Control method of interconnection transfer power controller and interconnection transfer power controller

Abstract

The present application discloses a control method of an interconnected power transfer controller and an interconnected power transfer controller, which belongs to the field of high-voltage direct current transmission technology. The embodiment of the present application provides a control method that first confirms the voltage vector of each AC system, which is a first voltage vector and a second voltage vector; obtains the voltage vector difference through the first voltage vector and the second voltage vector; confirms the impedance and current control target values ​​of the phase-splitting reactance; obtains the voltage vector of the phase-splitting reactance based on the impedance and current control target values; obtains the voltage source converter compensation voltage vector based on the voltage vector difference and the voltage vector of the phase-splitting reactance. The control method provided by the present application takes current as the control target, and the power flow regulation capability is no longer limited by the influence of the distributed parameters of the transmission line, and has the advantage of plug-and-play when planning the system installation location. At the same time, the present application takes voltage as the control reference, and by controlling the current DC control power, the continuous adjustable transmission power can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of high-voltage direct current transmission, and in particular to a control method for an interconnected transfer power controller and an interconnected transfer power controller. Background Art

[0002] The power system is a complex nonlinear dynamic system, which is formed by the interconnection and mutual influence of transmission and distribution lines and various equipment to form a huge dimensional power network. It is currently developing in the direction of high voltage, large capacity, large scale and long distance. With the global economic integration, the power industry faces unprecedented challenges in environmental protection, industrial adjustment, power demand and power market:

[0003] a. Increase transmission capacity. Electricity demand is growing steadily, but it is unevenly distributed geographically. Available power sources are often far from the growing load centers. Due to constraints such as policies and regulations, environmental protection and costs, new power sources and lines are being reduced, which makes the need to increase transmission capacity more prominent.

[0004] b. Maintain system stability. Due to the electromagnetic loop network and overloaded lines in the power grid, the voltage quality has deteriorated and the stability of the power system has decreased. In recent years, there have been many catastrophic power accidents. Therefore, it is required to maximize the efficiency of existing power generation and transmission equipment without reducing the feasibility and safety of existing transmission power.

[0005] c. Optimize system operation. Due to the rapid increase in the number of changes in power delivery determined by operational changes or power markets, system control has become more complex and the overall system flow needs to be optimized. This optimization requires comprehensive consideration of the overall operation in an increasingly large area.

[0006] The existing UPFC takes direct or indirect impedance regulation as the control target, and relies on the change of the impedance distribution of the entire system to regulate the power flow. There are the following constraints: First, with the large-scale access of new energy, the impedance characteristics of distributed power sources have a certain degree of dispersion and randomness, making the impedance distribution characteristics of the power system more complex. The impedance regulation method will face the problems of increased difficulty in regulation and reduced regulation accuracy, and large-scale changes in line impedance will face the risk of system oscillation; second, the regulation effect is closely related to the system impedance distribution, the project site selection is restricted by many conditions, and the technical and economic evaluation cycle is long; third, the regulation capacity is restricted by the grid, and third, when the system operation mode changes, the power that can be leveraged by the impedance change may be greatly reduced. In general, the flexibility and safety of the impedance regulation method of the existing power flow controller are limited.

[0007] There is an urgent need to invent a current source control method to eliminate the adverse effects of traditional impedance control, make the control more direct and effective, and have higher precision, and effectively avoid existing problems. Summary of the invention

[0008] Purpose of the invention: The purpose of the embodiments of the present application is to provide a control method for an interconnected transfer power controller and an interconnected transfer power controller, aiming to solve the technical problems of low flexibility and safety in impedance regulation of power systems through power flow controllers in the prior art.

[0009] Technical solution: In a first aspect, an embodiment of the present application provides a control method of an interconnection transfer power controller, which is used to control the interconnection transfer power controller, wherein the interconnection transfer power controller includes a voltage source converter and a phase-splitting reactor, wherein the voltage source converter is connected to the phase-splitting reactor, and the voltage source converter and the phase-splitting reactor are configured to connect a first AC system and a second AC system in phase; the control method includes:

[0010] confirming a first voltage vector and a second voltage vector, wherein the first voltage vector is a voltage vector of the first AC system, and the second voltage vector is a voltage vector of the second AC system;

[0011] Based on the first voltage vector and the second voltage vector, obtaining a voltage vector difference;

[0012] confirming the impedance and current control target value of the phase-splitting reactance;

[0013] Based on the impedance and the current control target value, obtaining a voltage vector of the phase-splitting reactance;

[0014] Based on the voltage vector difference and the voltage vector of the phase-splitting reactance, obtaining a compensation voltage vector of a voltage source converter;

[0015] The voltage source converter outputs a compensation voltage based on the compensation voltage vector.

[0016] In some embodiments, the characterization formula of the voltage vector of the phase-splitting reactance includes:

[0017]

[0018] in, is the voltage vector of the phase-splitting reactance; j is an imaginary unit; X L is the impedance of the phase-splitting reactance L; I is the current value of the first module.

[0019] In some embodiments, the characterization formula of the current control target value includes:

[0020] or

[0021] Wherein, I2 is the current control target value; S is the power control target value, Wherein, P is the target value of active power, Q is the target value of reactive power; V1 is the voltage value of the first AC system (10); and V2 is the voltage value of the second AC system.

