Transmitting and receiving end coordination control device, direct current power transmission system and power control method
By introducing a coordinated control device for the sending end in the DC transmission system, the linear self-immune disturbance controller eliminates the coupling between active power and reactive power in the current source converter, the problem of limited output power regulation capability in traditional technology is solved. , achieving more efficient power regulation.
Patent Information
- Application Number
- CN202411552930.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-01
- Publication Date
- 2025-02-18
AI Technical Summary
In traditional DC transmission technology, there is a coupling between the active power and reactive power of the current source converter, resulting in limited output power regulation capabilities and the decoupling of active power and reactive power cannot be achieved.
Provide a coordinated control device for sending the receiving end, including a model construction and processing module and a linear self-immune controller. By establishing a mathematical model and observing the coupling terms, the impact of the coupling terms on active power and reactive power in real time is eliminated, thereby adjusting the current source. output power of type converter.
It realizes the decoupling of active power and reactive power, improves the regulation capability of the output power of the current source converter, and enhances the flexibility and efficiency of the DC transmission system.
Smart Images
Figure CN119482643A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of power grid control, and in particular to a transmitting-receiving-end coordinated control device, a direct current transmission system and a power control method. Background Art
[0002] In order to reasonably control the investment scale of the project, hybrid multi-terminal DC transmission technology that integrates traditional DC transmission technology and flexible DC transmission technology will be the development direction of long-distance and large-capacity power transmission in the future.
[0003] However, in traditional DC transmission technology, although corresponding power control method strategies have been proposed for analyzing the operating characteristics of current source converters (CSC) in pulse width modulation (PWM) mode, the proposed strategies can achieve active power and reactive power control.
[0004] However, there is still coupling between the active power and reactive power of the current source converter. Traditional strategies cannot achieve the decoupling of active power and reactive power, resulting in the output power regulation capability of the current source converter being limited. Summary of the invention
[0005] Based on this, it is necessary to provide a transmitting and receiving end coordinated control device, a DC transmission system and a power control method, which can realize the decoupling of active power and reactive power to improve the regulation capability of the output power of the current source converter.
[0006] According to some embodiments, one aspect of the present disclosure provides a transmitting and receiving end coordinated control device, which is applied to a direct current transmission system. The transmitting and receiving end coordinated control device includes: a model building and processing module and a linear anti-disturbance control controller. The model building and processing module is used to establish a mathematical model according to the topological structure of the current source converter, and obtain the coupling terms of active power and reactive power in the output power of the current source converter based on the mathematical model. The linear anti-disturbance control controller is used to observe the coupling term, obtain the coupling term observation result, and eliminate the coupling of the coupling term to the active power and reactive power in real time according to the coupling term observation result, and adjust the output power of the current source converter according to the decoupled active power and reactive power.
[0007] According to some embodiments, the linear anti-disturbance controller includes: a linear extended state observation module, a proportional differential control module and a linear state error feedback control law module. The linear extended state observation module is used to observe the coupling term to obtain multiple observation values. The proportional differential control module is used to receive the reference variable and a related part of the observation value to output the state quantity to the linear state error feedback control law unit. The linear state error feedback control law module is used to receive the state quantity and another related part of the observation value to obtain the elimination term, and decouple the active power and reactive power in real time according to the elimination term to adjust the output power of the current source converter.
[0008] According to some embodiments, another aspect of the present disclosure provides a direct current transmission system, comprising: an inverter station and a transmitting and receiving end coordination controller as described in some of the above embodiments; wherein the inverter station is provided with a current source converter; the transmitting and receiving end coordination controller is located in the inverter station and connected to the current source converter.
[0009] According to some embodiments, the current source converter has a power device. The transmitting and receiving end coordination controller is connected to the power device and is used to control the power device to be turned on or off according to the decoupled active power and reactive power.
[0010] According to some embodiments, the power device includes an integrated gate commutated transistor or an insulated gate bipolar transistor.
[0011] According to some embodiments, another aspect of the present disclosure provides a power control method applied to a direct current power transmission system, comprising the following steps.
[0012] A mathematical model is established based on the topological structure of the current source converter.
[0013] Based on the mathematical model, the coupling terms of active power and reactive power in the output power of the current source converter are obtained.
