Power decoupling control method and system based on injection type power grid commutation converter

Abstract

The invention provides a power decoupling control method and system based on an injection-type power grid commutation converter, relates to the field of power grid commutation converters, is applied to the injection-type power grid commutation converter, and comprises an upper bridge group and a lower bridge group which are consistent in structure, the upper bridge group and the lower bridge group are connected in parallel at an alternating current side, and the upper bridge group and the lower bridge group are connected in series at a direct current side port. The upper bridge group comprises an upper bridge LCC thyristor main bridge and an upper bridge shunt module; the method comprises the following steps: acquiring an active power reference value, a reactive power reference value, an active power measured value and a reactive power measured value of the injection type power grid commutation converter; determining a trigger angle of the upper bridge group and a trigger angle of the lower bridge group based on the active power reference value, the reactive power reference value, the active power measured value and the reactive power measured value; and according to the trigger angle of the upper bridge group, the trigger angle of the lower bridge group and the trigger constraint set, generating a trigger signal to control the operation of the injection-type power grid commutation converter, thereby realizing power decoupling control of the injection-type power grid commutation converter.

Description

Technical Field

[0001] The present invention relates to the field of line-commutated converters, and particularly to a power decoupling control method and system based on an injection-type line-commutated converter. Background Art

[0002] The Reinjection Line Commutated Converter (RLCC) is a new type of converter formed based on the harmonic injection theory, aiming to improve commutation reliability and optimize power control capabilities through specific technical means. The existing RLCC is composed of a shunt module formed by reverse-blocking fully-controlled devices cascaded on the DC side of the LCC. Essentially, it belongs to a current-source converter and is fully applicable to high-voltage direct current transmission scenarios. The RLCC inherently has the advantages of the LCC being suitable for ultra-high power applications, and by injecting the DC current processed by the shunt module into the LCC, zero-current commutation of the LCC thyristors can be achieved, enabling turn-off capabilities, suppressing commutation failures, and achieving leading or lagging power operation. Additionally, when the waveform of the injected DC current into the LCC is closer to the ideal injection waveform, the AC-side current is closer to a sine waveform, and even external filtering devices may not be required. Compared with the LCC, the RLCC has significantly improved commutation failure suppression and AC / DC side current harmonic suppression.

[0003] Although the shunt module enables the thyristors to have turn-off capabilities, the existing RLCC can actually only control the trigger angle of the main bridge. Therefore, there are certain disadvantages in power control flexibility, restricting its development. For example, applying DC voltage control and power factor correction control to a Current Source Converter (CSC) using fully-controlled reverse-blocking power devices has the ability to operate with a high power factor. However, fundamental frequency modulation makes the CSC using fully-controlled power devices have only a single control variable, the trigger angle, and cannot achieve power decoupling control. By mathematically modeling the CSC and establishing an inner and outer loop control strategy with the capacitor voltage as the control target, although active and reactive power decoupling control can be achieved, affected by the circuit characteristics of the CSC, the amplitude and phase of the capacitor voltage will change simultaneously, and the active and reactive powers are inevitably linked, which means that the CSC can only have partial decoupling control capabilities.

[0004] Therefore, a power decoupling control method and system based on an injection-type line-commutated converter are needed to achieve power decoupling control of the injection-type line-commutated converter. Summary of the Invention

[0005] The present invention provides a power decoupling control method and system based on an injection-type line-commutated converter, which is applied to an injection-type line-commutated converter. The injection-type line-commutated converter includes an upper bridge group and a lower bridge group. The upper bridge group and the lower bridge group have the same structure. The upper bridge group and the lower bridge group are connected in parallel on the AC side and in series at the DC side ports. The upper bridge group includes an upper bridge LCC thyristor main bridge and an upper bridge shunt module. The method includes: obtaining the reference value of the active power, the reference value of the reactive power, the measured value of the active power, and the measured value of the reactive power of the injection-type line-commutated converter; determining the trigger angle of the upper bridge group and the trigger angle of the lower bridge group based on the reference value of the active power, the reference value of the reactive power, the measured value of the active power, and the measured value of the reactive power; generating a trigger signal according to the trigger angle of the upper bridge group, the trigger angle of the lower bridge group, and the trigger constraint set, and controlling the operation of the injection-type line-commutated converter.

