Full-control alternating current interconnection device control method and system based on power characteristic analysis

Abstract

The invention discloses a full-control AC interconnection device control method and system based on power characteristic analysis, and the method comprises the steps: constructing a first voltage compensation vector diagram according to a topological structure of a full-control AC interconnection device; according to the first voltage compensation vector diagram, constructing a first power flow regulation characteristic curve when a reactive power coordination control module in the full-control AC interconnection device works independently; according to the first voltage compensation vector diagram, constructing a second power flow regulation characteristic curve when a flexible power flow control module in the full-control AC interconnection device works independently; determining control strategies of a reactive power coordination control module and a flexible power flow control module according to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve; the full-control AC interconnection device is adjusted according to control strategies of the reactive power coordination control module and the flexible power flow control module, the stability of the full-control AC interconnection device accessing a power grid can be effectively improved, and stable operation of a power system is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible alternating current transmission, in particular to a full-controlled alternating current interconnection device control method and system based on power characteristic analysis. BACKGROUND

[0002] With the large-scale access of new energy and power electronic devices to the power grid, the controllability of system transmission line power flow is insufficient, and the power quality of the power grid is reduced. As a new type of flexible alternating current transmission device, the full-controlled alternating current interconnection device has the advantages of flexible and rapid regulation of power flow and voltage of the power system, rapid control of system faults, and therefore has great application prospects.

[0003] Because the full-controlled alternating current device contains a large number of power electronic devices, the dynamic interaction characteristics and nonlinear characteristics between the device and the control are more complex and variable, which causes the full-controlled alternating current interconnection device to easily cause multi-mode oscillation after being connected to the power grid, threatening the stable operation of the power system after the full-controlled alternating current interconnection device is connected to the power grid. SUMMARY

[0004] In view of the problems existing in the prior art, the embodiments of the present application provide a full-controlled alternating current interconnection device control method and system based on power characteristic analysis, which can effectively improve the stability of the full-controlled alternating current interconnection device connected to the power grid and ensure the stable operation of the power system.

[0005] In a first aspect, the embodiments of the present application provide a full-controlled alternating current interconnection device control method based on power characteristic analysis, comprising: According to the topology structure of the full-controlled alternating current interconnection device, a first voltage compensation vector diagram is constructed; According to the first voltage compensation vector diagram, a first power flow regulation characteristic curve of the full-controlled alternating current interconnection device when the reactive power coordination control module works alone is constructed; According to the first voltage compensation vector diagram, a second power flow regulation characteristic curve of the full-controlled alternating current interconnection device when the flexible power flow control module works alone is constructed; According to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve, the control strategy of the reactive power coordination control module and the flexible power flow control module is determined; According to the control strategy of the reactive power coordination control module and the flexible power flow control module, the full-controlled alternating current interconnection device is adjusted.

[0006] As an improvement of the above-mentioned scheme, the full-control AC interconnection device comprises: a plurality of flexible power flow control modules, a plurality of reactive power coordination control modules, a parallel compensation control module, and a short-circuit current control module; wherein the plurality of flexible power flow control modules, the plurality of reactive power coordination control modules, the parallel compensation control module, and the short-circuit current control module are connected in parallel to the busbar of the power grid.

[0007] As an improvement of the above-mentioned scheme, according to the topology structure of the full-control AC interconnection device, a first voltage compensation vector diagram is constructed, comprising: According to the topology structure of the full-control AC interconnection device, the vector relationship between the voltage and the current of the flexible power flow control module, the reactive power coordination control module, the parallel compensation control module, and the short-circuit current control module in the full-control AC interconnection device when working is determined. According to the vector relationship between the voltage and the current of the flexible power flow control module, the reactive power coordination control module, the parallel compensation control module, and the short-circuit current control module in the full-control AC interconnection device when working, a first voltage compensation vector diagram is constructed.

[0008] As an improvement of the above-mentioned scheme, according to the first voltage compensation vector diagram, a first power flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when working alone is constructed, comprising: According to the first voltage compensation vector diagram, a second voltage compensation vector diagram of the reactive power coordination control module in the full-control AC interconnection device when working alone is constructed. According to the second voltage compensation vector diagram, a first line current of the reactive power coordination control module in the full-control AC interconnection device when working alone is determined. According to the first line current, a first active power and a first reactive power at the end of the line connected with the full-control AC interconnection device are calculated. According to the first active power and the first reactive power, a first power flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when working alone is constructed.

[0009] As an improvement of the above-mentioned scheme, according to the first active power and the first reactive power, a first power flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when working alone is constructed, comprising: According to the first active power, a first active power flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when working alone is established. According to the first reactive power, a first reactive power flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when working alone is established. According to the first active power flow regulation characteristic curve and the first reactive power flow regulation characteristic curve, a first power flow regulation characteristic curve of the reactive power coordinated control module working alone in the full-controllable AC interconnection device is obtained.

[0010] As an improvement of the above scheme, the second power flow regulation characteristic curve of the flexible power flow control module working alone in the full-controllable AC interconnection device is constructed according to the first voltage compensation vector diagram, comprising: According to the first voltage compensation vector diagram, a third voltage compensation vector diagram of the flexible power flow control module working alone in the full-controllable AC interconnection device is constructed; According to the third voltage compensation vector diagram, a second line current of the flexible power flow control module working alone in the full-controllable AC interconnection device is determined; According to the second line current, a second active power and a second reactive power at the end of the line to which the full-controllable AC interconnection device is connected are calculated; According to the second active power and the second reactive power, the second power flow regulation characteristic curve of the flexible power flow control module working alone in the full-controllable AC interconnection device is constructed.

