CN111509686A

CN111509686A - Fault redundancy control method for modular direct current energy consumption device

Info

Publication number: CN111509686A
Application number: CN202010316344.9A
Authority: CN
Inventors: 谢晔源; 王宇; 李海英; 曹冬明; 姚宏洋; 李汉杰
Original assignee: NR Electric Co Ltd; NR Engineering Co Ltd
Current assignee: NR Electric Co Ltd; NR Engineering Co Ltd
Priority date: 2020-04-21
Filing date: 2020-04-21
Publication date: 2020-08-07
Anticipated expiration: 2040-04-21
Also published as: DE112021000163T5; CN111509686B; WO2021212987A1

Abstract

The application relates to a fault redundancy control method for a modular direct current energy consumption device, wherein the modular direct current energy consumption device is formed by serially connecting a plurality of sub-modules which are connected in series, and the control method comprises the following steps: accumulating the number of the fault submodules; determining the level of a redundancy mode according to the number of the fault sub-modules, and entering a corresponding redundancy mode; at least one of the redundancy modes includes jumping out of the current redundancy mode and automatically entering a higher level redundancy mode when the number of faulty sub-modules reaches an upper threshold of the current redundancy mode.

Description

Fault redundancy control method for modular direct current energy consumption device

Technical Field

The application relates to the technical field of power electronics, in particular to a fault redundancy control method for a modular direct-current energy consumption device.

Background

The method has clear standard requirements for the new energy grid-connected low-voltage ride through capability at home and abroad. For a new energy system which adopts a high-voltage flexible direct-current transmission technology and is connected to the grid, for example, a power generation end is an inertial power supply similar to wind power, when the voltage of an alternating-current power grid drops due to the fault of a power receiving end, active power cannot be sent out or only part of the active power can be sent out to the alternating-current power grid due to the fact that a power transmission end converter is used for power control. The surplus active power may cause the voltage of the dc transmission line to increase. This voltage rise jeopardizes the safety of the flexible dc converter valve and the like. It is often necessary to provide dc energy consumers in the dc link to consume excess energy and limit the dc link voltage.

In the prior art, the dc energy consuming device usually adopts a modular manner. In order to ensure the reliability of the energy consuming devices once a module fails, prior art practices bypass the failed module. When the number of the module bypasses exceeds a certain value, the energy consumption device stops running for the safety of the energy consumption device and loses energy consumption capability. At this time, the converter is exposed to suddenly increased direct-current voltage, so that the converter is emergently locked and shut down, and the impact on a power grid is caused. Too high dc voltage can also cause damage to the sub-modules of the converter with serious consequences. The reliability of the converter and the reliability of the direct current energy consumption device are difficult to be considered. Therefore, coordination and trade-off between converter reliability and reliability of the dc energy consuming devices are required to achieve the final goal of improving the reliability of the whole system.

Disclosure of Invention

The application aims to provide a fault redundancy control method for a modular direct current energy consumption device.

An embodiment of the present application provides a fault redundancy control method for a modular dc energy consuming device, the modular dc energy consuming device being formed by serially connecting a plurality of sub-modules connected in series, the control method comprising: accumulating the number of the fault submodules; determining the level of a redundancy mode according to the number of the fault sub-modules, and entering a corresponding redundancy mode; at least one of the redundancy modes includes jumping out of the current redundancy mode and automatically entering a higher level redundancy mode when the number of faulty sub-modules reaches an upper threshold of the current redundancy mode.

Furthermore, the modular direct current energy consumption device can be formed by connecting M sub-modules in series, wherein M is an integer greater than or equal to 2; the modular direct current energy consumption device also comprises energy consumption resistors, and the energy consumption resistors are connected with the M sub-modules in series or/and distributed in each sub-module; the sub-module comprises a capacitor, a power semiconductor device and a bypass switch, and the on-off of the power semiconductor device controls the input and the exit of the energy consumption resistor in the circuit; the sub-module is short-circuited after the bypass switch is closed; the modular direct current energy consumption device also comprises a main control system and a sub-module control system, wherein the sub-module comprises the sub-module control system, and the main control system is communicated with the sub-module control system from bottom to top and is communicated with an external control system from top to bottom; the energy consumption resistor is connected with the sub-module and the energy consumption resistor in series, and the energy consumption resistor is connected with the sub-module and the energy consumption resistor in series; in the energy consumption state, the modular direct current energy consumption device controls the voltage of a direct current line by controlling the on/off of the power semiconductor devices in the sub-modules; wherein the redundancy mode comprises: 1) Primary redundancy mode: after the submodule fails, closing the bypass switch, wherein the submodule failures comprise submodule communication failures and submodule non-communication failures; 2) secondary redundancy mode: after the submodule communication fault occurs in the submodule, the submodule control system controls the power semiconductor device to be switched on and off according to a submodule capacitor voltage value; the bypass switch is closed after the submodule generates the submodule non-communication fault; 3) three-level redundancy mode: under the energy consumption state, changing the control target of the direct current line voltage, and actively reducing the direct current line voltage stability performance of the modular direct current energy consumption device; 4) four-level redundancy mode: under the energy consumption state, the modular direct current energy consumption device does not control the voltage of the direct current line any more, and the energy consumption resistor is switched in; the control method includes at least two of the four redundancy modes.

The control method is used for considering both the reliability of the system and the reliability of the energy consumption device through the setting and switching control of various redundancy modes.

The redundancy modes of the direct current energy consumption device are arranged in a grading mode, the redundancy modes are switched according to the number of sub-modules with faults, along with the increase of the grade number of the redundancy modes, the performance of the corresponding device is continuously deteriorated, different processing modes are executed according to the deterioration, the state of the device is fed back to the controller of the converter in real time, the redundancy of the sub-modules of the energy consumption device is fully utilized in the grading processing mode, and the reliability of the device and the reliability of a system are considered.

The invention classifies the submodule faults of the direct current energy consumption device, and automatically controls the direct current voltage by using the submodule control system under the communication fault, thereby fully utilizing the energy consumption capability of the device.

