阅读说明：本技术 主动换相型高压直流输电换流器 (Active phase-change type high-voltage direct-current transmission converter ) 是由 李子欣 徐飞 赵聪 高范强 王平 李耀华 于 2019-10-23 设计创作，主要内容包括：一种主动换相型高压直流输电换流器,由逆阻型可关断器件S11、S12、S13、S14、S15、S16、S21、S22、S23、S24、S25、S26、第一直流滤波电感L<Sub>dc1</Sub>和第二直流滤波电感L<Sub>dc2</Sub>组成。通过调节所述的逆阻型可关断器件S11、S12、S13、S14、S15、S16的开关时刻及导通时间,对流过第一直流滤波电感的电流i<Sub>dc1</Sub>进行控制,通过调节所述的逆阻型可关断器件S21、S22、S23、S24、S25、S26的开关时刻及导通时间对流过第二直流滤波电感的电流i<Sub>dc2</Sub>进行控制。所述主动换相型高压直流输电换流器的三相交流侧电流与所连接的三相交流电源电压均同相位。在避免现有的基于晶闸管的电网换相换流器换相失败的情况下,不采用额外无功补偿设备实现了换流器单位功率因数运行,相比现有技术具有更好的可靠性和经济性。(An active phase-change type high-voltage direct-current transmission converter comprises reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25 and S26, a first direct-current filter inductor L dc1 And a second DC filter inductor L dc2 And (4) forming. By adjusting the switching time and the conducting time of the reverse-resistance type turn-off devices S11, S12, S13, S14, S15 and S16, the current i flowing through the first direct-current filter inductor is converted into the current i dc1 Controlling the current i flowing through the second DC filter inductor by adjusting the switching time and the conducting time of the reverse resistance type turn-off devices S21, S22, S23, S24, S25 and S26 dc2 And (5) controlling. And the three-phase alternating current side current of the active phase-change type high-voltage direct-current transmission converter and the voltage of a connected three-phase alternating current power supply are in the same phase. Under the condition of avoiding the commutation failure of the existing thyristor-based power grid commutation converter, the unit power factor operation of the converter is realized without adopting extra reactive compensation equipment, and the thyristor-based power grid commutation converter has better reliability and economy compared with the prior art.)

