Frequency control method, device, medium and equipment of DC asynchronous interconnection system

Abstract

The present application discloses a frequency control method, device, medium and equipment for a DC asynchronous interconnection system. The method includes: determining a target power variation according to a first frequency deviation corresponding to a rectifier-side AC system and a second frequency deviation corresponding to an inverter-side AC system; determining a first DC current variation and a first DC voltage variation according to the target power variation and a preset reactive power; determining a second DC voltage variation according to the target power variation and a preset minimum arc-off angle; determining a target DC voltage variation and a target DC current variation according to the first DC voltage variation and the second DC voltage variation, and adjusting the current DC current and the current DC voltage of the inverter-side converter station according to the two target variations, so that the AC systems on both sides operate at the same frequency after the adjustment, avoiding the arc-off angle corresponding to the inverter-side converter station being less than the preset minimum arc-off angle, and minimizing the difference between the reactive power consumed by the inverter-side converter station and the preset reactive power.

Description

Technical Field

[0001] The present application relates to the field of power grid control technology, and in particular to a frequency control method, device, medium and equipment for a direct current asynchronous interconnection system. Background Art

[0002] In an asynchronous interconnected system, each regional AC system is connected together through a DC line to achieve long-distance power transmission. The frequencies of each regional AC system are not affected by each other and can operate at different frequencies. However, the special structural form and operating characteristics of the asynchronous interconnected system make the regional AC systems no longer have the ability to support each other when DC transmission power disturbances occur, which deteriorates the frequency regulation performance of the multi-regional power grid and reduces the stability of the multi-regional system frequency.

[0003] For example, in the line commutated converter high-voltage direct current (LCC HVDC) system, in the related technology, although the frequency of the rectifier side AC system and the inverter side AC system is adjusted by DC transmission power, the control of the reactive power consumed by the inverter side converter station and the corresponding arc extinction angle of the inverter side converter station is ignored. The uncontrolled change of reactive power consumption by the inverter side converter station may bring negative effects such as significant fluctuations in the inverter side AC voltage, thereby affecting the stable operation of the power grid. In addition, the adjustment of DC transmission power may cause the arc extinction angle corresponding to the inverter side converter station to be less than the specified minimum arc extinction angle, thereby leading to a series of risks such as inverter side commutation failure. Summary of the invention

[0004] In view of this, the present application provides a frequency control method, device, medium and equipment for a DC asynchronous interconnection system. When a DC transmission power disturbance occurs, the current voltage frequency corresponding to the rectifier side AC system and the inverter side AC system is adjusted by the target DC voltage change and the target DC current change, so that the voltage frequency of the rectifier side AC system and the inverter side AC system are unified after adjustment, while avoiding the arc extinction angle corresponding to the inverter side converter station being less than the preset minimum arc extinction angle, and minimizing the difference between the reactive power consumed by the inverter side converter station after adjustment and the preset reactive power, thereby effectively suppressing AC voltage fluctuations and improving the stability of power grid operation.

[0005] According to one aspect of the present application, a frequency control method for a DC asynchronous interconnection system is provided, comprising: determining a target power variation for adjusting a current DC transmission power according to a first frequency deviation corresponding to a rectifier-side AC system and a second frequency deviation corresponding to an inverter-side AC system; determining a first DC current variation and a first DC voltage variation according to the target power variation and a preset reactive power, wherein the first DC current variation and the first DC voltage variation are used to keep the reactive power consumed by the inverter-side converter station after adjustment equal to the preset reactive power; determining a second DC voltage variation according to the target power variation and a preset minimum arc-off angle corresponding to the inverter-side converter station, wherein the second DC voltage variation is a maximum voltage variation corresponding to a current DC voltage of the inverter-side converter station; determining a target DC voltage variation according to the first DC voltage variation and the second DC voltage variation, and determining a target DC current variation according to the target DC voltage variation; and adjusting the current DC voltage of the inverter-side converter station and the current DC current of the DC line respectively according to the target DC voltage variation and the target DC current variation, with the first frequency deviation being equal to the second frequency deviation as a constraint.

[0006] Optionally, the target DC voltage change is determined according to the first DC voltage change and the second DC voltage change, and the target DC current change is determined according to the target DC voltage change, specifically including: if the first DC voltage change is less than or equal to the second DC voltage change, the first DC voltage change is determined as the target DC voltage change; if the first DC voltage change is greater than the second DC voltage change, the second DC voltage change is determined as the target DC voltage change; if the target DC voltage change is the first DC voltage change, the first DC current change is determined as the target DC current change; if the target DC voltage change is the second DC voltage change, the target DC current change is determined according to the second DC voltage change and the preset minimum arc extinction angle.

[0007] Optionally, determining the target DC current change based on the second DC voltage change and the preset minimum arc extinction angle specifically includes: determining the first DC voltage of the inverter side converter station based on the sum of the second DC voltage change and the current DC voltage of the inverter side converter station; determining the first DC current of the DC line based on the first DC voltage and the preset minimum arc extinction angle; determining the target DC current change based on the difference between the first DC current and the current DC current of the DC line.

[0008] Optionally, determining a first DC current change and a first DC voltage change according to the target power change and the preset reactive power specifically includes: determining the target DC transmission power according to the sum of the target power change and the current DC transmission power; determining the second DC current of the DC line according to the target DC transmission power and the preset reactive power; determining the first DC current change according to the difference between the second DC current and the current DC current of the DC line; determining the second DC voltage of the inverter side converter station according to the target DC transmission power and the preset reactive power; and determining the first DC voltage change according to the difference between the second DC voltage and the current DC voltage of the inverter side converter station.

[0009] Optionally, determining the second DC voltage change according to the target power change and the preset minimum arc extinction angle corresponding to the inverter side converter station specifically includes: determining the target DC transmission power according to the sum of the target power change and the current DC transmission power; determining the first DC voltage of the inverter side converter station according to the target DC transmission power and the preset minimum arc extinction angle; determining the second DC voltage change according to the difference between the first DC voltage and the current DC voltage of the inverter side converter station.

[0010] Optionally, the target power change amount for adjusting the current DC transmission power is determined based on the first frequency deviation corresponding to the rectifier-side AC system and the second frequency deviation corresponding to the inverter-side AC system, specifically including: determining the first frequency deviation based on the difference between a preset rated frequency and a first current voltage frequency of the rectifier-side AC system; determining the second frequency deviation based on the difference between the preset rated frequency and the second current voltage frequency of the inverter-side AC system; if the first frequency deviation is not equal to the second frequency deviation, determining the target frequency deviation based on the difference between the second frequency deviation and the first frequency deviation; determining the first control amount based on the product of a preset proportional coefficient and the target frequency deviation; determining the second control amount based on a preset integral coefficient and the target frequency deviation; and determining the target power change amount based on the sum of the first control amount and the second control amount.

[0011] Optionally, the target power change for adjusting the current DC transmission power is determined based on the first frequency deviation corresponding to the rectifier-side AC system and the second frequency deviation corresponding to the inverter-side AC system, specifically including: obtaining a frequency adjustment range; determining a target frequency deviation based on a difference between the second frequency deviation and the first frequency deviation; if the target frequency deviation is within the frequency adjustment range, determining the target power change.