Drawings

Fig. 1 is a schematic flow chart illustrating a method for controlling a modular dc energy consuming device according to an embodiment of the present application.

Fig. 2 is a schematic diagram illustrating an application scenario of the method illustrated in fig. 1.

Fig. 3 shows a schematic topology of a modular dc energy consuming device according to the method of fig. 1.

Fig. 4A-4D are schematic diagrams illustrating sub-modules of the modular dc energy consuming device of fig. 3.

Fig. 5 is a schematic flow chart illustrating a method for controlling a modular dc energy consuming device according to another embodiment of the present application.

Fig. 6 shows a flowchart of the expanding step of S120 in the method shown in fig. 5.

FIG. 7 is a flow diagram illustrating a primary redundancy scheme in the method of FIG. 5.

FIG. 8 is a flow diagram illustrating a secondary redundancy scheme in the method of FIG. 5.

FIG. 9 illustrates a flow diagram of the three-level redundancy scheme in the method of FIG. 5.

FIG. 10 is a flow diagram illustrating a four-level redundancy scheme in the method of FIG. 5.

Detailed Description

The following description is provided for the embodiments of the present disclosure relating to a method for controlling fault redundancy of a modular dc energy consuming device, and those skilled in the art can understand the advantages and effects of the present disclosure from the disclosure of the present disclosure. The invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. The drawings of the present invention are for illustrative purposes only and are not intended to be drawn to scale. The following embodiments will further explain the related art of the present invention in detail, but the disclosure is not intended to limit the scope of the present invention.

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 some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be understood that the terms "first," "second," "third," and "fourth," etc. in the claims, description, and drawings of the present application are used for distinguishing between different objects and not for describing a particular order. The terms "comprises" and "comprising," when used in the specification and claims of this application, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is also to be understood that the terminology used in the description of the present application herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the application. As used in the specification and claims of this application, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the term "and/or" as used in the specification and claims of this application refers to any and all possible combinations of one or more of the associated listed items and includes such combinations.

Fig. 1 is a schematic flow chart illustrating a method for controlling a modular dc energy consuming device according to an embodiment of the present application. Fig. 2 is a schematic diagram illustrating an application scenario of the method illustrated in fig. 1. Fig. 3 shows a schematic topology of a modular dc energy consuming device according to the method of fig. 1. Fig. 4A-4D are schematic diagrams illustrating sub-modules of the modular dc energy consuming device of fig. 3.

The method of fig. 1 can be applied to the modular dc energy consuming device 20 of fig. 2. As shown in fig. 2, the apparatus is formed by connecting M sub-modules 4 in series, where M is an integer greater than or equal to 2; the device further comprises a resistor 5, which is connected in series with the M sub-modules or/and distributed in each sub-module.

The resistors play a role in energy consumption, can be arranged in a concentrated mode and connected with the M sub-modules in series, can also be distributed in each sub-module, and can also adopt the two modes simultaneously, namely that one part of the resistors are arranged in a concentrated mode, and other resistors are distributed in each sub-module.

The sub-module comprises a capacitor, a power semiconductor device and a bypass switch, and the on and off of the power semiconductor device control the input and the exit of a resistor in the circuit. And after the bypass switch is closed, the sub-module is short-circuited.

Examples of 4 typical sub-modules are listed below, as shown in FIGS. 4A-4D:

(1) submodule structure 1: as shown in fig. 4A, the sub-module includes a first power semiconductor device and a voltage clamping unit, wherein a collector of the first power semiconductor device serves as a positive terminal of the sub-module, and an emitter of the first power semiconductor device serves as a negative terminal of the sub-module; the voltage clamping unit is formed by serially connecting a capacitor, second power and an equalizing resistor, and is connected with the first power semiconductor device in parallel; the third power semiconductor device is connected in parallel to two ends of the second power and balance resistor which are connected in series; the power semiconductor device further comprises a bypass switch which is connected in parallel to two ends of the first power semiconductor device.

Preferably, the first power semiconductor device is a fully-controlled power semiconductor device and may be an IGBT/IGCT, the second power semiconductor device may be an IGBT/IGCT/thyristor, and the third power semiconductor device is a diode.

When the submodule is adopted, the energy consumption resistor is preferably arranged outside the submodule in a centralized mode and is connected with the submodule in series, and the balance resistor in the submodule is mainly used as a discharge resistor of the capacitor to adjust the capacitor voltage of the submodule.

(2) Submodule structure 2: as shown in fig. 4B, the sub-module includes a capacitor, a power semiconductor device, a resistor, a first bypass switch and a second bypass switch, wherein an anode of the capacitor is used as an anode of the sub-module, a cathode of the capacitor is used as a cathode of the sub-module, the power semiconductor device is connected in series with the resistor and then connected in parallel with the capacitor, the first bypass switch is connected in parallel with the capacitor, and the second bypass switch is connected in parallel with the power semiconductor device; in this embodiment, the resistors are mainly used for dissipating energy, and belong to a mode that energy dissipation resistors are distributed in each submodule. When the bypass command is executed, the second bypass switch is closed, the capacitor discharges through the energy consumption resistor, and then the first bypass switch is closed. Preferably, the power semiconductor device is a fully-controlled power semiconductor device, and may be an IGBT/IGCT.

(3) Submodule structure 3: as shown in fig. 4C, the sub-module includes a capacitor, a first power semiconductor device, a second power semiconductor device, a third power semiconductor device, a resistor, and a bypass switch; wherein the cathode of the second power semiconductor device is used as the anode of the submodule, and the anode is used as the cathode of the submodule; the first power semiconductor device is connected with the resistor in series and then connected with the capacitor in parallel, the negative electrode of the capacitor is connected with the anode of the second power semiconductor device, and the positive electrode of the capacitor is connected with the cathode of the second power semiconductor device through the third power semiconductor device; the bypass switch is connected in parallel with the second power semiconductor device.

Preferably, the first power semiconductor device is a fully-controlled power semiconductor device, and may be an IGBT/IGCT, and the second and third power semiconductor devices are diodes.

In this embodiment, the resistors are mainly used for dissipating energy, and belong to a mode that energy dissipation resistors are distributed in each submodule.