1. An active commutation type HVDC converter, characterized in that: the active phase-change type high-voltage direct-current transmission converter comprises reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25, S26, direct-current filter inductance L_dcA first coupling transformer (1) anda second coupling transformer (2); the three-phase connecting terminals on the three-phase current-intersecting side of the active phase-changing type high-voltage direct-current transmission converter are A, B, C respectively; the primary three-phase connecting terminals of the first connecting transformer (1) are respectively A1, B1 and C1, the secondary three-phase connecting terminals of the first connecting transformer (1) are respectively a1, B1 and C1, and the primary three-phase connecting terminals A1, B1 and C1 of the first connecting transformer (1) are respectively connected to a three-phase alternating current connecting terminal A, B, C; the primary three-phase connecting terminals of the second coupling transformer (2) are respectively A2, B2 and C2, the secondary three-phase connecting terminals of the second coupling transformer (2) are respectively a2, B2 and C2, and the primary three-phase connecting terminals A2, B2 and C2 of the second coupling transformer (2) are respectively connected to the three-phase alternating current connecting terminal A, B, C; the anode of the reverse blocking type turn-off device S11 is connected to the point P1, and the cathode of S11 is connected to the point a 1; the anode of the reverse blocking type turn-off device S14 is connected to the point a1, and the cathode of S14 is connected to the point M; the anode of the reverse blocking type turn-off device S13 is connected to the point P1, and the cathode of S13 is connected to the point b 1; the anode of S16 is connected to point b1, and the cathode of S16 is connected to point M; the anode of the S15 is connected to the point P1, and the cathode of the reverse blocking type turn-off device S15 is connected to the point c 1; the anode of the reverse blocking type turn-off device S12 is connected to the point c1, and the cathode of S12 is connected to the point M; the anode of the reverse blocking type turn-off device S21 is connected to the point M, and the cathode of S21 is connected to the point a 2; the anode of the reverse blocking type turn-off capable device S24 is connected to the point a2, and the cathode of S24 is connected to the point N; the anode of the reverse-blocking type turn-off device S23 is connected to the point M, and the cathode of S23 is connected to the point b 2; the anode of the reverse blocking type turn-off capable device S26 is connected to the point b2, and the cathode of S26 is connected to the point N; the anode of the reverse blocking type turn-off device S25 is connected to the point M, and the cathode of S25 is connected to the point c 2; the anode of the reverse blocking type turn-off device S22 is connected to the point c2, and the cathode of S22 is connected to the point N; DC filter inductor L_dcOne end of which is connected to point P and the other end is connected to point P1; the point P is used as a high-voltage direct-current output positive connecting terminal of the active phase change type high-voltage direct-current transmission converter, and the point N is used as a high-voltage direct-current output negative connecting terminal of the active phase change type high-voltage direct-current transmission converter; the current flowing from point A1 to point A is i_a1The current flowing from point B1 to point B is i_b1The current flowing from point C1 to point C is i_c1From point A2The current flowing to the point A is i_a2The current flowing from point B2 to point B is i_b2The current flowing from point C2 to point C is i_c2(ii) a The current flowing from the point A to the three-phase alternating current power supply of the active phase-change type high-voltage direct current transmission converter is i_agThe current flowing from the point B to the three-phase AC power supply is i_bgThe current flowing from the point C to the three-phase AC power supply is i_cgAnd satisfies the following conditions: i.e. i_ag＝i_a1+i_a2，i_bg＝i_b1+i_b2，i_cg＝i_c1+i_c2(ii) a From point P via DC filter inductor L_dcThe current flowing to point P1 is i_dc(ii) a The three-phase alternating current power supply voltages connected with the three-phase connecting terminal A, B, C on the alternating current side of the active phase-change type high-voltage direct current transmission converter are respectively u_sa、u_sbAnd u_scAnd u is_sa、u_sbAnd u_scA sine wave of equal voltage amplitude and frequency F, u_saInitial phase angle lead u_sbInitial phase angle of 120 DEG u_sbInitial phase angle lead u_scThe initial phase angle is 120 deg..

2. The active commutation type hvdc transmission converter in accordance with claim 1, wherein: the voltage at the sides a1, B1 and C1 of the first connecting transformer (1) is the same as the phase of the three-phase voltage at the sides A1, B1 and C1, the ratio of the amplitude is K, and K is a positive number; the voltages at the sides a1, B1 and C1 of the second coupling transformer (2) have the same phase as the three-phase voltages at the sides A1, B1 and C1, and the amplitude ratio is K.