[0006] Further, determining the trigger angle of the upper bridge group and the trigger angle of the lower bridge group based on the reference value of the active power, the reference value of the reactive power, the measured value of the active power, and the measured value of the reactive power includes: determining the reference value of the active current and the reference value of the reactive current of the AC side current of the injection-type line-commutated converter based on the reference value of the active power, the reference value of the reactive power, the measured value of the active power, and the measured value of the reactive power; calculating a first intermediate trigger angle and a second intermediate trigger angle according to the reference value of the active current and the reference value of the reactive current of the AC side current of the injection-type line-commutated converter; and determining the trigger angle of the upper bridge group and the trigger angle of the lower bridge group according to the first intermediate trigger angle and the second intermediate trigger angle.

[0007] Further, the first intermediate trigger angle and the second intermediate trigger angle are calculated based on the following formulas: , where is the first intermediate trigger angle, is the reference value of the active current, is the reference value of the reactive current, is the second intermediate trigger angle, is the current modulation coefficient of the upper bridge group and the lower bridge group, is the DC current.

[0008] Further, the trigger angle of the upper bridge group and the trigger angle of the lower bridge group are calculated based on the following formulas: , , where is the trigger angle of the upper bridge group, is the trigger angle of the lower bridge group.

[0009] Furthermore, the upper-bridge shunt module includes an upper-bridge first injection branch and an upper-bridge second injection branch, and the upper-bridge first injection branch and the upper-bridge second injection branch have the same structure; the upper-bridge LCC thyristor main bridge includes an upper-bridge Y-bridge thyristor group and an upper-bridge D-bridge thyristor group, and the upper-bridge Y-bridge thyristor group and the upper-bridge D-bridge thyristor group have the same structure; the upper-bridge first injection branch is electrically connected to the upper-bridge Y-bridge thyristor group, and the output end of the upper-bridge Y-bridge thyristor group is electrically connected to the Y-type winding of the upper-bridge phase-shifting transformer; the upper-bridge second injection branch is electrically connected to the upper-bridge D-bridge thyristor group, and the output end of the upper-bridge D-bridge thyristor group is electrically connected to the D-type winding of the upper-bridge phase-shifting transformer.

[0010] Furthermore, the upper-bridge first injection branch includes an upper-bridge first fully-controlled injection switch, an upper-bridge second fully-controlled injection switch, and an upper-bridge first injection inductor. The upper-bridge first injection inductor is connected to the DC side port of the upper-bridge group, and the upper-bridge first fully-controlled injection switch tube is in parallel with the upper-bridge second fully-controlled injection switch; the upper-bridge second injection branch includes an upper-bridge third fully-controlled injection switch, an upper-bridge fourth fully-controlled injection switch, and an upper-bridge second injection inductor. The upper-bridge second injection inductor is connected to the DC side port of the upper-bridge group, and the upper-bridge third fully-controlled injection switch tube is in parallel with the upper-bridge fourth fully-controlled injection switch; the output end of the upper-bridge first fully-controlled injection switch and the output end of the upper-bridge third fully-controlled injection switch are electrically connected to the upper-bridge Y-bridge thyristor group, and the output end of the upper-bridge second fully-controlled injection switch and the output end of the upper-bridge fourth fully-controlled injection switch are electrically connected to the upper-bridge D-bridge thyristor group; the upper-bridge Y-bridge thyristor group includes an upper-bridge Y-bridge 6-pulse three-phase bridge.

[0011] Furthermore, the trigger constraint set includes: the thyristor switching frequencies of the upper-bridge Y-bridge thyristor group and the upper-bridge D-bridge thyristor group of the upper-bridge LCC thyristor main bridge are 50 Hz, the trigger pulse intervals between adjacent numbered thyristor switches in the upper-bridge Y-bridge thyristor group are 60°, the trigger pulse intervals between adjacent numbered thyristor switches in the upper-bridge D-bridge thyristor group are 60°, and the pulse widths of the thyristor switches in the upper-bridge Y-bridge thyristor group and the upper-bridge D-bridge thyristor group are 120°; the trigger pulse intervals between the thyristor switches with the same serial number in the upper-bridge Y-bridge thyristor group and the upper-bridge D-bridge thyristor group are 30°, and the thyristor switches in the upper-bridge Y-bridge thyristor group lead the thyristor switches with the same serial number in the upper-bridge D-bridge thyristor group.

[0012] Furthermore, the trigger constraint set includes: the upper-bridge shunt module adopts a seven-level injection form, the switching frequency is 300 Hz, and the width of each level is 5°; the switching pulse of the upper-bridge shunt module provides a zero level at the natural commutation point of the upper-bridge LCC thyristor main bridge.