(4) Submodule structure 4: as shown in fig. 4D, similar to the sub-module structure 3, wherein the second power semiconductor device is a fully-controlled power semiconductor device, preferably an IGBT/IGCT, in this manner, the dissipation resistor is preferably arranged outside the sub-module in a centralized manner and connected in series with the sub-module, and the resistor in the sub-module mainly functions as a discharge resistor of the capacitor, and the capacitor voltage of the sub-module is adjusted by turning on and off the first power semiconductor device.

This is seen. In the embodiment, no matter what arrangement mode is adopted for the resistors, the power semiconductor devices distributed in each submodule control the input and the exit of the energy consumption resistors in the circuit so as to achieve the aim of controlling the energy consumption speed.

The structure 1 and the structure 4 respectively comprise two groups of fully-controlled power semiconductor devices, wherein the connection and disconnection of one group of power semiconductor devices control the on and off of a centralized resistor, and the connection and disconnection of the other group of power semiconductor devices control the capacitance voltage of a submodule; the structure 2 and the structure 3 only comprise a group of fully-controlled power semiconductor devices, the purpose of energy consumption is achieved by controlling the on and off of energy consumption resistors in the sub-modules, and meanwhile, the capacitor voltage of the sub-modules is stabilized.

The implementation of the above four sub-modules is a typical application, and other sub-modules applying the above energy consumption principle are all applicable to the control method of the present invention.

As shown in fig. 2, the device further comprises a main control system 1 and a sub-module control system, wherein the main control system communicates with the sub-module control system 2 from the lower part and communicates with an external control system 3 from the upper part; in this embodiment, the external control system is a control system of the inverter.

The device is connected in parallel between direct current lines and has a standby state and an energy consumption state; in the standby state, the energy consumption resistor is not put into use; in the energy consumption state, the device controls the direct-current voltage of the circuit by controlling the on and off of the power semiconductor devices in the sub-modules.

As shown in fig. 1, the device control method is divided into the following four redundancy modes according to sub-module failure conditions:

1) primary redundancy mode: and after the sub-module fails, closing the bypass switch.

2) Secondary redundancy mode: after the sub-module has communication fault, the sub-module control system controls the on-off of the power semiconductor device according to the sub-module capacitor voltage value; and closing the bypass switch after the submodule has a non-communication fault.

3) Three-level redundancy mode: and under the energy consumption state, the control target of the line direct-current voltage is changed, and the line direct-current voltage stability of the device is actively reduced.

4) Four-level redundancy mode: in the energy consumption state, the device does not control the voltage of the direct current line any more and puts the resistor into operation all the time.

The device control method includes at least two of the four redundancy modes; and when the number of the fault sub-modules in each redundancy mode reaches a preset value, jumping out of the mode and automatically entering the next redundancy mode.

The embodiment of fig. 1 is a case where all four redundancy modes are included.

When all the redundancy modes are tripped out, the device stops running and cuts off the connection with the direct current line.

Preferably, the four redundancy modes are switched in the order of the number of stages from small to large.

For example, four redundancy modes are included, according to the switching mode of a first level, a second level, a third level and a fourth level; or three redundancy modes are included according to the switching modes of a first level, a second level and a fourth level.

Wherein, preferably, when the redundant mode reaches the third level, the device sends an alarm signal to an external control system; when the redundant mode reaches the fourth level, the device sends a serious alarm signal to an external control system.

As shown in fig. 1, before the device enters the failure redundancy control, the entering redundancy mode is first selected according to the number of failed sub-modules in the initial state, preferably, starting from the primary redundancy mode, and other situations are also included, such as when a plurality of failed sub-modules are simultaneously present after the device is initialized, and the possibility of skipping the previous redundancy mode may occur.

The primary redundancy mode control method comprises the following steps:

step 1: the number of sub-modules allowed to fail in the mode is set to X.

Step 2: when the line voltage is normal, the device is in a standby state; when the direct current overvoltage of the line occurs, the device enters an energy consumption state; the master control system monitors the status of the sub-modules. The line voltage may be a direct current line voltage less than or equal to a first voltage threshold, and the line direct current overvoltage may be a direct current voltage greater than the first voltage threshold, as follows.

And step 3: and (2) if the sub-module fails in the process of the step (2), the main control system or the sub-module control system issues a bypass command.

And 4, step 4: and the main control system cumulatively records the number of the sub-modules of the fault bypass.

And 5: and repeating the step 2-4, and when the number of the fault bypass sub-modules is larger than or equal to X, jumping out of the mode and entering the next redundancy mode.

The secondary redundancy mode control method is as follows.

Step 1: the number of submodules allowing the bypass of the non-communication fault in the mode is set to be Y1, and the number of submodules of the communication fault is set to be Y2.

Step 2: when the line voltage is normal, the device is in a standby state; when the direct current overvoltage of the line occurs, the device enters an energy consumption state; the master control system monitors the status of the sub-modules.

And step 3: and (2) if the sub-module non-communication fault occurs in the process of the step (2), the main control system or the sub-module control system issues a bypass command.

And 4, step 4: and 2, if the sub-module communication fault occurs in the process of the step 2, controlling the sub-module capacitor voltage to be stabilized in a certain range by controlling the on-off of the power semiconductor device in the off-line mode of the sub-module control system.

And 5: and the main control system cumulatively records the number of the sub-modules of the bypass and the number of the sub-modules of the communication fault.

Step 6: and (5) repeating the step (2) to the step (5), and jumping out of the mode and entering the next redundancy mode when the number of the fault bypass sub-modules is more than or equal to Y1 or the number of the communication fault sub-modules is more than or equal to Y2.

The three-level redundancy mode control method comprises the following steps:

step 1: the number of submodules allowing the bypass of the non-communication fault in the mode is set to be Z1, and the number of submodules of the communication fault is set to be Z2.

Step 2: the master control system monitors the state of the sub-modules; if the energy consumption device is in an energy consumption state, adjusting a control target of the line direct-current voltage, and actively reducing the line direct-current voltage stability of the device; if the mobile terminal is in the standby state, the original state is maintained.