[0014] Observe the coupling terms and obtain the coupling term observation results.
[0015] According to the observation result of the coupling term, the coupling of the coupling term to the active power and the reactive power is eliminated in real time, and the output power of the current source converter is adjusted according to the decoupled active power and reactive power.
[0016] According to some embodiments, observing the coupling term to obtain the coupling term observation result, and according to the coupling term observation result, eliminating the coupling of the coupling term to the active power and reactive power in real time, and adjusting the output power of the current source converter according to the decoupled active power and reactive power, includes the following steps.
[0017] The coupling terms are observed based on the linear expansion state observation module to obtain multiple observation values.
[0018] The proportional-derivative control module receives a reference variable and a portion of related observation values to output a state quantity to a linear state error feedback control law module.
[0019] Based on the linear state error feedback control law module, the state quantity and another part of related observation values are received to obtain the elimination term, and the active power and reactive power are decoupled in real time according to the elimination term to adjust the output power of the current source converter.
[0020] According to some embodiments, establishing a mathematical model according to the topological structure of the current source converter includes: establishing an instantaneous model of the current source converter according to the topological structure of the current source converter; and determining the mathematical model of the current source converter in a two-phase rotating coordinate system based on the Park transformation according to the instantaneous model.
[0021] According to some embodiments, the step of obtaining the coupling terms of active power and reactive power in the output power of the current source converter based on a mathematical model includes the following steps.
[0022] According to the mathematical model of the current source converter in the two-phase rotating coordinate system, the active power P in the output power of the current source converter is determined based on voltage phase locking. CSC and reactive power Q CSC , and the active power P CSC and the reactive power Q CSC The coupling term i gd With the coupling term i gq ;
[0023] in, ;u gd is the voltage component of the AC side voltage of the current source converter on the d-axis of the two-phase rotating coordinate system, i gd is the current component of the AC side current of the current source converter on the d-axis of the two-phase rotating coordinate system, i gq It is the current component of the AC side current of the current source converter on the q-axis of the two-phase rotating coordinate system.
[0024] According to some embodiments, establishing a transient model of the current source converter according to the topological structure of the current source converter comprises the following steps.
[0025] According to the topological structure of the current source converter, the grid-connected current expression of the current source converter is obtained.
[0026] The arm switch state of the current source converter is determined based on a three-valued logic switch function.
[0027] According to the three-valued logic switching function, the bridge arm current model and DC side voltage expression of the current source converter are obtained, and combined with the grid current expression, the transient model of the current source converter is established.
[0028] According to some embodiments, obtaining a bridge arm current model of a current source converter and a DC side voltage expression of the current source converter according to a three-valued logic switch function includes the following steps.
[0029] Remove the high-frequency components in the three-valued logic switching function, and obtain the target switching function S based on the fundamental component in the three-valued logic switching function. X (x=a,b,c), target switching function S X for: ; Among them, S a is the target switching function of phase A of the current source converter, S b The target switching function of the current source converter phase B, S c is the target switching function of the C phase of the current source converter, m is the current modulation ratio, ω is the angular frequency of the current source converter, and α is the trigger hysteresis angle of the current source converter.
[0030] Based on the target switching function, the bridge arm current model of the current source converter and the DC side voltage expression of the current source converter are obtained.
[0031] In the disclosed embodiment, a model building and processing module is provided in the coordinated control device at the transmitting and receiving ends, and a mathematical model of the current source converter can be established through the model building and processing module, and the coupling terms of active power and reactive power in the output power of the current source converter can be obtained based on the mathematical model; and a linear anti-disturbance rejection controller is provided in the coordinated control device at the transmitting and receiving ends, and the coupling terms can be observed through the linear anti-disturbance rejection controller to obtain the coupling term observation results, and the coupling of the coupling terms to the active power and reactive power can be eliminated in real time according to the coupling term observation results, and the output power of the current source converter can be adjusted according to the decoupled active power and reactive power, thereby eliminating the coupling of the coupling terms to the active power and reactive power in real time, and effectively realizing the decoupling of active power and reactive power in the DC transmission system, so as to improve the regulation capability of the output power of the current source converter. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0033] Figure 1A schematic diagram of the structure of a transmission and reception end coordination control device provided in an embodiment of the present disclosure;
[0034] Figure 2 A control principle diagram of a transmitting-receiving-end coordination control device provided in an embodiment of the present disclosure;
[0035] Figure 3 A schematic diagram of a topological structure of a direct current transmission system provided in an embodiment of the present disclosure;
[0036] Figure 4 A schematic diagram of a topological structure of a current source converter provided in an embodiment of the present disclosure;
[0037] Figure 5 A schematic diagram of a power control method according to an embodiment of the present disclosure;
[0038] Figure 6 An electrical parameter vector diagram of a current source converter provided in an embodiment of the present disclosure;
[0039] Figure 7 A schematic diagram of a mathematical model of a current source converter provided in an embodiment of the present disclosure.