[0013] Further, the trigger constraint set includes: the upper-bridge Y-bridge first fully-controlled injection switch and the upper-bridge Y-bridge second fully-controlled injection switch of the upper-bridge first injection branch are complementarily turned on; the upper-bridge Y-bridge third fully-controlled injection switch and the upper-bridge Y-bridge fourth fully-controlled injection switch of the upper-bridge second injection branch are complementarily turned on.

[0014] The present invention provides a power decoupling control system based on an injection-type line-commutated converter, which is used to execute the above-mentioned power decoupling control method based on an injection-type line-commutated converter, and includes: a data acquisition module, which is used to acquire the active power reference value, reactive power reference value, measured active power value, and measured reactive power value of the injection-type line-commutated converter; a parameter determination module, which is used to determine the trigger angle of the upper-bridge group and the trigger angle of the lower-bridge group based on the active power reference value, reactive power reference value, measured active power value, and measured reactive power value; an operation control module, which is used to generate a trigger signal according to the trigger angle of the upper-bridge group, the trigger angle of the lower-bridge group, and the trigger constraint set, and control the operation of the injection-type line-commutated converter.

[0015] Compared with the prior art, the power decoupling control method and system based on an injection-type line-commutated converter provided by the present invention have at least the following beneficial effects: Power decoupling control enables independent adjustment of active power and reactive power. By obtaining the active power reference value and reactive power reference value and comparing them with the measured values, the trigger angles of the upper-bridge group and the lower-bridge group can be adjusted respectively, so as to accurately control the active power and reactive power output by the converter and meet the different power requirements of the power system. For example, when more active power needs to be transmitted to the power grid, relevant parameters can be adjusted separately to increase the active power output; when the system voltage needs to be regulated, the reactive power output can be independently controlled. It can quickly respond to changes in active power and reactive power in the system. When the load or power generation situation of the power grid changes, the control method can quickly calculate a new trigger angle according to the deviation between the reference value and the measured value, generate a trigger signal, and enable the converter to timely adjust the output power to maintain the power balance of the system.

[0016] By accurately controlling the reactive power output, the power decoupling control method helps to maintain the stability of the AC bus voltage. In the power grid, the balance of reactive power is crucial for voltage stability. When the system needs reactive power support, the converter can timely provide the required reactive power to prevent voltage fluctuations and voltage collapse, and improve the voltage stability of the power system.

[0017] When a fault or disturbance occurs in the system, the power decoupling control can quickly adjust the output power of the converter, provide necessary power support, and help the system quickly resume stable operation. For example, during a fault, the converter can adjust the active and reactive power outputs to reduce the power deficit in the system and alleviate the fluctuations of frequency and voltage.

[0018] The main bridge of the LCC thyristor adopts a parallel LCC structure, inheriting the characteristics of high power density of LCC, and can achieve efficient power conversion. Due to the high power density, the injection-type line-commutated converter can achieve large-capacity power transmission in a smaller physical space, which is suitable for application scenarios with limited space. The injection-type line-commutated converter further modulates the constant DC current by cascading a shunt module composed of reverse-blocking fully-controlled devices on the DC side, making the AC side current harmonics extremely low, approaching the output characteristics of the MMC. The existence of the shunt module enables the injection-type line-commutated converter to have four-quadrant operation ability, and can flexibly control the transmission of active power and reactive power to meet different needs of the power grid.

[0019] The shunt module enables the thyristor valve of the parallel LCC main bridge to have zero-current turn-off ability, effectively avoiding the risk of commutation failure. This is particularly important during AC system faults or disturbances, and can ensure the stable operation of the system. The suppression of commutation failure improves the reliability of the system and reduces power outages caused by commutation failure.

[0020] The injection-type line-commutated converter can operate in four quadrants, that is, it can independently control the transmission of active power and reactive power to achieve power decoupling control. This helps to maintain the voltage stability and power balance of the power grid. The four-quadrant operation ability enables the injection-type line-commutated converter to adapt to different power grid conditions, including various scenarios such as power generation, power consumption, and reactive power compensation.

