determine, according to each corresponding superposition value, the number of power modules to be respectively connected between the target port and each phase of the ac power grid.

Accordingly, the selection control unit 840 includes: the second selecting subunit 842 is configured to select, according to the number, a power module to be accessed from the second bridge arms of the corresponding branches of each phase.

In some embodiments, first determination unit 820 includes a conversion subunit 821 and a coefficient subunit 822.

The conversion subunit 821 is configured to convert the current setting value into a first voltage value. The coefficient subunit 822 is configured to multiply the first voltage value by a predetermined coefficient to obtain a voltage set point.

In some embodiments, the apparatus further comprises a third determination unit 850, a fourth determination unit 860, and a conversion unit 870.

The third determining unit 850 is configured to determine a voltage compensation value of the power module according to the current set value and the current measured value.

The fourth determining unit 860 is configured to determine a d-axis voltage reference value of the three-phase ac power according to the voltage compensation value of the power module and the voltage measurement value of each power module.

The conversion unit 870 is configured to convert the d-axis voltage reference value of the three-phase ac power into a voltage control target value of each phase in the three-phase ac power of the ac power grid.

The specific description and the beneficial effects of the above device refer to the method embodiment shown in fig. 5, and are not repeated.

The embodiment of the present disclosure also provides a control device for a dc ice melting device, which may be used to implement the control method for a dc ice melting device described in fig. 7. As shown in fig. 9, the apparatus includes a first acquisition unit 910, a second acquisition unit 920, a fifth determination unit 930, a sixth determination unit 940, and a selection control unit 950.

The first obtaining unit 910 is configured to obtain a current working mode of the dc ice melting device, where the working mode includes a STATCOM mode and an ice melting mode.

The second obtaining unit 920 is configured to obtain a voltage compensation value of the power module when the current operation mode is the ice melting mode.

The fifth determining unit 930 is configured to determine a voltage control target value of each phase in the three-phase power of the ac power grid according to the voltage compensation value of the power module and the voltage measurement value of each power module.

The sixth determining unit 940 is configured to determine, according to a voltage control target value of each phase in the three phases of the ac power grid, a number of power modules to be connected between the ice melting line and the ac power grid.

The selection control unit 950 is configured to select power modules to be connected according to the number, and control the selected power modules to be connected between the ice melting line and the ac power grid.

In some embodiments, the second acquisition unit 920 includes an acquisition subunit 921 and a calculation subunit 922.

The acquisition subunit 921 is configured to acquire a current set point and a current measured value for the ice-melting line.

The calculating subunit 922 is configured to calculate a voltage compensation value of the power module according to the current set value and the current measured value.

The specific description and the beneficial effects of the above device refer to the method embodiment shown in fig. 7, and are not repeated.

Embodiments of the present invention also provide a controller, as shown in fig. 10, which may include a processor 1001 and a memory 1002, where the processor 1001 and the memory 1002 may be connected by a bus or otherwise, and in fig. 10, the connection is exemplified by a bus.

The processor 1001 may be a central processing unit (Central Processing Unit, CPU). The processor 1001 may also be a chip such as other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or a combination thereof.

The memory 1002 is used as a non-transitory computer readable storage medium, and may be used to store a non-transitory software program, a non-transitory computer executable program, and a module, such as program instructions/modules corresponding to a control method of the dc-ice melting apparatus in an embodiment of the present invention (for example, the first acquiring unit 810, the first determining unit 820, the second determining unit 830, and the selection control unit 840 shown in fig. 8, or the first acquiring unit 910, the second acquiring unit 920, the fifth determining unit 930, the sixth determining unit 940, and the selection control unit 950 shown in fig. 9). The processor 1001 executes various functional applications of the processor and data classification by executing non-transitory software programs, instructions and modules stored in the memory 1002, that is, implements the control method of the dc ice melting apparatus in the above-described method embodiment.