Step 6: and (5) repeating the step (2) to the step (5), and jumping out of the mode and entering the next redundancy mode when the number of the fault bypass sub-modules is more than or equal to Z1 or the number of the communication fault sub-modules is more than or equal to Z2.

The four-level redundancy mode control method comprises the following steps:

step 1: the number of sub-modules allowed to fail in this mode is set to W.

Step 2: the master control system monitors the state of the sub-modules; if the energy consumption device is in an energy consumption state, all energy consumption resistors are put into use; if the mobile terminal is in the standby state, the original state is maintained.

And step 3: if sub-module failure occurs in the process of step 2, the main control system or the sub-module control system issues a bypass command;

and 4, step 4: the master control system accumulates the number of sub-modules that have been bypassed.

And 5: and (4) repeating the step (2) to the step (4), and jumping out of the mode when the number of the fault bypass sub-modules is larger than or equal to W.

In the four-level redundancy mode control method, when an uplink communication fault of the submodule control system to the main control system occurs, the main control system increases the number of the bypass submodules and the number of the communication fault submodules at the same time. In this case, since the master control system cannot obtain the status of the sub-module control system, the most serious fault condition is treated, that is, both bypass and communication faults are considered.

In the four-level redundancy mode control method, an autonomous voltage-sharing strategy is executed when the power semiconductor device is in a standby state, and under the autonomous voltage-sharing strategy, the submodule control system controls the submodule capacitor voltage to be within a certain range by controlling the power semiconductor device to be switched on and off.

Wherein the bypass switch is a high-speed mechanical switch or a power semiconductor device, or a combination of the two; the high-speed mechanical switch receives command action switching-on of the sub-module control system; the power semiconductor device breaks down the short circuit when bearing overvoltage, so that the sub-module is bypassed.

The communication mode of the master control system and the sub-module control system is one-to-one communication mode, or one-to-many master-slave communication mode, or hand-in-hand looped network communication mode.

Wherein the external control system is a control system of a converter capable of controlling a direct-current voltage or transmission power of a direct-current line on which the device is located.

In the four-level redundancy mode control method, the power semiconductor device of the fault-free sub-module receives the instruction of the main control system and executes the turn-on or turn-off command; and the power semiconductor device of the communication fault submodule receives an instruction of the submodule control system and executes a switching-on or switching-off command.

In the four-stage redundancy mode control method, the manner of closing the bypass switch includes:

closing the master control: and a bypass command is given by the main control system to trigger the switch mechanism to be closed.

And (3) closing the sub-modules: when communication is in fault, the sub-die control system gives a bypass command to trigger the switch mechanism to be closed.

And (3) passive closing: the switch mechanism is automatically triggered to close through a hardware loop.

Breakdown is closed: breaking down a short circuit when the power semiconductor device bears overvoltage; corresponding to the bypass scheme of fig. 4D.

The specific method for changing the control target of the line direct-current voltage in the step 2 of the three-level redundancy mode comprises the following steps:

increasing the width of a hysteresis control loop: if the device adopts a hysteresis control mode to control the direct current line voltage, namely the direct current line voltage is controlled between a high voltage limit value and a low voltage limit value, the difference between the high voltage limit value and the low voltage limit value is increased.

Increasing the closed-loop control target value: and if the device adopts a mode of closed-loop regulation of the voltage of the direct current line, the voltage control target value of the direct current line is improved.

And in the step 6 of the secondary redundancy mode, when the sum of the number of the bypassed submodules and the number of the submodules with the communication faults is greater than or equal to a preset total limit YN, the current mode is also skipped, and the next mode is entered, wherein YN is less than or equal to Y1+ Y2.

In step 6 of the three-level redundancy mode, when the sum of the number of bypassed sub-modules and the number of communication-failed sub-modules is greater than or equal to a preset total limit value ZN, the current mode is skipped, and the next mode is entered, wherein ZN is less than or equal to Z1+ Z2.

As shown in fig. 5, the method 2000 may be used to control a modular dc energy consuming device. The topology structure, the application scenario, and the sub-modules of the energy consumption device may be as shown in fig. 2 to 4, which are not described herein. The method 2000 may include: s210 and S220.

In S210, determining the number Nb of faulty submodules in the energy consuming device may be included. Alternatively, the fault may include a communication fault and a non-communication fault. The number Nb of fault submodules may include at least one of a number Nbc of communication fault submodules, a number Nbb of non-communication fault submodules, and a number Nbs of fault bypass submodules, and may further include a sum of at least two of the above three items. Wherein, the number Nbs of the fault short-circuit sub-modules is the number of the fault sub-modules which have been bypassed.

In S220, a redundancy mode level L m may be determined based on the number of failed sub-modules Nb and a corresponding redundancy mode is entered, in method 2000, at least two redundancy mode levels may be included, and at least two corresponding level redundancy modes may be included, wherein each level redundancy module may correspond to a different entry threshold and exit threshold.

As shown in the example embodiment illustrated in FIG. 6, the method 2000 may include 4 levels of redundancy patterns, and may include four corresponding redundancy patterns, namely, a primary redundancy pattern M L1, a secondary redundancy pattern M L2, a tertiary redundancy pattern M L3, and a quaternary redundancy pattern M L4.

As shown in fig. 6, S220 may include: s221, S222, S223, and S224, and S230, S240, S250, S260, and S270.

In S221, it may be determined whether the number Nb of faulty submodules is less than the first threshold X. If the judgment result is yes, the step S230 is entered; if the judgment result is no, the process proceeds to S222.

In S222, it may be determined whether the number Nb of faulty submodules is less than the second threshold Y. If the judgment result is yes, the step S240 is entered; if the judgment result is no, the process proceeds to S223. Optionally, the number of failed sub-modules may include the number of communication failed sub-modules Nbc and the number of failure bypass sub-modules Nbs. Alternatively, the judgment section in S222 may be replaced with: and judging whether the communication fault submodule quantity Nbc is less than the threshold Y2 and the fault bypass submodule quantity Nbs is less than the threshold Y1.

