CN112510979B

CN112510979B - Converter fault-tolerant control method and system and wind generating set

Info

Publication number: CN112510979B
Application number: CN202011339776.8A
Authority: CN
Inventors: 张鲁华; 吴延俊; 葛昊祥; 宋敬波; 宋程; 崔秀亮; 寻征轩
Original assignee: Shanghai Electric Wind Power Group Co Ltd
Current assignee: Shanghai Electric Wind Power Group Co Ltd
Priority date: 2020-11-25
Filing date: 2020-11-25
Publication date: 2022-11-01
Anticipated expiration: 2040-11-25
Also published as: WO2022110679A1; CN112510979A

Abstract

The embodiment of the invention provides a converter fault-tolerant control method and system and a wind generating set. The method is applied to a wind generating set and comprises the following steps: when a converter of the wind generating set breaks down, controlling the converter to enter a fault shutdown state; diagnosing the fault state type of the converter; and when the diagnosed fault state type of the converter belongs to a preset fault state type, controlling the converter to enter a fault-tolerant operation state from a fault shutdown state, wherein in the fault-tolerant operation state, at least one part of devices which do not have faults in the converter is used for continuously carrying out derating power generation on the wind generating set. Therefore, the converter still has certain derating power generation capacity when a specific fault occurs, and the shutdown power generation loss caused by the fault is reduced.

Description

Converter fault-tolerant control method and system and wind generating set

Technical Field

The embodiment of the invention relates to the technical field of wind power, in particular to a converter fault-tolerant control method and system and a wind generating set.

Background

With the gradual depletion of energy sources such as coal and petroleum, human beings increasingly pay more attention to the utilization of renewable energy sources. Wind energy is increasingly gaining attention as a clean renewable energy source in all countries of the world. The wind power generation device is very suitable for and can be used for generating electricity by utilizing wind power according to local conditions in coastal islands, grassland pasturing areas, mountain areas and plateau areas with water shortage, fuel shortage and inconvenient traffic. Wind power generation refers to converting kinetic energy of wind into electric energy by using a wind turbine generator.

As the power capacity of the wind power generation converter gradually increases, the number of power switching devices (such as Insulated Gate Bipolar Transistors (IGBTs)) included in the converter also gradually increases, which results in an equal ratio increase of the probability of device failure in the quality guarantee period. Therefore, the converter is required to have a fault-tolerant operation capability in a certain fault state in addition to the fault protection capability. That is, if the fault condition is within a certain controllable range, the device should continue to generate electricity in the fault condition.

At present, the wind power generation converter generally belongs to serious faults of power switching devices, so that a wind power generation unit is directly stopped, and actually, if the faults are classified and analyzed in detail, the converter still has a certain derating power generation capacity in some fault states.

Disclosure of Invention

The embodiment of the invention aims to provide a converter fault-tolerant control method, a converter fault-tolerant control system and a wind generating set, so that a converter still has a certain derating power generation capacity when a specific fault occurs, and the loss of shutdown power generation caused by the fault is reduced.

One aspect of the embodiment of the invention provides a fault-tolerant control method for a converter, which is applied to a wind generating set. The method comprises the following steps: when a converter of the wind generating set fails, controlling the converter to enter a fault shutdown state; diagnosing a fault state type of the converter; and when the diagnosed fault state type of the converter belongs to a preset fault state type, controlling the converter to enter a fault-tolerant operation state from the fault shutdown state, wherein in the fault-tolerant operation state, at least one part of devices which do not have faults in the converter is used for continuing derating power generation of the wind generating set.

The embodiment of the invention also provides a fault-tolerant control system of the converter, which is applied to a wind generating set. The system comprises a converter, a converter controller and a main controller, wherein the converter, the converter controller and the main controller are used for the wind generating set. The converter controller is used for diagnosing the fault state type of the converter when the converter fails. The main controller is used for controlling the converter to enter a fault shutdown state when the converter fails, and controlling the converter to enter a fault-tolerant operation state from the fault shutdown state when the diagnosed fault state type of the converter belongs to a preset fault state type, wherein in the fault-tolerant operation state, the main controller continues derating the wind generating set by using at least one part of devices which do not fail in the converter.