[0012] According to another aspect of the present application, a frequency control device of a DC asynchronous interconnection system is provided, comprising: a determination module, for determining a target power variation for adjusting the current DC transmission power according to a first frequency deviation corresponding to the rectifier-side AC system and a second frequency deviation corresponding to the inverter-side AC system; and, for determining a first DC current variation and a first DC voltage variation according to the target power variation and a preset reactive power, wherein the first DC current variation and the first DC voltage variation are used to keep the reactive power consumed by the inverter-side converter station after adjustment equal to the preset reactive power; and, for determining a second DC voltage variation according to the target power variation and a preset minimum arc-off angle corresponding to the inverter-side converter station, wherein the second DC voltage variation is a maximum voltage variation corresponding to the current DC voltage of the inverter-side converter station; and, for determining a target DC voltage variation according to the first DC voltage variation and the second DC voltage variation, and for determining a target DC current variation according to the target DC voltage variation;

[0013] The adjustment module is used to adjust the current DC voltage of the inverter side converter station and the current DC current of the DC line respectively according to the target DC voltage change and the target DC current change, with the first frequency deviation being equal to the second frequency deviation as a constraint.

[0014] According to another aspect of the present application, a readable storage medium is provided, on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of the frequency control method of the above-mentioned DC asynchronous interconnection system are implemented.

[0015] According to another aspect of the present application, a computer device is provided, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, wherein the processor implements the steps of the frequency control method of the above-mentioned DC asynchronous interconnection system when executing the program.

[0016] By means of the above technical scheme, the present application provides a frequency control method, device, medium and equipment for a DC asynchronous interconnection system. When the current voltage frequencies corresponding to the rectifier-side AC system and the inverter-side AC system are not equal, the target power change amount used to adjust the current DC transmission power is determined by the frequency deviations corresponding to the rectifier-side AC system and the inverter-side AC system, so that the adjusted rectifier-side AC system and the inverter-side AC system operate at the same frequency. In addition, while achieving the same frequency operation of the AC systems on both sides through the target power change amount, the first DC voltage change amount that can keep the reactive power of the inverter-side converter station constant is determined. Furthermore, according to the target power change amount, the maximum allowable change amount of the current DC voltage of the inverter-side converter station, that is, the second DC voltage change amount, is determined when the arc extinction angle corresponding to the inverter-side converter station is greater than the preset minimum arc extinction angle. And according to the first DC voltage change and the second DC voltage change, the target DC voltage change and the target DC current change are determined, and the current DC voltage of the inverter side converter station and the current DC current of the DC line are adjusted by the target DC voltage change and the target DC current change, so that the voltage frequency of the rectifier side AC system and the inverter side AC system are equal after adjustment, while avoiding the arc extinction angle corresponding to the inverter side converter station being less than the preset minimum arc extinction angle, preventing the inverter side converter station from commutation failure, and minimizing the difference between the reactive power consumed by the inverter side converter station after adjustment and the preset reactive power, thereby effectively suppressing AC voltage fluctuations and ensuring stable operation of the power grid.

[0017] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0019] Figure 1 A schematic flow chart of a frequency control method for a DC asynchronous interconnected system provided in an embodiment of the present application is shown;

[0020] Figure 2 A schematic diagram of the structure of a grid-commutated converter type high voltage direct current transmission system provided in an embodiment of the present application is shown;

[0021] Figure 3 A structural block diagram of a frequency control device for a DC asynchronous interconnected system provided in an embodiment of the present application is shown;

[0022] Figure 4(a) shows a DC transmission power curve provided by an embodiment of the present application;

[0023] Figure 4 (b) shows a reactive power curve diagram of an inverter-side converter station consumed by an embodiment of the present application;

[0024] Figure 5 A reactive power curve diagram of another inverter-side converter station consumed provided by an embodiment of the present application is shown;

[0025] Figure 6 The overall structural diagram of the frequency control method of the DC asynchronous interconnection system provided in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0026] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0027] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application.

[0028] Those skilled in the art will appreciate that, unless expressly stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, or there may be intermediate elements. In addition, the "connection" or "connection" used herein may include wireless connection or wireless fusion. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0029] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of the present application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art.

[0030] The frequency control method of the DC asynchronous interconnected system provided in the embodiment of the present application can be applied to the terminal, can also be applied to the server, and can also be software running in the terminal or the server. In some embodiments, the terminal can be a smart phone, a tablet computer, a laptop computer, a desktop computer, etc.; the server side can be configured as an independent physical server, or a server cluster or distributed system composed of multiple physical servers, and can also be configured as a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms; the software can be an application of the frequency control method of the DC asynchronous interconnected system, etc., but is not limited to the above forms.

[0031] It should be noted that if Figure 2 As shown, the embodiments of the present application are described based on a line commutated converter high-voltage direct current (LCC HVDC) in an asynchronous interconnected system. For ease of description, the "line commutated converter high-voltage direct current" is referred to as the "high-voltage direct current transmission system" in the following. The two sides of the high-voltage direct current transmission system are the rectifier side AC system and the inverter side AC system, respectively. The AC power of the rectifier side AC system is converted into DC power by the rectifier side converter station to realize the transmission of current from the rectifier side AC system to the DC line. The inverter side converter station converts the DC power back to AC power and feeds it into the inverter side AC system, thereby realizing long-distance power transmission. The DC transmission power is the power transmitted by the DC line in the high-voltage direct current transmission system, which can also be called active power.

[0032] In this embodiment, a frequency control method for a DC asynchronous interconnection system is provided. Figure 1 As shown, the method includes:

[0033] S101, determining a target power variation for adjusting a current DC transmission power according to a first frequency deviation corresponding to a rectifier-side AC system and a second frequency deviation corresponding to an inverter-side AC system.

[0034] It should be noted that if a DC transmission power disturbance occurs, such as a fault in the AC system on one side, such as a generator tripping, or a continuous large load on the AC system on one side, the voltage frequency in the rectifier side AC system or the inverter side AC system will change, making it impossible for the AC systems on both sides to operate stably at the preset rated frequency, resulting in a frequency deviation between the current voltage frequency corresponding to the rectifier side AC system or the inverter side AC system and the preset rated frequency.

[0035] The target power change is the amount by which the current DC transmission power needs to change when reaching the required target DC transmission power.

[0036] In this embodiment, the first frequency deviation and the second frequency deviation are used to detect in real time whether the voltage frequencies of the rectifier-side AC system and the inverter-side AC system are equal, so as to determine whether a DC transmission power disturbance occurs in the high-voltage DC transmission system, and respond in time when the first frequency deviation and the second frequency deviation are not equal, and adjust the current DC transmission power by the target power change amount, so that the adjusted rectifier-side AC system and the inverter-side AC system operate at the same frequency, so as to capture the transient changes of the voltage frequency of the AC systems on both sides during the operation of the high-voltage DC transmission system by the first frequency deviation and the second frequency deviation, so as to more effectively cope with the dynamic changes of the frequency, respond more quickly, and make adjustments in time, so as to realize the sharing of frequency modulation resources between the rectifier-side AC system and the inverter-side AC system, and help to achieve more accurate same-frequency control.