Memory 1002 may include a storage program area that may store an operating system, at least one application program required for functionality, and a storage data area; the storage data area may store data created by the processor 1001, and the like. In addition, the memory 1002 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, memory 1002 may optionally include memory located remotely from processor 1001, such remote memory being connectable to processor 1001 through a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The one or more modules are stored in the memory 1002, which when executed by the processor 1001, performs the control method of the direct current ice melting apparatus in the embodiment shown in fig. 5 to 7.

The details of the controller may be understood by referring to the related descriptions and effects in the corresponding embodiments of fig. 5 to 7, which are not repeated here.

It will be appreciated by those skilled in the art that implementing all or part of the above-described embodiment method may be implemented by a computer program to instruct related hardware, where the program may be stored in a computer readable storage medium, and the program may include the above-described embodiment method when executed. Wherein the storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a Flash Memory (Flash Memory), a Hard Disk (HDD), or a Solid State Drive (SSD); the storage medium may also comprise a combination of memories of the kind described above.

In the 90 s of the 20 th century, improvements to one technology could clearly be distinguished as improvements in hardware (e.g., improvements to circuit structures such as diodes, transistors, switches, etc.) or software (improvements to the process flow). However, with the development of technology, many improvements of the current method flows can be regarded as direct improvements of hardware circuit structures. Designers almost always obtain corresponding hardware circuit structures by programming improved method flows into hardware circuits. Therefore, an improvement of a method flow cannot be said to be realized by a hardware entity module. For example, a programmable logic device (Programmable Logic Device, PLD) (e.g., field programmable gate array (Field Programmable Gate Array, FPGA)) is an integrated circuit whose logic function is determined by the programming of the device by a user. A digital system is "integrated" on a PLD by the designer's own programming without requiring the chip manufacturer to design and fabricate application-specific integrated circuit chips 2. Moreover, nowadays, instead of manually manufacturing integrated circuit chips, such programming is mostly implemented with "logic compiler" software, which is similar to the software compiler used in program development and writing, and the original code before the compiling is also written in a specific programming language, which is called hardware description language (Hardware Description Language, HDL), but HDL is not only one, but a plurality of kinds, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), lava, lola, myHDL, PALASM, RHDL (Ruby Hardware Description Language), etc., VHDL (Very-High-Speed Integrated Circuit Hardware Description Language) and Verilog2 are most commonly used at present. It will also be apparent to those skilled in the art that a hardware circuit implementing the logic method flow can be readily obtained by merely slightly programming the method flow into an integrated circuit using several of the hardware description languages described above.

In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are referred to each other, and each embodiment is mainly described as different from other embodiments.

The system, apparatus, module or unit set forth in the above embodiments may be implemented in particular by a computer chip or entity, or by a product having a certain function.

For convenience of description, the above devices are described as being functionally divided into various units, respectively. Of course, the functions of each element may be implemented in one or more software and/or hardware elements when implemented in the present application.

From the above description of embodiments, it will be apparent to those skilled in the art that the present application may be implemented in software plus a necessary general purpose hardware platform. Based on such understanding, the technical solutions of the present application may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the methods of some parts of the embodiments of the present application.

The subject application is operational with numerous general purpose or special purpose computer system environments or configurations. For example: personal computers, server computers, hand-held or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like.

The application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.

In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for a hardware+program class embodiment, the description is relatively simple, as it is substantially similar to the method embodiment, as relevant see the partial description of the method embodiment.

The foregoing describes specific embodiments of the present disclosure. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Although the present description provides method operational steps as described in the examples or flowcharts, more or fewer operational steps may be included based on conventional or non-inventive labor. The order of steps recited in the embodiments is merely one way of performing the order of steps and does not represent a unique order of execution. When implemented by an actual device or client product, the instructions may be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment) as shown in the embodiments or figures.