Still another aspect of an embodiment of the present invention provides a wind turbine generator system including a tower, a nacelle mounted on a top end of the tower, a hub mounted on an end of the nacelle, and a plurality of blades mounted on the hub. The wind generating set further comprises the converter fault-tolerant control system.

The fault-tolerant control method and the fault-tolerant control system for the converter and the wind generating set with the fault-tolerant control system for the converter in the embodiment of the invention provide a fault-tolerant operation strategy in a fault state, so that the converter of the wind generating set can continue derating power generation by using the remaining good devices in the converter under a certain fault type condition, and thus, the power generation loss of the wind generating set in a specific fault time can be reduced.

Drawings

FIG. 1 is a side schematic view of a wind turbine generator system according to an embodiment of the present invention;

FIG. 2 is a schematic block diagram of a fault tolerant control system for a converter in accordance with one embodiment of the present invention;

fig. 3 is a schematic structural diagram of a machine side converter/grid side converter according to an embodiment of the present invention;

fig. 4 is a schematic diagram of an machine side converter/grid side converter with first fault condition type/second fault condition type in accordance with an embodiment of the present invention;

FIG. 5 is a schematic diagram of a machine side converter of the type having a third fault condition in accordance with an embodiment of the present invention;

fig. 6 is a flowchart of a fault-tolerant control method of a converter according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus consistent with certain aspects of the invention, as detailed in the appended claims.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, technical or scientific terms used in the embodiments of the present invention should have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. The terms "first," "second," and the like, as used in the description and in the claims, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one. "plurality" or "a number" means two or more. Unless otherwise indicated, "front", "rear", "lower" and/or "upper" and the like are for convenience of description and are not limited to one position or one spatial orientation. The word "comprising" or "comprises", and the like, means that the element or item listed after "comprises" or "comprising" is inclusive of the element or item listed after "comprising" or "comprises", and the equivalent thereof, and does not exclude additional elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

Fig. 1 discloses a schematic side view of a wind park 100 according to an embodiment of the invention. As shown in fig. 1, a wind park 100 comprises a plurality of blades 101, a nacelle 102, a hub 103 and a tower 104. A tower 104 extends upwardly from a foundation (not shown), a nacelle 102 is mounted on top of the tower 104, a hub 103 is mounted at one end of the nacelle 102, and a plurality of blades 101 are mounted on the hub 103.

The wind generating set 100 of the embodiment of the present invention further includes a converter fault tolerance control system 200. Fig. 2 discloses a schematic block diagram of a converter fault-tolerant control system 200 according to an embodiment of the present invention. As shown in fig. 2, a converter fault-tolerant control system 200 according to an embodiment of the present invention includes a converter 201, a converter controller 202, and a main controller 203 for a wind turbine generator system 100. The converter 201 comprises a machine side converter 301 for connection with a generator 401 of the wind park 100 and a grid side converter 302 for connection to a grid 402. The machine-side converter 301 and the grid-side converter 302 are connected by positive and

negative dc buses

501, 502. The converter controller 202 is connected to the machine-side converter 301 and the grid-side converter 302, respectively, for controlling the machine-side converter 301 and the grid-side converter 302, respectively. The master controller 203 is connected to the converter controller 202.

When the converter 201 fails, the converter controller 202 may diagnose the type of fault condition of the converter 201. For example, the converter controller 202 may detect the fault status type of the converter 201 by reading a fault feedback signal of the power switching device or by fault status sampling data.

Moreover, when the converter 201 fails, the main controller 203 may control the converter 201 to enter a fault-tolerant operation state, and when the main controller 203 determines that the fault state type of the converter 201 diagnosed by the converter controller 202 belongs to a predetermined fault state type, the main controller 203 may control the converter 201 to enter the fault-tolerant operation state from the fault-shutdown state. In some embodiments, the main controller 203 may select to enable the converter 201 to enter the fault-tolerant operating state or to remain in the fault-shutdown state through preset parameters of a user or manual operation. After the converter controller 202 receives the fault-tolerant operation command from the main controller 203, the converter controller 202 controls the converter 201 to enter a fault-tolerant operation state. Wherein, when the converter 201 is in a fault tolerant operation state, the main controller 203 may continue derating the wind generating set 100 by using at least a part of devices in the converter 201 that do not have faults.