3. The active commutation type hvdc transmission converter in accordance with claim 1, wherein: the current flows through the DC filter inductor L by adjusting the switching time and the conducting time of the reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25 and S26_dcCurrent i of_dcControlling; the switching time and the on-time of the reverse-resistance type turn-off device S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25, S26 are determined as follows: within 1/F of each cycle, the active commutationThree-phase AC power source voltage u connected to AC side three-phase connection terminal A, B, C of type HVDC converter_saAnd u_scAre all positive, and u_sa＝u_scIs defined as T₀(ii) a The switching frequencies of the reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25 and S26 are all F, the on-angle in each period of 1/F is 1/F/3, and the off-time in each period of 1/F is 2/F/3; defining the adjustment time T_R，T_RIs a positive number, and 0 is more than or equal to T_RLess than or equal to 1/F/2, and the turn-on time of the reverse resistance type turn-off device S11 is T₀-T_RThe turn-off time is T₀-T_R+ 1/F/3; the turn-on time of the reverse-resistance type turn-off device S12 is T₀-T_R+1/F/6, turn-off time T₀-T_R+ 1/F/2; the turn-on time of the reverse-resistance type turn-off device S13 is T₀-T_R+1/F/3, turn-off time T₀-T_R+ 2/F/3; the turn-on time of the reverse-resistance type turn-off device S14 is T₀-T_R+1/F/2, turn-off time T₀-T_R+ 5/F/6; the turn-on time of the reverse-resistance type turn-off device S15 is T₀-T_R+2/F/3, turn-off time T₀-T_R+ 1/F; the turn-on time of the reverse-resistance type turn-off device S16 is T₀-T_R+5/F/6, turn-off time T₀-T_R+ 7/F/6; the turn-on time of the reverse-resistance type turn-off device S21 is T₀+T_RThe turn-off time is T₀+T_R+ 1/F/3; the turn-on time of the reverse-resistance type turn-off device S22 is T₀+T_R+1/F/6, turn-off time T₀+T_R+ 1/F/2; the turn-on time of the reverse-resistance type turn-off device S23 is T₀+T_R+1/F/3, turn-off time T₀+T_R+ 2/F/3; the turn-on time of the reverse-resistance type turn-off device S24 is T₀+T_R+1/F/2, turn-off time T₀+T_R+ 5/F/6; the turn-on time of the reverse-resistance type turn-off device S25 is T₀+T_R+2/F/3, turn-off time T₀+T_R+ 1/F; the turn-on time of the reverse-resistance type turn-off device S26 is T₀+T_R+5/F/6, at turn-offIs carved as T₀+T_R+ 7/F/6; if the condition of more than 1/F occurs in the moment of the switching-on or switching-off, subtracting 1/F from the moment of the switching-on or switching-off to be used as the actual moment of the switching-on or switching-off; if the on or off time is less than 0, the on or off time plus 1/F is used as the actual on or off time.

4. The active commutation type hvdc transmission converter in accordance with claim 3, wherein: by adjusting said adjustment time T_RTo the current-flowing DC filter inductance L_dcCurrent i of_dcControlling; when the average voltage value between the direct current side connecting terminals P and N of the active phase-change type high-voltage direct-current transmission converter is positive, if the current i of the direct current filter inductor is positive_dcIf it is less than the reference value, the control time T is reduced_ROtherwise, increase the adjustment time T_R(ii) a When the average voltage value between the direct current side connecting terminals P and N of the active phase-conversion type high-voltage direct-current transmission converter is negative, if the current i of the direct current filter inductor is negative_dcIf it is less than the reference value, the adjustment time T is increased_ROtherwise, the regulation time T is reduced_R。

5. The active phase change hvdc transmission converter in accordance with claim 1 further comprising: alternating current i_a1，i_b1，i_c1The fundamental wave components of (1) are all ahead of respective alternating three-phase voltage u_sa，u_sb，u_sc(ii) a Alternating current i_a2，i_b2，i_c2The fundamental wave components of (1) are all lagged by respective AC three-phase voltages u_sa，u_sb，u_sc(ii) a Alternating current i_ag，i_bg，i_cgThe fundamental wave components of (a) are all connected with respective alternating three-phase voltages u_sa，u_sb，u_scThe phases are the same.

Technical Field

The invention relates to an active phase-change type high-voltage direct-current transmission converter.

Background

In the field of High Voltage Direct Current (HVDC), an existing Converter mainly includes a thyristor-based grid Commutated Converter (LCC) and a Voltage-Source Converter (VSC) -based flexible dc Converter.

Because the thyristor in LCC-HVDC is a passive commutation device, the turn-off is determined by an external circuit, and the controllable quantity only has a trigger angle, the risk of commutation failure exists, and harmonic wave and reactive current are large. The invention patent CN201310430659 proposes an improved circuit capable of reducing the risk of commutation failure, but cannot completely solve the commutation failure problem of LCC-HVDC. However, the dc side of the VSC-HVDC converter generally needs a dc capacitor, for example, patent CN201080066222, and when a dc short circuit occurs, such a converter is difficult to perform fault ride-through operation. Although a Modular Multilevel Converter (MMC) based on a full-bridge type sub-module can realize direct-current side fault ride-through of an HVDC system, compared with a traditional circuit topology based on a half-bridge sub-module, the full-bridge type MMC has the defects that the number of power semiconductors and sub-module capacitors required by the full-bridge type MMC is large, the manufacturing cost of the Converter is high, the loss is remarkably increased, and the popularization and the application of the Converter are limited.