[0011] As an improvement of the above scheme, the control strategy of the reactive power coordinated control module and the flexible power flow control module is determined according to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve, comprising: According to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve, a control target of the reactive power coordinated control module and the flexible power flow control module is determined; wherein the control target comprises line reactive power flow and line active power flow; According to the control target of the reactive power coordinated control module, a control strategy of the reactive power coordinated control module is determined; According to the control target of the flexible power flow control module, a control strategy of the flexible power flow control module is determined.

[0012] As an improvement of the above scheme, the control strategy of the reactive power coordinated control module is determined according to the control target of the reactive power coordinated control module, comprising: According to the circuit topology of the reactive power coordinated control module, an equivalent circuit model of the reactive power coordinated control module is constructed; According to the equivalent circuit model and the control target of the reactive power coordinated control module, the control strategy of the reactive power coordinated control module is determined.

[0013] As an improvement of the above scheme, the control strategy of the flexible power flow control module is determined according to the control target of the flexible power flow control module, comprising: According to the circuit topology of the flexible power flow control module, an equivalent circuit model of the flexible power flow control module is constructed; According to the equivalent circuit model of the flexible power flow control module and the control target, a control strategy of the flexible power flow control module is determined.

[0014] In a second aspect, an embodiment of the present application provides a full-control AC interconnection device control system based on power characteristic analysis, comprising: A voltage compensation vector diagram module is configured to construct a first voltage compensation vector diagram according to the topology structure of the full-control AC interconnection device; A first power flow regulation characteristic curve construction module is configured to construct a first power flow regulation characteristic curve of the reactive power coordinated control module of the full-control AC interconnection device working alone according to the first voltage compensation vector diagram; A second power flow regulation characteristic curve construction module is configured to construct a second power flow regulation characteristic curve of the flexible power flow control module of the full-control AC interconnection device working alone according to the first voltage compensation vector diagram; A control strategy determination module is configured to determine the control strategy of the reactive power coordinated control module and the flexible power flow control module according to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve; An adjustment module is configured to adjust the full-control AC interconnection device according to the control strategy of the reactive power coordinated control module and the flexible power flow control module.

[0015] Compared with the prior art, the full-control AC interconnection device control method and system based on power characteristic analysis provided by the embodiment of the present application first constructs a first voltage compensation vector diagram according to the topology structure of the full-control AC interconnection device; then constructs a first power flow regulation characteristic curve of the reactive power coordinated control module of the full-control AC interconnection device working alone according to the first voltage compensation vector diagram; constructs a second power flow regulation characteristic curve of the flexible power flow control module of the full-control AC interconnection device working alone according to the first voltage compensation vector diagram; then determines the control strategy of the reactive power coordinated control module and the flexible power flow control module according to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve; finally adjusts the full-control AC interconnection device according to the control strategy of the reactive power coordinated control module and the flexible power flow control module, which can effectively improve the stability of the full-control AC interconnection device connected to the power grid and ensure the stable operation of the power system. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the present application, the drawings used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0017] Figure 1 is a flow chart of a control method of an all-controlling AC interconnection device based on power characteristic analysis provided by an embodiment of the present application; Figure 2 is a circuit topology schematic diagram of an all-controlling AC interconnection device provided by an embodiment of the present application; Figure 3 is a first voltage compensation vector diagram of an all-controlling AC interconnection device provided by an embodiment of the present application; Figure 4 is a second voltage compensation vector diagram of a reactive power coordination control module when the module works alone provided by an embodiment of the present application; Figure 5 is a first active power flow regulation characteristic curve schematic diagram of a reactive power coordination control module provided by an embodiment of the present application; Figure 6 is a first reactive power flow regulation characteristic curve schematic diagram of a reactive power coordination control module provided by an embodiment of the present application; Figure 7 is a third voltage compensation vector diagram of a flexible power flow control module when the module works alone provided by an embodiment of the present application; Figure 8 is a second active power flow regulation characteristic curve schematic diagram of a flexible power flow control module provided by an embodiment of the present application; Figure 9 is a second reactive power flow regulation characteristic curve schematic diagram of a flexible power flow control module provided by an embodiment of the present application; Figure 10 is a schematic diagram of an equivalent model of a flexible power flow control module provided by an embodiment of the present application; Figure 11 is a schematic diagram of a control strategy of a parallel side of a flexible power flow control module provided by an embodiment of the present application; Figure 12 is a schematic diagram of a control strategy of a series side of a flexible power flow control module provided by an embodiment of the present application; Figure 13 is a schematic diagram of an equivalent model of a reactive power coordination control module provided by an embodiment of the present application; Figure 14 is a schematic diagram of a control strategy of a reactive power coordination control module provided by an embodiment of the present application; Figure 15This is a structural block diagram of a fully controllable AC interconnection device control system based on power characteristic analysis provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It is understood that the various numerical designations used in the embodiments of this invention are merely for descriptive convenience and are not intended to limit the scope of this application. The order of the process numbers does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

[0020] See Figure 1 , Figure 1 This is a flowchart illustrating a fully controllable AC interconnection device control method based on power characteristic analysis, provided in an embodiment of the present invention. The fully controllable AC interconnection device control method based on power characteristic analysis specifically includes: S11: Construct the first voltage compensation vector diagram based on the topology of the fully controlled AC interconnection device; S12: Based on the first voltage compensation vector diagram, construct the first power flow regulation characteristic curve when the reactive power coordination control module in the fully controlled AC interconnection device works alone; S13: Based on the first voltage compensation vector diagram, construct the second power flow regulation characteristic curve when the flexible power flow control module in the fully controlled AC interconnection device works alone; S14: Determine the control strategies of the reactive power coordination control module and the flexible power flow control module based on the first power flow regulation characteristic curve and the second power flow regulation characteristic curve; S15: Adjust the fully controlled AC interconnection device according to the control strategies of the reactive power coordination control module and the flexible power flow control module.

