CN118508494A - Extra-high voltage flexible direct-current power surplus overvoltage suppression method, system and medium - Google Patents
Extra-high voltage flexible direct-current power surplus overvoltage suppression method, system and medium Download PDFInfo
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Abstract
The invention relates to a method, a system and a medium for inhibiting surplus overvoltage of extra-high voltage flexible direct current power, which comprise the following steps: acquiring alternating current positive sequence voltage of a receiving end of a converter valve, and setting a direct current voltage tracking alternating current voltage regulating function so as to control port direct current voltage of the receiving end in real time; when the direct-current voltage of the port of the receiving end is controlled, the number of the conducted modules is regulated by quickly regulating, the capacitance voltage of the modules is kept unchanged, and when the direct-current voltage is lower than a set value, the full-bridge module is utilized to keep the output alternating-current voltage of the converter unchanged; the transmitting end controller controls the direct current through the constant direct current, and rapidly limits the direct current below a rated value. The invention solves the problem of overvoltage of the submodule caused by surplus power on the premise of not depending on a direct-current energy consumption device, realizes the limit utilization of the power transmission capacity of the converter station, and ensures the continuous power transmission capacity and stability of the sending and receiving end alternating-current system.
Description
Technical Field
The invention relates to the technical field of stability analysis of an electric power system, in particular to a method, a system and a medium for inhibiting surplus overvoltage of extra-high voltage flexible direct current power.
Background
The flexible direct-current transmission system is an indispensable advanced transmission technology for building a novel power system, and can better adapt to complex and changeable power requirements. The flexible control characteristic enables the system to be more stable and controllable, and improves the reliability and safety of the power system. By adopting extra-high voltage transmission, the transmission loss can be greatly reduced, and the power grid efficiency is improved. Compared with the traditional power transmission system, the ultra-high voltage flexible direct-current power transmission system can realize long-distance crossing, reduce the number of power transmission lines, save land and reduce environmental impact. Meanwhile, due to the adoption of the flexible direct current transmission technology, the system support requirement during large-scale new energy output is reduced, and island output of the large-scale new energy is realized. However, in the extra-high voltage flexible direct current system, the surplus problem of the extra-high voltage flexible direct current system power is serious when the receiving end alternating current power grid is in fault, the voltage level of the submodule is high, and the system is easily locked, and even serious accidents of equipment damage are caused. Particularly, when the transmission distance is far, the transmitting-end converter station is limited by long communication time, and can not timely receive signals for reducing the running power, and meanwhile, the transmitting end can not sense the overvoltage of the receiving end due to the long direct current electric distance, so that the power surplus is more serious.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a method, a system and a medium for inhibiting surplus overvoltage of extra-high voltage flexible direct current power, which can realize stable crossing of alternating current faults without depending on a direct current energy consumption device and avoid blocking caused by fault crossing failure.
In order to achieve the above purpose, the present invention adopts the following technical scheme: an extra-high voltage flexible direct current power surplus overvoltage suppression method comprises the following steps: acquiring alternating current positive sequence voltage of a receiving end of a converter valve, and setting a direct current voltage tracking alternating current voltage regulating function so as to control port direct current voltage of the receiving end in real time; when the direct-current voltage of the port of the receiving end is controlled, the number of the conducted modules is regulated by quickly regulating, the capacitance voltage of the modules is kept unchanged, and when the direct-current voltage is lower than a set value, the full-bridge module is utilized to keep the output alternating-current voltage of the converter unchanged; the transmitting end controller controls the direct current through the constant direct current, and rapidly limits the direct current below a rated value.
Further, setting a dc voltage tracking ac voltage regulation function, comprising:
The direct current voltage value which is required to be quickly regulated under different fault types is determined through off-line simulation, the random curves of the direct current voltage and the alternating current voltage of the whole domain are determined through a multipoint fitting method, and the regulating function is determined in a segmented curve mode.
Further, determining the adjustment function in the form of a piecewise curve includes:
Performing simulation calculation on module overvoltage electromagnetic transient states of the flexible direct current converter valve under four fault types, namely single-phase earth fault, interphase short circuit fault, two-phase earth fault and three-phase metal short circuit fault, under all operation modes, and determining the maximum direct current voltage required to be regulated for ensuring that the overvoltage of the converter valve does not exceed a limit value under each fault type;
And determining a regulating primer P factor according to the maximum direct current voltage and the alternating current positive sequence voltage under four faults, and obtaining a regulating function by the regulating primer P factor.