[0040] Explanation of the accompanying drawings: 11. Model building and processing module; 12. Linear active disturbance rejection controller; 121. Extended state observation module; 122. Proportional differential control module; 123. Linear state error feedback control law module; 21. Rectification station; 22. Inversion station; 221. Unipolar rectification circuit; 3. Power device. DETAILED DESCRIPTION
[0041] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.
[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.
[0043] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.
[0044] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.
[0045] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.
[0046] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.
[0047] The present disclosure aims to provide a transmitting-receiving-end coordinated control device, a direct current transmission system and a power control method, which can realize the decoupling of active power and reactive power to improve the regulation capability of the output power of a current source converter.
[0048] Some embodiments of the present disclosure provide a transmission and reception end coordinated control device for application in a direct current transmission system. Figure 1 The transmitting and receiving end coordinated control device includes a model building and processing module 11 and a linear anti-disturbance control controller 12. The model building and processing module 11 is used to establish a mathematical model according to the topological structure of the current source converter, and obtain the coupling terms of active power and reactive power in the output power of the current source converter based on the mathematical model. The linear anti-disturbance control controller 12 is used to observe the coupling terms to obtain the coupling term observation results, and according to the coupling term observation results, eliminate the coupling of the coupling terms to the active power and reactive power in real time, and adjust the output power of the current source converter according to the decoupled active power and reactive power.
[0049] In the transmitting and receiving end coordinated control device of the above-mentioned embodiment, a mathematical model of the current source converter can be established through the model construction and processing module, and the coupling terms of active power and reactive power in the output power of the current source converter can be obtained based on the mathematical model; and the coupling terms can be observed through the linear anti-disturbance controller to obtain the coupling term observation results, and the coupling of the coupling terms to the active power and reactive power can be eliminated in real time according to the coupling term observation results, and the output power of the current source converter can be adjusted according to the decoupled active power and reactive power, thereby eliminating the coupling of the coupling terms to the active power and reactive power in real time, and effectively realizing the decoupling of active power and reactive power in the DC transmission system, so as to improve the regulation capability of the output power of the current source converter.
[0050] It can be understood that the linear active disturbance rejection controller (LADRC) is a controller used to reduce the impact of external disturbances on the system, which can enable the system to better maintain stability and accuracy. The linear active disturbance rejection controller combines the characteristics of adaptive control and anti-disturbance control, and can effectively suppress the impact of external disturbances on the system.
[0051] See also Figure 2 In some embodiments, the ADRC module 12 includes a linear extended state observation module 121, a proportional differential control module 122, and a linear state error feedback control law module 123. The linear extended state observation module 121 is used to observe the coupling term to obtain multiple observation values; the proportional differential control module 122 is used to receive the reference variable and a part of the related observation values to output the state quantity to the linear state error feedback control law module 123; the linear state error feedback control law module 123 is used to receive the state quantity and another part of the related observation values to obtain the elimination term, and decouple the active power and reactive power in real time according to the elimination term to adjust the output power of the current source converter.
[0052] For example, the linear expansion state observation module 121 is used to observe the coupling term to obtain a first observation value z1, a second observation value z2, and a third observation value z3.
[0053] Here, it can be understood that the Linear Extended State Observer (LESO), as a control theory method for estimating the state of a system, can estimate the state variables of the system by measuring the output and input of the system, so that state feedback control can be implemented in the control system. The essence of the Linear Extended State Observer is to regard all uncertain disturbances in the control system as a whole, that is, the lumped disturbance, and define it as a new state variable, called the extended state, so as to estimate the lumped disturbance using the principle of the state observer, and then eliminate this disturbance to improve the performance of the system.