In S223, it may be determined whether the number Nb of faulty submodules is less than the third threshold Z. If the judgment result is yes, the step S250 is entered; if the judgment result is no, the process proceeds to S224. Optionally, the number of failed sub-modules may include the number of communication failed sub-modules Nbc and the number of failure bypass sub-modules Nbs. Alternatively, the judging section of S223 may be replaced with: whether the communication fault submodule quantity Nbc is less than the threshold value Z2 and the fault bypass submodule quantity Nbs is less than the threshold value Z1 is judged.

In S224, it may be determined whether the number Nb of faulty submodules is less than the fourth threshold W. If the judgment result is yes, the step S260 is entered; and if the judgment result is not yes, the step S270 is entered, and the operation is stopped.

The steps S230-S260 may include entering a primary redundancy mode M L1, entering a four redundancy mode M L4, and executing an operation corresponding to the redundancy mode, in any of steps S230-S260, determining whether an exit condition of the current redundancy mode is satisfied, if the exit condition of the current redundancy mode is satisfied, exiting the current redundancy mode, entering a next-stage redundancy mode directly after exiting the current redundancy mode, or entering step S210 again, determining a redundancy mode level L M again according to the number of sub-modules with faults, and entering a redundancy mode corresponding to the redundancy mode level L M.

The S270 may be entered when the exit condition of the highest-level redundancy mode is satisfied, optionally, the operations specifically included by the primary redundancy mode M L1-the quad redundancy mode M L4 may be as shown in the example embodiments illustrated in FIGS. 7-10. the primary redundancy mode M L1-the quad redundancy mode M L4 will be exemplified in detail later.

In S270, the energy consuming device may stop operating and may disconnect the dc link.

Step S120 in the method shown in fig. 1 may not be limited to the flow shown in fig. 6.

As shown in fig. 3, the modular dc energy consuming device to which the method 2000 is applied may alternatively comprise a plurality of sub-modules connected in series. Each submodule can be used for controlling the input or not and the input level of the energy consumption resistor. The energy consumption resistance can be more than one. Each energy consumption resistor can be arranged independently of the sub-modules and is controlled by the corresponding sub-module; the energy consumption resistor can also be arranged inside the sub-module and controlled by the sub-module.

The energy consuming device may enter an energy consuming state when the dc link voltage exceeds a first voltage threshold. In the energy consumption state, a plurality of sub-modules in the energy consumption device can cooperate with each other. Each submodule can control the input level of the corresponding energy consumption resistor. Therefore, redundant electric energy in the direct current line can be consumed controllably, and the voltage of the direct current line can be regulated to be within a preset range in the mode. Alternatively, there may be some redundancy in sub-modules configured in the energy consuming device. That is, in general, when the energy consumption device can operate normally through some of the sub-modules included in the plurality of sub-modules, the dc line voltage can be maintained within the predetermined range.

Optionally, the sub-module may include a bypass switch and a power semiconductor device. The input or non-input of the energy consumption resistor can be controlled by the on/off of the power semiconductor, and the input level of the energy consumption resistor can be controlled by the matching of the on duration and the off duration of the power semiconductor. When the bypass switch is closed, the submodule is bypassed and no longer has an influence on the dc line.

The sub-module may further comprise a sub-module control system for controlling at least one of the bypass switch and the power semiconductor device. Optionally, the energy consuming device may include a master control system in communication with the sub-module control systems. The master control system can indirectly acquire the state of the sub-module through communication with the sub-module control system, and can indirectly control at least one of a bypass switch and a power semiconductor device of the sub-module through the sub-module control system.

Optionally, the sub-modules may also include hardware circuits. The hardware loop may control at least one of the power semiconductor switch and the bypass switch by hardware logic.

Optionally, the sub-module may also comprise an overvoltage breakdown power semiconductor device. The overvoltage breakdown power semiconductor device can take the voltage at two ends of the overvoltage breakdown power semiconductor device as a judgment basis for judging whether the submodule fails or not. The overvoltage breakdown power semiconductor device can also generate overvoltage breakdown when the voltage at two ends exceeds a second preset voltage threshold value, and bypasses the sub-module where the overvoltage breakdown power semiconductor device is located.

The method can enter a primary mode M L1 when the number of faulty sub-modules in the energy consumption device is small, wherein the small number of faulty sub-modules can be that the number of sub-modules in the energy consumption device which are faulty is far smaller than the redundant configuration of the energy consumption device, and the energy consumption device can utilize normal sub-modules to regulate the voltage of the direct current line to be within a preset range in an energy consumption mode.

As shown in FIG. 7, the primary redundancy mode may include: s231, S232, S233, S234, S236, S237, S238, and S239.

In S231, a sub-module status of at least one sub-module within the apparatus may be monitored. The sub-module status may include a normal status and a fault status. The fault condition may include a non-communication fault and a communication fault. The communication failure may include an upstream communication failure and a downstream communication failure. Optionally, when an uplink communication fault occurs, the master control system cannot acquire the status of the sub-module. The worst case can be used for judgment. That is, it can be determined that the submodule has both a non-communication failure and a communication failure.

Alternatively, the status of the sub-modules may be monitored by the main control system through communication in S231. Sub-module status may also be monitored autonomously by a sub-module control system within the sub-module. Hardware logic can also be utilized by the hardware loop to monitor the communication state of the sub-modules. The state of the sub-module can be monitored by monitoring the voltage at two ends of the overvoltage breakdown power semiconductor device through the overvoltage breakdown power semiconductor device.

In S232, at least one sub-module having a fault may be determined in the energy consumption device according to the monitoring result in S231, and the at least one sub-module having the fault may be bypassed. The fault may be a fault of all sub-modules including a non-communication fault and a communication fault.

Optionally, the main control system may send a bypass instruction to the sub-module control system of the sub-module, and the sub-module control system controls the bypass switch to be closed after receiving the bypass instruction, so as to achieve the purpose of bypassing the sub-module. Optionally, the sub-module control system may also autonomously control the bypass switch to be closed when the communication fails, so as to achieve the purpose of bypassing the sub-module. Optionally, the hardware loop can automatically trigger the switch mechanism to cause the bypass switch to be closed, so as to achieve the purpose of bypassing the submodule. The purpose of bypassing the submodule can be achieved by means of overvoltage breakdown of the power semiconductor device due to overvoltage breakdown.