Disclosure of Invention

The invention aims to overcome the defects of the existing HVDC converter technology and provides an active phase-commutation high-voltage direct-current transmission converter.

The invention relates to an active phase-change type high-voltage direct-current transmission converter, which comprises reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25, S26, a direct-current filter inductor L_dcThe first connecting transformer and the second connecting transformer; the three-phase connecting terminals on the three-phase current-intersecting side of the active phase-changing type high-voltage direct-current transmission converter are A, B, C respectively; the primary three-phase connecting terminals of the first connecting transformer are respectively A1, B1 and C1, the secondary three-phase connecting terminals of the first connecting transformer are respectively a1, B1 and C1, and the first connecting transformer isThe primary three-phase connecting terminals A1, B1 and C1 are respectively connected to a three-phase alternating current connecting terminal A, B, C; the primary three-phase connecting terminals of the second coupling transformer are respectively A2, B2 and C2, the secondary three-phase connecting terminals of the second coupling transformer are respectively a2, B2 and C2, and the primary three-phase connecting terminals A2, B2 and C2 of the second coupling transformer are respectively connected to a three-phase alternating-current connecting terminal A, B, C; the anode of the reverse-resistance type turn-off device S11 is connected to the point P1, and the cathode of the reverse-resistance type turn-off device S11 is connected to the point a 1; the anode of the reverse-resistance type turn-off device S14 is connected to the point a1, and the cathode of the reverse-resistance type turn-off device S14 is connected to the point M; the anode of the reverse-resistance type turn-off device S13 is connected to the point P1, and the cathode of the reverse-resistance type turn-off device S13 is connected to the point b 1; the anode of the reverse-resistance type turn-off device S16 is connected to the point b1, and the cathode of the turn-off device S16 is connected to the point M; the anode of the reverse-resistance type turn-off device S15 is connected to the point P1, and the cathode of the reverse-resistance type turn-off device S15 is connected to the point c 1; the anode of the reverse-resistance type turn-off device S12 is connected to the point c1, and the cathode of the reverse-resistance type turn-off device S12 is connected to the point M; the anode of the reverse-resistance type turn-off device S21 is connected to the point M, and the cathode of the turn-off device S21 is connected to the point a 2; the anode of the turn-off capable device S24 is connected to the point a2, and the cathode of the reverse resistance type turn-off capable device S24 is connected to the point N; the anode of the reverse-resistance type turn-off device S23 is connected to the point M, and the cathode of the reverse-resistance type turn-off device S23 is connected to the point b 2; the anode of the reverse-resistance type turn-off device S26 is connected to the point b2, and the cathode of the reverse-resistance type turn-off device S26 is connected to the point N; the anode of the reverse-resistance type turn-off device S25 is connected to the point M, and the cathode of the turn-off device S25 is connected to the point c 2; the anode of the reverse blocking type turn-off capable device S22 is connected to the point c2, and the cathode of the reverse blocking type turn-off capable device S22 is connected to the point N. DC filter inductor L_dcOne end of which is connected to the point P, a DC filter inductor L_dcThe other end of which is connected to point P1. And the point P is used as a high-voltage direct-current output positive connecting terminal of the active phase change type high-voltage direct-current transmission converter, and the point N is used as a high-voltage direct-current output negative connecting terminal of the active phase change type high-voltage direct-current transmission converter. The current flowing from the primary side three-phase connection terminal A1 of the first connection transformation to the point A is i_a1The primary three-phase connection terminal B1 of the first connection transformation flows to the point Bi_b1The current flowing to the point C of the primary side three-phase connection terminal C1 of the first connection transformation is i_c1The current flowing from the primary three-phase connection terminal A2 of the second connection transformer to the point A is i_a2The current flowing to the point B from the primary three-phase connection terminal B2 of the second connection transformer is i_b2The current flowing to the point C from the primary three-phase connection terminal C2 of the second connection transformer is i_c2. The current flowing from the connecting terminal A at the three-phase current intersection side of the active phase-change type high-voltage direct-current transmission converter to the three-phase alternating-current power supply is i_agThe current flowing from the three-phase current-intersecting side connection terminal B to the three-phase AC power supply is i_bgThe current flowing from the three-phase AC power supply to the connection terminal C on the three-phase current-intersecting side is i_cgAnd satisfies the following conditions: i.e. i_ag＝i_a1+i_a2，i_bg＝i_b1+i_b2，i_cg＝i_c1+i_c2. From point P via DC filter inductor L_dcThe current flowing to point P1 is i_dc. The three-phase alternating current power supply voltages connected with the three-phase connecting terminal A, B, C on the alternating current side of the active phase-change type high-voltage direct current transmission converter are respectively u_sa、u_sbAnd u_scAnd u is_sa、u_sbAnd u_scAre equal in voltage amplitude and frequency are all sine waves of F, u_saInitial phase angle lead u_sbInitial phase angle of 120 DEG u_sbInitial phase angle lead u_scThe initial phase angle is 120 deg..