The system, apparatus, module or unit set forth in the above embodiments may be implemented in particular by a computer chip or entity, or by a product having a certain function. One typical implementation is a computer. In particular, the computer may be, for example, a personal computer, a laptop computer, a car-mounted human-computer interaction device, a cellular telephone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

Although the present description provides method operational steps as described in the examples or flowcharts, more or fewer operational steps may be included based on conventional or non-inventive means. The order of steps recited in the embodiments is merely one way of performing the order of steps and does not represent a unique order of execution. When implemented in an actual device or end product, the instructions may be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment, or even in a distributed data processing environment) as illustrated by the embodiments or by the figures. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, 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, method, article, or apparatus. Without further limitation, it is not excluded that additional identical or equivalent elements may be present in a process, method, article, or apparatus that comprises a described element.

For convenience of description, the above devices are described as being functionally divided into various modules, respectively. Of course, when implementing the embodiments of the present disclosure, the functions of each module may be implemented in the same or multiple pieces of software and/or hardware, or a module that implements the same function may be implemented by multiple sub-modules or a combination of sub-units, or the like. The above-described apparatus embodiments are merely illustrative, for example, the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

Those skilled in the art will also appreciate that, in addition to implementing the controller in a pure computer readable program code, it is well possible to implement the same functionality by logically programming the method steps such that the controller is in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. Such a controller can be regarded as a hardware component, and means for implementing various functions included therein can also be regarded as a structure within the hardware component. Or even means for achieving the various functions may be regarded as either software modules implementing the methods or structures within hardware components.

The present description is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the specification. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In one typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.

The memory may include volatile memory in a computer-readable medium, random Access Memory (RAM) and/or nonvolatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). Memory is an example of computer-readable media.

Computer readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of storage media for a computer include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Disks (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium which can be used to store information that can be accessed by a computing device. Computer-readable media, as defined herein, does not include transitory computer-readable media (transmission media), such as modulated data signals and carrier waves.

It will be appreciated by those skilled in the art that embodiments of the present description may be provided as a method, system, or computer program product. Accordingly, the present specification embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present description embodiments may take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present embodiments may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The embodiments of the specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.

In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, as relevant to see a section of the description of method embodiments. In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments of the present specification. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

The foregoing is merely an example of an embodiment of the present disclosure and is not intended to limit the embodiment of the present disclosure. Various modifications and variations of the illustrative embodiments will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, or the like, which is within the spirit and principles of the embodiments of the present specification, should be included in the scope of the claims of the embodiments of the present specification.

Claims

1. A control method of a direct current ice melting apparatus, comprising:

acquiring a current working mode of a direct current ice melting device, wherein the working mode comprises a STATCOM mode and an ice melting mode;

under the condition that the current working mode is a STATCOM mode, determining a voltage set value of a target port for accessing an ice melting line to be a first value, wherein the first value is 0; under the condition that the current working mode is an ice melting mode, acquiring a current set value of an ice melting line connected with the target port, and determining a voltage set value of the target port according to the current set value;

determining the number of power modules to be connected between the target port and the alternating current power grid according to the voltage set value and the voltage control target value of each phase in the three-phase power of the alternating current power grid;

And selecting the power modules to be accessed according to the number, and controlling the selected power modules to be accessed between the target port and the alternating current power grid.

2. The method of claim 1, wherein the direct current ice melting device comprises a direct current bus, the target port is connected with a positive electrode wire and a negative electrode wire on a first side of the direct current bus, three branches are connected between the positive electrode wire and the negative electrode wire on a second side of the direct current bus, and each branch is correspondingly connected with one phase of three phases of three-phase electricity of an alternating current power grid; the method comprises the steps of taking a connection point of a branch and an alternating current power grid as a demarcation point, dividing the branch into a first bridge arm and a second bridge arm, and connecting the first bridge arm and the second bridge arm of each branch in series with at least two power modules.

3. The method of claim 1, wherein controlling access of the selected power module between the target port and an ac power grid comprises:

and controlling the selected power module to be connected between the target port and the alternating current power grid by controlling a bypass switch connected with each selected power module in parallel to be in an off state.