[0021] Due to the adoption of reverse-blocking fully-controlled devices, the injection-type line-commutated converter can achieve zero-current turn-off during the switching process, reducing the switching loss and improving the overall efficiency of the system. Zero switching loss means lower energy loss and less heat generation, thus reducing the operating cost and maintenance cost of the system. Description of the Drawings

[0022] This specification will be further described in the form of exemplary embodiments, and these exemplary embodiments will be described in detail through the drawings. These embodiments are not restrictive. In these embodiments, the same numbers represent the same structures, where: Figure 1 is a schematic flow chart of the power decoupling control method based on the injection-type line-commutated converter shown in some embodiments of this specification; Figure 2 is a schematic circuit diagram of the injection-type line-commutated converter shown in some embodiments of this specification; Figure 3 is a schematic diagram of the vector relationship between the AC side voltage and current shown in some embodiments of this specification; Figure 4 is a power decoupling control block diagram under the rectification state shown in some embodiments of this specification; Figure 5 is a schematic diagram of the trigger signal timing shown in some embodiments of this specification; Figure 6 is an explanatory diagram of relevant physical quantities on the AC and DC sides shown in some embodiments of this specification; Figure 7 is a schematic diagram of the modules of the power decoupling control system based on an injection - type line - commutated converter shown in some embodiments of this specification. Detailed implementation manners

[0023] To more clearly illustrate the technical solutions of the embodiments of this specification, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some examples or embodiments of this specification. For those of ordinary skill in the art, without creative efforts, this specification can also be applied to other similar scenarios based on these drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the drawings represent the same structure or operation.

[0024] The power decoupling control method based on an injection - type line - commutated converter can be applied to an injection - type line - commutated converter. Figure 2 is a schematic circuit diagram of an injection - type line - commutated converter shown in some embodiments of this specification. As Figure 2 shown, the injection - type line - commutated converter includes an upper bridge group and a lower bridge group. The structures of the upper bridge group and the lower bridge group are the same. The upper bridge group and the lower bridge group are connected in parallel on the AC side and in series at the DC - side ports. The upper bridge group includes an upper - bridge LCC thyristor main bridge and an upper - bridge shunt module. I dc is the DC current. i rYhj (j = a, b, c) and i rDhj are respectively the three - phase currents of the Y - bridge and the D - bridge on the secondary side of the phase - shifting transformer of the upper bridge group. i rYlj (j = a, b, c) and i rDlj are respectively the three - phase currents of the Y - bridge and the D - bridge on the secondary side of the phase - shifting transformer of the lower bridge group. i rhj is the three - phase AC current of the upper bridge group. i rlj is the three - phase AC current of the lower bridge group. i rj is the AC - side current of the injection - type line - commutated converter. U dcr is the DC - side voltage. U dcYh and UdcDh The DC voltages of the Y-bridge and D-bridge of the upper bridge group respectively, U dcYl and U dcDl The DC voltages of the Y-bridge and D-bridge of the upper bridge group respectively. Taking the upper bridge group as an example, the description is as follows.

[0025] As Figure 2 shown, the upper bridge group includes an upper bridge LCC thyristor main bridge and an upper bridge shunt module. The upper bridge shunt module is arranged between the upper bridge LCC thyristor main bridge and the AC side port of the upper bridge group. The upper bridge LCC thyristor main bridge includes an upper bridge Y-bridge thyristor group ( Figure 2 the valve group T in Yh1 -T Yh6 ), and an upper bridge D-bridge thyristor group ( Figure 2 the valve group T in Dh1 -T Dh6 ). The structures of the upper bridge Y-bridge thyristor group and the upper bridge D-bridge thyristor group are the same. T Yh1 -T Yh6 , T Dl1 -T Yl6 are all semi-controlled devices, thyristors. The upper bridge shunt module includes an upper bridge first injection branch and an upper bridge second injection branch, and the structures of the upper bridge first injection branch and the upper bridge second injection branch are the same; the upper bridge first injection branch is electrically connected to the upper bridge Y-bridge thyristor group, and the output end of the upper bridge Y-bridge thyristor group is electrically connected to the Y-type winding of the upper bridge phase-shifting transformer; the upper bridge second injection branch is electrically connected to the upper bridge D-bridge thyristor group, and the output end of the upper bridge D-bridge thyristor group is electrically connected to the D-type winding of the upper bridge phase-shifting transformer.

