CN116865332B - Flexible direct current fault ride-through control method and device, storage medium and equipment - Google Patents

Abstract

The present application provides a flexible DC fault ride-through control method, device, storage medium and equipment. The method includes: obtaining the AC side terminal voltage of the converter valve and the external power of the flexible DC converter station; if the AC side terminal voltage is less than the low voltage ride-through threshold, triggering the low voltage ride-through, obtaining the active power command value during the fault; determining the second integral coefficient during the fault according to the difference between the active power command value and the external power; switching the integral coefficient of the voltage outer loop controller from the first integral coefficient before the fault to the second integral coefficient; the difference between the active power command value and the external power during the fault and the second integral coefficient are negatively correlated; obtaining the AC side terminal voltage in real time; if the real-time value of the AC side terminal voltage is higher than the low voltage ride-through threshold, performing fault recovery, and switching the integral coefficient of the voltage outer loop controller to the first integral coefficient. The present application can improve the stability of the island system where new energy is sent out via flexible DC.

Description

Flexible DC fault ride-through control method, device, storage medium and equipment

Technical Field

The present application relates to the field of power system control technology, and in particular to a flexible DC fault ride-through control method, device, storage medium and computer equipment.

Background technique

Accelerating the construction of large-scale wind power and photovoltaic bases with a focus on deserts, Gobi and desert areas is a major strategic demand for the current power system construction. This type of large-scale pure new energy base has a large installed capacity and a wide distribution area, and often adopts a flexible DC island transmission mode. The existing flexible DC VF control (constant AC voltage/constant frequency control) mode fault ride-through strategy is mostly aimed at offshore wind power transmission systems. The transmission system of a large pure new energy base has a higher probability of failure and requires higher stability of the transmission end system after the failure.

In order to ensure the transient stability of the sending end of a large-scale pure renewable energy base, the new energy at the sending end needs to actively reduce power during the fault and slow down the power recovery rate. However, in order to prevent the integral control saturation during the fault, the existing flexible direct current adopts the method of freezing the outer loop controller during the fault. For the sending end system of a large-scale pure renewable energy base, this will result in the sending end system having no power supply capable of regulating the voltage during the transient process. This can easily lead to voltage stability problems after a fault occurs in the sending end system of a large renewable energy base. If a normal control outer loop controller is used, when the fault is deep, transient stability problems will be caused due to excessive deviation of the outer loop and too fast action.

Summary of the invention

The embodiments of the present application provide a flexible DC fault ride-through control method, apparatus, storage medium and device, which can improve system stability.

In a first aspect, the present application provides a flexible DC fault ride-through control method, which is applied to a flexible DC converter station in a pure new energy transmission system via a flexible DC island. The method comprises:

Acquiring the AC side terminal voltage of the converter valve and the external power transmission of the flexible DC converter station;

If the AC side terminal voltage is less than the low voltage ride-through threshold, the low voltage ride-through is triggered to obtain the active power command value during the fault period;

Determining a second integral coefficient during a fault period according to a difference between the active power command value and the external power;

Switching the integral coefficient of the voltage outer loop controller from the first integral coefficient before the fault to the second integral coefficient; wherein the first integral coefficient is greater than the second integral coefficient, and the difference between the active power command value during the fault and the external power is negatively correlated with the second integral coefficient;

Obtain AC side terminal voltage in real time;

If the real-time value of the AC side terminal voltage is higher than the low voltage ride-through threshold, fault recovery is performed and the integral coefficient of the voltage outer loop controller is switched to the first integral coefficient.

In one embodiment, obtaining the active power command value during the fault period includes:

Obtain the external power of the flexible DC converter station within a preset time before triggering low voltage ride-through;

Calculating an average value of the external power transmitted by the flexible DC converter station within the preset time period;

The average value is determined as the active power command value during the fault period.

In one embodiment, the preset duration is greater than or equal to 60 seconds.