In S233, the number of faulty submodules may be accumulated. Optionally, the number of fault submodules may include at least one of the number of non-communication fault submodules, the number of communication fault submodules, and the number of fault bypass submodules, and the number of fault submodules may also include a sum of at least two of the three.

In S234, the operating state of the energy consuming device may be determined from the dc line voltage. Alternatively, the operating state of the energy consuming device may include a standby state and an energy consuming state. Optionally, when the dc line voltage is less than or equal to the first voltage threshold, the energy consuming device may enter a standby state; when the dc link voltage is greater than the first voltage threshold, the energy consuming device may enter an energy consuming state. S234 may further include: if the energy consuming device is in a standby state, S237 may be entered; if the energy consuming device is in an energy consuming state, S236 may be entered.

In S236, a general energy consuming process may be performed. In the ordinary energy consumption treatment, the energy consumption resistor can be put into use by controlling the on/off of the power semiconductor device. And the input level of the energy consumption resistor can be controlled by controlling the on/off of the power semiconductor device. Therefore, the redundant electric energy in the direct current line can be consumed controllably, and the voltage of the direct current line can be regulated. The input level of the energy consumption resistor can be adjusted by controlling the on-time and the off-time of the power semiconductor device in each period. And the power consumption capability of the energy consumption resistor and the voltage regulation capability of the sub-module are regulated accordingly.

In S237, an autonomous voltage-sharing strategy may be performed, and the voltage across each sub-module may be adjusted by controlling the on/off of the power semiconductor device of each sub-module, respectively. So that the dc line voltage is relatively uniformly received by each sub-module. The voltage expectations across the various sub-modules may be assigned by the main control system. And the submodule control system of each submodule can regulate the voltage at two ends of the submodule to be the voltage expectation by controlling the on/off of the power semiconductor device. In S237, the dissipative resistance input level can be made negligibly small by controlling the on/off of the power semiconductor device.

Wherein S234-S237 may be disposed before S231-S233, or disposed after S231-S233. S234-S237 may also be performed in parallel with or interspersed with S231-S233.

In S238, it may be determined whether an exit condition of the primary redundancy mode is satisfied. If the judgment result is negative, the step S231 is entered; if yes, the process may proceed to S239 to exit the current redundancy mode. Alternatively, the exit condition for the primary redundancy mode may be: the number Nb of the fault sub-modules is larger than or equal to a first threshold value X.

In the primary redundancy mode M L1 shown in fig. 7, bypass processing may be performed for any faulty submodule, so that it is ensured that the energy consuming device can adjust the dc link voltage in an energy consuming manner using the normal submodule, so that the dc link can maintain an optimal state and the converter connected to the energy consuming device can be ensured to be in an optimal reliable state.

Optionally, the secondary redundancy mode M L2 may be entered when the number of faulty sub-modules in the energy consumption device is large, and optionally, the "large number of faulty sub-modules" may be that the energy consumption device is difficult to regulate the dc line voltage within a preset range in an energy consumption manner only by using normal sub-modules.

As shown in fig. 8, the secondary redundancy mode may include: s241, S242, S243, S244, S246, S247, S248, and S249. S241, S243-S246, and S249 may be similar to S231, S233-S237, and S239 in fig. 7, respectively, and are not described herein again.

In S242, it may be determined that the sub-module status includes at least one sub-module having a non-communication failure in the energy consumption device according to the monitoring result in S241. And may bypass the at least one sub-module. The bypass manner in S242 may be similar to that in S232, and is not described herein.

In S247, for normal sub-modules, an autonomous voltage-sharing strategy may be performed, which may be as described in S237. For the sub-module with only communication fault, the sub-module control system can automatically adjust the voltage at the two ends of the sub-module in an off-line mode according to a preset voltage control target.

In S248, the exit condition of the secondary redundancy mode M L2 may be that the number Nbs of the fault bypass sub-modules is greater than or equal to the threshold Y1 or the number Nbc of the communication failure sub-modules is greater than or equal to the threshold Y2., or the exit condition of the secondary redundancy mode M L2 may be that the number Nbs of the fault bypass sub-modules + the number Nbc of the communication failure sub-modules is greater than or equal to the threshold YN., optionally, YN may be less than or equal to the sum of Y1 and Y2.

In the secondary redundancy mode M L2 shown in fig. 8, a non-fatal fault (communication fault) can be used to participate in the normal operation of the energy consuming device, and when the number of sub-modules with faults is relatively large, the energy consuming device can be maintained to operate relatively normally.

Optionally, the three-level redundancy mode M L3 may be entered when the number of faulty submodules in the energy consuming device is large, where the "large number of faulty submodules" may be that the number of faulty submodules exceeds the redundant configuration of the energy consuming device, and the energy consuming device is difficult to regulate the voltage of the dc line within the preset range in an energy consuming manner.

As shown in fig. 9, S250 may include: s251, S252, S253, S254, S256, S257, S258, and S259. Wherein, S251-S254, S257, S259 may be respectively similar to those shown in fig. 8: S241-S244, S247, and S249 are similar and will not be described.

At S256, a derating regulation power consumption process may be performed, the DC link voltage regulation target may be actively reduced at this step or upon entering the tertiary redundancy mode M L3, and the DC link voltage may be regulated in a power consumption manner at this step based on the reduced DC link voltage regulation target, such that the DC link voltage is in a relatively acceptable state.

Further, reducing the dc line voltage regulation target may include: the adjustment range of the voltage of the direct current line is reduced, and the adjustment target of the voltage stability of the direct current line is lowered. Furthermore, if the modular dc energy dissipation device controls the dc line voltage in a hysteresis control manner, i.e. the dc line voltage is controlled between the high voltage limit and the low voltage limit, the difference between the high voltage limit and the low voltage limit can be increased. And if the modular direct current energy consumption device adopts a direct current line voltage closed loop regulation mode, the direct current line voltage control target value is improved.