The fault-tolerant operation strategy of the fault-tolerant control system 200 of the embodiment of the invention can enable the converter 201 of the wind generating set 100 to continue derating power generation by using the good devices remained in the converter 201 under a certain fault type condition, thereby reducing the power generation loss of the wind generating set 100 in a specific fault time.

Fig. 3 discloses a schematic structural diagram of a machine-side converter 301/grid-side converter 302 according to an embodiment of the present invention. As shown in fig. 3, each of the machine-side converter 301 and the grid-side converter 302 comprises a plurality of phase modules 600, such as an a-phase module 600, a B-phase module 600, a C-phase module 600, etc. Each phase module 600 includes an upper power switching device Q1 and a lower power switching device Q2 connected in series, and an upper diode D1 connected in inverse parallel with the upper power switching device Q1 and a lower diode D2 connected in inverse parallel with the lower power switching device Q2. The upper and lower power switches Q1 and Q2 may comprise IGBTs, for example. The control terminals of the upper power switch Q1 and the lower power switch Q2 of each phase module 600 are connected to the converter controller 202, respectively. The converter controller 202 may send a control Pulse signal, such as a Pulse Width Modulation (PWM) signal, to the control terminals of the upper power switch Q1 and the lower power switch Q2 of each phase module 600 in the machine-side converter 301 or the grid-side converter 302, respectively.

With reference to fig. 3, taking three phases as an example, for the machine-side converter 301, a connection point of the upper power switch Q1 and the lower power switch Q2 of the a-phase module 600 in the machine-side converter 301 may be connected to a generator a phase of the wind turbine generator system 100 through a single-phase filter circuit 601, for example, a connection point of the upper power switch Q1 and the lower power switch Q2 of the B-phase module 600 may be connected to a generator B phase through a single-phase filter circuit 601, and a connection point of the upper power switch Q1 and the lower power switch Q2 of the C-phase module 600 may be connected to a generator C phase through a single-phase filter circuit 601, for example. For the grid-side converter 302, the connection point of the upper power switching device Q1 and the lower power switching device Q2 of the a-phase module 600 in the grid-side converter 302 may be connected to the grid a-phase through a single-phase filter circuit 601, the connection point of the upper power switching device Q1 and the lower power switching device Q2 of the B-phase module 600 may be connected to the grid B-phase through the single-phase filter circuit 601, and the connection point of the upper power switching device Q1 and the lower power switching device Q2 of the C-phase module 600 may be connected to the grid C-phase through the single-phase filter circuit 601.

In some embodiments, the predetermined fault status types according to the embodiments of the present invention may include a first fault status type, where the number of the phase modules 600 that have not failed in the machine-side converter 301 is two or more. For example, the a-phase module 600 and the B-phase module 600 have no failure, and the C-phase module, the 8230module, and the N-phase module 600 have a failure. Fig. 4 discloses a schematic diagram of a machine side converter 301 of the first fault status type according to an embodiment of the invention, using three phases as an example. As shown in fig. 4, in the machine-side converter 301, the a-phase module 600 and the B-phase module 600 are not faulty, and the C-phase module 600 is faulty.

In the first fault-condition type, the fault type of the faulty phase module 600 in the machine-side converter 301 may include, for example, an open-circuit fault occurring in at least one of the upper power switch Q1, the upper diode D1, the lower power switch Q2, and the lower diode D2. For example, the upper power switch Q1, the lower power switch Q2, the upper diode D1, and the lower diode D2 in the C-phase module 600 in the machine side converter 301 shown in fig. 4 all fail.

When the predetermined fault state type of the converter 201 belongs to the first fault state type, the converter controller 202 may find out the faulty phase module 600 through a detection means, and the main controller 203 may lock the faulty phase module 600 and continue to control the non-faulty phase module 600.