In one embodiment, during the low voltage ride-through period, the method further comprises:

Regularly obtaining the external power transmission of the flexible DC converter station;

The second integral coefficient is dynamically adjusted according to the real-time value of the external power transmitted by the flexible DC converter station.

In one of the embodiments, during the low voltage ride-through period, after determining the first integral coefficient according to the difference between the active power command value and the external power, the method further includes:

Calculating a second proportional coefficient during a fault period according to the first integral coefficient, the second integral coefficient, and a first proportional coefficient of a voltage outer loop controller before a fault;

The proportional coefficient of the voltage outer loop controller is switched from the first proportional coefficient to the second proportional coefficient, and then switched back to the first proportional coefficient when fault recovery is performed.

In a second aspect, the present application provides a flexible DC fault ride-through control device, which is applied to a flexible DC converter station in a pure new energy transmission system via a flexible DC island, and the device includes:

A first acquisition module is used to acquire the AC side terminal voltage of the converter valve and the external power transmission of the flexible DC converter station;

A low voltage ride-through module, used to initiate a low voltage ride-through when the voltage at the AC side terminal is less than a low voltage ride-through threshold, and obtain an active power command value during the fault period;

A first determination module, configured to determine a second integral coefficient during a fault period according to a difference between the active power command value and the external power;

A first switching module is used to switch the integral coefficient of the voltage outer loop controller from the first integral coefficient before the fault to the second integral coefficient; wherein the first integral coefficient is greater than the second integral coefficient, and the difference between the active power command value and the external power during the fault is negatively correlated with the second integral coefficient;

The second acquisition module is used to obtain the AC side terminal voltage in real time;

A fault recovery module is used to perform fault recovery and switch the integral coefficient of the voltage outer loop controller to the first integral coefficient when the real-time value of the AC side terminal voltage is higher than the low voltage crossing threshold.

In one embodiment, the low voltage ride through module includes:

A power acquisition unit, used for acquiring the external power of the flexible DC converter station within a preset time period before triggering low voltage ride-through;

A calculation unit, used to calculate an average value of the external power transmitted by the flexible DC converter station within the preset time period;

The command value configuration unit is used to determine the average value as the active power command value during the fault period.

In one embodiment, the device further comprises:

A power monitoring module, used for periodically acquiring the external power transmitted by the flexible DC converter station during low voltage ride-through;

A dynamic adjustment module is used to dynamically adjust the second integral coefficient according to the real-time value of the external power transmitted by the flexible DC converter station during low voltage ride-through.

In a third aspect, the present application provides a storage medium storing computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the flexible DC fault ride-through control method as described in any of the above embodiments.

In a fourth aspect, the present application provides a computer device, comprising: one or more processors, and a memory;

The memory stores computer-readable instructions, and when the one or more processors execute the computer-readable instructions, the steps of the flexible DC fault ride-through control method as described in any one of the above embodiments are performed.

It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

The flexible DC fault ride-through control method, device, storage medium and computer equipment provided in the present application monitor the AC side terminal voltage of the converter valve and the external power transmission of the flexible DC converter station, trigger the low voltage ride-through process when the AC side terminal voltage is less than the low voltage ride-through threshold, determine the second integral coefficient of the voltage outer loop controller during the fault period according to the difference between the active power command value and the external power transmission during the fault period and switch it, reduce the integral coefficient of the voltage outer loop controller, until the real-time value of the AC side terminal voltage is higher than the low voltage ride-through threshold, end the low voltage ride-through and enter the fault recovery process, and switch the integral coefficient of the voltage outer loop controller back to the first integral coefficient before the fault, so that the outer loop of the flexible DC converter station maintains a certain integral capacity during the fault period, while avoiding the current command value from changing too much from the steady-state value due to the influence of voltage deviation, thereby improving the transient stability of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG1 is a schematic diagram of an application scenario of a flexible DC fault ride-through control method in one embodiment;

FIG2 is a schematic flow chart of a flexible DC fault ride-through control method in one embodiment;

FIG3 is a schematic diagram showing the correlation between the difference between the active power command value and the external power and the second integral coefficient in one embodiment;

FIG4 is a schematic diagram of fault ride-through control logic in one embodiment;

FIG5 is a flow chart of the steps of obtaining the active power command value during a fault period in one embodiment;

FIG6 is a structural block diagram of a flexible DC fault ride-through control device in one embodiment;

FIG. 7 is a diagram showing the internal structure of a computer device in one embodiment.