In S258, the exit condition of the tertiary redundancy mode M L3 may be that the number of fault bypass sub-modules Nbs is greater than or equal to the threshold Z1 or that the number of communication fault sub-modules Nbc is greater than or equal to the threshold Z2., or that the exit condition of the tertiary redundancy mode M L3 may be that the number of fault bypass sub-modules Nbs + the number of communication fault sub-modules Nbc is greater than or equal to the threshold ZN., optionally, ZN may be less than or equal to the sum of Z1 and Z2.

Optionally, in the three-level redundancy mode M L3, sending an alarm signal may be further included.

In the three-level redundancy mode M L shown in fig. 9, when the number of faulty submodules of the energy consuming device is large, and the energy consuming device is difficult to maintain the dc line voltage within the preset range beyond the redundancy of the energy consuming device, the energy consuming device may actively adjust the target by reducing the dc line voltage, and when the energy consuming device is in the energy consuming state, adjust the dc line voltage to a relatively acceptable temporary state, maintain the dc line in a relatively normal state, and win time for system maintenance.

Optionally, the four-level redundancy mode M L4 may be entered when the number of faulty sub-modules in the energy consuming device is very large, which may be that the number of faulty sub-modules significantly exceeds the redundancy range of the energy consuming device.

As shown in fig. 10, S260 may include: s261, S262, S263, S264, S266, S267, S268, and S269. Wherein, S261-S264, S267, S269 can be respectively similar to those shown in fig. 8: S241-S244, S247, and S249 are similar and will not be described.

In S266, full power consumption may be performed. Alternatively, the full dissipation may include all dissipation resistors that are put into the dissipation device. The input level of the dissipation resistor is increased as much as possible without any further regulation expectations for the dc link voltage.

In S268, whether the exit condition of the four-level redundancy mode M L4 is met or not can be judged, if the judgment result is yes, otherwise, S261 can be entered, if the judgment result is yes, S269 can be entered, and the current redundancy mode exits, optionally, the exit condition of the four-level redundancy mode M L4 can be that the number Nb of the fault sub-modules is larger than or equal to the fourth threshold value W.

In the four-level redundancy mode shown in fig. 10, when the number of fault submodules in the energy consuming device greatly exceeds the redundancy configuration of the energy consuming device, the energy consuming device can put in all energy consuming resistors in the energy consuming state and put in the maximum energy consuming capacity, the direct-current line voltage is maintained in a relatively better state within the capacity range of the energy consuming device, and time is saved for system maintenance.

The redundancy modes of the direct current energy consumption device are arranged in a grading mode, the redundancy modes are switched according to the number of sub-modules with faults, along with the increase of the grade number of the redundancy modes, the performance of the corresponding device is continuously deteriorated, different processing modes are executed according to the deterioration, the state of the device is fed back to the controller of the current converter in real time, the redundancy of the sub-modules of the energy consumption device is fully utilized in the grading processing mode, and the reliability of the energy consumption device and the reliability of a system are considered.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments. The technical features of the embodiments may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application, and the description of the embodiments is only intended to facilitate the understanding of the methods and their core concepts of the present application. Meanwhile, a person skilled in the art should, according to the idea of the present application, change or modify the embodiments and applications of the present application based on the scope of the present application. In view of the above, the description should not be taken as limiting the application.

Claims

1. A method for controlling fault redundancy of a modular dc energy consuming device, the modular dc energy consuming device being composed of a plurality of sub-modules connected in series, the method comprising:

accumulating the number of the fault submodules;

determining the level of a redundancy mode according to the number of the fault sub-modules, and entering a corresponding redundancy mode;

at least one of the redundancy modes includes jumping out of the current redundancy mode and automatically entering a higher level redundancy mode when the number of faulty sub-modules reaches an upper threshold of the current redundancy mode.

2. The control method according to claim 1, wherein the modular dc energy consumption device is formed by connecting M sub-modules in series, M being an integer greater than or equal to 2; the modular direct current energy consumption device also comprises energy consumption resistors, and the energy consumption resistors are connected with the M sub-modules in series or/and distributed in each sub-module;

the sub-module comprises a capacitor, a power semiconductor device and a bypass switch, and the on-off of the power semiconductor device controls the input and the exit of the energy consumption resistor in the circuit; the sub-module is short-circuited after the bypass switch is closed;

the modular direct current energy consumption device also comprises a main control system and a sub-module control system, wherein the sub-module comprises the sub-module control system, and the main control system is communicated with the sub-module control system from bottom to top and is communicated with an external control system from top to bottom;

the energy consumption resistor is connected with the sub-module and the energy consumption resistor in series, and the energy consumption resistor is connected with the sub-module and the energy consumption resistor in series; in the energy consumption state, the modular direct current energy consumption device controls the voltage of a direct current line by controlling the on/off of the power semiconductor devices in the sub-modules;

wherein the redundancy mode comprises:

1) primary redundancy mode: after the submodule fails, closing the bypass switch, wherein the submodule failures comprise submodule communication failures and submodule non-communication failures;

2) secondary redundancy mode: after the submodule communication fault occurs in the submodule, the submodule control system controls the power semiconductor device to be switched on and off according to a submodule capacitor voltage value; the bypass switch is closed after the submodule generates the submodule non-communication fault;

3) three-level redundancy mode: under the energy consumption state, changing the control target of the direct current line voltage, and actively reducing the direct current line voltage stability performance of the modular direct current energy consumption device;

4) four-level redundancy mode: under the energy consumption state, the modular direct current energy consumption device does not control the voltage of the direct current line any more, and the energy consumption resistor is switched in;

the control method includes at least two of the four redundancy modes.

3. The method for controlling fault redundancy of the modular direct current energy consumption device according to claim 2, wherein when all redundancy modes are tripped, the modular direct current energy consumption device stops operating and disconnects the connection with the direct current line.

4. The method for controlling fault redundancy of a modular direct current energy consumption device according to claim 2, wherein the four redundancy modes are switched in the order of the number of stages from small to large.