[0037] Further, as a refinement and expansion of the specific implementation methods of the above-mentioned embodiment, in order to fully illustrate the specific implementation process of this embodiment, S101, that is, the step of determining the target power change for adjusting the current DC transmission power according to the first frequency deviation corresponding to the rectifier side AC system and the second frequency deviation corresponding to the inverter side AC system, specifically includes: determining the first frequency deviation according to the difference between the preset rated frequency and the first current voltage frequency of the rectifier side AC system; determining the second frequency deviation according to the difference between the preset rated frequency and the second current voltage frequency of the inverter side AC system; if the first frequency deviation is not equal to the second frequency deviation, determining the target frequency deviation according to the difference between the second frequency deviation and the first frequency deviation; determining the first control amount according to the product of the preset proportional coefficient and the target frequency deviation; determining the second control amount according to the preset integral coefficient and the target frequency deviation; determining the target power change according to the sum of the first control amount and the second control amount.

[0038] In this embodiment, if the first frequency deviation is not equal to the second frequency deviation, that is, the AC systems on both sides cannot operate at the same frequency, the frequency modulation resources of the AC systems on both sides cannot be shared, so that after the DC transmission power disturbance occurs, the frequency of the AC system on one side is easily too high or too low, exceeding the national standard, thereby affecting the stable operation of the high-voltage DC transmission system. This embodiment detects the first frequency deviation and the second frequency deviation in real time, and responds in time when the first frequency deviation and the second frequency deviation are not equal, so as to prevent the voltage frequency of the AC system on one side from being abnormal. Further, the target power variation is determined by the first frequency deviation and the second frequency deviation. According to the principle of frequency and power coupling, after the current DC transmission power is adjusted according to the target power variation, the first frequency deviation and the second frequency deviation can be made equal, so that the voltage frequency of the rectifier side AC system and the inverter side AC system after adjustment is equal. Then, the sharing of the frequency modulation resources of the AC systems on both sides under the DC transmission power disturbance is realized, so that the AC systems on both sides jointly bear the DC transmission power disturbance, and ensure that the AC system on the rectifier side and the AC system on the inverter side stably operate near the preset rated frequency.

[0039] Exemplarily, the first frequency deviation is determined according to the difference between the preset rated frequency and the first current voltage frequency of the rectifier-side AC system. The second frequency deviation is determined according to the difference between the preset rated frequency and the second current voltage frequency of the inverter-side AC system. If the first frequency deviation is not equal to the second frequency deviation, the target frequency deviation is determined according to the difference between the second frequency deviation and the first frequency deviation. Further, the first control amount is determined according to the product of the preset proportional coefficient and the target frequency deviation. And the second control amount is determined according to the preset integral coefficient and the target frequency deviation. Thus, the target power change amount is determined according to the sum of the first control amount and the second control amount.

[0040] Among them, the target power change is expressed as:

[0041]

[0042] In formula (1), is the target power change, K P is the preset proportional coefficient, Δf2 is the second frequency deviation, Δf1 is the first frequency deviation, K I is the preset integral coefficient, t is the unit time, Δf1=Δf N -f1, Δf2 = Δf N -f2, f1 is the first current voltage frequency, f2 is the second current voltage frequency, f N is the preset rated frequency.

[0043] In this embodiment, stable control of the target frequency deviation is achieved through the combination of proportional control law and integral control law, and the target power change output by the proportional control law and the integral control law is used to adjust the DC transmission power so that the first frequency deviation is equal to the second frequency deviation, thereby improving the accuracy and stability of frequency control.

[0044] Among them, the preset rated frequency is set according to the rated frequency of the AC system specified in the actual application scenario. For example, the preset rated frequency is set to 50HZ in accordance with national regulations. The preset proportional coefficient determines the instantaneous response speed to the target frequency deviation. It is necessary to determine a suitable value based on the response speed requirements and stability considerations in the actual scenario. For example, a larger preset proportional coefficient value can make the response speed of this embodiment to the target frequency deviation faster. In addition, the preset integral coefficient determines the ability to eliminate the target frequency deviation. It is necessary to determine the value of the preset integral coefficient based on the trade-off between the target frequency deviation elimination speed and stability in the actual scenario. For example, a larger preset integral coefficient value helps to eliminate the target frequency deviation faster. In the actual scenario, it is necessary to reasonably adjust the values ​​of the preset proportional coefficient and the preset integral coefficient according to actual needs, so that this embodiment can reduce oscillation while responding quickly to ensure the stable operation of the high-voltage direct current transmission system.

[0045] Further, as a refinement and expansion of the specific implementation methods of the above-mentioned embodiment, in order to fully illustrate the specific implementation process of this embodiment, S101, that is, the step of determining the target power change for adjusting the current DC transmission power according to the first frequency deviation corresponding to the rectifier side AC system and the second frequency deviation corresponding to the inverter side AC system, specifically includes: obtaining the frequency adjustment range; determining the target frequency deviation according to the difference between the second frequency deviation and the first frequency deviation; if the target frequency deviation is within the frequency adjustment range, determining the target power change.

[0046] In this embodiment, by reasonably setting the frequency adjustment range, when the voltage frequency fluctuation of the AC systems on both sides is within the normal range, unnecessary frequency modulation actions are reduced, and the frequency control cost and equipment loss are reduced. When the voltage frequency fluctuation of the AC systems on both sides is within the frequency adjustment range, timely response is made, so that the voltage frequency of the AC systems on both sides can be restored to the vicinity of the preset rated frequency as soon as possible, and the same-frequency stable operation of the AC systems on both sides is achieved.

[0047] The frequency adjustment range needs to be set by comprehensively considering the characteristics of the HVDC transmission system, operation requirements and other factors to achieve the best frequency control effect and system stability. For example, the frequency adjustment range is set to be greater than 0.05 Hz or less than -0.05 Hz.

[0048] Exemplarily, if the first frequency deviation is not equal to the second frequency deviation, the target frequency deviation is determined according to the difference between the second frequency deviation and the first frequency deviation. If the voltage frequency of the AC system on one side fluctuates only slightly on the basis of the same frequency operation of the AC systems on both sides, for example, the voltage frequency of the AC system on the rectifier side changes by 0.01 Hz due to random small power fluctuations or measurement errors, that is, the target frequency deviation is 0.01 Hz, and at this time the target frequency deviation does not fall within the set frequency adjustment range, then the frequency modulation action is not performed, so as to avoid the frequent action of the frequency modulation resources of the AC systems on both sides due to frequent small frequency deviations, and to achieve reasonable control of the voltage frequency of the AC systems on both sides.

[0049] In one embodiment, the frequency control method of the DC asynchronous interconnection system provided in this embodiment also includes: filtering the first frequency deviation and the second frequency deviation to remove noise and interference signals in the first frequency deviation and the second frequency deviation, and smoothing small fluctuations in the first frequency deviation and the second frequency deviation to make the first frequency deviation and the second frequency deviation more stable, thereby improving the quality and accuracy of the first frequency deviation and the second frequency deviation.

[0050] S102: Determine a first DC current change and a first DC voltage change according to a target power change and a preset reactive power.

[0051] The first DC current change and the first DC voltage change are used to keep the reactive power consumed by the inverter-side converter station after adjustment equal to the preset reactive power.

[0052] In this embodiment, on the basis of adjusting the current DC transmission power according to the target power change, the reactive power consumed by the inverter side converter station is controlled to reduce the impact of the DC transmission power adjustment on the reactive power consumed by the inverter side converter station, so that the reactive power consumed by the inverter side converter station remains unchanged, thereby effectively suppressing the AC voltage fluctuation on the inverter side.