[0022] In some embodiments, the step of obtaining the current control target value includes:

[0023] Based on the target value of active power of the target system, the target value of reactive power, the current value of each phase, and the voltage value of each phase, the compensation value of active power of the target system, the actual value of active power, the compensation value of reactive power, and the actual value of reactive power are obtained;

[0024] After making a difference between the compensation value of the active power and the actual value of the active power, the difference is input into a PI regulator to obtain a d-axis component of the current control target value;

[0025] After making a difference between the reactive power compensation value and the actual reactive power value, the difference is input into a PI regulator to obtain a q-axis component of the current control target value;

[0026] confirming the current control target value based on a d-axis component of the current control target value and a q-axis component of the current control target value;

[0027] Wherein, the target system is the first AC system or the second AC system.

[0028] In some embodiments, the step of obtaining the current control target value includes:

[0029] Based on the target value of active power of the target system and the actual value of active power, obtaining a difference in active power;

[0030] Based on the difference in active power, obtaining a d-axis component of the current control target value through a PI regulator;

[0031] Based on the target value of reactive power of the target system and the actual value of reactive power, obtaining a reactive power difference;

[0032] Based on the reactive power difference, obtaining a q-axis component of the current control target value through the PI regulator;

[0033] confirming the current control target value based on a d-axis component of the current control target value and a q-axis component of the current control target value;

[0034] Wherein, the target system is the first AC system or the second AC system.

[0035] In some embodiments, the step of obtaining the current control target value includes:

[0036] Confirming each phase voltage value of a target system, and performing dq transformation to obtain a d-axis component and a q-axis component of the target system voltage, wherein the target system is the first AC system or the second AC system;

[0037] Confirming a target value of active power and a target value of reactive power of the target system;

[0038] acquiring a d-axis component of the current control target value based on the d-axis component of the target system voltage and the target value of active power of the target system;

[0039] acquiring a q-axis component of the current control target value based on the q-axis component of the target system voltage and the target value of reactive power of the target system;

[0040] The current control target value is confirmed based on the d-axis component of the current control target value and the q-axis component of the current control target value.

[0041] In some embodiments, the step of obtaining a compensation voltage vector of a voltage source converter based on the voltage vector difference and the voltage vector of the phase-splitting reactance comprises:

[0042] Confirming the d-axis component and the q-axis component of the current control target value, and the d-axis component and the q-axis component of the actual value of the interconnection transfer power controller current;

[0043] The d-axis component of the current control target value and the d-axis component of the actual current value of the interconnected transfer power controller are subtracted and input into a PI controller to obtain the d-axis component of the voltage error value;

[0044] The q-axis component of the current control target value and the q-axis component of the actual current value of the interconnected transfer power controller are subtracted and input into a PI controller to obtain the q-axis component of the voltage error value;

[0045] Obtaining a d-axis component of a compensation voltage vector of the voltage source converter based on a d-axis component of the voltage error value, a d-axis component of the voltage vector difference, and a q-phase cross-decoupling value of a voltage vector of the phase-splitting reactance;

[0046] Obtaining a q-axis component of a compensation voltage vector of the voltage source converter based on a q-axis component of the voltage error value, a q-axis component of the voltage vector difference, and a d-phase cross-decoupling value of a voltage vector of the phase-splitting reactance;

[0047] A compensation voltage vector of the voltage source converter is determined based on a d-axis component of the compensation voltage vector of the voltage source converter and a q-axis component of the compensation voltage vector of the voltage source converter.

[0048] In a second aspect, an embodiment of the present application further provides an interconnection transfer power controller, the interconnection transfer power controller comprising a control unit, the control unit storing a control program, the control program being configured to execute the control method as described in any one of the first aspects;

[0049] and a voltage source converter and a split-phase reactor, wherein the voltage source converter, the split-phase reactor and the control unit are connected, the voltage source converter and the split-phase reactor are configured to connect the first AC system and the second AC system in phases, and the voltage source converter comprises:

[0050] a first module, the first module being configured to be connected in series between the first AC system and the second AC system in phase separation;

[0051] a second module, wherein an input end of the second module is configured to be connected to the first AC system or the second AC system, and an output end of the second module is connected to the first module;

[0052] The split-phase reactor is connected in series with the first module, and the split-phase reactor is configured to be connected in series between the first module and the first AC system or the second AC system.

[0053] In some embodiments, the first module includes a full-bridge module, and the AC end of the full-bridge module is configured to be connected in series with the first AC system and the second AC system;

[0054] The second module includes an AC / DC converter and a first transformer, the primary side of the first transformer is configured as the input end of the second module, the secondary side of the first transformer is connected to the AC side of the AC / DC converter, and the DC side of the AC / DC converter is connected to the DC side of the full-bridge module.

[0055] In some embodiments, the primary side of the first transformer is configured to be connected to the first AC system to receive AC power from the first AC system.

[0056] In some embodiments, the first module includes a second transformer, the primary side of the second transformer being configured to connect the first AC system and the second AC system in series;

[0057] The second module includes an AC / AC converter and a third transformer, the primary side of the third transformer is configured as the input end of the second module, the secondary side of the third transformer is connected to the AC input side of the AC / AC converter, and the AC output side of the AC / AC converter is connected to the secondary side of the second transformer.

[0058] In some embodiments, when there are multiple AC / AC converters, the output sides of the multiple AC / AC converters are connected in series and then connected in series with the secondary side of the second transformer.

[0059] In some embodiments, the first module further includes a blocking unit connected in series between the primary side of the second transformer and the phase-splitting reactor.