[0021] Furthermore, such as Figure 2 The topology of the fully controlled AC interconnection device shown includes: multiple flexible power flow control modules P, multiple reactive power coordination control modules Q, parallel compensation control modules G, and short-circuit current control modules D; wherein, the multiple flexible power flow control modules P, the multiple reactive power coordination control modules Q, the parallel compensation control modules G, and the short-circuit current control modules D are connected in parallel to the grid bus.

[0022] Wherein, the parallel compensation control module G comprises a first three-phase converter VSC1 and a first capacitor C1 (DC capacitor), a first parallel transformer TR1 and a switch K, wherein the first three-phase converter VSC1 is composed of a plurality of second type transistors VT2, such as an insulated gate bipolar transistor combined with a thyristor.

[0023] Wherein, the main function of the parallel compensation control module G is to realize voltage and reactive power parallel compensation, and meanwhile has the functions of power quality treatment and wide frequency oscillation suppression. The circuit structure of the parallel compensation control module G is similar to that of the static synchronous compensator, and the main body is a self-commutated voltage type three-phase full-bridge inverter.

[0024] The parallel side of the flexible power flow control module P is composed of a second parallel transformer TR2, a second three-phase converter VSC2 and a second capacitor C2 (common DC capacitor); the series side is a first single-phase converter SPC1 directly connected into the line. Wherein, the first single-phase converter SPC1 is composed of a plurality of first type transistors VT1, such as an insulated gate bipolar transistor with a capacitor; the second three-phase converter VSC2 is composed of a plurality of second type transistors VT2, such as an insulated gate bipolar transistor combined with a thyristor.

[0025] Wherein, the main function of the flexible power flow control module P is to accurately track the voltage difference of the power supply point, quickly, flexibly and fully regulate the power flow, and realize full-range flexible power flow regulation.

[0026] The reactive power coordination control module Q is composed of a second single-phase converter SPC2 connected into the power line in groups of (A, B, C three single-phase) and a third capacitor C3 (DC capacitor). Wherein, the second single-phase converter SPC2 is composed of a plurality of first type transistors VT1, such as an insulated gate bipolar transistor with a capacitor.

[0027] Wherein, the reactive power coordination control module Q adjusts the reactive component perpendicular to the line current to assist power flow regulation and short circuit control. In addition, the module can be locked to assist short circuit current control during short circuit fault.

[0028] The short circuit current control module D comprises a parallel structure composed of IGBT and diode, eight diodes and two fourth and fifth capacitors C4 and C5 for blocking DC.

[0029] Wherein, during normal operation, the short circuit current control module D bypasses through the current branch, and when the system has a short circuit, the diode charges the DC capacitor (i.e. the fourth and fifth capacitors C4 and C5 mentioned above) to reach the blocking voltage, so as to achieve the purpose of fast blocking of fault current.

[0030] Wherein, in the full-control AC interconnection device topology shown in Figure 2 V L , VR respectively, L is a line inductance, V P , V Q respectively, I is a line current amplitude of the full-controlled AC interconnection device, I G is a current amplitude injected into the PCC by the shunt compensation control module G, V g is a grid voltage amplitude, Lg is a grid inductance, Ig is a grid output current amplitude.

[0031] The embodiment of the application is based on the topology of the full-controlled AC interconnection device and the functions of each module, constructs a first voltage compensation vector diagram of the full-controlled AC interconnection device, based on the constructed first voltage compensation vector diagram, further constructs a first power flow regulation characteristic curve when the reactive power coordination control module works alone and a second power flow regulation characteristic curve when the flexible power flow control module works alone in the full-controlled AC interconnection device; then determines the control strategy of the reactive power coordination control module and the control strategy of the flexible power flow control module based on power characteristic analysis according to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve; finally, adjusts and controls the full-controlled AC interconnection device based on the control strategy of the reactive power coordination control module and the control strategy of the flexible power flow control module. The embodiment of the application determines the control strategies of the reactive power coordination control module and the flexible power flow control module by jointly analyzing the interaction characteristics and power characteristics of the two modules, which can effectively improve the stability of the full-controlled AC interconnection device connected to the grid, ensures the stable operation of the power system, and fills the gap of the control strategy of the full-controlled AC interconnection device.

[0032] In an alternative embodiment, S11: constructing a first voltage compensation vector diagram according to the topology of the full-controlled AC interconnection device, comprising: determining the vector relationship among voltages and currents when the flexible power flow control module, the reactive power coordination control module, the shunt compensation control module and the short-circuit current control module work in the full-controlled AC interconnection device according to the topology of the full-controlled AC interconnection device; constructing a first voltage compensation vector diagram according to the vector relationship among voltages and currents when the flexible power flow control module, the reactive power coordination control module, the shunt compensation control module and the short-circuit current control module work in the full-controlled AC interconnection device.

[0033] For example, based on the topology of the full-controlled AC interconnection device and the functions of each module, a first voltage compensation vector diagram of the full-controlled AC interconnection device is constructed, as shown in Figure 3 ; wherein, is , the synthesized vector voltage, Vp, Vqare the output voltage amplitude of the flexible power flow control module P, the output voltage amplitude of the reactive power coordination control module Q respectively, P Q are the corresponding vector voltages, Vp, Vqare the vector voltage amplitude of the corresponding vector voltages Vp, Vqare the phase of the common coupling point voltage amplitude V L , the phase of the line current I, are the vector current of the line current I; Vp, Vqare the common coupling point voltage amplitude V L , the line end voltage amplitude V R are the corresponding vector voltages; V X Vp, Vqare the line reactance voltage drop amplitude, V X = ωLI, ω is the angular frequency of the line current; Vp, Vqare the vector voltage of the line reactance voltage drop amplitude.