5. The method for controlling the fault redundancy of the modular direct current energy consumption device as claimed in claim 2, wherein when the redundancy mode level reaches three levels, the device sends an alarm signal to an external control system; when the level of the redundancy mode reaches four levels, the device sends a serious alarm signal to an external control system.

6. The method for controlling fault redundancy of a modular direct current energy consumption device according to claim 2, wherein the primary redundancy mode control method comprises the following steps:

step 1: setting the number of sub-modules which are allowed to fail in the mode as X;

step 2: monitoring the state of the sub-module;

and 4, step 4: the main control system accumulates and records the number of sub-modules of the fault bypass;

7. The method for controlling the fault redundancy of the modular direct current energy consumption device as claimed in claim 2, wherein the secondary redundancy mode control method comprises the following steps:

step 1: setting the number of sub-modules allowing non-communication fault bypass to occur in the mode as Y1 and the number of sub-modules allowing communication fault bypass to occur in the mode as Y2;

step 2: monitoring the state of the sub-module;

and step 3: in the step 2, if the sub-module non-communication fault occurs, the main control system or the sub-module control system issues a bypass command;

and 4, step 4: in the step 2, if a sub-module communication fault occurs, the sub-module control system controls the on-off of the power semiconductor device in an off-line mode to control the sub-module capacitor voltage to be stabilized within a preset range;

and 5: the main control system cumulatively records the number of the sub-modules of the bypass and the number of the sub-modules of the communication fault;

step 6: and (5) repeating the step 2-5, and jumping out of the mode when the number of the fault bypass sub-modules is more than or equal to Y1 or the number of the communication fault sub-modules is more than or equal to Y2, and entering the next redundancy mode.

8. The method for controlling fault redundancy of a modular direct current energy consumption device according to claim 2, wherein the three-level redundancy mode control method comprises the following steps:

step 1: setting the number of the submodules which are allowed to generate the non-communication fault bypass in the mode as Z1, and the number of the submodules with the communication fault as Z2;

step 2: monitoring the state of the sub-module; if the modular direct current energy consumption device is in an energy consumption state, adjusting a control target of direct current line voltage, and actively reducing the direct current line voltage stability performance of the modular direct current energy consumption device;

step 6: and (5) repeating the step 2-5, and jumping out of the mode when the number of the fault bypass sub-modules is more than or equal to Z1 or the number of the sub-modules with communication faults is more than or equal to Z2, and entering the next redundancy mode.

9. The method for controlling fault redundancy of a modular direct current energy consumption device according to claim 1, wherein the four-level redundancy mode control method comprises the following steps:

step 1: setting the number of sub-modules which are allowed to have faults in the mode as W;

step 2: monitoring the state of the sub-module; if the modular direct current energy consumption device is in an energy consumption state, all energy consumption resistors are put into use;

and 4, step 4: the main control system cumulatively records the number of the sub-modules of the bypass;

10. The method for controlling the fault redundancy of the modular direct current energy consumption device according to at least one of claims 6 to 9, wherein when an uplink communication fault of the submodule control system to the main control system occurs, the main control system increases the number of bypass submodules and the number of communication fault submodules at the same time, and the submodule communication fault includes the uplink communication fault.

11. The method for controlling the fault redundancy of the modular direct current energy consumption device according to at least one of claims 6 to 9, wherein an autonomous voltage-sharing strategy is executed when the device is in a standby state, and under the autonomous voltage-sharing strategy, the submodule control system controls the submodule capacitor voltage to be within a preset range by controlling the power semiconductor device to be turned on and off.

12. The method for controlling a modular dc energy consuming device according to claim 2, wherein the bypass switch is a high speed mechanical switch or an overvoltage breakdown power semiconductor device, or a combination thereof; the high-speed mechanical switch receives command action switching-on of the sub-module control system; the overvoltage breakdown power semiconductor device breaks down a short circuit when bearing overvoltage, so that the sub-module is bypassed.

13. The method as claimed in claim 2, wherein the communication mode between the master control system and the slave control system is one-to-one, one-to-many, or a ring network with hands pulled.

14. The method for controlling a modular dc energy consuming device according to claim 2, wherein the external control system is a control system of an inverter capable of controlling the dc voltage or the transmission power of the dc line on which the device is located.

15. The method for controlling a modular dc consumer according to at least one of claims 6 to 9, wherein the power semiconductor devices of the fault-free sub-modules receive the command from the main control system to execute the turn-on or turn-off command; and the power semiconductor device of the communication fault submodule receives an instruction of the submodule control system and executes a switching-on or switching-off command.

16. Method for controlling a modular dc consumer according to at least one of claims 6 to 9, characterized in that the manner of closing the bypass switch comprises:

closing the master control: a main control system gives a bypass command to trigger the switch mechanism to be closed;

and (3) closing the sub-modules: when the communication is in fault, the sub-die control system gives a bypass command to trigger the switch mechanism to be closed;

and (3) passive closing: the switch mechanism is automatically triggered to be closed through a hardware loop;

breakdown is closed: the power semiconductor device breaks down the short circuit when subjected to an overvoltage by means of overvoltage.

17. The method for controlling a modular dc energy consuming device as claimed in claim 8, wherein the specific method for changing the control target of the dc line voltage in step 2 comprises:

increasing the width of a hysteresis control loop: if the modular direct current energy consumption device controls the direct current line voltage in a hysteresis control mode, namely the direct current line voltage is controlled between a high voltage limit value and a low voltage limit value, the difference between the high voltage limit value and the low voltage limit value is increased;

increasing the closed-loop control target value: and if the modular direct current energy consumption device adopts a direct current line voltage closed loop regulation mode, the direct current line voltage control target value is improved.

18. The method as claimed in claim 7, wherein in step 6, when the sum of the number of bypassed submodules and the number of communication failure submodules is greater than or equal to the predetermined total limit value YN, the current mode is also skipped, and the next mode is entered, wherein YN is less than or equal to Y1+ Y2.

19. The method as claimed in claim 7, wherein when the sum of the number of bypassed submodules and the number of communication failure submodules is greater than or equal to a predetermined total limit value ZN, step 6, the current mode is also skipped, and the next mode is entered, wherein ZN is less than or equal to Z1+ Z2.