The voltages at the sides a1, B1 and C1 of the first connecting transformer are the same as the phases of the three-phase voltages at the sides A1, B1 and C1, the amplitude ratio is K, and K is a positive number; the voltages at the sides a1, B1 and C1 of the second coupling transformer are the same as the three-phase voltages at the sides A1, B1 and C1 in phase, and the amplitude ratio is also K.

By adjusting the switching time and the on-time of the reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25 and S26, the current flows through the DC filter inductor L_dcCurrent i of_dcControlling; the switching time and the on-time of the reverse-resistance type turn-off device S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25, S26 are determined as follows:

u is the three-phase AC source voltage connected to the AC side three-phase connection terminal A, B, C of the active phase-change HVDC converter during 1/F of each cycle_saAnd u_scAre all positive and u_sa＝u_scIs defined as T₀. The switching frequencies of the reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25 and S26 are all F, the on-angle in each period of 1/F is 1/F/3, and the off-time in each period of 1/F is 2/F/3; defining the adjustment time T_R，T_RIs a positive number, and 0 is more than or equal to T_RLess than or equal to 1/F/2, and the turn-on time of the reverse resistance type turn-off device S11 is T₀-T_RThe turn-off time is T₀-T_R+ 1/F/3; the turn-on time of the reverse-resistance type turn-off device S12 is T₀-T_R+1/F/6, turn-off time T₀-T_R+ 1/F/2; the turn-on time of the reverse-resistance type turn-off device S13 is T₀-T_R+1/F/3, turn-off time T₀-T_R+ 2/F/3; the turn-on time of the reverse-resistance type turn-off device S14 is T₀-T_R+1/F/2, turn-off time T₀-T_R+ 5/F/6; the turn-on time of the reverse-resistance type turn-off device S15 is T₀-T_R+2/F/3, turn-off time T₀-T_R+ 1/F; the turn-on time of the reverse-resistance type turn-off device S16 is T₀-T_R+5/F/6, turn-off time T₀-T_R+ 7/F/6; the turn-on time of the reverse-resistance type turn-off device S21 is T₀+T_RThe turn-off time is T₀+T_R+ 1/F/3; the turn-on time of the reverse-resistance type turn-off device S22 is T₀+T_R+1/F/6, turn-off time T₀+T_R+ 1/F/2; the turn-on time of the reverse-resistance type turn-off device S23 is T₀+T_R+1/F/3, turn-off time T₀+T_R+ 2/F/3; the turn-on time of the reverse-resistance type turn-off device S24 is T₀+T_R+1/F/2, turn-off time T₀+T_R+ 5/F/6; the turn-on time of the reverse-resistance type turn-off device S25 is T₀+T_R+2/F/3, turn-off time T₀+T_R+ 1/F; reverse resistance type canThe turn-on time of the turn-off device S26 is T₀+T_R+5/F/6, turn-off time T₀+T_R+ 7/F/6; if the condition of more than 1/F occurs in the moment of the switching-on or switching-off, subtracting 1/F from the moment of the switching-on or switching-off to be used as the actual moment of the switching-on or switching-off; if the on or off time is less than 0, the on or off time plus 1/F is used as the actual on or off time.