In one embodiment, the master controller 203 may issue a continuous off signal to the power switching devices of the failed phase module 600 such that these power switching devices are turned off and the failed phase module 600 is blocked. The main controller 203 may recalculate the related control formula and control strategy (e.g., coordinate system transformation formula) of the converter 201 and related parameters (e.g., operating power limit value, dc voltage reference value, etc.) according to the new circuit topology after the failed phase module 600 is blocked, and the main controller 203 may send a control pulse signal, such as a PWM signal, to the power switching devices of the non-failed phase module 600. Therefore, the wind turbine generator system 100 can continue to generate electricity in a derated manner, and the loss of the amount of electricity generated during the shutdown due to the failure can be reduced.

In other embodiments, the predetermined fault status types according to the embodiments of the present invention may further include a second fault status type, where the second fault status type is that the number of the phase modules 600 that have not failed in the grid-side converter 302 is two or more than two. For example, the a-phase module 600 and the B-phase module 600 have no failure, and the C-phase module, the 8230module, and the N-phase module 600 have a failure. Fig. 4 also discloses a schematic diagram of a grid-side converter 302 with a second fault condition type according to another embodiment of the present invention. As shown in fig. 4, in the grid-side converter 302, the a-phase module 600 and the B-phase module 600 are not faulty, and the C-phase module 600 is faulty.

In the second fault-state type, the fault type of the failed phase module 600 in the grid-side converter 302 may include, for example, an open-circuit fault occurring in at least one of the upper power switch Q1, the upper diode D1, the lower power switch Q2, and the lower diode D2. For example, the upper power switch Q1, the lower power switch Q2, the upper diode D1, and the lower diode D2 in the C-phase module 600 in the grid-side converter 302 shown in fig. 4 all fail.

When the predetermined fault state type of the converter 201 belongs to the second fault state type, the converter controller 202 may find out the faulty phase module 600 through a detection means, and the main controller 203 may lock the faulty phase module 600 and continue to control the non-faulty phase module 600.

In one embodiment, the master controller 203 may issue a continuous off signal to the power switching devices of the failed phase module 600 such that these power switching devices are turned off and the failed phase module 600 is locked out. The main controller 203 may recalculate the related control formula and the control strategy (e.g., coordinate system transformation formula) of the converter 201 and related parameters (e.g., operating power limit value, dc voltage reference value, etc.) according to the new circuit topology after the failed phase module 600 is blocked, and the main controller 203 may send a control Pulse signal, such as a PWM (Pulse Width Modulation) signal, to the power switching devices of the phase module 600 that has not failed. Therefore, the wind turbine generator system 100 can continue to generate electricity in a derated manner, and the loss of the amount of electricity generated during the shutdown due to the failure can be reduced.

In still other embodiments, the predetermined fault status types according to the embodiments of the present invention may further include a third fault status type, where the third fault status type is when the generator type used by the wind turbine generator system 100 is a permanent magnet motor, and the number of the phase modules 600 that have not failed in the machine-side converter 301 is less than two. For example, only the a-phase module 600 has no fault, the B-phase, C-phase, \8230 \ 8230;, the N-phase module 600 has a fault. Fig. 5 discloses a schematic diagram of a machine side converter 301 of the third fault status type according to an embodiment of the invention, using three phases as an example. As shown in fig. 5, in the machine-side converter 301, the a-phase module 600, the B-phase module 600, and the C-phase module 600 all fail.

In the third fault status type, the fault type of the failed phase module 600 in the machine side converter 301 may include, for example, an open circuit fault of at least one of the upper power switch Q1 and the lower power switch Q2. For example, the upper power switch Q1 and the lower power switch Q2 in the a-phase module 600, the B-phase module 600, and the C-phase module 600 in the machine side converter 301 shown in fig. 5 all fail.

When the predetermined fault state type of the converter 201 belongs to a third fault state type, the main controller 203 may control all power switches in the machine-side converter 301 to send a continuous turn-off signal, turn off all power switches in the machine-side converter 301, and calculate the dc output voltage of the permanent magnet motor under the current rotation speed, where because all power switches in the machine-side converter 301 are turned off and the diodes in the machine-side converter 301 are normally turned on in the third fault state type, the dc output voltage of the permanent magnet motor may be rectified by the diodes at this time. The main controller 203 recalculates the relevant parameters (such as the operation power limiting value, the dc voltage reference value, the grid-side dc voltage feed-forward value, etc.) of the converter 201 according to the dc output voltage, and controls the grid-side converter 302 based on the recalculated relevant parameters of the converter 201.