[0053] Further, as a refinement and extension of the specific implementation methods of the above-mentioned embodiment, in order to fully illustrate the specific implementation process of this embodiment, S102, that is, the step of determining the first DC current change and the first DC voltage change according to the target power change and the preset reactive power, specifically includes: determining the target DC transmission power according to the sum of the target power change and the current DC transmission power; determining the second DC current of the DC line according to the target DC transmission power and the preset reactive power; determining the first DC current change according to the difference between the second DC current and the current DC current of the DC line; determining the second DC voltage of the inverter side converter station according to the target DC transmission power and the preset reactive power; determining the first DC voltage change according to the difference between the second DC voltage and the current DC voltage of the inverter side converter station.

[0054] In this embodiment, the target DC transmission power is determined according to the target power change, and the first DC voltage change and the first DC current change required to maintain the reactive power consumed by the inverter side converter station unchanged are calculated according to the target DC transmission power, so that the current DC voltage of the inverter side converter station and the current DC current of the DC line are adjusted according to the first DC voltage change and the first DC current change, so as to meet the co-frequency operation of the AC systems on both sides while keeping the reactive power consumed by the inverter side converter station constant, preventing abnormal fluctuations in the AC voltage on the inverter side, and avoiding risks such as commutation failure on the inverter side.

[0055] Specifically, based on the principle of coupling between DC transmission power and reactive power in conventional DC systems, after the current DC transmission work power is adjusted to the target DC transmission power according to the target power change, the reactive power consumed by the inverter side converter station will change accordingly. For example, if the current DC transmission work power is less than the target DC transmission power, that is, the DC transmission power increases after adjustment, the reactive power consumed by the inverter side converter station will also increase, and the increase in reactive power consumed by the inverter side converter station will cause the voltage of the common node on the inverter side to drop, that is, the voltage of the node at the DC-AC junction on the inverter side will drop, resulting in risks such as abnormal fluctuations in the inverter side AC voltage and commutation failure on the inverter side. After determining the target DC transmission power that can meet the co-frequency operation of the AC systems on both sides, this embodiment further determines the first DC current change corresponding to the DC line and the first DC voltage change corresponding to the inverter station on the inverter side according to the preset reactive power to be maintained by the inverter station on the inverter side, so that after the current DC current of the DC line and the current DC voltage of the inverter station on the inverter side are adjusted accordingly according to the first DC current change and the first DC voltage change, the voltage frequency of the AC systems on both sides can be equal, and the reactive power consumed by the inverter station on the inverter side is equal to the preset reactive power.

[0056] The preset reactive power is set according to the reactive power to be maintained by the inverter-side converter station in the actual scenario. For example, the preset reactive power is set to the rated reactive power so that the reactive power consumed by the inverter-side converter station after adjustment is maintained near the rated reactive power.

[0057] Exemplarily, the calculation formulas for DC transmission power and reactive power are determined based on a characteristic equation of a high voltage direct current transmission system.

[0058] P'=V(2)

[0059]

[0060] In formula (2), Pd c ' is the DC transmission power, Vd i ' is the DC voltage of the inverter side converter station, Id c' is the DC current. In formula (3), Qd c ' is the reactive power consumed by the inverter side converter station, B is the preset number of six-pulse rectifier bridges corresponding to the inverter side converter station, T is the preset transformation ratio corresponding to the inverter side converter station, i = 1 or 2, U PCC1 is the current voltage of the AC busbar on the rectifier side, U PCC2 is the current voltage of the AC busbar on the inverter side, U PCCi Take U PCC1 or U PCC2 Either value will do.

[0061] Based on the concept of this embodiment, formula (2) and formula (3) can be expressed as:

[0062]

[0063] In formula (4), Pdc0 is the current DC transmission power, is the target power change, Pdc is the target DC transmission power after the current DC transmission power is adjusted according to the target power change, Vd i0 is the current DC voltage of the inverter side converter station, ΔVdcre f is the DC voltage increment reference value (the first DC voltage change), V di is the DC voltage reference value of the inverter side converter station (the current DC voltage of the inverter side converter station is adjusted according to the first DC voltage change amount), V di =V di0 +ΔV dcref , I dc0 is the current DC current of the DC line, ΔI dcref is the DC current increment reference value (the first DC current change), I dc is the DC current reference value of the DC line (the second DC current after the current DC current of the DC line is adjusted according to the first DC current change amount), I dc =I dc0 +ΔI dcref In formula (5), Q dc0 is the preset reactive power.

[0064] Further, according to equations (4) and (5), the DC voltage increment reference value (first DC voltage variation) ΔV is determined: dcref and DC current increment reference value (first DC current change) ΔI dcref expression.

[0065]

[0066] in,

[0067] According to equations (6) and (7), the target DC transmission power is first determined based on the sum of the target power change and the current DC transmission power. Next, the second DC voltage of the inverter side converter station is determined based on the target DC transmission power and the preset reactive power, and the first DC voltage change is determined based on the difference between the second DC voltage and the current DC voltage of the inverter side converter station. At the same time, the second DC current of the DC line is determined based on the target DC transmission power and the preset reactive power, and the first DC current change is determined based on the difference between the second DC current and the current DC current of the DC line.

[0068] For example, Figure 4 (a) and Figure 4 As shown in (b), Figure 4 The DC transmission power of curve l1 in (a) is P dc When the DC current is 100V and the DC voltage is 100V, the DC current is 100V and the DC voltage is 100V. ... dc0 When the DC current is 1000V, the DC voltage of the inverter side converter station is 1000V. The point O is the current operating point of the high-voltage DC transmission system; the curve Q c1 The reactive power consumed by the inverter side converter station is Q dc0 When the first DC voltage change and the first DC current change are adjusted, the DC transmission power changes from the operating point O on the curve l2 to the curve l1, and the DC current and the DC voltage of the inverter side converter station corresponding to any point on the curve l1 can achieve the first frequency deviation equal to the second frequency deviation. Then, according to the curve l1 and the curve Q c1 The second DC voltage and the second DC current are determined so that when the current DC transmission power reaches the target transmission power, the reactive power consumed by the inverter side converter station is maintained unchanged, thereby determining the first DC voltage change and the first DC current change.

[0069] It should be noted that, when the high-voltage direct current transmission system controlled in this embodiment is operating normally and no direct current transmission power disturbance has occurred, the voltage frequency of the rectifier-side AC system is equal to the voltage frequency of the inverter-side AC system, and both are preset rated frequencies. And the direct current of the DC line, the direct voltage of the inverter-side converter station, the direct current transmission power, and the reactive power consumed by the inverter-side converter station are all at rated values. If the high-voltage direct current transmission system has a direct current transmission power disturbance for the first time, resulting in unequal voltage frequencies of the AC systems on both sides, the rated value corresponding to the direct current of the DC line is used as the current direct current, and similarly, the rated value corresponding to the direct voltage of the inverter-side converter station is used as the current direct voltage, the rated value corresponding to the direct current transmission power is used as the current direct current transmission power, and the rated value corresponding to the reactive power consumed by the inverter-side converter station is used as the preset reactive power, thereby determining the first direct current change and the first direct voltage change.

[0070] S103: Determine a second DC voltage change according to the target power change and a preset minimum arc extinction angle corresponding to the inverter-side converter station.

[0071] The second DC voltage change is the maximum voltage change corresponding to the current DC voltage of the inverter side converter station.

[0072] It is worth mentioning that the first DC voltage change amount and the second DC voltage change amount are both the amounts that need to be changed when the current DC voltage of the inverter side converter station reaches the required target DC voltage.