[0060] In some embodiments, the blocking unit comprises:

[0061] A disconnecting subunit, the disconnecting subunit comprising a diode rectifier bridge and a blocking capacitor, the blocking capacitor being connected in parallel with a DC side of the diode rectifier bridge;

[0062] A bypass subunit is connected in parallel with the DC side or the AC side of the diode rectifier bridge.

[0063] In some embodiments, it also includes:

[0064] a first voltage acquisition unit, wherein the first voltage acquisition unit is configured to be connected to the first AC system to acquire a voltage of the first AC system;

[0065] a second voltage collection unit, wherein the second voltage collection unit is configured to be connected to the second AC system to collect a voltage of the second AC system;

[0066] A current collection unit, wherein the current collection unit is connected to the first module and is configured to collect current of the first module.

[0067] In some embodiments, there is a common reference point between the AC voltages of the first AC system and the second AC system, and the common reference point includes a ground point;

[0068] The first voltage acquisition unit and the second voltage acquisition unit are located at the end of the interconnection transfer power controller, or are located on a transmission line that is a certain distance away from the interconnection transfer power controller.

[0069] In some embodiments, the phase-splitting reactance includes a series-connected reactor, an equivalent reactance of a transmission line and / or a leakage reactance of a transformer.

[0070] Beneficial effect: The embodiment of the present application provides a control method for an interconnected transfer power controller, which is used to control the interconnected transfer power controller. The embodiment of the present application provides a control method that first confirms the voltage vectors of each AC system connected to the interconnected transfer power controller, which are the first voltage vector and the second voltage vector; obtains the voltage vector difference through the first voltage vector and the second voltage vector; confirms the impedance and current control target values ​​of the phase-splitting reactance; obtains the voltage vector of the phase-splitting reactance based on the impedance and current control target values; obtains the voltage source converter compensation voltage vector based on the voltage vector difference and the voltage vector of the phase-splitting reactance. The control method provided by the present application takes current as the control target, and the power flow regulation capability is no longer limited by the influence of the distributed parameters of the transmission line. It has the advantage of plug-and-play when planning the system installation location, and there is no need to perform system simulation verification. At the same time, the present application takes voltage as the control reference, and by controlling the current DC control power, it can achieve continuous adjustable transmission power, higher power flow control accuracy, and good stability.

[0071] An embodiment of the present application provides an interconnected power transfer controller for connecting a first AC system and a second AC system, including a control unit, a voltage source converter and a phase-splitting reactor. The control unit stores a control program, and the control program is used to execute the control method of the interconnected power transfer controller provided in the embodiment of the present application. The voltage source converter includes a first module and a second module. The first module is connected in series between the first AC system and the second AC system in phase separation, and the phase-splitting reactor is connected in series between the first module and the second AC system. The input end of the second module is connected to the first AC system or the second AC system, and the output end of the second module is connected to the first module. The present application converts impedance control into current source control, so that the power regulation of the series-parallel topology is no longer affected by the system grid, thereby improving the flexibility and safety of power regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0073] Figure 1 A first structural diagram of an interconnected power transfer controller provided in an embodiment of the present application (showing a first AC system and a second AC system);

[0074] Figure 2 It is a cascade circuit diagram of multiple full-bridge modules;

[0075] Figure 3 A connection circuit diagram of a plurality of full-bridge modules, a plurality of AC / DC converters and a first transformer;

[0076] Figure 4 is a circuit diagram of a second transformer;

[0077] Figure 5 A store route diagram for a second transformer, a plurality of AC / AC converters, a third transformer and a disconnecting unit;

[0078] Figure 6 is a circuit diagram of a second transformer and a blocking unit;

[0079] Figure 7 A circuit diagram of a bypass subunit connected in parallel to the AC side of a diode rectifier bridge;

[0080] Figure 8 A circuit diagram of a bypass subunit connected in parallel to the DC side of a diode rectifier bridge;

[0081] Fig. 9 A three-phase connection diagram of a first AC system, a second AC system, a first module and a second module (in this case, the first module includes a second transformer, and the second module includes a third transformer and an AC / AC converter);

[0082] Fig.10 A second structural diagram of the interconnection transfer power controller (showing a first voltage acquisition module, a second voltage acquisition module and a current acquisition module based on the first structure);

[0083] Fig.11 A sequential flow chart of a control method of an interconnected power transfer controller provided in an embodiment of the present application;

[0084] Fig.12 An equivalent vector diagram of the control method for the interconnection transfer power controller;

[0085] Fig.13 A structural flow chart of a control method for an interconnection transfer power controller;

[0086] Fig.14 A structural flow chart of a first step of obtaining a current control target value;

[0087] Fig.15 The structural flow chart of the second step of obtaining the current control target value

[0088] Fig.16 A structural flow chart of a third step of obtaining a current control target value;

[0089] Figure numerals: 10, first AC system; 20, second AC system; 30, first module; 31, full-bridge module; 32, second transformer; 33, blocking unit; 331, breaking sub-unit; 3311, diode rectifier bridge; 3312, blocking capacitor; 332, bypass sub-unit; 40, phase-splitting reactor; 50, second module; 51, AC / DC converter; 52, first transformer; 53, AC / AC converter; 54, third transformer; 60, first voltage acquisition unit; 70, second voltage acquisition unit; 80, current acquisition unit; 90, voltage source converter. DETAILED DESCRIPTION