In one embodiment, when the calculated dc output voltage is higher than the grid-side minimum rectified voltage, the main controller 203 PWM-controlled rectifies the grid-side converter 302.

In another embodiment, when the calculated dc output voltage of the permanent magnet motor after diode rectification is lower than the minimum grid-side rectified voltage, since the output port voltage of the permanent magnet motor can be increased by increasing the rotation speed of the permanent magnet motor within a certain rotation speed range, the main controller 203 can also perform acceleration control on the permanent magnet motor, for example, the main controller 203 can accelerate the permanent magnet motor by changing the pitch (increasing the wind energy capturing capability by opening the pitch) or the like, so that the dc output voltage of the permanent magnet motor after uncontrolled rectification is increased to be higher than the minimum grid-side rectified voltage, and energy flows from the machine-side converter 301 to the grid-side converter 302 to perform power networking. After the rotating speed of the permanent magnet motor is increased, the controller carries out PWM controllable rectification on the grid-side converter 302 based on the converter 201 related parameters recalculated by the direct current output voltage.

According to the converter fault-tolerant control system 200 and the wind generating set 100 with the converter fault-tolerant control system 200, provided by the embodiment of the invention, the fault-tolerant operation strategy algorithm of the converter 201 is added under a specific fault working condition, so that the converter 201 still has a certain derating power generation capacity when the phase module 600 has a specific fault, and the generated energy loss caused by the fault during shutdown can be reduced.

The embodiment of the invention also provides a fault-tolerant control method of the converter, which is applied to the wind generating set 100. Fig. 6 discloses a flow chart of a fault-tolerant control method of a converter according to an embodiment of the invention. As shown in the figure, the fault-tolerant control method of the converter according to an embodiment of the present invention may include steps S11 to S14.

In step S11, when the converter 201 of the wind turbine generator system 100 fails, the converter 201 is controlled to enter a fault-stop state.

In step S12, the fault state type of the converter 201 is diagnosed.

In some embodiments, the fault condition type of the current transformer 201 may be detected by reading a fault feedback signal of the power switching device or by fault condition sampling data.

In step S13, it is determined whether the diagnosed fault condition type of the converter 201 belongs to a predetermined fault condition type? In the case where the determination result is yes, the process proceeds to step S14.

In step S14, if the diagnosed fault state type of the converter 201 belongs to a predetermined fault state type, the converter 201 is controlled to enter a fault tolerant operation state from a fault shutdown state, wherein in the fault tolerant operation state, derating power generation of the wind turbine generator system 100 is continued by using at least a part of devices in the converter 201 which do not have faults.

The converter 201 may include a machine side converter 301 for connection with a generator of the wind turbine generator system 100 and a grid side converter 302 for connection to a grid, each of the machine side converter 301 and the grid side converter 201 including a plurality of phase modules 600, each of the phase modules 600 including an upper power switching device Q1 and a lower power switching device Q2 connected in series, and an upper diode D1 connected in anti-parallel with the upper power switching device Q1 and a lower diode D2 connected in anti-parallel with the lower power switching device Q2.

In some embodiments, the predetermined fault status types may include at least one of a first fault status type and a second fault status type, the first fault status type being that the number of non-faulty phase modules 600 in the machine-side converter 301 is two or more phases, and the second fault status type being that the number of non-faulty phase modules 600 in the grid-side converter 302 is two or more phases. The fault type of the failed phase module 600 includes an open circuit fault of at least one of the upper power switch Q1, the upper diode D1, the lower power switch Q2, and the lower diode D2 in the first fault state type and the second fault state type.

Controlling into the fault-tolerant operating state upon occurrence of the first fault state type and the second fault state type may include: blocking the failed phase module 600; and control continues for the phase module 600 that has not failed. In one embodiment, blocking the failed phase module 600 may include: a continuous off signal is sent to the power switch of the failed phase module 600. Continuing control of the non-failed phase module 600 may include: a control pulse signal is sent to the power switching devices of the non-failed phase module 600.