[0073] It should be noted that the arc extinction angle is an important parameter of the converter valve in the converter station. The arc extinction angle represents the time interval from the end of the current conduction of the converter valve to the zero crossing point of the ideal sinusoidal commutation voltage. This time interval is expressed in electrical angles. In the DC power transmission system, in order to prevent commutation failure, it is stipulated that the arc extinction angle of the converter in the inverter side converter station cannot be less than the minimum arc extinction angle. Therefore, the preset minimum arc extinction angle in this embodiment needs to be specifically set according to parameters such as the ability of the converter valve to withstand voltage and current in the actual application scenario. For example, the preset minimum arc extinction angle is set to any value between 15° and 20°, such as 18°.

[0074] In this embodiment, the maximum amount by which the current DC voltage of the inverter side converter station can change when the current DC transmission power reaches the target DC transmission power is determined according to the preset minimum arc extinction angle corresponding to the inverter side converter station, so as to prevent the adjustment of the DC transmission power from causing the arc extinction angle of the converter in the inverter side converter station to be less than the preset minimum arc extinction angle, so as to avoid causing negative effects such as commutation failure, thereby ensuring the stable operation of the high-voltage DC transmission system.

[0075] Further, as a refinement and extension of the specific implementation methods of the above-mentioned embodiment, in order to fully illustrate the specific implementation process of this embodiment, S103, that is, the step of determining the second DC voltage change according to the target power change and the preset minimum arc extinction angle corresponding to the inverter side converter station, specifically includes: determining the target DC transmission power according to the sum of the target power change and the current DC transmission power; determining the first DC voltage of the inverter side converter station according to the target DC transmission power and the preset minimum arc extinction angle; determining the second DC voltage change according to the difference between the first DC voltage and the current DC voltage of the inverter side converter station.

[0076] In this embodiment, the regulation of the current DC voltage of the inverter side converter station is limited according to the preset minimum arc extinction angle corresponding to the inverter side converter station, so that the arc extinction angle of the converter in the inverter side converter station after adjustment is greater than the preset minimum arc extinction angle, thereby preventing the risk of inverter side commutation failure and ensuring the stable operation of the high-voltage DC transmission system.

[0077] For example, based on the quasi-steady-state equation of a conventional DC transmission system, the DC voltage of the inverter-side converter station can be expressed as:

[0078]

[0079] In formula (8), γ is the arc extinction angle of the converter in the inverter side converter station, X Ti It is the preset leakage inductance value of the converter in the inverter side converter station.

[0080] Furthermore, combining equation (2) and equation (8), the DC voltage of the inverter side converter station can be expressed as:

[0081]

[0082] Furthermore, as shown in formula (9), the maximum DC voltage allowed by the inverter side converter station when the target DC transmission power is reached is determined according to the preset minimum arc extinction angle corresponding to the inverter side converter station, that is, the first DC voltage.

[0083]

[0084] In formula (10), is the maximum DC voltage (first DC voltage) allowed by the inverter side converter station, γ lim It is the preset minimum arc extinction angle.

[0085] Therefore, according to the difference between the first DC voltage and the current DC voltage of the inverter-side converter station, the maximum allowable DC voltage variation of the current DC voltage of the inverter-side converter station, that is, the second DC voltage variation, is determined.

[0086]

[0087] In formula (11), is the maximum allowable DC voltage variation (second DC voltage variation) of the current DC voltage of the inverter side converter station.

[0088] In actual application scenarios, different application scenarios require different preset reactive powers. Figure 5 As shown, Figure 5 Middle curve l1, curve l2, curve Q c1 and operating point O and Figure 4 has the same meaning as in. Figure 5 Middle Curve Q c2 Indicates the straight line of the relationship between the DC current and the DC voltage of the inverter side converter station when the reactive power consumed by the inverter side converter station needs to be maintained at the target reactive power. Among them, the target reactive power is not equal to the preset reactive power. Straight line F is the straight line of the relationship between the DC current and the DC voltage of the inverter side converter station when the arc extinction angle of the converter in the inverter side converter station is equal to the preset minimum arc extinction angle. The points above the straight line F are the operating points where the arc extinction angle of the converter in the inverter side converter station is less than the preset minimum arc extinction angle, and the points below the straight line F are the operating points where the arc extinction angle of the converter in the inverter side converter station is greater than the preset minimum arc extinction angle.

[0089] Exemplarily, if the reactive power consumed by the inverter side converter station needs to be maintained at a preset reactive power, the operating point of the high voltage direct current transmission system can be adjusted from point O to point B after adjustment according to the first DC voltage change and the first DC current change. At this time, the operating point B is located in the area below the straight line F, indicating that the arc extinction angle of the converter in the inverter side converter station after adjustment is greater than the preset minimum arc extinction angle, and therefore will not affect the normal operation of the high voltage direct current transmission system. It is thus determined that the DC current and the current DC voltage of the inverter side converter station can be adjusted according to the first DC current change and the first DC voltage change, so that the reactive power consumed by the inverter side converter station is kept constant while the AC systems on both sides operate at the same frequency. However, if the reactive power consumed by the inverter-side converter station needs to be maintained at the target reactive power, the operating point of the high-voltage direct current transmission system may be adjusted from point O to point C after adjustment according to the first DC voltage change and the first DC current change. At this time, the operating point C is located in the area above the straight line F, which indicates that the arc extinction angle of the converter in the inverter-side converter station after adjustment is greater than the preset minimum arc extinction angle, which may lead to dangers such as commutation failure on the inverter side, affecting the normal operation of the high-voltage direct current transmission system. Therefore, at this time, the DC current and the current DC voltage of the inverter-side converter station cannot be adjusted according to the first DC current change and the first DC voltage change.

[0090] S104, determining a target DC voltage change according to the first DC voltage change and the second DC voltage change, and determining a target DC current change according to the target DC voltage change.

[0091] S105, taking the first frequency deviation being equal to the second frequency deviation as a constraint condition, and adjusting the current DC voltage of the inverter-side converter station and the current DC current of the DC line according to the target DC voltage change and the target DC current change.

[0092] In this embodiment, the target DC voltage change and the target DC current change are determined according to the first DC voltage change and the second DC voltage change, and the current DC transmission power is adjusted by the target DC voltage change and the target DC current change, so that the voltage frequency of the rectifier side AC system and the inverter side AC system after adjustment is unified, while avoiding the arc extinction angle corresponding to the inverter side converter station being less than the preset minimum arc extinction angle, preventing the inverter side converter station from failing in commutation, and keeping the reactive power consumed by the inverter side converter station constant as much as possible, thereby effectively suppressing AC voltage fluctuations and ensuring stable operation of the power grid.

[0093] Further, as a refinement and expansion of the specific implementation methods of the above-mentioned embodiment, in order to fully illustrate the specific implementation process of this embodiment, the target DC voltage change is determined according to the first DC voltage change and the second DC voltage change, and the target DC current change is determined according to the target DC voltage change. The steps specifically include: if the first DC voltage change is less than or equal to the second DC voltage change, the first DC voltage change is determined as the target DC voltage change; if the first DC voltage change is greater than the second DC voltage change, the second DC voltage change is determined as the target DC voltage change; if the target DC voltage change is the first DC voltage change, the first DC current change is determined as the target DC current change; if the target DC voltage change is the second DC voltage change, the target DC current change is determined according to the second DC voltage change and the preset minimum arc extinction angle.