[0090] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0091] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0092] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0093] See also Figures 11 to 16, an embodiment of the present application provides a control method for an interconnected transfer power controller, which is used to control the interconnected transfer power controller. A control method provided by an embodiment of the present application first confirms the voltage vectors of each AC system connected to the interconnected transfer power controller, which are the first voltage vector and the second voltage vector; obtains the voltage vector difference through the first voltage vector and the second voltage vector; confirms the impedance and current control target values ​​of the phase-splitting reactance 40; obtains the voltage vector of the phase-splitting reactance 40 based on the impedance and current control target values; obtains the compensation voltage vector of the voltage source converter 90 based on the voltage vector difference and the voltage vector of the phase-splitting reactance 40. The control method provided by the present application takes current as the control target, and the power flow regulation capability is no longer limited by the influence of the distributed parameters of the transmission line. It has the advantage of plug-and-play when planning the system installation location, and there is no need to perform system simulation verification. At the same time, the present application takes voltage as the control reference, and by controlling the current DC control power, it can achieve continuous adjustable transmission power, higher power flow control accuracy, and good stability.

[0094] In some embodiments, the interconnection power transfer controller includes a voltage source converter 90 and a phase-splitting reactor 40, the voltage source converter 90 is connected to the phase-splitting reactor 40, and the voltage source converter 90 and the phase-splitting reactor 40 are configured to connect the first AC system 10 and the second AC system 20 in phases; see Figures 11 to 16 , an embodiment of the present application provides a control method for an interconnected power transfer controller, which specifically includes the following steps:

[0095] Step 100 : confirming a first voltage vector and a second voltage vector, wherein the first voltage vector is a voltage vector of the first AC system 10 , and the second voltage vector is a voltage vector of the second AC system 20 .

[0096] Step 200: Obtain a voltage vector difference based on a first voltage vector and a second voltage vector.

[0097] In some embodiments, the voltage vector difference characterization formula includes:

[0098]

[0099] in, is a voltage vector difference between the first voltage vector and the second voltage vector; is the first voltage vector; is the second voltage vector.

[0100] Step 300: confirm the impedance of the phase-splitting reactor 40 and the current control target value.

[0101] In some embodiments, the characterization formula of the current control target value includes:

[0102] or

[0103] Among them, I2 is the current control target value; S is the power control target value, Wherein, P is the target value of active power, Q is the target value of reactive power; V1 is the voltage value of the first AC system 10 ; and V2 is the voltage value of the second AC system 20 .

[0104] See also Fig.13 and Fig.14 In some embodiments, the step of obtaining the current control target value includes:

[0105] Step 300a1: Based on the target value Pref of the active power of the target system, the target value Qref of the reactive power, the current value of each phase and the voltage value of each phase, obtain the compensation value Pcref of the active power of the target system, the actual value Pc of the active power, the compensation value Qcref of the reactive power and the actual value Qc of the reactive power; wherein the target system is the first AC system 10 or the second AC system 20.

[0106] Specifically, see Fig.14 Taking a three-phase AC system as an example, the three phases include phase a, phase b and phase c respectively, the current value of each phase includes phase a current value Ia, phase b current value Ia and phase c current value Ia, and the voltage value of each phase includes phase a voltage Ua1 of the first AC system 10, phase a voltage Ua2 of the second AC system 20, phase b voltage Ub1 of the first AC system 10, phase b voltage Ub2 of the second AC system 20, phase c voltage Uc1 of the first AC system 10 and phase c voltage Uc2 of the second AC system 20.

[0107] See also Fig.14 In some embodiments, the target value Pref of the active power of the target system, the target value Qref of the reactive power, the current value of each phase and the voltage value of each phase are input into the compensation power calculation module to obtain the compensated value Pcref of the active power of the target system, the actual value Pc of the active power, the compensated value Qcref of the reactive power and the actual value Qc of the reactive power.

[0108] Step 300a2: After taking the difference between the active power compensation value Pcref and the actual value Pc of the active power, the difference is input into a PI regulator (proportional-integral regulator, including a Proportional-proportional part and an Integral-integral part) to obtain the d-axis component Idref of the current control target value.

[0109] Step 300a3: After making a difference between the reactive power compensation value Qcref and the actual reactive power value Qc, the difference is input into the PI regulator to obtain the q-axis component Iqref of the current control target value.

[0110] Step 300 a 4 : Based on the d-axis component Idref of the current control target value and the q-axis component Iqref of the current control target value, confirm the current control target value.

[0111] See also Fig.13 and Fig.15 In some embodiments, the step of obtaining the current control target value includes:

[0112] Step 300b1: based on the target value Pref of active power of the target system and the actual value Pc of active power, obtaining the difference of active power; wherein the target system is the first AC system 10 or the second AC system 20 .

[0113] Step 300b2: Based on the difference in active power, the d-axis component Idref of the current control target value is obtained through the PI regulator.

[0114] Step 300b3: Based on the target value Qref of the target system reactive power and the actual value Qc of the reactive power, the difference of the reactive power is obtained.

[0115] Step 300b4: Based on the difference in reactive power, the q-axis component Iqref of the current control target value is obtained through the PI regulator.

[0116] Step 300b5: confirm the current control target value based on the d-axis component Idref of the current control target value and the q-axis component Iqref of the current control target value.