[0026] In some embodiments, the upper bridge first injection branch includes an upper bridge first fully controlled injection switch T Yrh1 , an upper bridge second fully controlled injection switch T Drh1 , and an upper bridge first injection inductor L h1 . The upper bridge first injection inductor is connected to the DC side port of the upper bridge group, and the upper bridge first fully controlled injection switch tube is in parallel with the upper bridge second fully controlled injection switch; the upper bridge second injection branch includes an upper bridge third fully controlled injection switch T Yrhn , an upper bridge fourth fully controlled injection switch T Drhn , and an upper bridge second injection inductor L hn . The upper bridge second injection inductor is connected to the DC side port of the upper bridge group, and the upper bridge third fully controlled injection switch tube is in parallel with the upper bridge fourth fully controlled injection switch; the output end of the upper bridge first fully controlled injection switch and the output end of the upper bridge third fully controlled injection switch are electrically connected to the upper bridge Y-bridge thyristor group, and the output end of the upper bridge second fully controlled injection switch and the output end of the upper bridge fourth fully controlled injection switch are electrically connected to the upper bridge D-bridge thyristor group; the upper bridge Y-bridge thyristor group includes an upper bridge Y-bridge 6-pulse three-phase bridge ( Figure 2 the valve group T inYh1 -T Yh6 ).

[0027] As Figure 2 shown, the lower bridge group includes the lower bridge LCC thyristor main bridge and the lower bridge shunt module. A lower bridge shunt module is disposed between the lower bridge LCC thyristor main bridge and the AC side port of the lower bridge group. The lower bridge LCC thyristor main bridge includes a lower bridge Y-bridge thyristor group ( Figure 2 the valve group T in Yl1 -T Yl6 ), and a lower bridge D-bridge thyristor group ( Figure 2 the valve group T in Dl1 -T Dl6 ). The lower bridge shunt module includes a lower bridge first injection branch and a lower bridge second injection branch. The lower bridge first injection branch includes a lower bridge first fully controlled injection switch T Yrl1 , a lower bridge second fully controlled injection switch T Drl1 , and a lower bridge first injection inductor L l1 . The lower bridge second injection branch includes a lower bridge third fully controlled injection switch T Yrln , a lower bridge fourth fully controlled injection switch T Drln , and a lower bridge second injection inductor L ln .

[0028] Figure 1 is a schematic flow chart of a power decoupling control method based on an injection-type line-commutated converter according to some embodiments of this specification. As Figure 1 shown, the power decoupling control method based on an injection-type line-commutated converter may include the following steps.

[0029] Step 110, obtaining the active power reference value, reactive power reference value, measured active power, and measured reactive power of the injection-type line-commutated converter.

[0030] Specifically, under the condition of balanced three-phase grid voltage, taking the direction of the AC bus voltage phasor U r as the d-axis direction, there is u rd = U m , u rq = 0, U m is the modulus of the AC bus voltage phasor, then , wherein, is the active power on the AC side, is the reactive power on the AC side, is the component of the AC bus voltage on the d axis, is the component of the AC-side current on the d axis, is the component of the AC-side current on the q axis.

[0031] The measured active power and the measured reactive power can be calculated according to the above formulas.

[0032] Step 120: Based on the active power reference value, the reactive power reference value, the measured active power, and the measured reactive power, determine the trigger angles of the upper bridge group and the lower bridge group.

[0033] In some embodiments, step 120 specifically includes: Based on the active power reference value, the reactive power reference value, the measured active power, and the measured reactive power, determining the trigger angles of the upper bridge group and the lower bridge group includes: Based on the active power reference value, the reactive power reference value, the measured active power, and the measured reactive power, determine the reference active current value and the reference reactive current value of the AC-side current of the injection-type line-commutated converter; According to the reference active current value and the reference reactive current value of the AC-side current of the injection-type line-commutated converter, calculate the first intermediate trigger angle and the second intermediate trigger angle; According to the first intermediate trigger angle and the second intermediate trigger angle, determine the trigger angles of the upper bridge group and the lower bridge group.

[0034] Specifically, Figure 6 is the diagram of relevant physical quantities on the AC and DC sides shown in some embodiments of this specification. As Figure 6 shown, take the AC bus voltage phasor as the reference phasor. The AC bus voltage phasor , the upper bridge group, the lower bridge group, and the AC-side current phasor of the injection-type line-commutated converter are respectively: , , , , wherein, , , and are the instantaneous voltage values of the three phases a , b , c of the AC bus, is the amplitude of the AC bus voltage, is the angular frequency of the AC voltage, is the time variable, is the firing angle of the upper bridge group, is the firing angle of the lower bridge group.

[0035] Taking phase A as an example for analysis, the AC side current of the injection-type line-commutated converter can be expressed as: , The phasor of the AC side current is expressed in polar coordinate form as: , From the above analysis, the vector relationship between the AC side voltage and current as shown in Figure 3 can be obtained. In Figure 3 , is the phase angle, is the equivalent resistance, is the equivalent reactance. Thus, it can be known that the amplitude of the AC side current of the injection-type line-commutated converter is controlled by , and the phase is controlled by .