Detailed ways

The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

For the island transmission system, the existing flexible DC mostly adopts the VF control method, that is, the given frequency generates the control phase, and the d-axis and q-axis control branches are divided into outer loop and inner loop control. In the existing flexible DC fault ride-through control method, during the fault ride-through period, after the low voltage ride-through signal is detected, the outer loop controller is frozen, the output current limits the current amplitude according to the voltage drop degree, and then proportionally distributes the d-axis current command value and the q-axis current command value according to the size of the outer loop output d-axis current command value to obtain the limited d-axis current command value and q-axis current command. However, freezing the outer loop controller will cause the sending end system to have no power supply that can regulate the voltage during the transient process, which is easy to cause voltage stability problems after the sending end system fails. When the fault is deep, it will cause transient stability problems due to excessive deviation and too fast action of the outer loop.

Based on the above problems, an embodiment of the present application provides a flexible DC fault ride-through control method, which is applied to a flexible DC converter station in a pure new energy transmission system via a flexible DC island. Pure new energy refers to only new energy generator sets, such as only photovoltaic power generation, or photovoltaic power generation and wind power discharge, etc. The embodiment of the present application takes the scenario shown in Figure 1 as an example to illustrate that the photovoltaic power generation base transmits power through a long line impedance and realizes power transmission through a flexible DC converter. A three-phase grounding fault occurs at the busbar of the flexible DC converter port, and the photovoltaic power generation base adopts a power reduction control strategy for fault ride-through control.

As shown in FIG2 , an embodiment of the present application provides a flexible DC fault ride-through control method, the method comprising:

Step S201, obtaining the AC side terminal voltage of the converter valve and the external power transmission of the flexible DC converter station.

The converter valve is the core equipment of the flexible DC transmission project, which is mainly composed of IGBT, control drive unit, cooling system, saturated reactor, capacitor, resistor, etc. Different from the semi-controlled device thyristor used in conventional DC transmission projects, the converter valve of the flexible DC project mostly uses the fully controlled device IGBT, which can realize the conversion of AC and DC by controlling its opening and closing. The AC side terminal voltage of the converter valve and the external power of the flexible DC converter station are obtained by real-time measurement through detection equipment.

Step S202: If the AC side voltage is less than the low voltage ride-through threshold, the low voltage ride-through is triggered to obtain the active power command value during the fault period.

The low voltage ride-through threshold is a preset voltage threshold used to determine whether the flexible DC terminal needs to enter the low voltage ride-through process. When the AC side voltage is less than the low voltage ride-through threshold, the low voltage ride-through process is not performed and the active power command value during the fault period is obtained.

Step S203: according to the active power command value The difference ΔP _e from the external power P _e determines the second integral coefficient k _iac2 during the fault period.

Referring to Figure 3, the active power command value during the fault period is The difference ΔP _e between the power P and the external power P is negatively correlated with the second integral coefficient _kiac2 , that is, the larger ΔP _{e is} , the smaller the second integral coefficient _kiac2 is.

Step S204: Switch the integral coefficient of the voltage outer loop controller from the first integral coefficient k _iac1 before the fault to the second integral coefficient k _iac2 .

Among them, the first integral coefficient is greater than the second integral coefficient, and switching the integral coefficient to the second integral coefficient k _iac2 is to reduce the integral coefficient of the voltage outer loop controller to reduce the change speed of the current command value affected by the voltage deviation during the fault period.