[0117] See also Fig.13 and Fig.16 In some embodiments, the step of obtaining the current control target value includes:

[0118] Step 300c1: confirm the voltage value of each phase of the target system, and perform dq transformation (DQ Transformation, a coordinate transformation method commonly used in power systems, used to convert a three-phase AC circuit into a rotating coordinate system for analysis and control), to obtain the d-axis component Ud and the q-axis component Uq of the target system voltage, wherein the target system is the first AC system 10 or the second AC system 20;

[0119] Step 300c2: confirming the target value Pref of active power and the target value Qref of reactive power of the target system;

[0120] Step 300c3: based on the d-axis component Ud of the target system voltage and the target value Pref of the active power of the target system, obtaining the d-axis component Idref of the current control target value;

[0121] Step 300c4: based on the q-axis component Uq of the target system voltage and the target value Qref of the reactive power of the target system, obtaining the q-axis component Iqref of the current control target value;

[0122] Step 300c5: confirm the current control target value based on the d-axis component Idref of the current control target value and the q-axis component Iqref of the current control target value.

[0123] Step 400: Obtain the voltage vector of the phase-splitting reactance 40 based on the impedance and current control target value.

[0124] In some embodiments, the voltage vector of the phase-splitting reactance 40 is represented by:

[0125]

[0126] in, is the voltage vector of the phase-splitting reactance 40; j is an imaginary unit; X L is the impedance of the phase reactor 40L; I1 is the current value of the first module 30.

[0127] Step 500 : Based on the voltage vector difference and the voltage vector of the phase-splitting reactance 40 , obtain the compensation voltage vector of the voltage source converter 90 .

[0128] In some embodiments, the characterization formula of the compensation voltage vector of the voltage source converter 90 includes:

[0129]

[0130] in, is the compensation voltage vector of the voltage source converter 90; is a voltage vector difference between the first voltage vector and the second voltage vector; is the voltage vector of the phase-splitting reactance 40.

[0131] See also Fig.13 , step 500 specifically includes:

[0132] Step 510: Confirm the d-axis component Idref and the q-axis component Iqref of the current control target value, and the d-axis component Id and the q-axis component Iq of the actual value of the interconnected transfer power controller current.

[0133] Step 520: Subtract the d-axis component Idref of the current control target value from the d-axis component Id of the actual value of the interconnected transfer power controller current and input the resultant difference into the PI controller to obtain the d-axis component of the voltage error value.

[0134] Step 530: Subtract the q-axis component Iqref of the current control target value from the q-axis component Iq of the actual value of the interconnected transfer power controller current and input the resultant difference into a PI controller to obtain the q-axis component of the voltage error value.

[0135] Step 540: Based on the d-axis component of the voltage error value, the d-axis component ΔUsd of the voltage vector difference and the q-phase cross-decoupling value of the voltage vector of the phase-splitting reactance 40, obtain the d-axis component of the compensation voltage vector of the voltage source converter 90.

[0136] Step 550: Based on the q-axis component of the voltage error value, the q-axis component ΔUsq of the voltage vector difference and the d-phase cross-decoupling value of the voltage vector of the phase-splitting reactance 40, obtain the q-axis component of the compensation voltage vector of the voltage source converter 90.

[0137] Step 560 : Confirm the compensation voltage vector of the voltage source converter 90 based on the d-axis component of the compensation voltage vector of the voltage source converter 90 and the q-axis component of the compensation voltage vector of the voltage source converter 90 .

[0138] In some embodiments, the AC signal of the AC system is transformed from a stationary coordinate system to a rotating coordinate system using a dq transformation method: the d-axis component and q-axis component of the voltage sampling value and the d-axis component and q-axis component of the current sampling value are respectively obtained by dq transformation of the three-phase voltage sampling value and the three-phase current sampling value, and the phase-locked angle of the dq transformation and the inverse transformation is based on the voltage reference value or the voltage of the target system.

[0139] In some embodiments, the q-phase cross-decoupling value of the voltage vector of the phase-splitting reactance 40 is: IqωLd, wherein Iq is the q-axis component of the actual value of the current of the interconnected transfer power controller, ω is the angular frequency, and Ld is the d-axis component of the inductance of the phase-splitting reactance 40; the d-phase cross-decoupling value of the voltage vector of the phase-splitting reactance 40 is: IdωLq, wherein Id is the d-axis component of the actual value of the current of the interconnected transfer power controller; Lq is the q-axis component of the inductance of the phase-splitting reactance 40.

[0140] Step 600: The voltage source converter 90 outputs a compensation voltage based on a compensation voltage vector.

[0141] It can be understood that the embodiment of the present application provides a control method for an interconnected transfer power controller, which is used to control the interconnected transfer power controller. The control method provided by the embodiment of the present application first confirms that the voltage vectors of each AC system connected to the interconnected transfer power controller are the first voltage vector and the second voltage vector; obtains the voltage vector difference through the first voltage vector and the second voltage vector; confirms the impedance and current control target values ​​of the phase-splitting reactance 40; obtains the voltage vector of the phase-splitting reactance 40 based on the impedance and current control target values; obtains the compensation voltage vector of the voltage source converter 90 based on the voltage vector difference and the voltage vector of the phase-splitting reactance 40. The control method provided by the present application takes current as the control target, and the power flow regulation capability is no longer limited by the influence of the distributed parameters of the transmission line. It has the advantage of plug-and-play when planning the system installation location, and there is no need to perform system simulation verification. At the same time, the present application takes voltage as the control reference, and by controlling the current DC control power, it can realize the continuous adjustable transmission power, higher power flow control accuracy and good stability.