[0094] In this implementation, if the first DC voltage change is less than or equal to the second DC voltage change, the current DC current of the DC line and the current DC voltage of the inverter side converter station are adjusted according to the first DC current change and the first DC voltage change, so as to achieve the same frequency operation of the AC systems on both sides while keeping the reactive power consumed by the inverter side converter station constant, and ensure that the arc extinction angle of the converter in the inverter side converter station is greater than the preset minimum arc extinction angle corresponding to the inverter side converter station, effectively suppressing the AC voltage fluctuation on the inverter side and preventing the risk of commutation failure caused by the adjustment of DC transmission power.

[0095] Furthermore, if the first DC voltage variation is greater than the second DC voltage variation, it indicates that the high voltage DC transmission system controlled by this embodiment lacks sufficient control margin to maintain constant reactive power. In this case, priority is given to controlling the co-frequency operation of the AC systems on both sides, sacrificing some reactive power regulation performance.

[0096] Exemplarily, if the first DC voltage change is less than or equal to the second DC voltage change, it is determined that the arc extinction angle corresponding to the first DC voltage change is greater than the preset minimum arc extinction angle corresponding to the inverter side converter station, so the first DC voltage change is determined as the target DC voltage change, the first DC current change is determined as the target DC current change, and the current DC voltage of the inverter side converter station is adjusted to the second DC voltage according to the first DC voltage change. Then, the current DC current of the DC line is adjusted to the second DC current according to the first DC current change, so that the current DC transmission power reaches the target DC transmission power, so that the first frequency deviation is equal to the second frequency deviation, while keeping the reactive power consumed by the inverter side converter station equal to the preset reactive power, and ensuring that the arc extinction angle of the converter in the inverter side converter station is greater than the preset minimum arc extinction angle corresponding to the inverter side converter station.

[0097] Furthermore, if the first DC voltage change is greater than the second DC voltage change, it means that when the current DC transmission power is adjusted by the first DC voltage change to achieve the same frequency operation of the two-side AC system and keep the reactive power consumption of the inverter-side converter station constant, the arc extinction angle of the converter in the inverter-side converter station will be less than the preset minimum arc extinction angle, thereby causing a series of risks such as commutation failure. Therefore, when the first DC voltage change is greater than the second DC voltage change, the second DC voltage change is determined as the target DC voltage change. Then, the target DC current change is determined based on the second DC voltage change and the preset minimum arc extinction angle. Therefore, the current DC voltage of the inverter side converter station and the current DC current of the DC line are adjusted according to the second DC voltage change and the target DC current change, so that the current DC transmission power can reach the target DC transmission power corresponding to the target power change, thereby satisfying the co-frequency operation of the AC systems on both sides, while minimizing the difference between the reactive power consumed by the inverter side converter station after adjustment and the preset reactive power, and ensuring that the arc extinction angle of the converter in the inverter side converter station after adjustment is not less than the preset minimum arc extinction angle.

[0098] Furthermore, as a refinement and extension of the specific implementation methods of the above-mentioned embodiments, in order to fully illustrate the specific implementation process of this embodiment, the target DC current change is determined according to the second DC voltage change and the preset minimum arc extinction angle, specifically including: determining the first DC voltage of the inverter side converter station according to the sum of the second DC voltage change and the current DC voltage of the inverter side converter station; determining the first DC current of the DC line according to the first DC voltage and the preset minimum arc extinction angle; determining the target DC current change according to the difference between the first DC current and the current DC current of the DC line.

[0099] Exemplarily, the first DC current is expressed as:

[0100]

[0101] In formula (12), I dc2 is the first direct current.

[0102] Furthermore, the target DC current change is expressed as:

[0103] ΔI dcref2 =I dc2 -I dc0 (13)

[0104] In formula (13), ΔI dcref2 is the target DC current change.

[0105] In this embodiment, the current DC voltage of the inverter side converter station is adjusted to the first DC voltage according to the second DC voltage change, and the current DC current of the DC line is adjusted to the first DC current according to the target DC current change, so that the current DC transmission power can reach the target DC transmission power corresponding to the target power change, thereby realizing the co-frequency operation of the AC systems on both sides, reducing the impact of the change in reactive power consumed by the inverter side converter station on the high-voltage DC transmission system, and ensuring that the arc extinction angle of the converter in the inverter side converter station after adjustment is not less than the preset minimum arc extinction angle.

[0106] It should be noted that the first DC current change amount and the second DC current change amount are both the amounts that need to be changed when the current DC current of the DC line reaches the required target DC current.

[0107] It is worth mentioning that, according to the actual situation of the DC transmission power disturbance, this embodiment only adjusts the required change of the DC current and the required change of the DC voltage of the inverter side converter station. Therefore, after the two-side AC system operates at the same frequency, the DC current and the DC voltage of the inverter side converter station can be kept near their corresponding rated values, thereby ensuring the stable operation of the asynchronous interconnection system. In addition, the form of sampling the DC voltage change and the DC current change in this embodiment can better cope with various disturbances and changes in the asynchronous interconnection system. When a DC transmission power disturbance occurs, a rapid response can be made so that the current DC voltage and the current DC current reach the corresponding target values. In addition, adjustment based on relative changes can reduce the accumulated error in the long-term operation of the asynchronous interconnection system to a certain extent, so as to achieve precise regulation and ensure the stable operation of the asynchronous interconnection system.

[0108] In actual application scenarios, constant current control and constant voltage control can be used to control DC transmission power in a quasi-steady state. For example, constant current control adjusts the current DC current to the desired target value by adjusting the trigger angle of the rectifier-side converter according to the target DC current change, and constant voltage control adjusts the DC voltage of the inverter-side converter station to the desired target value by adjusting the advance trigger angle of the inverter-side converter according to the target DC voltage change.

[0109] In one embodiment, if Figure 6 As shown, in this embodiment, the frequency control method of the DC asynchronous interconnected system is called ABFS (Active Bilateral Frequency Support, ABFS) control method. The ABFS control method obtains the first current voltage frequency of the rectifier side AC system and the second current voltage frequency of the inverter side AC system through the same frequency control module. The same frequency control module determines the target power change amount through the first current voltage frequency and the second current voltage frequency, and transmits the target power change amount to the reactive power control module. The reactive power control module obtains the current voltage of the rectifier side AC bus and the current voltage of the inverter side AC bus, and determines the target DC current change amount and the target DC voltage change amount according to the current voltage of the rectifier side AC bus or the current voltage of the inverter side AC bus, and according to the target power change amount. Therefore, the ABFS control method adjusts the current DC current of the DC line and the current DC voltage of the inverter-side converter station to the required target values ​​through constant current control and constant voltage control according to the target DC current change and the target DC voltage change, so that the current DC transmission power reaches the target DC transmission power corresponding to the target power change, so that the AC systems on both sides can operate at the same frequency, while minimizing the difference between the reactive power consumed by the inverter-side converter station after adjustment and the preset reactive power, and ensuring that the arc extinction angle of the converter in the inverter-side converter station after adjustment is not less than the preset minimum arc extinction angle.