Step S205, obtaining the AC side terminal voltage in real time.

During the low voltage ride-through period, it is also necessary to obtain the AC side terminal voltage in real time to determine whether to end the low voltage ride-through and perform fault recovery.

Step S206: If the real-time value of the AC side terminal voltage is higher than the low voltage ride-through threshold, fault recovery is performed, and the integral coefficient of the voltage outer loop controller is switched to the first integral coefficient k _iac1 .

When the fault recovery process is entered, the integral coefficient of the voltage outer loop controller is switched back to the first integral coefficient k _iac1 before the fault.

Referring to FIG4, the fault ride-through control logic in this embodiment is shown. In normal condition, lvrt=0, and the integral coefficient of the flexible DC voltage outer loop controller adopts the first integral coefficient k _iac1 . In case of fault, lvrt=1, and the integral coefficient of the flexible DC voltage outer loop controller adopts the second integral coefficient k _iac2 . The outer loop voltage deviation generates the current command through proportional integral control and Then the final current command is generated through proportional limiting value/> and/>

In this embodiment, by monitoring the AC side terminal voltage of the converter valve and the external power transmission of the flexible DC converter station, the low voltage ride-through process is triggered when the AC side terminal voltage is less than the low voltage ride-through threshold, and the second integral coefficient k _ia of the voltage outer loop controller during the fault period is determined according to the difference between the active power command value and the external power transmission during the fault period and switched, and the integral coefficient of the voltage outer loop controller is reduced until the real-time value of the AC side terminal voltage is higher than the low voltage ride-through threshold, the low voltage ride-through is terminated and the fault recovery process is entered, and the integral coefficient of the voltage outer loop controller is switched back to the first integral coefficient k _iac1 before the fault, so that the outer loop of the flexible DC converter station maintains a certain integral capacity during the fault period, while avoiding the current command value from changing too fast due to the influence of the voltage deviation and deviating too much from the steady-state value, thereby improving the transient stability of the system.

As shown in FIG5 , in one embodiment, obtaining the active power command value during the fault period includes:

Step S501, obtaining the external power delivered by the flexible DC converter station within a preset time period before triggering low voltage ride-through;

Step S502, calculating the average value of the external power transmitted by the flexible DC converter station within a preset time period;

Step S503: determine the average value as the active power command value during the fault period.

In this embodiment, the average value of the external power during the preset time between triggering the low voltage ride-through is used as the active power command value during the fault period, that is, the steady-state value before the fault is used as the reference value, and the measurement error during operation and the error caused by normal fluctuations are reduced by taking the average value, thereby improving the system stability during the low voltage ride-through process. In one embodiment, the preset time is greater than or equal to 60s.

In one embodiment, during the low voltage ride-through period, the flexible DC fault ride-through control method further includes:

Obtain the external power of the flexible DC converter station on a regular basis;

The second integral coefficient is dynamically adjusted according to the real-time value of the external power transmitted by the flexible DC converter station.

In this embodiment, if the external power changes during the low voltage ride-through period, the first integral coefficient is dynamically adjusted, that is, the first integral coefficient is dynamically adjusted according to the difference between the active power command value and the real-time value of the external power.

In one embodiment, during the low voltage ride-through period, after determining the first integral coefficient according to the difference between the active power command value and the external power, the flexible DC fault ride-through control method further includes:

Calculate the second proportional coefficient _kp2 during the fault period according to the first integral coefficient _kiac1 , the second integral coefficient _kiac2 and the first proportional coefficient _kp1 of the voltage outer loop controller before the fault;

The proportional coefficient of the voltage outer loop controller is switched from the first proportional coefficient k _p1 to the second proportional coefficient k _p2 , and then switched back to the first proportional coefficient k _p1 when fault recovery is performed.