[0034] According to Figure 2 , the flexible power flow control module P provides voltage in phase / anti-phase with the line current, the reactive power coordination control module Q provides voltage perpendicular to the line current, by adjusting the amplitude and phase angle of , the amplitude and phase angle of the synthesized voltage vector can be changed.

[0035] In an alternative embodiment, S12: according to the first voltage compensation vector diagram, a first power flow regulation characteristic curve when the reactive power coordination control module in the full-control AC interconnection device works alone is constructed, comprising: According to the first voltage compensation vector diagram, a second voltage compensation vector diagram when the reactive power coordination control module in the full-control AC interconnection device works alone is constructed; According to the second voltage compensation vector diagram, a first line current when the reactive power coordination control module in the full-control AC interconnection device works alone is determined; According to the first line current, a first active power and a first reactive power at the line end where the full-control AC interconnection device is connected are calculated; According to the first active power and the first reactive power, a first power flow regulation characteristic curve when the reactive power coordination control module in the full-control AC interconnection device works alone is constructed.

[0036] ​​​Specifically, the first power flow regulation characteristic curve of the full-control AC interconnection device when the reactive power coordination control module works alone is constructed according to the first active power and the first reactive power. The first active power flow regulation characteristic curve of the full-control AC interconnection device when the reactive power coordination control module works alone is established according to the first active power. The first reactive power flow regulation characteristic curve of the full-control AC interconnection device when the reactive power coordination control module works alone is established according to the first reactive power. The first power flow regulation characteristic curve of the full-control AC interconnection device when the reactive power coordination control module works alone is obtained according to the first active power flow regulation characteristic curve and the first reactive power flow regulation characteristic curve.

[0037] For example, when the reactive power coordination control module Q works alone, the vector relationship between the voltage and the current is as shown in a second voltage compensation vector diagram. Figure 4 According to the second voltage compensation vector diagram, at this time, the line current of the full-control AC interconnection device can be expressed as: (1) ; wherein, X L is the line reactance, X L =jωL, j is the imaginary unit. Due to the compensation effect of the parallel compensation control module G, the amplitude of the point of common coupling voltage is unchanged, and the phase of the line end voltage is taken as 0. Based on the above formula (1), the first line current under the condition that the reactive power coordination control module Q works alone, denoted as , can be obtained.

[0038] (2) ; At this time, the tangent value of the phase angle of the first line current is: (3) ; The first active power and the first reactive power at the line end under the condition that the reactive power coordination control module Q works alone are calculated as follows: (4) ; (5) ; wherein, P1 represents the first active power, and Q1 represents the first reactive power. Since the phase difference of the voltage at the first end and the last end of the line in the power system is very small, the point of common coupling voltage , the line end voltage , the line reactance , and the first power flow regulation characteristic curve of the full-control AC interconnection device when the reactive power coordination control module Q works alone is as shown in a first power flow regulation characteristic curve diagram.Figure 5 and Figure 6 as shown, including a first active power flow regulation characteristic curve and a first reactive power flow regulation characteristic curve; wherein, Figure 5 represents the first active power flow regulation characteristic curve under the sole operation of the reactive power coordination control module Q, which describes the relationship between the output voltage V Q and the first active power P1. Figure 6 represents the first reactive power flow regulation characteristic curve under the sole operation of the reactive power coordination control module Q, which describes the relationship between the output voltage V Q and the first reactive power Q1.

[0039] In an optional embodiment, S13: constructing a second power flow regulation characteristic curve of the flexible power flow control module in the full-controlled AC interconnection device when the flexible power flow control module works alone according to the first voltage compensation vector diagram, including: constructing a third voltage compensation vector diagram of the flexible power flow control module in the full-controlled AC interconnection device when the flexible power flow control module works alone according to the first voltage compensation vector diagram; determining a second line current of the flexible power flow control module in the full-controlled AC interconnection device when the flexible power flow control module works alone according to the third voltage compensation vector diagram; calculating a second active power and a second reactive power at the end of the line where the full-controlled AC interconnection device is connected according to the second line current; constructing a second power flow regulation characteristic curve of the flexible power flow control module in the full-controlled AC interconnection device when the flexible power flow control module works alone according to the second active power and the second reactive power.

[0040] For example, when the flexible power flow control module P works alone, the vector relationship between voltage and current is as shown in the third voltage compensation vector diagram Figure 7 According to the third voltage compensation vector diagram, at this time, the line current of the full-controlled AC interconnection device can be represented as: (6) ; (7) ; Because of the compensation effect of the shunt compensation control module G, the amplitude of the point of common coupling voltage is unchanged, and the phase of the line end voltage is taken as 0, based on the above formulas (6), (7), the second line current under the sole operation of the flexible power flow control module P can be obtained, denoted as .

[0041] (8) ; At this time, the tangent value of the phase angle of the second line current is: (9); The second active power and the second reactive power at the end of the line when the flexible power flow control module P is running alone are calculated as follows: (10); (11); Wherein, P2 represents the second active power, and Q2 represents the second reactive power. Since the phase difference of the voltage at the beginning and end of the line in the power system is very small, the voltage at the point of common coupling is , the voltage at the end of the line is , the line reactance is , the second power flow regulation characteristic curve of the full-bridge AC interconnection device when the flexible power flow control module P is running alone is shown in Figure 8 and Figure 9 , including the second active power flow regulation characteristic curve and the second reactive power flow regulation characteristic curve; wherein, Figure 8 represents the second active power flow regulation characteristic curve under the condition that the flexible power flow control module P is running alone, which describes the relationship between the output voltage V P of the flexible power flow control module P and the second active power P2; Figure 9 represents the second reactive power flow regulation characteristic curve under the condition that the flexible power flow control module P is running alone, which describes the relationship between the output voltage V P of the flexible power flow control module P and the second reactive power Q2.