In other embodiments, the predetermined fault status types may further include a third fault status type, where the third fault status type is when the generator type used by the wind turbine generator system 100 is a permanent magnet motor and the number of non-faulty phase modules 600 in the machine side converter 301 is less than two. In the third fault state type, the fault type of the failed phase module 600 includes an open circuit fault occurring in at least one of the upper power switch Q1 and the lower power switch Q2.

Upon occurrence of the third fault state type, controlling into a fault tolerant operational state may include: sending out a continuous turn-off signal to all power switching devices in the machine side converter 301; calculating the direct current output voltage of the permanent magnet motor under the current rotating speed; and controlling the grid-side converter 302 based on the dc output voltage.

In an embodiment, the fault-tolerant control method for a converter according to the embodiment of the present invention may further include: when the dc output voltage is lower than the lowest net-side rectified voltage, the permanent magnet motor may be accelerated by, for example, changing a pitch, so that the dc output voltage of the permanent magnet motor is increased to be higher than the lowest net-side rectified voltage. Wherein the grid-side converter 302 is controlled based on the dc output voltage after the rotational speed of the permanent magnet motor has increased.

The fault-tolerant control method of the converter according to the embodiment of the present invention has similar beneficial technical effects to the fault-tolerant control system 200 of the converter described above, and therefore, the details are not repeated herein.

The converter fault-tolerant control method, the converter fault-tolerant control system and the wind generating set provided by the embodiment of the invention are described in detail above. The converter fault-tolerant control method, the converter fault-tolerant control system and the wind turbine generator system according to the embodiments of the present invention are described herein by using specific examples, and the description of the above embodiments is only for helping understanding the core idea of the present invention, and is not intended to limit the present invention. It should be noted that, for those skilled in the art, without departing from the spirit and principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications should fall within the scope of the appended claims.

Claims

1. A fault-tolerant control method of a converter is applied to a wind generating set and is characterized in that: the method comprises the following steps:

when a converter of a wind generating set fails, controlling the converter to enter a fault shutdown state, wherein the converter comprises a machine side converter connected with a generator of the wind generating set and a grid side converter connected with a power grid, each of the machine side converter and the grid side converter comprises a plurality of phase modules, each phase module comprises an upper power switch device and a lower power switch device which are connected in series, an upper diode connected with the upper power switch device in an inverse parallel manner and a lower diode connected with the lower power switch device in an inverse parallel manner;

diagnosing a fault state type of the converter; and

when the diagnosed fault state type of the converter belongs to a preset fault state type, controlling the converter to enter a fault-tolerant operation state from the fault shutdown state, wherein in the fault-tolerant operation state, at least one part of devices which do not have faults in the converter is used for continuously carrying out derating power generation on the wind generating set,

the predetermined fault state type comprises at least one of a first fault state type and a second fault state type, the first fault state type is that the number of the phase modules which do not have faults in the machine side converter is two or more than two phases, and the second fault state type is that the number of the phase modules which do not have faults in the grid side converter is two or more than two phases; the preset fault state types further comprise a third fault state type, the third fault state type is that when the type of the generator used by the wind generating set is a permanent magnet motor, the number of the phase modules which do not have faults in the machine side converter is less than two phases,

the entering into the fault-tolerant operating state comprises:

sending continuous turn-off signals to all power switching devices in the machine side converter;

calculating the direct current output voltage of the permanent magnet motor under the current rotating speed; and

controlling the grid-side converter based on the DC output voltage.

2. The method of claim 1, wherein: the diagnosing the fault state type of the converter comprises the following steps:

and detecting the fault state type of the converter through a fault feedback signal of a power switch signal or through fault state sampling data.

3. The method of claim 1, wherein: the type of fault of the failed phase module includes an open circuit fault in at least one of the upper power switch, the upper diode, the lower power switch, and the lower diode.

4. The method of claim 1, wherein: the entering of the fault tolerant operating state comprises:

blocking the failed phase module; and

and continuing to control the phase module which does not have the fault.