The second proportionality coefficient is calculated according to the following formula:

In this embodiment, during low voltage crossing, the integral coefficient and proportional coefficient of the voltage outer loop controller are adjusted at the same time. The proportional coefficient will affect the degree of change of the current command value with the deviation of the voltage command value, which can help limit the current command value from deviating too much from the steady-state value, and the fault recovery process switches back to the first proportional coefficient before the fault.

It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

The flexible DC fault ride-through control device provided in an embodiment of the present application is described below. The flexible DC fault ride-through control device described below and the flexible DC fault ride-through control method described above can be referenced to each other.

As shown in FIG6 , an embodiment of the present application provides a flexible DC fault ride-through control device 600, which is applied to a flexible DC converter station in a pure new energy transmission system via a flexible DC island. The device includes:

The first acquisition module 601 is used to acquire the AC side terminal voltage of the converter valve and the external power transmission of the flexible DC converter station;

A low voltage ride through module 602, configured to initiate a low voltage ride through when the voltage at the AC side terminal is less than a low voltage ride through threshold, and obtain an active power command value during the fault period;

A first determination module 603, configured to determine a second integral coefficient during a fault period according to a difference between the active power command value and the external power;

A first switching module 604 is used to switch the integral coefficient of the voltage outer loop controller from the first integral coefficient before the fault to the second integral coefficient; wherein the first integral coefficient is greater than the second integral coefficient, and the difference between the active power command value and the external power during the fault is negatively correlated with the second integral coefficient;

The second acquisition module 605 is used to acquire the AC side terminal voltage in real time;

The fault recovery module 606 is used to perform fault recovery and switch the integral coefficient of the voltage outer loop controller to the first integral coefficient when the real-time value of the AC side terminal voltage is higher than the low voltage crossing threshold.

In one embodiment, the low voltage ride through module includes:

A power acquisition unit, used for acquiring the external power of the flexible DC converter station within a preset time period before triggering low voltage ride-through;

A calculation unit, used to calculate an average value of the external power transmitted by the flexible DC converter station within the preset time period;

The command value configuration unit is used to determine the average value as the active power command value during the fault period.

In one embodiment, the device further comprises:

A power monitoring module, used for periodically acquiring the external power transmitted by the flexible DC converter station during low voltage ride-through;

A dynamic adjustment module is used to dynamically adjust the second integral coefficient according to the real-time value of the external power transmitted by the flexible DC converter station during low voltage ride-through.

In one embodiment, the device further comprises:

A second calculation module is used to calculate a second proportional coefficient during a fault period according to the first integral coefficient, the second integral coefficient and the first proportional coefficient of the voltage outer loop controller before the fault during a low voltage ride-through period;

The second switching module is used to switch the proportional coefficient of the voltage outer loop controller from the first proportional coefficient to the second proportional coefficient until it is switched back to the first proportional coefficient when fault recovery is performed.

The division of each module in the above-mentioned flexible DC fault ride-through control device is only for illustration. In other embodiments, the flexible DC fault ride-through control device can be divided into different modules as needed to complete all or part of the functions of the above-mentioned flexible DC fault ride-through control device. Each module in the above-mentioned flexible DC fault ride-through control device can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

In one embodiment, the present application further provides a storage medium, wherein the storage medium stores computer-readable instructions, and when the computer-readable instructions are executed by one or more processors, the one or more processors perform the following steps:

Acquiring the AC side terminal voltage of the converter valve and the external power transmission of the flexible DC converter station;

If the AC side terminal voltage is less than the low voltage ride-through threshold, the low voltage ride-through is triggered to obtain the active power command value during the fault period;

Determining a second integral coefficient during a fault period according to a difference between the active power command value and the external power;

Switching the integral coefficient of the voltage outer loop controller from the first integral coefficient before the fault to the second integral coefficient; wherein the first integral coefficient is greater than the second integral coefficient, and the difference between the active power command value during the fault and the external power is negatively correlated with the second integral coefficient;

Obtain AC side terminal voltage in real time;

If the real-time value of the AC side terminal voltage is higher than the low voltage ride-through threshold, fault recovery is performed and the integral coefficient of the voltage outer loop controller is switched to the first integral coefficient.