[0142] Accordingly, see Figures 1 to 10 The embodiment of the present application also provides an interconnection transfer power controller for connecting the first AC system 10 and the second AC system 20, including a control unit, a voltage source converter 90 and a phase-splitting reactor 40. The control unit stores a control program, and the control program is used to execute the control method of the interconnection transfer power controller provided in the embodiment of the present application. The voltage source converter 90 includes a first module 30 and a second module 50. The first module 30 is connected in series between the first AC system 10 and the second AC system 20 in phase separation, and the phase-splitting reactor 40 is connected in series between the first module 30 and the second AC system 20. The input end of the second module 50 is connected to the first AC system 10 or the second AC system 20, and the output end of the second module 50 is connected to the first module 30. The present application converts impedance control into current source control, so that the power regulation of the series-parallel topology is no longer affected by the system grid, thereby improving the flexibility and safety of power regulation.

[0143] In some embodiments, the AC voltages of the first AC system 10 and the second AC system 20 have a common reference point. Specifically, the common reference point includes a ground point.

[0144] In some embodiments, the phase-splitting reactance 40 includes an additional independent reactor connected in series, a transmission line equivalent reactance, and / or a leakage reactance of a transformer.

[0145] In some embodiments, the first module 30 is a series unit and the second module 50 is a parallel unit.

[0146] See also Figure 2In some embodiments, the first module 30 is one or more full-bridge modules 31. When there are multiple full-bridge modules 31, multiple full-bridge modules 31 are cascaded. Specifically, the full-bridge module 31 is a circuit composed of power semiconductor devices in a full-bridge connection form.

[0147] See also Figure 2 and Figure 3 In the above embodiment, the second module 50 is an AC / DC conversion unit (AC / DC conversion unit). Specifically, the second module 50 includes an AC / DC converter 51 (AC / DC converter) and a first transformer 52. The primary side of the first transformer 52 is configured as the input end of the second module 50, and is used to connect to the first AC system 10 to receive the AC power of the first AC system 10; the secondary side of the first transformer 52 is connected to the AC side of the AC / DC converter 51, and the DC side of the AC / DC converter 51 is connected to the DC side of the full-bridge module 31.

[0148] See also Figure 2 and Figure 3 In the above embodiment, when there are multiple full-bridge modules 31, multiple AC / DC converters 51 are correspondingly provided, and the corresponding full-bridge modules 31 are connected to the corresponding AC / DC converters 51. At the same time, the first transformer 52 is provided with multiple secondary sides, and each secondary side of the first transformer 52 is connected to the corresponding AC / DC converter 51.

[0149] See also Figure 4 In some embodiments, the first module 30 includes a second transformer 32 , the primary side of the second transformer 32 is configured to connect the first AC system 10 and the second AC system 20 in series, and the secondary side of the second transformer 32 is connected to the second module 50 .

[0150] See also Figure 4 and Figure 5 In the above embodiment, the second module 50 is an AC / AC conversion unit. Specifically, the second module 50 includes an AC / AC converter 53 and a third transformer 54, the primary side of the third transformer 54 is configured as the input end of the second module 50, and is used to connect to the first AC system 10 to receive the AC power of the first AC system 10; the secondary side of the third transformer 54 is connected to the AC input side of the AC / AC converter 53 (AC / AC converter), and the AC output side of the AC / AC converter 53 is connected to the secondary side of the second transformer 32.

[0151] See also Figure 4 and Figure 5 In the above embodiment, when there are multiple AC / AC converters 53 , the output sides of the multiple AC / AC converters 53 are connected in series and then connected in series with the secondary side of the second transformer 32 .

[0152] See also Figure 4 and Figure 5 In the above embodiment, when there are multiple AC / AC converters 53 , multiple secondary sides of the third transformer 54 are correspondingly provided, and the secondary side of each third transformer 54 is connected to the corresponding AC / AC converter 53 .

[0153] See also Figure 4 and Figure 5 The AC / AC converter 53 is composed of an AC / DC converter and a DC / AC converter (direct current / alternating current converter) connected back to back; when there are multiple AC / AC converters 53, multiple DC / AC converter outputs are cascaded; the AC / DC converter and the DC / AC converter include two-level, three-level or cascaded multi-level circuits composed of power semiconductor devices.

[0154] See also Figure 5 and Figure 6 In the above embodiment, the first module 30 further includes a blocking unit 33 , which is connected in series between the primary side of the second transformer 32 and the phase-splitting reactor 40 .

[0155] See also Figures 5 to 9 In the above embodiment, the blocking unit 33 includes a disconnecting subunit 331 and a bypass subunit 332. The disconnecting subunit 331 includes a diode rectifier bridge 3311 and a blocking capacitor 3312. The blocking capacitor 3312 is connected in parallel to the DC side of the diode rectifier bridge 3311; the bypass subunit 332 is connected in parallel to the DC side or AC side of the diode rectifier bridge 3311. Specifically, the bypass subunit 332 includes a bidirectionally conductive power semiconductor device.

[0156] See also Fig.10 In some embodiments, the interconnected transfer power controller also includes a first voltage acquisition unit 60, a second voltage acquisition unit 70 and a current acquisition unit 80. The first voltage acquisition unit 60 is configured to be connected to the first AC system 10 to acquire the voltage of the first AC system 10; the second voltage acquisition unit 70 is configured to be connected to the second AC system 20 to acquire the voltage of the second AC system 20; the current acquisition unit 80 is connected to the first module 30, and the current acquisition unit 80 is configured to acquire the current of the first module 30.