Further, setting a dc voltage tracking ac voltage regulation function, comprising:
the method comprises the steps of collecting the change of alternating voltage, the change of direct current and the change of module capacitance voltage in real time, and calculating the direct voltage value to be adjusted at each moment in real time on line in a control protection system.
Further, the direct current voltage value to be adjusted at each moment is calculated in real time on line in the control protection system, and is as follows:
In the method, in the process of the invention, As a direct-current voltage value, U pos is an alternating-current voltage acquired in real time, I dc is a direct-current acquired in real time, U c is an average capacitance voltage U c of the converter valve module, and t is a moment; is the rated value of the voltage of the alternating current bus, Is a direct current voltage rating.
Further, adjust through the module quantity that fast adjustment switched on, include:
and adjusting the dq conversion outer ring direct-current voltage control command value U dcref, and adjusting the direct-current voltage command value U dcref2 used in the latest level approximation link to be a direct-current voltage value U dc, wherein the capacitance voltage value used in the latest level approximation link for calculating the number of conducting modules is kept unchanged.
Further, the sending end controller controls the current through constant direct current, comprising:
In the process of receiving end regulation, the transmitting end constant direct current controller adopts a dynamic control parameter direct current regulation method, when the difference between the direct current and a reference value is larger than a current rated value delta I set, the control parameter is rapidly increased, the transmitting end direct current voltage is reduced, and the direct current is rapidly reduced; when the difference between the direct current and the reference value is smaller than the current rated value delta I set, the control parameter is reduced to a normal value.
An extra-high voltage flexible direct current power surplus overvoltage suppression system, comprising: the voltage regulating function module is used for obtaining alternating current positive sequence voltage of the receiving end of the converter valve, and setting a direct current voltage tracking alternating current voltage regulating function so as to control port direct current voltage of the receiving end in real time; the voltage suppression module is used for adjusting the number of the conducted modules by quickly adjusting the direct-current voltage of the port of the receiving end, keeping the capacitance voltage of the modules unchanged, and keeping the output alternating-current voltage of the converter unchanged by using the full-bridge module when the direct-current voltage is lower than a set value; and the transmitting end control module is used for controlling the direct current through the constant direct current control, so that the direct current is rapidly limited below the rated value.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform any of the methods described above.
A computing apparatus, comprising: one or more processors, memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing any of the methods described above.
Due to the adoption of the technical scheme, the invention has the following advantages:
1. the invention provides a method for solving overvoltage under surplus power of an extra-high voltage flexible direct current full-half-bridge hybrid converter valve by controlling without depending on a direct current energy consumption device for the first time, and the quantity of full-bridge and half-bridge modules which are conducted is flexibly controlled by applying the characteristic of voltage decoupling of an alternating current side of the full-half hybrid converter valve, so that the direct current voltage is regulated in real time along with the alternating current voltage, and the surplus power flowing in the direct current side is effectively reduced. The invention greatly reduces the investment cost of engineering and avoids the increase of the number of the direct current energy consumption devices or the converter valve modules.
2. The invention not only avoids the increase of equipment investment, but also realizes the real-time balance of direct current side and alternating current power, furthest reserves the direct current power transmission during the fault period, and takes the minimum equipment investment and the optimization of system performance into account.
3. The invention realizes the remarkable effect of canceling the configuration of the energy consumption device, effectively solves the technical problem of engineering and reduces the investment of the engineering.