[0054] Afterwards, the proportional-derivative control module 122 is used to receive the reference variable i gdref And the related first observation value z1, the second observation value z2, to output the state quantity u0 to the linear state error feedback control law module 123. The linear state error feedback control law module 123 is used to receive the state u0 and the third observation value z3 to output the elimination term u, and the elimination term u is used to eliminate the coupling of the coupling term to the active power and the reactive power in real time.
[0055] See also Figure 3 Some embodiments of the present disclosure also provide a DC power transmission system, which includes a rectifier station 21 and an inverter station 22. The input end of the rectifier station 21 is connected to the sending-end power grid W2 of the system, the first output end is connected to the first DC line D1, and the second output end is connected to the second DC circuit D2. The first input end of the inverter station 22 is connected to the first DC line D1, the second input end is connected to the second DC circuit D2, and the output end is connected to the receiving-end power grid W1 of the system.
[0056] For example, the sending-end power grid W2 may be at least one of an AC power grid, a large-scale wind power station, and a large-scale photovoltaic power station.
[0057] For example, the receiving-end power grid W1 may be at least one of an AC power grid and a large-scale offshore wind power grid.
[0058] In some embodiments, please refer to Figure 3 The rectifier station 21 is provided with a modular multilevel converter (MMC for short). The inverter station 22 is provided with a current source converter (CSC for short).
[0059] It can be understood that the DC power transmission system provided by the embodiment of the present disclosure further includes: the transmitting and receiving end coordination controller as described in some of the above embodiments; wherein the transmitting and receiving end coordination controller is located in the inverter station 22 and connected to the current source converter. The DC power transmission system of the embodiment of the present disclosure also has the beneficial effects of the above transmitting and receiving end coordination controller, and because the transmitting and receiving end coordination controller can realize the decoupling of the active power and reactive power of the current source converter in the inverter station 22, it can improve the overall regulation capability of the DC power transmission system for the output power.
[0060] In some embodiments, please refer to Figure 3 At least two unipolar inverter circuits 221 are arranged in the inverter station 22, wherein any unipolar inverter circuit 221 can be formed based on two current source converters. The output end of the current source converter is connected to the receiving end grid W1 via the corresponding converter transformer.
[0061] For example, Figure 3 As shown, in a unipolar inverter circuit 221, the first end of the first current source converter CSC#1 is connected to the first DC line D1, the second end of the first current source converter CSC#1 is connected in series to the first end of the second current source converter CSC#2, and the second end of the second current source converter CSC#1 is grounded.
[0062] For example, the first current source converter CSC#1 is connected to the receiving grid W1 via the converter transformer T1, and the second current source converter CSC#2 is connected to the receiving grid W1 via the converter transformer T2; wherein the converter transformer T1 can adopt a three-three (Y / Y) connection, and the converter transformer T2 can adopt a star-three (Δ / Y) connection.
[0063] It can be understood that the three-three (Y / Y) connection refers to the three-phase transformer high-voltage winding and low-voltage winding are connected in star connection. The three-three (Y / Y) connection is suitable for symmetrical loads and asymmetrical loads, and can provide good phase balance. The star-three (Δ / Y) connection refers to the three-phase transformer high-voltage winding using star connection, and the low-voltage winding using delta connection.
[0064] In some embodiments, please refer to Figure 3 At least two monopolar rectifier circuits 211 are arranged in the rectifier station 21, wherein any monopolar rectifier circuit 21 can be formed based on two modular multilevel converters. The input end of the modular multilevel converter can be connected to the sending-end power grid W2 via the corresponding converter transformer.
[0065] For example, Figure 3As shown, in a unipolar rectifier circuit 211, a first end of a first modular multilevel converter MMC#1 is connected to a first DC line D1, a second end of the first modular multilevel converter MMC#1 is connected to a first end of a second modular multilevel converter MMC#2, and a second end of the second modular multilevel converter MMC#2 is grounded.
[0066] For example, the first modular multilevel converter MMC#1 is connected to the sending-end power grid W2 via a converter transformer T3, and the second modular multilevel converter MMC#1 is connected to the sending-end power grid W2 via a converter transformer T4; wherein the converter transformer T3 can adopt a three-three (Y / Y) connection, and the converter transformer T4 can adopt a star-three (Δ / Y) connection.