5. The method of claim 4, wherein: the blocking the failed phase module comprises: sending a continuous turn-off signal to a power switch device of the phase module with the fault;

the continuing control of the phase module that has not failed comprises:

and sending out a control pulse signal to the power switch device of the phase module which does not have the fault.

6. The method of claim 1, wherein: the type of fault of the failed phase module includes an open circuit fault in at least one of the upper power switch and the lower power switch.

7. The method of claim 1, wherein: further comprising:

accelerating the permanent magnet motor when the DC output voltage is lower than the lowest network-side rectified voltage so as to increase the DC output voltage of the permanent magnet motor to be higher than the lowest network-side rectified voltage,

wherein the grid-side converter is controlled based on the DC output voltage after the permanent magnet motor speed is increased.

8. The method of claim 7, wherein: the accelerating the permanent magnet motor comprises:

and accelerating the permanent magnet motor in a variable pitch mode.

9. A fault-tolerant control system of a converter is applied to a wind generating set and is characterized in that: the system comprises:

the converter for the wind generating set comprises a machine side converter connected with a generator of the wind generating set and a grid side converter connected to a power grid, each of the machine side converter and the grid side converter comprises a plurality of phase modules, each phase module comprises an upper power switch device and a lower power switch device which are connected in series, an upper diode connected with the upper power switch device in an inverse parallel mode and a lower diode connected with the lower power switch device in an inverse parallel mode;

the converter controller is used for diagnosing the fault state type of the converter when the converter fails; and

a main controller, configured to control the converter to enter a fault shutdown state when the converter fails, and control the converter to enter a fault-tolerant operating state from the fault shutdown state when a diagnosed fault state type of the converter belongs to a predetermined fault state type, where in the fault-tolerant operating state, the main controller continues derating power generation of the wind turbine generator system by using at least a part of devices in the converter that do not fail, the predetermined fault state type includes at least one of a first fault state type and a second fault state type, the first fault state type is that the number of phase modules in the machine-side converter that do not fail is two or more phases, the second fault state type is that the number of phase modules in the grid-side converter that do not fail is two or more phases, the predetermined fault state type further includes a third fault state type, and the third fault state type is that when the generator type used by the wind turbine generator system is a permanent magnet motor, and the number of phase modules in the machine-side converter that do not fail is less than two phases,

the main controller is used for sending continuous turn-off signals to all power switching devices in the machine side converter, calculating the direct current output voltage of the permanent magnet motor under the current rotating speed and controlling the grid side converter based on the direct current output voltage.

10. The system of claim 9, wherein: the converter controller detects the fault state type of the converter by reading a fault feedback signal of a power switch device or by fault state sampling data.

11. The system of claim 9, wherein: the fault type of the failed phase module includes an open circuit fault of at least one of the upper power switch, the upper diode, the lower power switch, and the lower diode.

12. The system of claim 9, wherein: the main controller is used for blocking the phase module which fails and continuously controlling the phase module which does not fail.

13. The system of claim 12, wherein: the main controller is used for sending a continuous turn-off signal to a power switch device of the failed phase module; and the main controller is used for sending a control pulse signal to the power switching device of the phase module which does not have a fault.

14. The system of claim 9, wherein: the type of fault of the failed phase module includes an open circuit fault of at least one of the upper power switch and the lower power switch.

15. The system of claim 9, wherein: the main controller is further configured to accelerate the permanent magnet motor when the dc output voltage is lower than a minimum grid-side rectified voltage, so that the dc output voltage of the permanent magnet motor is increased to be higher than the minimum grid-side rectified voltage,

wherein the controller controls the grid-side converter based on the DC output voltage after the permanent magnet motor speed increases.

16. The system of claim 15, wherein: the main controller is used for accelerating the permanent magnet motor in a variable pitch mode.

17. A wind generating set, it includes a tower section of thick bamboo, install in the cabin of tower section of thick bamboo top, install in the wheel hub of cabin one end and install in a plurality of blades on the wheel hub, its characterized in that: it still includes: a converter fault tolerant control system as claimed in any one of claims 9 to 16.