Drawings
FIG. 1 is a flowchart of an overall overvoltage suppression method in an embodiment of the present invention;
FIG. 2 is an overvoltage suppression control loop under the fault of an alternating current system of the extra-high voltage flexible direct current full-half bridge hybrid converter valve based on an offline calculation determined adjusting function in the embodiment of the invention;
FIG. 3 is a representative Udc=for determining an adjustment function based on offline computation in an embodiment of the present invention A curve;
Fig. 4 is a simulated waveform of fault ride-through of the ac system when the overvoltage suppression method of the present invention is adopted in the embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which are obtained by a person skilled in the art based on the described embodiments of the invention, fall within the scope of protection of the invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
In order to solve the problem that the extra-high voltage flexible direct current system has serious power surplus when an alternating current power grid fails, a conventional solution is to configure a direct current energy consumption device, but the extra-high voltage energy consumption device adopts a large number of IGBT devices, so that the construction cost of the engineering is greatly increased, and the construction cost of the energy consumption device is about 4 hundred million by taking an ultra-high voltage flexible direct current engineering of +/-800 kV/8GW as an example. Therefore, the invention provides a method, a system and a medium for suppressing surplus overvoltage of extra-high voltage flexible direct current power, which are characterized in that alternating current-direct current voltage synchronous regulation control is designed at the receiving end of a convertor station, the state of alternating current voltage is monitored in real time, alternating current positive sequence voltage Upos is obtained, and a direct current voltage tracking alternating current voltage regulation function udc=is setAnd controlling the port direct current voltage of the receiving end in real time according to the regulating function. Two methods are used to determine the adjustment function: firstly, determining direct-current voltage values which are required to be quickly adjusted under different fault types through off-line simulation, and determining universal direct-current voltage and alternating-current voltage random curves through a multipoint fitting method; the second method is to collect the change of alternating voltage, direct current and module capacitance voltage in real time, and calculate the direct voltage value to be adjusted at each moment in real time on line in the control protection system. In the process of receiving end regulation, the sending end controller controls the direct current to be below a rated value through a constant direct current control. Therefore, the invention solves the problem of overvoltage of the submodule caused by surplus power on the premise of not depending on a direct current energy consumption device, realizes the limit utilization of the power transmission capacity of the converter station, ensures the continuous power transmission capacity and stability of the transmitting and receiving end alternating current system, meets the safe and stable operation requirement of the ultrahigh voltage flexible direct current transmission system, improves the overall availability of the system, and provides technical support for large-scale new energy to be transmitted through the ultrahigh voltage flexible direct current system.
In one embodiment of the invention, an extra-high voltage flexible direct current power surplus overvoltage suppression method is provided. In this embodiment, as shown in fig. 1, the method includes the following steps:
1) Acquiring an alternating current positive sequence voltage U pos of a receiving end of the converter valve, and setting a direct current voltage tracking alternating current voltage regulating function so as to control the port direct current voltage of the receiving end in real time; wherein the function is adjusted The method comprises the following steps: u dc =。
2) When the direct-current voltage of the port of the receiving end is controlled, the number of the conducted modules is regulated by quickly regulating, the capacitance voltage of the modules is kept unchanged, and when the direct-current voltage is lower than a set value, the full-bridge module is utilized to keep the output alternating-current voltage of the converter unchanged;
3) The transmitting end controller controls the direct current through the constant direct current, and rapidly limits the direct current below a rated value.
In the step 1), the setting of the dc voltage tracking ac voltage adjustment function may be performed by two methods. The first setting method comprises the following steps:
Direct-current voltage values which are required to be quickly adjusted under different fault types are determined through off-line simulation, universal direct-current voltage and alternating-current voltage random curves are determined through a multi-point fitting method, and an adjusting function U dc = is determined in a segmented curve mode 。
In this embodiment, determining the adjustment function in the form of a piecewise curve includes the steps of:
1.1 Simulation calculation is carried out on module overvoltage electromagnetic transient state of the flexible direct current converter valve under four fault types, namely single-phase earth fault, interphase short circuit fault, two-phase earth fault and three-phase metal short circuit fault, under all operation modes, and the maximum direct current voltage U dclim1、Udclim2、Udclim2g、Udclim3m which is required to be regulated and is used for ensuring that the overvoltage of the converter valve does not exceed a limit value under each fault type is determined;
Wherein, U dclim1 is the maximum direct current voltage required to be regulated for ensuring that the overvoltage of the converter valve does not exceed the limit value under single-phase grounding fault, U dclim2 is the maximum direct current voltage required to be regulated for ensuring that the overvoltage of the converter valve does not exceed the limit value under interphase short-circuit fault, U dclim2g is the maximum direct current voltage required to be regulated for ensuring that the overvoltage of the converter valve does not exceed the limit value under two-phase grounding fault, and U dclim3m is the maximum direct current voltage required to be regulated for ensuring that the overvoltage of the converter valve does not exceed the limit value under three-phase metal short-circuit fault.
1.2 Determining the adjusting primer P factor according to the maximum direct current voltage and the alternating current positive sequence voltage under four faults, and obtaining an adjusting function by the adjusting primer P factor.
The alternating current positive sequence voltages under four faults are U pos1、Upos2、Upos2g、Upos3m respectively.
The regulatory primer P factor is:
wherein, Is the initial value of the DC voltage.
In this embodiment, the adjustment function is: u dc =。
In the step 1), a second setting method for setting the dc voltage tracking ac voltage adjusting function is as follows: the method comprises the steps of collecting the change of alternating voltage, the change of direct current and the change of module capacitance voltage in real time, and calculating the direct voltage value to be adjusted at each moment in real time on line in a control protection system.