[0067] From the above, in the example where the rectifier station 21 includes two monopolar rectifier circuits 211 and the inverter station 22 includes two monopolar inverter circuits 221, the rectifier station 21 and the inverter station 22 together constitute a bipolar two-end neutral point grounding circuit. In this way, the bipolar two-end neutral point grounding circuit can be composed of two independently operated monopolar ground loop systems to ensure that the neutral points of the converter stations at both ends are grounded. Accordingly, the earth loop can be used as a backup conductor for the transmission system. It can be understood that when the DC transmission system is operating normally, the path of the DC current is the positive and negative poles, and the current directions of the positive and negative poles in the ground loop are opposite, that is, the current directions of the first DC circuit D1 and the second DC circuit D2 are opposite, and the current in the earth loop is the difference between the currents of the two poles.
[0068] In some embodiments, the current of the first DC circuit D1 is +800 kV, and the current of the second DC circuit D2 is -800 kV.
[0069] In some embodiments, please combine Figure 4 It is understood that the current source converter has a power device 3. The transmitting and receiving end coordination controller is connected to the power device 3, and is used to control the power device 3 to be turned on or off according to the decoupled active power and reactive power.
[0070] By way of example, the power device 3 is a fully controlled semiconductor power device.
[0071] By way of example, the power device 3 includes an integrated gate commutated transistor (IGCT) or an insulated gate bipolar transistor (IGBT).
[0072] Figure 4 Detailed topological structure of a current source converter in some embodiments is shown. Figure 4As shown, the current source converter includes an upper bridge arm and a lower bridge arm; the upper bridge arm includes a first fully-controlled device S1, a third fully-controlled device S3 and a fifth fully-controlled device S5 connected in parallel; the lower bridge arm includes a second fully-controlled device S2, a fourth fully-controlled device S4 and a sixth fully-controlled device S6 connected in parallel, the second fully-controlled device S2 is connected in series with the fifth fully-controlled device S5, the fourth fully-controlled device S4 is connected in series with the first fully-controlled device S1, and the sixth fully-controlled device S6 is connected in series with the third fully-controlled device S3.
[0073] For example, the first fully-controlled device S1, the second fully-controlled device S2, the third fully-controlled device S3, the fourth fully-controlled device S4, the fifth fully-controlled device S5 and the sixth fully-controlled device S6 are respectively the aforementioned power devices 3, for example, they may be integrated gate-commutated thyristors or insulated gate bipolar transistors.
[0074] For example, please continue to see Figure 4 In the current source converter, the input end of the upper bridge arm passes through the DC inductor L dc The input end of the lower bridge arm is directly connected to the corresponding DC line (for example, connected to the second DC line). In addition, the connection node between the upper bridge arm and the lower bridge arm is correspondingly connected to a three-phase AC circuit, such as a three-phase LC circuit, and can be connected to the AC power grid through the three-phase AC circuit. Among them, any phase LC circuit in the three-phase LC circuit can be composed of a series filter inductor L and an external filter capacitor C. In addition, please continue to refer to Figure 4 , Figure 4 The resistor R connected in series between the three-phase LC circuit and the AC power grid can be used to illustrate the equivalent resistance of the load or transmission line.
[0075] See also Figure 5 Some embodiments of the present disclosure also provide a power control method for application in a direct current power transmission system. The power control method includes the following steps S10 to S40.
[0076] Step S10: establishing a mathematical model according to the topological structure of the current source converter.
[0077] Step S20: obtaining coupling terms of active power and reactive power in the output power of the current source converter based on a mathematical model.
[0078] Step S30, observing the coupling item to obtain the coupling item observation result.
[0079] Step S40: according to the coupling item observation result, the coupling of the coupling item to the active power and the reactive power is eliminated in real time, and the output power of the current source converter is adjusted according to the decoupled active power and reactive power.
[0080] For example, steps S30 and S40 may be performed based on a linear active disturbance rejection controller.