[0042] In an optional embodiment, S14: determining the control strategy of the reactive power coordination control module and the flexible power flow control module according to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve, comprising: determining the control target of the reactive power coordination control module and the flexible power flow control module according to the first power flow regulation characteristic curve and the second power flow regulation characteristic curve; wherein, the control target includes the line reactive power flow and the line active power flow; determining the control strategy of the reactive power coordination control module according to the control target of the reactive power coordination control module; determining the control strategy of the flexible power flow control module according to the control target of the flexible power flow control module.

[0043] Specifically, the control strategy of the reactive power coordination control module is determined according to the control target of the reactive power coordination control module, comprising: constructing the equivalent circuit model of the reactive power coordination control module according to the circuit topology of the reactive power coordination control module; Based on the equivalent circuit model and control objective of the reactive power coordination control module, the control strategy of the reactive power coordination control module is determined.

[0044] Specifically, determining the control strategy of the flexible power flow control module based on the control objective of the flexible power flow control module includes: Based on the circuit topology of the flexible power flow control module, construct an equivalent circuit model of the flexible power flow control module; Based on the equivalent circuit model and control objective of the flexible power flow control module, the control strategy of the flexible power flow control module is determined.

[0045] For example, Figure 5 and Figure 6 The first power flow regulation characteristic curve shown is... Figure 8 and Figure 9 By comparing and analyzing the second power flow regulation characteristic curve shown, the output voltage V of the reactive power coordination control module Q can be obtained. Q Its active power flow regulation capability is superior to the output voltage V of the flexible power flow control module P. P The active power flow regulation capacity, while the output voltage V of the flexible power flow control module P. P Its reactive power flow regulation capability is superior to that of the reactive power coordination control module Q output voltage V. Q The reactive power flow regulation capability. Therefore, the control objective of the flexible power flow control module P is the reactive power flow of the line, and the control objective of the reactive power coordination control module Q is the active power flow of the line.

[0046] Based on the circuit topology of the flexible power flow control module P, the module is divided into a series side and a parallel side. An equivalent model of the flexible power flow control module P is established, such as... Figure 10 As shown, where V dc This is the DC-side capacitor voltage; u Pa u Pb u Pc The three-phase voltages (i.e., phases a, b, and c) of the transmission line are connected in series to the flexible power flow control module P; u se1 L1 is the output modulation voltage of the series side of the flexible power flow control module P; L1 is the filter inductor of the series side of the flexible power flow control module P; i is the phase current (line phase current) of the series side of the flexible power flow control module P; u d This refers to the output voltage on the parallel side; i sa i sb i sc The flexible power flow control module P outputs three-phase current (i.e., phases a, b, and c); u Ra u Rb u RcThe three-phase voltage (i.e., bus a, b, c phase voltage) of the bus connected in parallel with the flexible power flow control module P is taken as the input; and L is the output filter inductance of the flexible power flow control module P.

[0047] Based on Figure 10 the equivalent model of the flexible power flow control module P shown in the figure, the mathematical model of the parallel side of the flexible power flow control module P can be obtained, and is as follows: (12) ; Wherein, is a differential operator, and t represents a time variable. The Park transformation is performed on formula (12) to obtain the mathematical model in the dq axis, and is as follows: (13) ; (14) ; Wherein, , is the d-axis and q-axis component of the voltage at the parallel side of the flexible power flow control module P in the dq coordinate system; , is the d-axis and q-axis component of the current at the parallel side of the flexible power flow control module P in the dq coordinate system; , is the d-axis and q-axis component of the bus voltage at the access point of the parallel side of the flexible power flow control module P in the dq coordinate system, and PI represents a proportional integrator, represents a multiplier.

[0048] The parallel side of the flexible power flow control module P exchanges reactive power with the system to maintain the stability of the bus voltage amplitude (line end voltage amplitude) V R at the access point, and provides or absorbs the direct-current active power demand caused by the power exchange between the series side and the power grid, so it is necessary to maintain the stability of the common direct-current capacitor voltage V dc . The control strategy (control system structure) corresponding to the parallel side is as shown in Figure 11 ; in the control strategy shown in Figure 11 , V dcref is the direct-current capacitor voltage reference value of the flexible power flow control module P, V Rref is the grid-connected point voltage amplitude reference value of the flexible power flow control module P, i sdref is the d-axis component of the output current of the flexible power flow control module P at the grid-connected point, i sqref is the q-axis component of the output current of the flexible power flow control module P at the grid-connected point, u Pd represents the d-axis component of the output modulation voltage of the parallel side of the flexible power flow control module P, which is calculated from formula (13), and u Pq represents the q-axis component of the output modulation voltage of the parallel side of the flexible power flow control module P, which is calculated from formula (14).

[0049] based on Figure 10 The equivalent model of the flexible power flow control module P shown can be used to obtain the mathematical model of the series side of the flexible power flow control module P, as follows: (15); The formula for the single-phase Park transform is as follows: (16); Where, x α and x β For the orthogonal components in the stationary coordinate system, x β Advanced x α 90° Let d be the rotation angle of the d-axis relative to the stationary coordinate system.