In this embodiment, according to the ac voltage U pos, the dc current I dc, and the average capacitance voltage U c of the converter valve module, which are collected in real time, the dc voltage value to be adjusted at each moment is calculated in real time on line in the control protection system, where the dc voltage value is:
In the method, in the process of the invention, As a direct-current voltage value, U pos is an alternating-current voltage acquired in real time, I dc is a direct-current acquired in real time, U c is an average capacitance voltage U c of the converter valve module, and t is a moment; is the rated value of the voltage of the alternating current bus, Is a direct current voltage rating.
In the step 2), the number of the conducted modules is adjusted by fast adjusting, specifically: and adjusting the dq-transformed outer ring direct-current voltage control command value U dcref, and adjusting the direct-current voltage command value U dcref2 used in the latest level approximation link to be the direct-current voltage value U dc in the first method, wherein the capacitance voltage value used for calculating the number of conducting modules in the latest level approximation link is kept unchanged.
In the step 3), the sending end controller controls the current through constant direct current, specifically: in the process of receiving end regulation, the transmitting end constant direct current controller adopts a dynamic control parameter direct current regulation method, when the difference between the direct current and a reference value is larger than a current rated value delta I set, the control parameter is rapidly increased, the transmitting end direct current voltage is reduced, and the direct current is rapidly reduced; when the difference between the direct current and the reference value is smaller than the current rated value delta I set, the control parameter is reduced to a normal value.
In an embodiment, taking an extra-high voltage direct current transmission project with a voltage class of +/-800 kV, a transmission power of 8GW and a line length of 2400km as an example, the overvoltage suppression method of the invention comprises the following steps:
(1) And establishing a PSCAD simulation model, comprehensively scanning faults of various alternating current systems, determining the traversing capacity of various faults without additional strategies, if the fault traversing can be realized, not taking any measures, and if the fault traversing can not be realized, determining additional control strategies, wherein a control loop is shown in figure 2.
(2) The additional control strategies are: the novel AC/DC voltage synchronous regulation control is added to the receiving end converter station, the state of the AC voltage is monitored in real time, the AC positive sequence voltage U pos is obtained, and the DC voltage tracking AC voltage regulation function U dc = is setAnd controlling the port direct current voltage of the receiving end in real time according to the regulating function.
(3) The adjustment function is considered in two ways: the first method is to determine the direct current voltage value to be quickly adjusted under different fault types through off-line simulation, and determine the universal direct current voltage and alternating current voltage variable curves through a multi-point fitting method, wherein the curves are shown in fig. 3, and the curve one, the curve two and the curve three are respectively the direct current voltage and the alternating current voltage curves under three different line lengths; the second method is to collect the change of alternating voltage, direct current and module capacitance voltage in real time, and calculate the direct voltage value to be adjusted at each moment in real time on line in the control protection system. The first method is simpler and more convenient to realize online, has relatively more power loss, but the suppression of module overvoltage is more conservative; the second method is more complex to realize online, and needs to collect more real-time measurement quantities, so as to reduce power loss to the greatest extent. The two methods are adopted to respectively compare the overvoltage level and the power drop level of the converter valve under different fault conditions. And comprehensively evaluating and determining the adopted adjustment function method. In this example, the first method is used after comparison.
(4) After the direct current voltage value to be regulated is determined, the direct current voltage is regulated by rapidly regulating the number of conducted modules, the direct current voltage control command value U dcref of the outer ring direct current voltage requiring dq conversion and the direct current voltage command value U dcref2 used in the latest level approximation link are regulated to U dc in the first method, and the capacitance voltage value used for calculating the number of conducted modules in the latest level approximation link is kept unchanged.
The fault ride-through waveform of the post-strategy converter valve is shown in fig. 4, which shows that the module overvoltage is effectively limited within the tolerance range of the device by adopting the proposed control technology.
In one embodiment of the present invention, there is provided an extra-high voltage flexible direct current power surplus overvoltage suppression system including:
The voltage regulating function module is used for obtaining alternating current positive sequence voltage of the receiving end of the converter valve, and setting a direct current voltage tracking alternating current voltage regulating function so as to control port direct current voltage of the receiving end in real time;
The voltage suppression module is used for adjusting the number of the conducted modules by quickly adjusting the direct-current voltage of the port of the receiving end, keeping the capacitance voltage of the modules unchanged, and keeping the output alternating-current voltage of the converter unchanged by using the full-bridge module when the direct-current voltage is lower than a set value;
And the transmitting end control module is used for controlling the direct current through the constant direct current control, so that the direct current is rapidly limited below the rated value.