In one embodiment, the computer readable instructions, when executed by a processor, further implement the following steps:

Obtain the external power of the flexible DC converter station within a preset time before triggering low voltage ride-through;

Calculating an average value of the external power transmitted by the flexible DC converter station within the preset time period;

The average value is determined as the active power command value during the fault period.

In one embodiment, the computer readable instructions, when executed by a processor, further implement the following steps:

Regularly obtaining the external power transmission of the flexible DC converter station;

The second integral coefficient is dynamically adjusted according to the real-time value of the external power transmitted by the flexible DC converter station.

In one embodiment, the computer readable instructions, when executed by a processor, further implement the following steps:

Calculating a second proportional coefficient during a fault period according to the first integral coefficient, the second integral coefficient, and a first proportional coefficient of a voltage outer loop controller before a fault;

The proportional coefficient of the voltage outer loop controller is switched from the first proportional coefficient to the second proportional coefficient, and then switched back to the first proportional coefficient when fault recovery is performed.

In one embodiment, the present application further provides a computer device, wherein computer-readable instructions are stored in the computer device, and when the one or more processors execute the computer-readable instructions, the following steps are performed:

Acquiring the AC side terminal voltage of the converter valve and the external power transmission of the flexible DC converter station;

If the AC side terminal voltage is less than the low voltage ride-through threshold, the low voltage ride-through is triggered to obtain the active power command value during the fault period;

Determining a second integral coefficient during a fault period according to a difference between the active power command value and the external power;

Switching the integral coefficient of the voltage outer loop controller from the first integral coefficient before the fault to the second integral coefficient; wherein the first integral coefficient is greater than the second integral coefficient, and the difference between the active power command value and the external power during the fault is negatively correlated with the second integral coefficient;

Obtain AC side terminal voltage in real time;

If the real-time value of the AC side terminal voltage is higher than the low voltage ride-through threshold, fault recovery is performed and the integral coefficient of the voltage outer loop controller is switched to the first integral coefficient.

In one embodiment, when the processor executes the computer readable instructions, it further performs the following steps:

Obtain the external power of the flexible DC converter station within a preset time before triggering low voltage ride-through;

Calculating an average value of the external power transmitted by the flexible DC converter station within the preset time period;

The average value is determined as the active power command value during the fault period.

In one embodiment, when the processor executes the computer readable instructions, the processor further performs the following steps:

Regularly obtaining the external power transmission of the flexible DC converter station;

The second integral coefficient is dynamically adjusted according to the real-time value of the external power transmitted by the flexible DC converter station.

In one embodiment, when the processor executes the computer readable instructions, the processor further performs the following steps:

Calculating a second proportional coefficient during a fault period according to the first integral coefficient, the second integral coefficient, and a first proportional coefficient of a voltage outer loop controller before a fault;

The proportional coefficient of the voltage outer loop controller is switched from the first proportional coefficient to the second proportional coefficient, and then switched back to the first proportional coefficient when fault recovery is performed.

In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be shown in FIG7. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a flexible DC fault ride-through control method is implemented. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covered on the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

Those skilled in the art will understand that the structure shown in FIG. 7 is merely a block diagram of a partial structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can refer to each other.