[0157] In some embodiments, the first voltage acquisition unit 60 and the second voltage acquisition unit 70 are located at the end of the interconnection transfer power controller, or are located on a transmission line that is a certain distance away from the interconnection transfer power controller.

[0158] In some embodiments, the control unit comprises:

[0159] The outer loop controller is used to confirm the current control target value;

[0160] The inner loop controller is used to confirm a first voltage vector and a second voltage vector, the first voltage vector is the voltage vector of the first AC system 10, and the second voltage vector is the voltage vector of the second AC system 20; based on the first voltage vector and the second voltage vector, obtain a voltage vector difference; confirm the impedance of the phase-splitting reactance 40; based on the impedance and the current control target value, obtain the voltage vector of the phase-splitting reactance 40; based on the voltage vector difference and the voltage vector of the phase-splitting reactance 40, obtain a compensation voltage vector of the voltage source converter 90; the voltage source converter outputs a compensation voltage based on the compensation voltage vector.

[0161] It can be understood that an interconnection transfer power controller provided by an embodiment of the present application is used to connect a first AC system 10 and a second AC system 20, including a control unit, a voltage source converter 90 and a phase-splitting reactor 40. The control unit stores a control program, and the control program is used to execute the control method of the interconnection transfer power controller provided by the embodiment of the present application. The voltage source converter 90 includes a first module 30 and a second module 50. The first module 30 is connected in series between the first AC system 10 and the second AC system 20 in phase separation, and the phase-splitting reactor 40 is connected in series between the first module 30 and the second AC system 20. The input end of the second module 50 is connected to the first AC system 10 or the second AC system 20, and the output end of the second module 50 is connected to the first module 30. The present application converts impedance control into current source control, so that the power regulation of the series-parallel topology is no longer affected by the system grid, which improves the flexibility and safety of power regulation. .

[0162] The control method of the interconnected power transfer controller and the interconnected power transfer controller provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A control method for an interconnected power transfer controller, characterized in that: Used to control an interconnection transfer power controller, the interconnection transfer power controller comprising a voltage source converter (90) and a phase-splitting reactor (40), the voltage source converter (90) being connected to the phase-splitting reactor (40), the voltage source converter (90) and the phase-splitting reactor (40) being configured to connect a first AC system (10) and a second AC system (20) in phases; the control method comprising: Confirming a first voltage vector and a second voltage vector, wherein the first voltage vector is a voltage vector of the first AC system (10), and the second voltage vector is a voltage vector of the second AC system (20); Based on the first voltage vector and the second voltage vector, obtaining a voltage vector difference; confirming the impedance and current control target value of the phase-splitting reactance (40); Based on the impedance and the current control target value, obtaining a voltage vector of the phase-splitting reactance (40); Confirming the d-axis component and the q-axis component of the current control target value, and the d-axis component and the q-axis component of the actual value of the interconnection transfer power controller current; The d-axis component of the current control target value and the d-axis component of the actual current value of the interconnected transfer power controller are subtracted and input into a PI controller to obtain the d-axis component of the voltage error value; The q-axis component of the current control target value and the q-axis component of the actual current value of the interconnected transfer power controller are subtracted and input into a PI controller to obtain the q-axis component of the voltage error value; Based on the d-axis component of the voltage error value, the d-axis component of the voltage vector difference and the q-phase cross-decoupling value of the voltage vector of the phase-splitting reactance (40), obtaining the d-axis component of the compensation voltage vector of the voltage source converter (90); Based on the q-axis component of the voltage error value, the q-axis component of the voltage vector difference and the d-phase cross-decoupling value of the voltage vector of the phase-splitting reactance (40), obtaining the q-axis component of the compensation voltage vector of the voltage source converter (90); Determining the compensation voltage vector of the voltage source converter (90) based on the d-axis component of the compensation voltage vector of the voltage source converter (90) and the q-axis component of the compensation voltage vector of the voltage source converter (90); The voltage source converter (90) outputs a compensation voltage based on the compensation voltage vector.

2. The control method of the interconnected power transfer controller according to claim 1, characterized in that: The voltage vector representation formula of the phase splitting reactance (40) includes: in, is the voltage vector of the phase-splitting reactance (40); j is an imaginary unit; X L is the impedance of the phase-splitting reactance (40) L; I1 is the current value of the first module (30).

3. The control method of the interconnected power transfer controller according to claim 1, characterized in that: The characterization formula of the current control target value includes: or Wherein, I2 is the current control target value; S is the power control target value, Wherein, P is the target value of active power, Q is the target value of reactive power; V1 is the voltage value of the first AC system (10); and V2 is the voltage value of the second AC system (20).

4. The control method of the interconnected power transfer controller according to claim 1, characterized in that: The step of obtaining the current control target value comprises: Based on the target value of active power of the target system, the target value of reactive power, the current value of each phase, and the voltage value of each phase, the compensation value of active power of the target system, the actual value of active power, the compensation value of reactive power, and the actual value of reactive power are obtained; After making a difference between the compensation value of the active power and the actual value of the active power, the difference is input into a PI regulator to obtain a d-axis component of the current control target value; After making a difference between the reactive power compensation value and the actual reactive power value, the difference is input into a PI regulator to obtain a q-axis component of the current control target value; confirming the current control target value based on a d-axis component of the current control target value and a q-axis component of the current control target value; Wherein, the target system is a first AC system (10) or a second AC system (20).