In the above embodiment, setting the dc voltage tracking ac voltage adjustment function includes:
The direct current voltage value which is required to be quickly regulated under different fault types is determined through off-line simulation, the random curves of the direct current voltage and the alternating current voltage of the whole domain are determined through a multipoint fitting method, and the regulating function is determined in a segmented curve mode.
In this embodiment, determining the adjustment function in the form of a piecewise curve includes:
Performing simulation calculation on module overvoltage electromagnetic transient states of the flexible direct current converter valve under four fault types, namely single-phase earth fault, interphase short circuit fault, two-phase earth fault and three-phase metal short circuit fault, under all operation modes, and determining the maximum direct current voltage required to be regulated for ensuring that the overvoltage of the converter valve does not exceed a limit value under each fault type;
And determining a regulating primer P factor according to the maximum direct current voltage and the alternating current positive sequence voltage under four faults, and obtaining a regulating function by the regulating primer P factor.
In the above embodiment, setting the dc voltage tracking ac voltage adjustment function includes:
the method comprises the steps of collecting the change of alternating voltage, the change of direct current and the change of module capacitance voltage in real time, and calculating the direct voltage value to be adjusted at each moment in real time on line in a control protection system.
In this embodiment, the dc voltage value to be adjusted at each moment is calculated in real time on line in the control protection system, where the dc voltage value is:
In the method, in the process of the invention, As a direct-current voltage value, U pos is an alternating-current voltage acquired in real time, I dc is a direct-current acquired in real time, U c is an average capacitance voltage U c of the converter valve module, and t is a moment; For the ac voltage rating, Is a direct current voltage rating.
In the above embodiment, the adjustment by rapidly adjusting the number of on modules includes:
and adjusting the dq conversion outer ring direct-current voltage control command value U dcref, and adjusting the direct-current voltage command value U dcref2 used in the latest level approximation link to be a direct-current voltage value U dc, wherein the capacitance voltage value used in the latest level approximation link for calculating the number of conducting modules is kept unchanged.
In the above embodiment, the transmitting end controller controls the current by constant direct current, including:
In the process of receiving end regulation, the transmitting end constant direct current controller adopts a dynamic control parameter direct current regulation method, when the difference between the direct current and a reference value is larger than a current rated value delta I set, the control parameter is rapidly increased, the transmitting end direct current voltage is reduced, and the direct current is rapidly reduced; when the difference between the direct current and the reference value is smaller than the current rated value delta I set, the control parameter is reduced to a normal value.
The system provided in this embodiment is used to execute the above method embodiments, and specific flow and details refer to the above embodiments, which are not described herein.
A computing device provided in an embodiment of the present invention may be a terminal, which may include: a processor (processor), a communication interface (Communications Interface), a memory (memory), a display, and an input device. The processor, the communication interface and the memory complete communication with each other through a communication bus. The processor is configured to provide computing and control capabilities. The memory comprises a non-volatile storage medium storing an operating system and a computer program which when executed by the processor implements the methods of the embodiments described above; the internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The communication interface is used for carrying out wired or wireless communication with an external terminal, and the wireless mode can be realized through WIFI, a manager network, NFC (near field communication) or other technologies. The display screen can be a liquid crystal display screen or an electronic ink display screen, the input device can be a touch layer covered on the display screen, can also be a key, a track ball or a touch pad arranged on the shell of the computing equipment, and can also be an external keyboard, a touch pad or a mouse and the like. The processor may invoke logic instructions in memory.
Further, the logic instructions in the memory described above may be implemented in the form of software functional units and stored in a computer-readable storage medium when sold or used as a stand-alone product. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
In one embodiment of the present invention, a computer program product is provided, the computer program product comprising a computer program stored on a non-transitory computer readable storage medium, the computer program comprising program instructions which, when executed by a computer, are capable of performing the methods provided by the method embodiments described above.
In one embodiment of the present invention, a non-transitory computer readable storage medium storing server instructions that cause a computer to perform the methods provided by the above embodiments is provided.