[0081] In the embodiment of the present disclosure, by establishing a mathematical model of the current source type converter, the coupling terms of the active power and the reactive power in the output power of the current source type converter can be obtained based on the mathematical model, and the coupling terms are observed to obtain the coupling term observation results, so that according to the coupling term observation results, the coupling of the coupling terms to the active power and the reactive power can be eliminated in real time, and the output power of the current source type converter can be adjusted according to the decoupled active power and reactive power, so as to effectively improve the adjustment capability of the output power of the current source type converter.
[0082] In some embodiments, step S10, establishing a mathematical model of the current source converter according to the topological structure of the current source converter, includes the following steps S11 and S12.
[0083] Step S11, establishing a transient model of the current source converter according to the topological structure of the current source converter.
[0084] Step S12: determining the mathematical model of the current source converter in the two-phase rotating coordinate system according to the instantaneous model based on Park transformation.
[0085] In some embodiments, step S11, establishing a transient model of the current source converter according to the topological structure of the current source converter, may include the following steps S111 to S113.
[0086] Step S111: according to the topological structure of the current source converter, obtain the grid-connected current expression of the current source converter.
[0087] For example, please combine Figure 4 To understand, first, write the KVL equation for the loop formed by the three-phase AC circuit, filter capacitor C and filter inductor L in the topology of the current source converter, and you can get:
[0088] ;
[0089] In the formula, u cabc is the three-phase capacitor voltage, u gabc is the three-phase AC voltage, i gabc is the output current of the current source converter; L is the filter inductor, and R is the equivalent resistance.
[0090] Secondly, write the KCL equation for the output end of the upper and lower bridge arms in the current source converter, the intersection of the filter capacitor C and the filter inductor L, and we can get:
[0091] ;
[0092] In the formula, i pabc is the three-phase current of the bridge arm, and C is the filter capacitor.
[0093] Again, writing the KVL equation for the DC side of the DC transmission system yields:
[0094] ;
[0095] Where U dc is the DC voltage, I dc is the DC current, L dc is the DC inductance, u dc is the filtered voltage on the DC side.
[0096] From the above, combined with the voltage expression of the three-phase AC circuit, we can get the expression of the filter capacitor voltage.
[0097] The voltage expression of a three-phase AC circuit is: ;
[0098] Where Ug is the output voltage, θ is the phase difference between the capacitor voltage and the AC voltage, and ω is the angular frequency of the current source converter.
[0099] Correspondingly, the expression of the filter capacitor voltage is: ;
[0100] Where Uc is the filter capacitor voltage.
[0101] Combined with the expression of the filter capacitor voltage, the grid-connected current expression of the current source converter can be obtained as: Where I g is the output current.
[0102] Step S112: Determine the arm switch state of the current source converter based on the three-valued logic switch function.
[0103] For example, the three-valued logic switch function is: ;
[0104] Wherein, x can be a, b or c.
[0105] It can be understood that in order to meet the constraint that only one of the switches in the upper and lower three-phase bridge arms is in the on state when the fully controlled current source converter is working normally, the three-phase switch state must meet the following conditions: S a +S b +S c =0.
[0106] Step S113: According to the three-valued logic switch function, the bridge arm current model and the DC side voltage expression of the current source converter are obtained, and combined with the grid current expression, the transient model of the current source converter is established.
[0107] In some embodiments, step S113, obtaining the arm current model of the current source converter and the DC side voltage expression of the current source converter according to the three-valued logic switching function, may include the following steps S1131 and S1132.
[0108] Step S1131, remove the high frequency components in the three-valued logic switch function, and obtain the target switch function S based on the fundamental wave components in the three-valued logic switch function. x (x=a,b,c).
[0109] Target switching function S x for: ;
[0110] In the formula, S a is the target switching function of phase A of the current source converter, S b The target switching function of the current source converter phase B, S c is the target switching function of the C phase of the current source converter, m is the current modulation ratio, ω is the angular frequency of the current source converter, and α is the trigger hysteresis angle of the current source converter.
[0111] Step S1132, based on the target switching function, obtaining the arm current model of the current source converter and the DC side voltage expression of the current source converter.
[0112] For example, the bridge arm current model is: .
[0113] The DC side voltage expression is: .
[0114] Figure 6 An electrical parameter vector diagram of a current source converter is shown to represent the voltage and current vector relationship of the current source converter.
[0115] From above, combined Figure 6 , the instantaneous model of the current source converter can be obtained as:
[0116] .