The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. The flexible direct current fault ride through control method is characterized by being applied to a flexible direct current converter station in a system from which pure new energy is sent out through a flexible direct current island, and comprises the following steps:

acquiring alternating-current side end voltage of a converter valve and the output power of the flexible direct-current converter station;

if the voltage of the alternating-current side end is smaller than a low-voltage crossing threshold value, triggering low-voltage crossing and acquiring an active power instruction value in a fault period;

Determining a second integral coefficient during a fault according to the difference value between the active power instruction value and the output power;

Switching the integral coefficient of the voltage outer loop controller from a first integral coefficient before failure to the second integral coefficient; the first integral coefficient is larger than the second integral coefficient, and the difference value between the active power instruction value and the output power in the fault period and the second integral coefficient are in negative correlation;

acquiring the voltage of an alternating-current side end in real time;

If the real-time value of the alternating-current side terminal voltage is higher than the low-voltage crossing threshold value, fault recovery is executed, and the integral coefficient of the voltage outer loop controller is switched to the first integral coefficient;

Wherein the acquiring the active power command value during the fault includes:

acquiring the output power of the flexible direct current converter station within a preset time before triggering low voltage ride through;

calculating an average value of the output power of the flexible direct current converter station within the preset time period;

the average value is determined as an active power command value during the fault.

2. The flexible direct current fault ride-through control method according to claim 1, wherein the preset time period is greater than or equal to 60s.

3. The flexible direct current fault ride-through control method of claim 1, wherein during low voltage ride-through, the method further comprises:

the method comprises the steps of regularly obtaining the output power of the flexible direct current converter station;

And dynamically adjusting the second integral coefficient according to the real-time value of the output power of the flexible direct current converter station.

4. A flexible direct current fault ride through control method according to any one of claims 1 to 3, wherein, during low voltage ride through, after performing the determination of the second integral factor from the difference between the active power command value and the outgoing power, further comprising:

calculating a second proportional coefficient during the fault according to the first integral coefficient, the second integral coefficient and the first proportional coefficient of the voltage outer loop controller before the fault;

and switching the scaling factor of the voltage outer loop controller from the first scaling factor to the second scaling factor until the first scaling factor is switched back when fault recovery is performed.

5. The utility model provides a flexible direct current fault ride through controlling means which characterized in that is applied to the flexible direct current converter station in pure new forms of energy via flexible direct current island delivery system, said device includes:

the first acquisition module is used for acquiring alternating-current side terminal voltage of the converter valve and the output power of the flexible direct-current converter station;

the low voltage ride through module is used for sending low voltage ride through when the voltage of the alternating current side end is smaller than a low voltage ride through threshold value, and acquiring an active power instruction value in a fault period;

the first determining module is used for determining a second integral coefficient during the fault according to the difference value between the active power instruction value and the output power;

The first switching module is used for switching the integral coefficient of the voltage outer loop controller from the first integral coefficient before failure to the second integral coefficient; the first integral coefficient is larger than the second integral coefficient, and the difference value between the active power instruction value and the output power in the fault period and the second integral coefficient are in negative correlation;

The second acquisition module is used for acquiring the alternating-current side terminal voltage in real time;

The fault recovery module is used for executing fault recovery when the real-time value of the alternating-current side terminal voltage is higher than the low-voltage crossing threshold value, and switching the integral coefficient of the voltage outer loop controller to the first integral coefficient;

wherein, the low voltage ride through module includes:

The power acquisition unit is used for acquiring the output power of the flexible direct current converter station within a preset time before triggering the low voltage ride through;

the calculating unit is used for calculating the average value of the output power of the flexible direct current converter station in the preset time length;

And the command value configuration unit is used for determining the average value as the active power command value during the fault.

6. The flexible direct current fault ride-through control device of claim 5, further comprising:

the power monitoring module is used for regularly acquiring the output power of the flexible direct current converter station during the low voltage ride through period;

and the dynamic adjustment module is used for dynamically adjusting the second integral coefficient according to the real-time value of the output power of the flexible direct current converter station during the low voltage ride through period.

7. A storage medium, characterized by: the storage medium having stored therein computer readable instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of the flexible direct current fault ride-through control method of any of claims 1 to 4.

8. A computer device, comprising: one or more processors, and memory;

The memory has stored therein computer readable instructions which, when executed by the one or more processors, perform the steps of the flexible direct current fault ride-through control method of any of claims 1 to 4.