The foregoing embodiment provides a computer readable storage medium, which has similar principles and technical effects to those of the foregoing method embodiment, and will not be described herein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The method for inhibiting surplus overvoltage of extra-high voltage flexible direct current power is characterized by comprising the following steps of:
Acquiring alternating current positive sequence voltage of a receiving end of a converter valve, and setting a direct current voltage tracking alternating current voltage regulating function so as to control port direct current voltage of the receiving end in real time;
when the direct-current voltage of the port of the receiving end is controlled, the number of the conducted modules is regulated by quickly regulating, the capacitance voltage of the modules is kept unchanged, and when the direct-current voltage is lower than a set value, the full-bridge module is utilized to keep the output alternating-current voltage of the converter unchanged;
the transmitting end controller controls the direct current through the constant direct current, and rapidly limits the direct current below a rated value.
2. The extra-high voltage flexible direct current power surplus overvoltage suppression method according to claim 1, wherein setting a direct current voltage tracking alternating current voltage adjustment function comprises:
The direct current voltage value which is required to be quickly regulated under different fault types is determined through off-line simulation, the random curves of the direct current voltage and the alternating current voltage of the whole domain are determined through a multipoint fitting method, and the regulating function is determined in a segmented curve mode.
3. The extra-high voltage flexible dc power surplus overvoltage suppression method according to claim 2, wherein determining the adjustment function in the form of a piecewise curve includes:
Performing simulation calculation on module overvoltage electromagnetic transient states of the flexible direct current converter valve under four fault types, namely single-phase earth fault, interphase short circuit fault, two-phase earth fault and three-phase metal short circuit fault, under all operation modes, and determining the maximum direct current voltage required to be regulated for ensuring that the overvoltage of the converter valve does not exceed a limit value under each fault type;
And determining a regulating primer P factor according to the maximum direct current voltage and the alternating current positive sequence voltage under four faults, and obtaining a regulating function by the regulating primer P factor.
4. The extra-high voltage flexible direct current power surplus overvoltage suppression method according to claim 1, wherein setting a direct current voltage tracking alternating current voltage adjustment function comprises:
the method comprises the steps of collecting the change of alternating voltage, the change of direct current and the change of module capacitance voltage in real time, and calculating the direct voltage value to be adjusted at each moment in real time on line in a control protection system.
5. The method for suppressing surplus overvoltage of extra-high voltage flexible direct current power according to claim 4, wherein the direct current voltage value to be adjusted at each moment is calculated in real time on line in a control protection system, and is as follows:
In the method, in the process of the invention, As a direct-current voltage value, U pos is an alternating-current voltage acquired in real time, I dc is a direct-current acquired in real time, U c is an average capacitance voltage U c of the converter valve module, and t is a moment; is the rated value of the voltage of the alternating current bus, Is a direct current voltage rating.
6. The method for suppressing excess overvoltage of extra-high voltage flexible direct current power according to claim 1, wherein the adjusting by rapidly adjusting the number of conducted modules comprises:
and adjusting the dq conversion outer ring direct-current voltage control command value U dcref, and adjusting the direct-current voltage command value U dcref2 used in the latest level approximation link to be a direct-current voltage value U dc, wherein the capacitance voltage value used in the latest level approximation link for calculating the number of conducting modules is kept unchanged.
7. The method for suppressing surplus overvoltage of extra-high voltage flexible direct current power according to claim 1, wherein the transmitting end controller controls the current by a constant direct current, comprising:
In the process of receiving end regulation, the transmitting end constant direct current controller adopts a dynamic control parameter direct current regulation method, when the difference between the direct current and a reference value is larger than a current rated value delta I set, the control parameter is rapidly increased, the transmitting end direct current voltage is reduced, and the direct current is rapidly reduced; when the difference between the direct current and the reference value is smaller than the current rated value delta I set, the control parameter is reduced to a normal value.
8. An extra-high voltage flexible direct current power surplus overvoltage suppression system, which is characterized by comprising:
The voltage regulating function module is used for obtaining alternating current positive sequence voltage of the receiving end of the converter valve, and setting a direct current voltage tracking alternating current voltage regulating function so as to control port direct current voltage of the receiving end in real time;
The voltage suppression module is used for adjusting the number of the conducted modules by quickly adjusting the direct-current voltage of the port of the receiving end, keeping the capacitance voltage of the modules unchanged, and keeping the output alternating-current voltage of the converter unchanged by using the full-bridge module when the direct-current voltage is lower than a set value;
And the transmitting end control module is used for controlling the direct current through the constant direct current control, so that the direct current is rapidly limited below the rated value.
9. A computer readable storage medium storing one or more programs, wherein the one or more programs comprise instructions, which when executed by a computing device, cause the computing device to perform any of the methods of claims 1-7.
10. A computing device, comprising: one or more processors, memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing any of the methods of claims 1-7.
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