[0110] The present application provides a frequency control method, device, medium and equipment for a DC asynchronous interconnection system. When the current voltage frequencies corresponding to the rectifier-side AC system and the inverter-side AC system are not equal, the target power change amount used to adjust the current DC transmission power is determined by the frequency deviations corresponding to the rectifier-side AC system and the inverter-side AC system, so that the adjusted rectifier-side AC system and the inverter-side AC system operate at the same frequency. In addition, while achieving the same frequency operation of the AC systems on both sides through the target power change amount, a first DC voltage change amount that can keep the reactive power of the inverter-side converter station constant is determined. Furthermore, according to the target power change amount, the maximum allowable change amount of the current DC voltage of the inverter-side converter station, that is, the second DC voltage change amount, is determined when the arc extinction angle corresponding to the inverter-side converter station is greater than the preset minimum arc extinction angle. And according to the first DC voltage change and the second DC voltage change, the target DC voltage change and the target DC current change are determined, and the current DC voltage of the inverter side converter station and the current DC current of the DC line are adjusted by the target DC voltage change and the target DC current change, so that the voltage frequency of the rectifier side AC system and the inverter side AC system are equal after adjustment, while avoiding the arc extinction angle corresponding to the inverter side converter station being less than the preset minimum arc extinction angle, preventing the inverter side converter station from commutation failure, and minimizing the difference between the reactive power consumed by the inverter side converter station after adjustment and the preset reactive power, thereby effectively suppressing AC voltage fluctuations and ensuring stable operation of the power grid.

[0111] It should be noted that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0112] Furthermore, if Figure 3 As shown, as a specific implementation of the frequency control method of the above-mentioned DC asynchronous interconnection system, an embodiment of the present application provides a frequency control device 300 of a DC asynchronous interconnection system, and the frequency control device 300 of the DC asynchronous interconnection system includes: a determination module 301 and an adjustment module 302.

[0113] Among them, the determination module 301 is used to determine the target power change for adjusting the current DC transmission power according to the first frequency deviation corresponding to the rectifier side AC system and the second frequency deviation corresponding to the inverter side AC system; determine the first DC current change and the first DC voltage change according to the target power change and the preset reactive power, wherein the first DC current change and the first DC voltage change are used to keep the reactive power consumed by the inverter side converter station after adjustment equal to the preset reactive power; determine the second DC voltage change according to the target power change and the preset minimum arc extinction angle corresponding to the inverter side converter station, wherein the second DC voltage change is the maximum voltage change corresponding to the current DC voltage of the inverter side converter station; determine the target DC voltage change according to the first DC voltage change and the second DC voltage change, and determine the target DC current change according to the target DC voltage change;

[0114] The adjustment module 302 is used to adjust the current DC voltage of the inverter side converter station and the current DC current of the DC line respectively according to the target DC voltage change and the target DC current change, with the first frequency deviation being equal to the second frequency deviation as a constraint.

[0115] In one embodiment, the determination module 301 is specifically used to: if the first DC voltage change is less than or equal to the second DC voltage change, determine the first DC voltage change as the target DC voltage change; if the first DC voltage change is greater than the second DC voltage change, determine the second DC voltage change as the target DC voltage change; if the target DC voltage change is the first DC voltage change, determine the first DC current change as the target DC current change; if the target DC voltage change is the second DC voltage change, determine the target DC current change based on the second DC voltage change and a preset minimum arc extinction angle.

[0116] In one embodiment, the determination module 301 is specifically used to: determine the first DC voltage of the inverter side converter station based on the sum of the second DC voltage change and the current DC voltage of the inverter side converter station; determine the first DC current of the DC line based on the first DC voltage and a preset minimum arc extinction angle; determine the target DC current change based on the difference between the first DC current and the current DC current of the DC line.

[0117] In one embodiment, the determination module 301 is specifically used to: determine the target DC transmission power according to the sum of the target power change and the current DC transmission power; determine the second DC current of the DC line according to the target DC transmission power and the preset reactive power; determine the first DC current change according to the difference between the second DC current and the current DC current of the DC line; determine the second DC voltage of the inverter side converter station according to the target DC transmission power and the preset reactive power; determine the first DC voltage change according to the difference between the second DC voltage and the current DC voltage of the inverter side converter station.

[0118] In one embodiment, the determination module 301 is specifically used to: determine the target DC transmission power based on the sum of the target power change and the current DC transmission power; determine the first DC voltage of the inverter side converter station based on the target DC transmission power and the preset minimum arc extinction angle; determine the second DC voltage change based on the difference between the first DC voltage and the current DC voltage of the inverter side converter station.

[0119] In one embodiment, the determination module 301 is specifically used to: determine a first frequency deviation based on a difference between a preset rated frequency and a first current voltage frequency of the rectifier-side AC system; determine a second frequency deviation based on a difference between a preset rated frequency and a second current voltage frequency of the inverter-side AC system; if the first frequency deviation is not equal to the second frequency deviation, determine a target frequency deviation based on the difference between the second frequency deviation and the first frequency deviation; determine a first control quantity based on the product of a preset proportional coefficient and the target frequency deviation; determine a second control quantity based on a preset integral coefficient and the target frequency deviation; and determine a target power change based on the sum of the first control quantity and the second control quantity.

[0120] In one embodiment, the determination module 301 is specifically used to: obtain a frequency adjustment range; determine a target frequency deviation according to a difference between the second frequency deviation and the first frequency deviation; and determine a target power variation if the target frequency deviation is within the frequency adjustment range.

[0121] The specific definition of the frequency control device of the DC asynchronous interconnection system can be found in the definition of the frequency control method of the DC asynchronous interconnection system mentioned above, which will not be repeated here. Each module in the frequency control device of the DC asynchronous interconnection system can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above 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 of the computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0122] Based on the above Figure 1 The method shown in the embodiment of the present application accordingly provides a readable storage medium on which a computer program is stored, and when the program is executed by a processor, the above-mentioned Figure 1The frequency control method of the DC asynchronous interconnected system is shown.

[0123] Based on this understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, USB flash drive, mobile hard disk, etc.), including a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods of various implementation scenarios of the present application.

[0124] Based on the above Figure 1 The method shown, and Figure 3 In order to achieve the above-mentioned purpose, the embodiment of the present application further provides a computer device, which can be a personal computer, a server, a network device, etc. The computer device includes a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to achieve the above-mentioned Figure 1 The frequency control method of the DC asynchronous interconnected system is shown.

[0125] Optionally, the computer device may further include a user interface, a network interface, a camera, a radio frequency (RF) circuit, a sensor, an audio circuit, a WI-FI module, etc. The user interface may include a display, an input unit such as a keyboard, etc., and the optional user interface may also include a USB interface, a card reader interface, etc. The network interface may optionally include a standard wired interface, a wireless interface (such as a Bluetooth interface, a WI-FI interface), etc.

[0126] Those skilled in the art will appreciate that the computer device structure provided in this embodiment does not limit the computer device, and may include more or fewer components, or a combination of certain components, or different component arrangements.

[0127] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages and saves the hardware and software resources of the computer device, and supports the operation of information processing programs and other software and / or programs. The network communication module is used to realize communication between the components inside the storage medium, and communication with other hardware and software in the physical device.

[0128] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform, or the embodiments of the present application can be implemented by hardware.

[0129] Those skilled in the art will appreciate that the accompanying drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the accompanying drawings are not necessarily necessary for implementing the present application. Those skilled in the art will appreciate that the modules in the devices in the implementation scenario can be distributed in the devices of the implementation scenario according to the description of the implementation scenario, or can be changed accordingly and located in one or more devices different from the present implementation scenario. The modules of the above-mentioned implementation scenario can be combined into one module, or can be further split into multiple submodules.