[0036] Using the equal-amplitude Park transformation, the AC side current of the injection-type line-commutated converter can be transformed into: , Let , , , can be expressed as: , Furthermore, the inverse calculation formulas for and can be obtained: , , where is the first intermediate firing angle, is the reference value of the active current, is the reference value of the reactive current, is the second intermediate firing angle, is the current modulation coefficient of the upper bridge group and the lower bridge group, is the DC current.

[0037] Figure 4 is the power decoupling control block diagram in the rectification state according to some embodiments of this specification. As shown in Figure 4 , through the PI regulator based on the active power reference value and the reactive power reference value , measured active power value , maximum d-axis current I d max , minimum d-axis current I d min , maximum q-axis current I q max , minimum q-axis current I q min and measured reactive power value Q r(meas) , generate the active current reference value of the AC side current of the injection-type line-commutated converter i rdref and reactive current reference value i rqref , and then according to , the back-calculation formula, calculate to obtain , , and then according to , calculate the firing angle of the upper bridge group and the firing angle of the lower bridge group to achieve a control closed-loop. If it operates in the inverter state, the 0° compensation angle needs to be replaced with 180°.

[0038] Step 130, generate trigger signals according to the firing angle of the upper bridge group, the firing angle of the lower bridge group and the trigger constraint set to control the operation of the injection-type line-commutated converter

[0039] In some embodiments, the trigger timing constraints include: The thyristor switching frequencies of the upper-bridge Y-bridge thyristor group and the upper-bridge D-bridge thyristor group of the upper-bridge LCC thyristor main bridge are 50Hz. The trigger pulse intervals between adjacent numbered thyristor switches in the upper-bridge Y-bridge thyristor group are 60°, and the trigger pulse intervals between adjacent numbered thyristor switches in the upper-bridge D-bridge thyristor group are 60°. The pulse widths of the thyristor switches in the upper-bridge Y-bridge thyristor group and the upper-bridge D-bridge thyristor group are 120°; The trigger pulse intervals between the thyristor switches with the same serial number in the upper-bridge Y-bridge thyristor group and the upper-bridge D-bridge thyristor group are 30°, and the thyristor switches in the upper-bridge Y-bridge thyristor group are ahead of the thyristor switches with the same serial number in the upper-bridge D-bridge thyristor group; The upper-bridge shunt module adopts a seven-level injection form, with a switching frequency of 300Hz and each level width of 5°. For the injected seven levels, within a 360° cycle, each switch of the upper-bridge shunt module traverses all set switch states; The switch pulse of the upper-bridge shunt module provides a zero level at the natural commutation point of the upper-bridge LCC thyristor main bridge to ensure that the upper-bridge LCC thyristor main bridge can achieve zero-current turn-off; The first fully-controlled injection switch of the upper-bridge Y-bridge in the first injection branch of the upper bridge and the second fully-controlled injection switch of the upper-bridge Y-bridge are complementary-conducted; The third fully-controlled injection switch of the upper-bridge Y-bridge in the second injection branch of the upper bridge and the fourth fully-controlled injection switch of the upper-bridge Y-bridge are complementary-conducted. At the same time, only one fully-controlled injection switch in one injection branch can be conducted; The triggering timing constraint of the lower-bridge group is the same as the above, and will not be elaborated here.

[0040] Figure 5 It is a schematic diagram of the triggering signal timing shown in some embodiments of this specification. As Figure 5 shown, both the upper-bridge group and the lower-bridge group are triggered in this way. The triggering angles of the upper-bridge group and the lower-bridge group are respectively used for control. The double control variables can realize power decoupling control. The thyristor-based line-commutated converter in the rectifier station can adopt Figure 5 the triggering signal timing shown for modulation. In the figure, represents the triggering signal of the * switch. For example, is the triggering signal of , is 's triggering signal.

[0041] Figure 7 It is a module schematic diagram of the power decoupling control system based on the injection-type line-commutated converter shown in some embodiments of this specification. As Figure 7 shown, the power decoupling control system based on the injection-type line-commutated converter can include a data acquisition module, a parameter determination module, and an operation control module.