5. The control method of the interconnected power transfer controller according to claim 1, characterized in that: The step of obtaining the current control target value comprises: Based on the target value of active power of the target system and the actual value of active power, obtaining a difference in active power; Based on the difference in active power, obtaining a d-axis component of the current control target value through a PI regulator; Based on the target value of reactive power of the target system and the actual value of reactive power, obtaining a reactive power difference; Based on the reactive power difference, obtaining a q-axis component of the current control target value through the PI regulator; confirming the current control target value based on a d-axis component of the current control target value and a q-axis component of the current control target value; Wherein, the target system is a first AC system (10) or a second AC system (20).

6. The control method of the interconnected power transfer controller according to claim 1, characterized in that: The step of obtaining the current control target value comprises: Confirming each phase voltage value of a target system and performing dq transformation to obtain a d-axis component and a q-axis component of the target system voltage, wherein the target system is the first AC system (10) or the second AC system (20); Confirming a target value of active power and a target value of reactive power of the target system; acquiring a d-axis component of the current control target value based on the d-axis component of the target system voltage and the target value of active power of the target system; acquiring a q-axis component of the current control target value based on the q-axis component of the target system voltage and the target value of reactive power of the target system; The current control target value is confirmed based on the d-axis component of the current control target value and the q-axis component of the current control target value.

7. An interconnection power transfer controller, characterized in that: The interconnected power transfer controller comprises a control unit, in which a control program is stored, and the control program is configured to execute the control method according to any one of claims 1 to 6; and a voltage source converter (90) and a split-phase reactor (40), wherein the voltage source converter (90), the split-phase reactor (40) and the control unit are connected, and the voltage source converter (90) and the split-phase reactor (40) are configured to connect the first AC system (10) and the second AC system (20) in phases, and the voltage source converter (90) comprises: A first module (30), the first module (30) being configured to be connected in series between the first AC system (10) and the second AC system (20) in phase separation; a second module (50), wherein an input end of the second module (50) is configured to be connected to the first AC system (10) or the second AC system (20), and an output end of the second module (50) is connected to the first module (30); The phase-splitting reactor (40) is connected in series with the first module (30), and the phase-splitting reactor (40) is configured to be connected in series between the first module (30) and the first AC system (10) or the second AC system (20).

8. The interconnection power transfer controller according to claim 7, characterized in that: The first module (30) comprises a full-bridge module (31), and an AC end of the full-bridge module (31) is configured to be connected in series with the first AC system (10) and the second AC system (20); The second module (50) comprises an AC / DC converter (51) and a first transformer (52), wherein the primary side of the first transformer (52) is configured as the input end of the second module (50), the secondary side of the first transformer (52) is connected to the AC side of the AC / DC converter (51), and the DC side of the AC / DC converter (51) is connected to the DC side of the full-bridge module (31).

9. The interconnection power transfer controller according to claim 8, characterized in that: The primary side of the first transformer (52) is configured to be connected to the first AC system (10) to receive AC power from the first AC system (10).

10. The interconnected power transfer controller according to claim 7, characterized in that: The first module (30) includes a second transformer (32), the primary side of the second transformer (32) being configured to connect the first AC system (10) and the second AC system (20) in series; The second module (50) comprises an AC / AC converter (53) and a third transformer (54), wherein the primary side of the third transformer (54) is configured as the input end of the second module (50), the secondary side of the third transformer (54) is connected to the AC input side of the AC / AC converter (53), and the AC output side of the AC / AC converter (53) is connected to the secondary side of the second transformer (32).

11. The interconnection power transfer controller according to claim 10, characterized in that: When there are multiple AC / AC converters (53), the output sides of the multiple AC / AC converters (53) are connected in series and then connected in series with the secondary side of the second transformer (32).

12. The interconnection power transfer controller according to claim 10, characterized in that: The first module (30) further comprises a blocking unit (33), wherein the blocking unit (33) is connected in series between the primary side of the second transformer (32) and the phase-splitting reactor (40).

13. The interconnected power transfer controller according to claim 12, characterized in that: The blocking unit (33) comprises: A disconnecting subunit (331), the disconnecting subunit (331) comprising a diode rectifier bridge (3311) and a blocking capacitor (3312), the blocking capacitor (3312) being connected in parallel to a DC side of the diode rectifier bridge (3311); A bypass subunit (332), wherein the bypass subunit (332) is connected in parallel with the DC side or the AC side of the diode rectifier bridge (3311).

14. The interconnected power transfer controller according to claim 12, characterized in that: Also includes: A first voltage acquisition unit (60), the first voltage acquisition unit (60) being configured to be connected to the first AC system (10) to acquire the voltage of the first AC system (10); A second voltage collection unit (70), the second voltage collection unit (70) being configured to be connected to the second AC system (20) to collect the voltage of the second AC system (20); A current collection unit (80), the current collection unit (80) is connected to the first module (30), and the current collection unit (80) is configured to collect the current of the first module (30).

15. The interconnection power transfer controller according to claim 14, characterized in that: The AC voltages of the first AC system (10) and the second AC system (20) have a common reference point, and the common reference point includes a grounding point; The first voltage acquisition unit (60) and the second voltage acquisition unit (70) are located at the end of the interconnection transfer power controller, or are located on a transmission line that is a certain distance away from the interconnection transfer power controller.

16. The interconnection power transfer controller according to claim 7, characterized in that: The phase-splitting reactance (40) comprises a series-connected reactor, a transmission line equivalent reactance and / or a transformer leakage reactance.

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