[0130] The above serial numbers of this application are only for description and do not represent the advantages and disadvantages of the implementation scenarios. The above disclosure is only a few specific implementation scenarios of this application, but this application is not limited to them, and any changes that can be thought of by technicians in this field should fall within the scope of protection of this application.

Claims

1. A frequency control method for a DC asynchronous interconnection system, characterized in that: The method comprises: Determine a target power variation for adjusting the current DC transmission power according to a first frequency deviation corresponding to the rectifier-side AC system and a second frequency deviation corresponding to the inverter-side AC system; Determine a first DC current change and a first DC voltage change according to the target power change and the preset reactive power, wherein the first DC current change and the first DC voltage change are used to keep the reactive power consumed by the inverter-side converter station after adjustment equal to the preset reactive power; Determine a second DC voltage change according to the target power change and a preset minimum arc extinction angle corresponding to the inverter-side converter station, wherein the second DC voltage change is a maximum voltage change corresponding to a current DC voltage of the inverter-side converter station; Determine a target DC voltage change according to the first DC voltage change and the second DC voltage change, and determine a target DC current change according to the target DC voltage change; Taking the first frequency deviation being equal to the second frequency deviation as a constraint condition, adjusting the current DC voltage of the inverter-side converter station and the current DC current of the DC line respectively according to the target DC voltage change and the target DC current change; The determining of the first DC current change and the first DC voltage change according to the target power change and the preset reactive power specifically includes: Determining a target DC transmission power according to the sum of the target power change and the current DC transmission power; Determining a second DC current of the DC line according to the target DC transmission power and the preset reactive power; determining a change in the first DC current according to a difference between the second DC current and a current DC current of the DC line; Determining a second DC voltage of the inverter-side converter station according to the target DC transmission power and the preset reactive power; Determine the first DC voltage change amount according to the difference between the second DC voltage and the current DC voltage of the inverter-side converter station; The determining the second DC voltage change amount according to the target power change amount and the preset minimum arc extinction angle corresponding to the inverter-side converter station specifically includes: Determining a target DC transmission power according to the sum of the target power change and the current DC transmission power; Determining a first DC voltage of the inverter-side converter station according to the target DC transmission power and the preset minimum arc extinction angle; The second DC voltage change is determined according to the difference between the first DC voltage and the current DC voltage of the inverter-side converter station.

2. The frequency control method of a DC asynchronous interconnection system according to claim 1, wherein determining a target DC voltage change according to the first DC voltage change and the second DC voltage change, and determining a target DC current change according to the target DC voltage change, specifically comprises: If the first DC voltage change is less than or equal to the second DC voltage change, determining the first DC voltage change as the target DC voltage change; If the first DC voltage change is greater than the second DC voltage change, determining the second DC voltage change as the target DC voltage change; If the target DC voltage change is the first DC voltage change, determining the first DC current change as the target DC current change; If the target DC voltage variation is the second DC voltage variation, the target DC current variation is determined according to the second DC voltage variation and the preset minimum arc extinction angle.

3. The frequency control method of the DC asynchronous interconnection system according to claim 2, characterized in that: The step of determining the target DC current variation according to the second DC voltage variation and the preset minimum arc extinction angle specifically includes: Determine a first DC voltage of the inverter side converter station according to the sum of the second DC voltage change and the current DC voltage of the inverter side converter station; determining a first DC current of the DC line according to the first DC voltage and the preset minimum arc extinction angle; The target DC current variation is determined according to a difference between the first DC current and a current DC current of the DC line.

4. The frequency control method of the DC asynchronous interconnection system according to claim 1, characterized in that: The determining, according to the first frequency deviation corresponding to the rectifier-side AC system and the second frequency deviation corresponding to the inverter-side AC system, a target power variation for adjusting the current DC transmission power specifically includes: Determining the first frequency deviation according to a difference between a preset rated frequency and a first current voltage frequency of the rectifier-side AC system; Determining the second frequency deviation according to a difference between the preset rated frequency and a second current voltage frequency of the inverter-side AC system; If the first frequency deviation is not equal to the second frequency deviation, determining a target frequency deviation according to a difference between the second frequency deviation and the first frequency deviation; Determining a first control amount according to the product of a preset proportional coefficient and the target frequency deviation; Determining a second control amount according to a preset integral coefficient and the target frequency deviation; The target power variation is determined according to the sum of the first control amount and the second control amount.

5. The frequency control method of the DC asynchronous interconnection system according to claim 1, characterized in that: The determining, according to the first frequency deviation corresponding to the rectifier-side AC system and the second frequency deviation corresponding to the inverter-side AC system, a target power variation for adjusting the current DC transmission power specifically includes: Get the frequency adjustment range; determining a target frequency deviation according to a difference between the second frequency deviation and the first frequency deviation; If the target frequency deviation is within the frequency adjustment range, the target power variation is determined.

6. A frequency control device for a DC asynchronous interconnection system, characterized in that: The device comprises: a determination module, configured to determine a target power variation for adjusting the current DC transmission power according to a first frequency deviation corresponding to the rectifier-side AC system and a second frequency deviation corresponding to the inverter-side AC system; and According to the target power change and the preset reactive power, determining a first DC current change and a first DC voltage change, wherein the first DC current change and the first DC voltage change are used to keep the reactive power consumed by the inverter-side converter station after adjustment equal to the preset reactive power; and determining a second DC voltage change according to the target power change and a preset minimum arc extinction angle corresponding to the inverter-side converter station, wherein the second DC voltage change is a maximum voltage change corresponding to a current DC voltage of the inverter-side converter station; and Determine a target DC voltage change according to the first DC voltage change and the second DC voltage change, and determine a target DC current change according to the target DC voltage change; an adjustment module, configured to adjust the current DC voltage of the inverter-side converter station and the current DC current of the DC line respectively according to the target DC voltage change and the target DC current change, with the first frequency deviation being equal to the second frequency deviation as a constraint; The determining of the first DC current change and the first DC voltage change according to the target power change and the preset reactive power specifically includes: Determining a target DC transmission power according to the sum of the target power change and the current DC transmission power; Determining a second DC current of the DC line according to the target DC transmission power and the preset reactive power; determining a change in the first DC current according to a difference between the second DC current and a current DC current of the DC line; Determining a second DC voltage of the inverter-side converter station according to the target DC transmission power and the preset reactive power; Determine the first DC voltage change amount according to the difference between the second DC voltage and the current DC voltage of the inverter-side converter station; The determining the second DC voltage change amount according to the target power change amount and the preset minimum arc extinction angle corresponding to the inverter-side converter station specifically includes: Determining a target DC transmission power according to the sum of the target power change and the current DC transmission power; Determining a first DC voltage of the inverter-side converter station according to the target DC transmission power and the preset minimum arc extinction angle; The second DC voltage change is determined according to the difference between the first DC voltage and the current DC voltage of the inverter-side converter station.

7. A readable storage medium having a program or instruction stored thereon, characterized in that: When the program or instruction is executed by the processor, the steps of the frequency control method of the DC asynchronous interconnection system as claimed in any one of claims 1 to 5 are implemented.

8. A computer device comprising a storage medium, a processor, and a computer program stored in the storage medium and executable on the processor, characterized in that: When the processor executes the program, the frequency control method of the DC asynchronous interconnection system according to any one of claims 1 to 5 is implemented.

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