[0117] Accordingly, please combine Figure 7 It is understood that in step S12, according to the instantaneous model, based on Park transformation, the mathematical model of the current source converter in the two-phase rotating coordinate system is determined as follows:
[0118] ;
[0119] ;
[0120] ;
[0121] .
[0122] Accordingly, in some embodiments, step S20, obtaining the coupling term of active power and reactive power in the output power of the current source converter based on the mathematical model, can be expressed as follows: according to the mathematical model of the current source converter in the two-phase rotating coordinate system, the active power P in the output power of the current source converter is determined based on the voltage phase lock. CSC and reactive power Q CSC , and the active power P CSC and reactive power Q CSC The coupling term i gd With the coupling term i gq ;in, ;u gd is the voltage component of the AC side voltage of the current source converter on the d-axis of the two-phase rotating coordinate system, i gd is the current component of the AC side current of the current source converter on the d-axis of the two-phase rotating coordinate system, i gq It is the current component of the AC side current of the current source converter on the q-axis of the two-phase rotating coordinate system.
[0123] From the above, it can be understood that by controlling the current component i on the d-axis gd and the current component i on the q axis gq The output power of the current source converter can be controlled. gd and i gq Due to the influence of capacitor voltage, grid voltage and dq axis interaction components, the active power P of the current source converter CSC and reactive power Q CSC Therefore, the above current component i gd and i gq That is the active power P CSC and reactive power Q CSC coupling term.
[0124] It is worth mentioning that, in some embodiments, the linear active disturbance rejection controller includes: a linear extended state observation module, a proportional differential control module and a linear state error feedback control law module. Accordingly, step S30, based on the linear active disturbance rejection controller, observes the coupling term to obtain the coupling term observation result, and step S40, according to the coupling term observation result, eliminates the coupling of the coupling term to the active power and reactive power in real time, and adjusts the output power of the current source converter according to the decoupled active power and reactive power, which may include the following steps S31~S33.
[0125] Step S31, observing the coupling term based on the linear extended state observation module to obtain multiple observation values.
[0126] For example, please combine Figure 2 It is understood that the linear expansion state observation module 121 is used to observe the coupling term to obtain a first observation value z1, a second observation value z2 and a third observation value z3.
[0127] Step S32 , receiving the reference variable and a part of the related observation values based on the proportional-derivative control module to output the state quantity to the linear state error feedback control law module.
[0128] For example, please combine Figure 2 It is understood that the proportional-derivative control module 122 is used to receive the reference variable i gdref And the related first observation value z1 and second observation value z2 are used to output the state quantity u0 to the linear state error feedback control law module 123.
[0129] Step S33, based on the linear state error feedback control law module receiving the state quantity and another part of the related observation value, obtain the elimination term, and decouple the active power and reactive power in real time according to the elimination term to adjust the output power of the current source converter.
[0130] For example, please combine Figure 2 It is understood that the linear state error feedback control law module 123 is used to receive the state u0 and the third observation value z3 to output the elimination term u, and the elimination term u is used to eliminate the coupling of the coupling term to the active power and the reactive power in real time.
[0131] It should be added that the relevant parameters and coefficients (e.g. Figure 2 A, B, C, D, k shown in p , k d b) can be set according to the requirements and calibrated by simulation. The embodiments of the present disclosure do not make specific limitations on this.
[0132] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.
[0133] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0134] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.
Claims
1. A transmission and reception end coordination control device, characterized in that: Applied to DC transmission systems, including: A model building and processing module, used to establish a mathematical model according to the topological structure of the current source converter, and obtain the coupling terms of active power and reactive power in the output power of the current source converter based on the mathematical model; A linear active disturbance rejection controller is used to observe the coupling term to obtain an observation result of the coupling term, and to eliminate the coupling of the coupling term to the active power and the reactive power in real time according to the observation result of the coupling term, and to adjust the output power of the current source converter according to the decoupled active power and the reactive power.
2. The transmitting and receiving end coordination control device according to claim 1, characterized in that: The linear active disturbance rejection controller comprises: A linear expansion state observation module, used for observing the coupling term to obtain a plurality of observation values; A proportional differential control module, used for receiving a reference variable and a related part of the observed value, so as to output a state quantity to a linear state error feedback control law unit; A linear state error feedback control law module is used to receive the state quantity and another related part of the observation value, obtain the elimination term, and decouple the active power and the reactive power in real time according to the elimination term to adjust the output power of the current source converter.