[0042] The data acquisition module is used to acquire the active power reference value, reactive power reference value, measured active power value, and measured reactive power value of the injection-type line-commutated converter; The parameter determination module is used to determine the triggering angle of the upper-bridge group and the triggering angle of the lower-bridge group based on the active power reference value, reactive power reference value, measured active power value, and measured reactive power value; The operation control module is used to generate triggering signals according to the triggering angle of the upper-bridge group, the triggering angle of the lower-bridge group, and the triggering constraint set, and control the operation of the injection-type line-commutated converter.

[0043] The power decoupling control system based on the injection-type line-commutated converter can be used to execute the power decoupling control method based on the injection-type line-commutated converter, which will not be elaborated here.

[0044] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this specification may be regarded as consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly presented and described in this specification.

Claims

1. A power decoupling control method for an injection-type line-commutated converter, characterized in that Applied to an injection-type line-commutated converter, wherein the injection-type line-commutated converter includes an upper bridge group and a lower bridge group. The structures of the upper bridge group and the lower bridge group are the same. The upper bridge group and the lower bridge group are connected in parallel on the AC side and in series at the DC side ports. The upper bridge group includes an upper bridge LCC thyristor main bridge and an upper bridge shunt module; The method includes: Obtaining the reference value of active power, the reference value of reactive power, the measured value of active power, and the measured value of reactive power of the injection-type line-commutated converter; Based on the reference value of active power, the reference value of reactive power, the measured value of active power, and the measured value of reactive power, determining the trigger angle of the upper bridge group and the trigger angle of the lower bridge group; Generating a trigger signal according to the trigger angle of the upper bridge group, the trigger angle of the lower bridge group, and the trigger constraint set to control the operation of the injection-type line-commutated converter.

2. The power decoupling control method based on an injection-type line-commutated converter according to claim 1, wherein The determining the trigger angle of the upper bridge group and the trigger angle of the lower bridge group based on the reference value of active power, the reference value of reactive power, the measured value of active power, and the measured value of reactive power includes: Based on the reference value of active power, the reference value of reactive power, the measured value of active power, and the measured value of reactive power, determining the reference value of active current and the reference value of reactive current of the AC side current of the injection-type line-commutated converter; Calculating a first intermediate trigger angle and a second intermediate trigger angle according to the reference value of active current and the reference value of reactive current of the AC side current of the injection-type line-commutated converter; Determining the trigger angle of the upper bridge group and the trigger angle of the lower bridge group according to the first intermediate trigger angle and the second intermediate trigger angle.

3. The power decoupling control method based on an injection-type line-commutated converter according to claim 2, wherein Calculating the first intermediate trigger angle and the second intermediate trigger angle based on the following formula: ， Among them, is the first intermediate firing angle, is the reference value of the active current, is the reference value of the reactive current, is the second intermediate firing angle, is the current modulation coefficient of the upper bridge group and the lower bridge group, is the DC current.

4. The power decoupling control method based on an injection-type line-commutated converter according to claim 3, characterized in that Calculating the trigger angle of the upper bridge group and the trigger angle of the lower bridge group based on the following formula: ， ， Among them, is the triggering angle of the upper bridge group, is the triggering angle of the lower bridge group.

5. The power decoupling control method based on an injection-type line-commutated converter according to any one of claims 1 to 4, characterized in that, The upper bridge shunt module includes an upper bridge first injection branch and an upper bridge second injection branch. The structures of the upper bridge first injection branch and the upper bridge second injection branch are the same; The upper bridge LCC thyristor main bridge includes an upper bridge Y-bridge thyristor group and an upper bridge D-bridge thyristor group. The structures of the upper bridge Y-bridge thyristor group and the upper bridge D-bridge thyristor group are the same; The upper bridge first injection branch is electrically connected to the upper bridge Y-bridge thyristor group, and the output end of the upper bridge Y-bridge thyristor group is electrically connected to the Y-type winding of the upper bridge phase-shifting transformer; The upper bridge second injection branch is electrically connected to the upper bridge D-bridge thyristor group, and the output end of the upper bridge D-bridge thyristor group is electrically connected to the D-type winding of the upper bridge phase-shifting transformer.