4. The method according to claim 2, wherein determining the number of power modules to be connected between the target port and the ac grid according to the voltage set value and the voltage control target value of each phase in the three phases of the ac grid, and selecting the power modules to be connected according to the number, comprises:

Respectively solving the difference value between the voltage set value and the voltage control target value of each phase to obtain each corresponding difference value;

determining the number of power modules to be respectively connected between the target port and each phase of the alternating current power grid according to each corresponding difference value;

selecting power modules to be accessed from the first bridge arm of the corresponding branch according to the number;

and/or the number of the groups of groups,

summing the voltage set value and the voltage control target value of each phase respectively to obtain each corresponding superposition value;

determining the number of power modules to be respectively connected between the target port and each phase of the alternating current power grid according to each corresponding superposition value;

and selecting the power modules to be accessed from the second bridge arms of the corresponding branches of each phase according to the quantity.

5. The method of claim 4, wherein determining a voltage set point from the current set point comprises:

converting the current set point into a first voltage value;

the first voltage value is multiplied by a predetermined coefficient to obtain a voltage set point.

6. The method of claim 1, further comprising, prior to determining the number of power modules to be accessed between the destination port and the ac grid based on the voltage set point and a voltage control target value for each of the three phases of the ac grid, the steps of:

Determining a voltage compensation value of the power module according to the current set value and the current measured value;

determining a d-axis voltage reference value of the three-phase alternating current according to the voltage compensation value of the power module and the voltage measurement value of each power module;

and converting the d-axis voltage reference value of the three-phase alternating current into a voltage control target value of each phase in the three-phase power of the alternating current power grid.

7. The method according to claim 1, characterized in that it comprises:

under the condition that the current working mode is an ice melting mode, acquiring a voltage compensation value of the power module;

according to the voltage compensation value of the power module and the voltage measurement value of each power module, determining a voltage control target value of each phase in three-phase power of an alternating current power grid;

determining the number of power modules to be connected between the ice melting line and the alternating current power grid according to the voltage control target value of each phase in the three-phase power of the alternating current power grid;

and selecting the power modules to be connected according to the quantity, and controlling the selected power modules to be connected between the ice melting line and the alternating current power grid.

8. A control device for a direct current ice melting apparatus, comprising:

The first acquisition unit is used for acquiring a current working mode of the direct-current ice melting device, wherein the working mode comprises a STATCOM mode and an ice melting mode;

the first determining unit is used for determining that the voltage set value of the target port for accessing the ice melting line is a first value and the first value is 0 when the current working mode is a STATCOM mode; under the condition that the current working mode is an ice melting mode, acquiring a current set value of an ice melting line connected with the target port, and determining a voltage set value of the target port according to the current set value;

the second determining unit is used for determining the number of power modules to be connected between the target port and the alternating current power grid according to the voltage set value and the voltage control target value of each phase in the three-phase power of the alternating current power grid;

and the selection control unit is used for selecting the power modules to be accessed according to the number and controlling the selected power modules to be accessed between the target port and the alternating current power grid.

9. The apparatus as recited in claim 8, further comprising:

The second acquisition unit is used for acquiring a voltage compensation value of the power module under the condition that the current working mode is an ice melting mode;

a fifth determining unit, configured to determine a voltage control target value of each phase in the three-phase power of the ac power grid according to the voltage compensation value of the power module and the voltage measurement value of each power module;

the sixth determining unit is used for determining the number of power modules to be connected between the ice melting line and the alternating current power grid according to the voltage control target value of each phase in the three-phase power of the alternating current power grid;

and the selection control unit is used for selecting the power modules to be accessed according to the number and controlling the selected power modules to be accessed between the ice melting line and the alternating current power grid.

10. A controller, comprising:

a memory and a processor in communication with each other, the memory having stored therein computer instructions which, upon execution, cause the processor to perform the steps of the method of any of claims 1 to 7.

11. A computer storage medium storing computer program instructions which, when executed, implement the steps of the method of any one of claims 1 to 7.