[0050] By combining (13) and (14), and performing a single-phase Park transformation, we can obtain the mathematical model of the P-series single-phase converter of the flexible power flow control module in the dq coordinate system, as follows: (17); (18); in, , The d-axis and q-axis components of the modulated voltage output from the P series side of the flexible power flow control module in the dq coordinate system; , These are the d-axis and q-axis components of the line phase current in the dq coordinate system; , The output voltage of the flexible power flow control module P on the series side consists of the d-axis and q-axis components.

[0051] Since the control objective of the P-series side of the flexible power flow control module is the reactive power flow of the line, a control strategy for the P-series side of the flexible power flow control module can be established as follows: Figure 12 As shown; in Figure 12 In the control strategy shown, Q represents the reactive power at the end of the line. ref u is the reference value for reactive power at the end of the line. Pdref The reference value for the d-axis component of the output voltage on the series side of the flexible power flow control module P is u. Pqref i is the reference value for the q-axis component of the output voltage on the series side of the flexible power flow control module P. dref i is the reference value for the d-axis component of the output current of the flexible power flow control module P. qref This is the reference value for the q-axis component of the output current of the flexible power flow control module P.

[0052] Similarly, based on the circuit topology of the reactive power coordination control module Q, an equivalent model of the reactive power coordination control module Q is established, such as...Figure 13 u is the output voltage of the reactive power coordinated control module Q, u Q is the output voltage of the reactive power coordinated control module Q, u se2 is the output modulation voltage of the reactive power coordinated control module Q, i is the line phase current, is the filter inductance, V dcQ is the DC capacitor voltage of the reactive power coordinated control module Q.

[0053] Based on the equivalent model of the reactive power coordinated control module Q shown in Figure 13 , the mathematical model of the reactive power coordinated control module Q can be obtained, as shown in the following: (19) ; After single-phase Park transformation, the following is obtained: (20) ; (21) ; wherein, , is the d-axis and q-axis components of the output modulation voltage of the reactive power coordinated control module Q in the dq coordinate system; , is the d-axis and q-axis components of the line phase current in the dq coordinate system; , is the d-axis and q-axis components of the output voltage of the reactive power coordinated control module Q.

[0054] To ensure the stable operation of the reactive power coordinated control module Q, the stability of the DC capacitor voltage needs to be maintained, so the reactive power coordinated control module Q needs to control its capacitor voltage value. Since the reactive power coordinated control module Q needs to control the line active power, the control strategy of the reactive power coordinated control module Q can be obtained as shown in Figure 14 ; in the control strategy shown in Figure 12 , P is the active power at the end of the line, P ref is the active power reference value at the end of the line, u Qdref is the d-axis component reference value of the output voltage of the reactive power coordinated control module Q at the series side, u Qqref is the q-axis component reference value of the output voltage of the reactive power coordinated control module Q at the series side, i dref is the d-axis component reference value of the output current of the reactive power coordinated control module Q, i qref is the q-axis component reference value of the output current of the reactive power coordinated control module Q.

[0055] Based on the control strategies of the parallel side and the series side of the flexible power flow control module P shown in Figure 11 and Figure 12 , the control strategy of the flexible power flow control module P can be obtained as shown in Figure 14The control strategy of the reactive power coordination control module Q shown can obtain the final control strategy of the full-control type AC interconnection device, and voltage control is performed on the flexible power flow control module and the reactive power coordination control module in the full-control type AC interconnection device according to the corresponding control strategy, so as to realize the adjustment of the full-control type AC interconnection device. The embodiments of the present application jointly analyze the interaction characteristics and power characteristics of the reactive power coordination control module and the flexible power flow control module of the full-control type AC interconnection device to determine the control strategies of the two modules. On the one hand, the embodiments of the present application can fill the gap of the existing control strategy of the full-control type AC interconnection device. On the other hand, the embodiments of the present application can reduce the risk of multi-mode oscillation caused by the full-control type AC interconnection device connected to the power grid, effectively improve the stability of the full-control type AC interconnection device connected to the power grid, and ensure the stable operation of the power system.

[0056] Referring to Figure 15 , Figure 15 is a structural block diagram of a full-control type AC interconnection device control system based on power characteristic analysis provided by the embodiments of the present application. The full-control type AC interconnection device control system based on power characteristic analysis comprises: a voltage compensation vector diagram module 11 configured to construct a first voltage compensation vector diagram according to the topological structure of the full-control type AC interconnection device; a first power flow adjustment characteristic curve construction module 12 configured to construct a first power flow adjustment characteristic curve of the reactive power coordination control module in the full-control type AC interconnection device working alone according to the first voltage compensation vector diagram; a second power flow adjustment characteristic curve construction module 13 configured to construct a second power flow adjustment characteristic curve of the flexible power flow control module in the full-control type AC interconnection device working alone according to the first voltage compensation vector diagram; a control strategy determination module 14 configured to determine the control strategies of the reactive power coordination control module and the flexible power flow control module according to the first power flow adjustment characteristic curve and the second power flow adjustment characteristic curve; an adjustment module 15 configured to adjust the full-control type AC interconnection device according to the control strategies of the reactive power coordination control module and the flexible power flow control module.

[0057] In an alternative embodiment, the full-control type AC interconnection device comprises a plurality of flexible power flow control modules, a plurality of reactive power coordination control modules, a parallel compensation control module, and a short-circuit current control module; wherein the plurality of flexible power flow control modules, the plurality of reactive power coordination control modules, the parallel compensation control module, and the short-circuit current control module are connected in parallel to a busbar of the power grid.