6. The power decoupling control method based on an injection-type line-commutated converter according to claim 5, wherein The upper bridge first injection branch includes an upper bridge first fully-controlled injection switch, an upper bridge second fully-controlled injection switch, and an upper bridge first injection inductor. The upper bridge first injection inductor is connected to the DC side port of the upper bridge group. The upper bridge first fully-controlled injection switch tube is connected in parallel with the upper bridge second fully-controlled injection switch; The upper bridge second injection branch includes an upper bridge third fully-controlled injection switch, an upper bridge fourth fully-controlled injection switch, and an upper bridge second injection inductor. The upper bridge second injection inductor is connected to the DC side port of the upper bridge group. The upper bridge third fully-controlled injection switch tube is connected in parallel with the upper bridge fourth fully-controlled injection switch; The output terminals of the first fully controlled injection switch of the upper bridge and the output terminals of the third fully controlled injection switch of the upper bridge are electrically connected to the thyristor group of the upper bridge Y-bridge, and the output terminals of the second fully controlled injection switch of the upper bridge and the output terminals of the fourth fully controlled injection switch of the upper bridge are electrically connected to the thyristor group of the upper bridge D-bridge; The thyristor group of the upper bridge Y-bridge includes a 6-pulse three-phase bridge of the upper bridge Y-bridge.

7. The power decoupling control method based on an injection-type line-commutated converter according to claim 6, characterized in that Generate trigger signals according to the trigger angle of the upper bridge group, the trigger angle of the lower bridge group, and the trigger constraint set to control the operation of the injection-type line-commutated converter; The trigger constraint set includes: The thyristor switching frequencies of the thyristor group of the upper bridge Y-bridge and the thyristor group of the upper bridge D-bridge of the upper bridge LCC thyristor main bridge are 50 Hz. The trigger pulse intervals of adjacent numbered thyristor switches in the thyristor group of the upper bridge Y-bridge are 60°, and the trigger pulse intervals of adjacent numbered thyristor switches in the thyristor group of the upper bridge D-bridge are 60°. The pulse widths of the thyristor switches in the thyristor group of the upper bridge Y-bridge and the thyristor group of the upper bridge D-bridge are 120°; The trigger pulse intervals of the thyristor switches with the same serial number in the thyristor group of the upper bridge Y-bridge and the thyristor group of the upper bridge D-bridge are 30°, and the thyristor switches in the thyristor group of the upper bridge Y-bridge lead the thyristor switches with the same serial number in the thyristor group of the upper bridge D-bridge.

8. The power decoupling control method based on an injection-type line-commutated converter according to claim 7, characterized in that, Generate trigger signals according to the trigger angle of the upper bridge group, the trigger angle of the lower bridge group, and the trigger constraint set to control the operation of the injection-type line-commutated converter; The injection-type line-commutated converter includes an upper bridge group and a lower bridge group. The structures of the upper bridge group and the lower bridge group are the same. The upper bridge group and the lower bridge group are connected in parallel on the AC side and in series at the DC side ports. The upper bridge group includes an upper bridge LCC thyristor main bridge and an upper bridge shunt module; The trigger constraint set includes: The upper bridge shunt module adopts a seven-level injection form, with a switching frequency of 300 Hz and a width of 5° for each level; The switching pulses of the upper bridge shunt module provide a zero level for the upper bridge LCC thyristor main bridge at the natural commutation point.

9. The power decoupling control method based on an injection-type line-commutated converter according to claim 8, wherein Generate trigger signals according to the trigger angle of the upper bridge group, the trigger angle of the lower bridge group, and the trigger constraint set to control the operation of the injection-type line-commutated converter; The upper bridge shunt module includes an upper bridge first injection branch and an upper bridge second injection branch, and the upper bridge first injection branch and the upper bridge second injection branch have the same structure; The trigger constraint set includes: The first fully controlled injection switch of the upper bridge Y-bridge of the upper bridge first injection branch and the second fully controlled injection switch of the upper bridge Y-bridge are complementary-conducted; The third fully controlled injection switch of the upper bridge Y-bridge of the upper bridge second injection branch and the fourth fully controlled injection switch of the upper bridge Y-bridge are complementary-conducted.

10. A power decoupling control system based on an injection-type line-commutated converter, characterized in that, For implementing the power decoupling control method based on the injection-type line-commutated converter according to any one of claims 1-9, including: A data acquisition module for acquiring the reference value of the active power, the reference value of the reactive power, the measured value of the active power, and the measured value of the reactive power of the injection-type line-commutated converter; A parameter determination module for determining the trigger angle of the upper bridge group and the trigger angle of the lower bridge group based on the reference value of the active power, the reference value of the reactive power, the measured value of the active power, and the measured value of the reactive power; The operation control module is used to generate a trigger signal according to the trigger angle of the upper bridge group, the trigger angle of the lower bridge group, and the trigger constraint set, and control the operation of the injection-type line-commutated converter.

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