3. A direct current transmission system, characterized in that: include: An inverter station and a transmitting and receiving end coordination controller as claimed in claim 1 or 2; Wherein, the inverter station is provided with a current source converter; The transmitting-receiving-end coordination controller is located in the inverter station and connected to the current source converter.
4. The direct current transmission system according to claim 3, characterized in that: The current source converter has a power device; the transmitting and receiving end coordination controller is connected to the power device and is used to control the opening or closing of the power device according to the decoupled active power and reactive power.
5. The direct current transmission system according to claim 4, characterized in that: The power device includes an integrated gate commutated transistor or an insulated gate bipolar transistor.
6. A power control method, characterized in that: Applied to DC transmission systems, including: Establish a mathematical model based on the topological structure of the current source converter; Obtaining coupling terms of active power and reactive power in the output power of the current source converter based on the mathematical model; Observing the coupling item to obtain a coupling item observation result; According to the observation result of the coupling term, the coupling of the coupling term to the active power and the reactive power is eliminated in real time, and the output power of the current source converter is adjusted according to the decoupled active power and the reactive power.
7. The power control method according to claim 6, characterized in that: The step of observing the coupling item to obtain a coupling item observation result, and eliminating the coupling of the coupling item to the active power and the reactive power in real time according to the coupling item observation result, and adjusting the output power of the current source converter according to the decoupled active power and the reactive power, comprises: Observe the coupling term based on a linear expansion state observation module to obtain multiple observation values; Based on the proportional-derivative control module receiving the reference variable and a related part of the observed value, the state quantity is output to the linear state error feedback control law module; Based on the linear state error feedback control law module, the state quantity and another related part of the observation value are received to obtain the elimination term, and the active power and the reactive power are decoupled in real time according to the elimination term to adjust the output power of the current source converter.
8. The power control method according to claim 6, characterized in that: The method of establishing a mathematical model according to the topological structure of the current source converter includes: Establishing a transient model of the current source converter according to the topological structure of the current source converter; According to the instantaneous model, the mathematical model of the current source converter in a two-phase rotating coordinate system is determined based on Park transformation.
9. The power control method according to claim 8, characterized in that: The step of obtaining the coupling term of active power and reactive power in the output power of the current source converter based on the mathematical model includes: According to the mathematical model of the current source converter in the two-phase rotating coordinate system, the active power P in the output power of the current source converter is determined based on voltage phase locking. CSC and reactive power Q CSC , and the active power P CSC and the reactive power Q CSC The coupling term i gd With the coupling term i gq ; in, ;u gd is the voltage component of the AC side voltage of the current source converter on the d-axis of the two-phase rotating coordinate system, i gd is the current component of the AC side current of the current source converter on the d-axis of the two-phase rotating coordinate system, i gq It is the current component of the AC side current of the current source converter on the q-axis of the two-phase rotating coordinate system.
10. The power control method according to claim 8, characterized in that: The step of establishing a transient model of the current source converter according to the topological structure of the current source converter comprises: According to the topological structure of the current source converter, obtaining a grid-connected current expression of the current source converter; Determining the arm switch state of the current source converter based on a three-valued logic switch function; According to the three-valued logic switch function, the bridge arm current model and the DC side voltage expression of the current source converter are obtained, and combined with the grid current expression, the transient model of the current source converter is established.
11. The power control method according to claim 10, characterized in that: According to the three-valued logic switch function, the bridge arm current model of the current source converter and the DC side voltage expression of the current source converter are obtained, including: Remove the high frequency component in the three-valued logic switch function, and obtain the target switch function S based on the fundamental component in the three-valued logic switch function. X (x=a,b,c), the target switching function S X for: ; Among them, S a is the target switching function of the current source converter phase A, S b The target switching function of the current source converter phase B, S c is the target switching function of the C phase of the current source converter, m is the current modulation ratio, ω is the angular frequency of the current source converter, and α is the trigger hysteresis angle of the current source converter; Based on the target switching function, a bridge arm current model of the current source converter and a DC side voltage expression of the current source converter are obtained.