[0058] In an alternative embodiment, the voltage compensation vector diagram module 11 comprises: A vector relationship determining unit is configured to determine vector relationships between voltages and currents of the flexible flow control module, the reactive power coordination control module, the shunt compensation control module, and the short-circuit current control module in the full-control AC interconnection device when the modules are working according to a topology of the full-control AC interconnection device. A first voltage compensation vector diagram constructing unit is configured to construct a first voltage compensation vector diagram according to the vector relationships between the voltages and the currents of the flexible flow control module, the reactive power coordination control module, the shunt compensation control module, and the short-circuit current control module in the full-control AC interconnection device when the modules are working.

[0059] In an alternative embodiment, the first flow regulation characteristic curve constructing module 12 comprises: A second voltage compensation vector diagram constructing unit is configured to construct a second voltage compensation vector diagram of the reactive power coordination control module in the full-control AC interconnection device when the module is working alone according to the first voltage compensation vector diagram. A first line current determining unit is configured to determine a first line current of the reactive power coordination control module in the full-control AC interconnection device when the module is working alone according to the second voltage compensation vector diagram. A first line end power determining unit is configured to calculate a first active power and a first reactive power of a line end where the full-control AC interconnection device is connected according to the first line current. A first curve constructing unit is configured to construct a first flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when the module is working alone according to the first active power and the first reactive power.

[0060] In an alternative embodiment, the first curve constructing unit comprises: A first active flow regulation characteristic curve constructing subunit is configured to establish a first active flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when the module is working alone according to the first active power. A first reactive flow regulation characteristic curve constructing subunit is configured to establish a first reactive flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when the module is working alone according to the first reactive power. A curve constructing subunit is configured to obtain the first flow regulation characteristic curve of the reactive power coordination control module in the full-control AC interconnection device when the module is working alone according to the first active flow regulation characteristic curve and the first reactive flow regulation characteristic curve.

[0061] In an alternative embodiment, the second flow regulation characteristic curve constructing module 13 comprises: The third voltage compensation vector diagram construction unit is configured to construct a third voltage compensation vector diagram of the flexible flow control module in the full-control AC interconnection device according to the first voltage compensation vector diagram; The second line current determination unit is configured to determine a second line current of the flexible flow control module in the full-control AC interconnection device according to the third voltage compensation vector diagram; The second line end power determination unit is configured to calculate a second active power and a second reactive power of a line end connected with the full-control AC interconnection device according to the second line current; The second curve construction unit is configured to construct a second flow regulation characteristic curve of the flexible flow control module in the full-control AC interconnection device according to the second active power and the second reactive power.

[0062] In an optional embodiment, the control strategy determination module 14 comprises: The control target determination unit is configured to determine control targets of the reactive power coordination control module and the flexible flow control module according to the first flow regulation characteristic curve and the second flow regulation characteristic curve; wherein the control targets comprise a line reactive power flow and a line active power flow; The first control strategy determination unit is configured to determine a control strategy of the reactive power coordination control module according to the control target of the reactive power coordination control module; The second control strategy determination unit is configured to determine a control strategy of the flexible flow control module according to the control target of the flexible flow control module.

[0063] In an optional embodiment, the first control strategy determination unit comprises: The first equivalent circuit model construction subunit is configured to construct an equivalent circuit model of the reactive power coordination control module according to a circuit topology of the reactive power coordination control module; The first control strategy determination subunit is configured to determine a control strategy of the reactive power coordination control module according to the equivalent circuit model and the control target of the reactive power coordination control module.

[0064] In an optional embodiment, the second control strategy determination unit comprises: The second equivalent circuit model construction subunit is configured to construct an equivalent circuit model of the flexible flow control module according to a circuit topology of the flexible flow control module; The second control strategy determination subunit is configured to determine a control strategy of the flexible flow control module according to the equivalent circuit model and the control target of the flexible flow control module.

[0065] It should be noted that the working process of each module in the full-control AC interconnection device control system based on power characteristic analysis described in the embodiments of the present application can refer to the working process of the full-control AC interconnection device control method based on power characteristic analysis described in the above embodiments, and the technical effects achieved are the same as those of the full-control AC interconnection device control method based on power characteristic analysis described in the above embodiments, which will not be described here.

[0066] It should be noted that the system embodiments described above are only schematic, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e. can be located in one place, or can be distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the embodiments. In addition, the connection relationship between the modules in the system embodiments provided by the present application indicates that there is a communication connection between them, which can be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement without creative labor.

[0067] The above is the preferred embodiment of the present application. It should be noted that for those skilled in the art, various improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements are also considered within the scope of protection of the present application.

Claims

1. A control method for a fully controllable AC interconnection device based on power characteristic analysis, characterized in that, include: Based on the topology of the fully controlled AC interconnection device, a first voltage compensation vector diagram is constructed. Based on the first voltage compensation vector diagram, construct the first power flow regulation characteristic curve when the reactive power coordination control module in the fully controlled AC interconnection device works alone; Based on the first voltage compensation vector diagram, construct the second power flow regulation characteristic curve when the flexible power flow control module in the fully controlled AC interconnection device works alone; Based on the first power flow regulation characteristic curve and the second power flow regulation characteristic curve, determine the control strategies of the reactive power coordination control module and the flexible power flow control module; The fully controlled AC interconnection device is adjusted according to the control strategies of the reactive power coordination control module and the flexible power flow control module.

2. The control method for a fully controllable AC interconnection device based on power characteristic analysis as described in claim 1, characterized in that, The fully controlled AC interconnection device includes: multiple flexible power flow control modules, multiple reactive power coordination control modules, parallel compensation control modules, and short-circuit current control modules; wherein, multiple flexible power flow control modules, multiple reactive power coordination control modules, the parallel compensation control modules, and the short-circuit current control modules are connected in parallel to the power grid bus.

3. The control method for a fully controllable AC interconnection device based on power characteristic analysis as described in claim 2, characterized in that, The construction of the first voltage compensation vector diagram based on the topology of the fully controlled AC interconnection device includes: Based on the topology of the fully controlled AC interconnection device, determine the vector relationship between voltage and current when the flexible power flow control module, reactive power coordination control module, parallel compensation control module, and short-circuit current control module in the fully controlled AC interconnection device are working. Based on the vector relationship between voltage and current when the flexible power flow control module, reactive power coordination control module, parallel compensation control module, and short-circuit current control module in the fully controlled AC interconnection device are working, a first voltage compensation vector diagram is constructed.

4. The control method for a fully controllable AC interconnection device based on power characteristic analysis as described in claim 1, characterized in that, The step of constructing the first power flow regulation characteristic curve of the reactive power coordination control module in the fully controlled AC interconnection device when it operates alone, based on the first voltage compensation vector diagram, includes: Based on the first voltage compensation vector diagram, construct a second voltage compensation vector diagram when the reactive power coordination control module in the fully controlled AC interconnection device works independently. Based on the second voltage compensation vector diagram, determine the first line current when the reactive power coordination control module in the fully controlled AC interconnection device operates alone; Based on the first line current, calculate the first active power and the first reactive power at the end of the line connected to the fully controlled AC interconnection device; Based on the first active power and the first reactive power, construct the first power flow regulation characteristic curve when the reactive power coordination control module in the fully controlled AC interconnection device works alone.

5. The control method for a fully controllable AC interconnection device based on power characteristic analysis as described in claim 4, characterized in that, The step of constructing the first power flow regulation characteristic curve of the reactive power coordination control module in the fully controlled AC interconnection device when it operates alone, based on the first active power and the first reactive power, includes: Based on the first active power, establish the first active power flow regulation characteristic curve when the reactive power coordination control module in the fully controlled AC interconnection device works alone; Based on the first reactive power, establish the first reactive power flow regulation characteristic curve when the reactive power coordination control module in the fully controlled AC interconnection device works alone; Based on the first active power flow regulation characteristic curve and the first reactive power flow regulation characteristic curve, the first power flow regulation characteristic curve of the reactive power coordination control module working alone in the fully controlled AC interconnection device is obtained.

6. The control method for a fully controllable AC interconnection device based on power characteristic analysis as described in claim 1, characterized in that, The step of constructing the second power flow regulation characteristic curve of the flexible power flow control module in the fully controlled AC interconnection device when it operates independently, based on the first voltage compensation vector diagram, includes: Based on the first voltage compensation vector diagram, construct the third voltage compensation vector diagram when the flexible power flow control module in the fully controlled AC interconnection device is working alone. Based on the third voltage compensation vector diagram, determine the second line current when the flexible power flow control module in the fully controlled AC interconnection device operates alone; Based on the second line current, calculate the second active power and the second reactive power at the end of the line connected to the fully controlled AC interconnection device; Based on the second active power and the second reactive power, a second power flow regulation characteristic curve is constructed when the flexible power flow control module in the fully controlled AC interconnection device operates alone.

7. The control method for a fully controllable AC interconnection device based on power characteristic analysis as described in claim 1, characterized in that, The step of determining the control strategies of the reactive power coordination control module and the flexible power flow control module based on the first power flow regulation characteristic curve and the second power flow regulation characteristic curve includes: Based on the first power flow regulation characteristic curve and the second power flow regulation characteristic curve, the control objectives of the reactive power coordination control module and the flexible power flow control module are determined; wherein, the control objectives include line reactive power flow and line active power flow. The control strategy of the reactive power coordination control module is determined based on the control objective of the reactive power coordination control module. The control strategy of the flexible power flow control module is determined based on the control objective of the flexible power flow control module.

8. The control method for a fully controllable AC interconnection device based on power characteristic analysis as described in claim 7, characterized in that, The step of determining the control strategy of the reactive power coordination control module based on the control objective of the reactive power coordination control module includes: Based on the circuit topology of the reactive power coordination control module, construct an equivalent circuit model of the reactive power coordination control module; Based on the equivalent circuit model and control objective of the reactive power coordination control module, the control strategy of the reactive power coordination control module is determined.

9. The control method for a fully controllable AC interconnection device based on power characteristic analysis as described in claim 7, characterized in that, The step of determining the control strategy of the flexible power flow control module based on the control objective of the flexible power flow control module includes: Based on the circuit topology of the flexible power flow control module, construct an equivalent circuit model of the flexible power flow control module; Based on the equivalent circuit model and control objective of the flexible power flow control module, the control strategy of the flexible power flow control module is determined.

10. A fully controllable AC interconnection device control system based on power characteristic analysis, characterized in that, include: The voltage compensation vector diagram module is used to construct the first voltage compensation vector diagram based on the topology of the fully controlled AC interconnection device. The first power flow regulation characteristic curve construction module is used to construct the first power flow regulation characteristic curve when the reactive power coordination control module in the fully controlled AC interconnection device works alone, based on the first voltage compensation vector diagram. The second power flow regulation characteristic curve construction module is used to construct the second power flow regulation characteristic curve when the flexible power flow control module in the fully controlled AC interconnection device works alone, based on the first voltage compensation vector diagram. The control strategy determination module is used to determine the control strategies of the reactive power coordination control module and the flexible power flow control module based on the first power flow regulation characteristic curve and the second power flow regulation characteristic curve. The adjustment module is used to adjust the fully controlled AC interconnection device according to the control strategies of the reactive power coordination control module and the flexible power flow control module.

Images