By adjusting said adjustment time T_RConvection current passing through DC filter inductor L_dcCurrent i of_dcControlling; when the average voltage value between the direct current side connecting terminals P and N of the active phase-change type high-voltage direct-current transmission converter is positive, if the current i of the direct current filter inductor is positive_dcIs less than i_dcAt the reference value of (1), the adjustment time T is reduced_ROtherwise, increase the adjustment time T_R(ii) a When the average voltage value between the direct current side connecting terminals P and N of the active phase-conversion type high-voltage direct-current transmission converter is negative, if the current i of the direct current filter inductor is negative_dcIs less than i_dcAt the reference value of (1), the adjustment time T is increased_ROtherwise, the regulation time T is reduced_R。

In the active phase-change type high-voltage direct-current transmission converter, the alternating current i_a1，i_b1，i_c1The fundamental wave components of (1) are all ahead of respective alternating three-phase voltage u_sa，u_sb，u_sc(ii) a Alternating current i_a2，i_b2，i_c2The fundamental wave components of (1) are all lagged by respective AC three-phase voltages u_sa，u_sb，u_sc(ii) a Alternating current i_ag，i_bg，i_cgThe fundamental wave components of (a) are all connected with respective alternating three-phase voltages u_sa，u_sb，u_scThe phases are the same.

Drawings

FIG. 1 is a schematic diagram of an active phase-change type HVDC converter circuit of the present invention;

fig. 2 is a simulation waveform diagram of a three-phase alternating-current side a-phase voltage and current when the active phase-change type high-voltage direct-current transmission converter adopts the control method.

Detailed Description

The invention is further described below with reference to the accompanying drawings and the detailed description.

Fig. 1 is a schematic diagram of an active phase-change type high-voltage direct-current transmission converter circuit of the invention. The active phase-change type high-voltage direct-current transmission converter comprises reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25, S26, direct-current filter inductance L_dcA first coupling transformer 1 and a second coupling transformer 2; the three-phase connecting terminals on the three-phase current-intersecting side of the active phase-changing type high-voltage direct-current transmission converter are A, B, C respectively; the primary three-phase connecting terminals of the first connecting transformer 1 are respectively A1, B1 and C1, the secondary three-phase connecting terminals of the first connecting transformer 1 are respectively a1, B1 and C1, and the primary three-phase connecting terminals A1, B1 and C1 of the first connecting transformer 1 are respectively connected to the three-phase alternating-current connecting terminal A, B, C; the primary three-phase connecting terminals of the second coupling transformer 2 are respectively A2, B2 and C2, the secondary three-phase connecting terminals of the second coupling transformer 2 are respectively a2, B2 and C2, and the primary three-phase connecting terminals A2, B2 and C2 of the second coupling transformer 2 are respectively connected to the three-phase alternating-current connecting terminal A, B, C; the anode of the reverse-resistance type turn-off device S11 is connected to the point P1, and the cathode of the reverse-resistance type turn-off device S11 is connected to the point a 1; the anode of the reverse-resistance type turn-off device S14 is connected to the point a1, and the cathode of the reverse-resistance type turn-off device S14 is connected to the point M; the anode of the reverse-resistance type turn-off device S13 is connected to the point P1, and the cathode of the reverse-resistance type turn-off device S13 is connected to the point b 1; the anode of the reverse-resistance type turn-off device S16 is connected to the point b1, and the cathode of the reverse-resistance type turn-off device S16 is connected to the point M; the anode of the reverse-resistance type turn-off device S15 is connected to the point P1, and the cathode of the reverse-resistance type turn-off device S15 is connected to the point c 1; the anode of the reverse-resistance type turn-off device S12 is connected to the point c1, and the cathode of the reverse-resistance type turn-off device S12 is connected to the point M; the anode of the reverse-resistance type turn-off device S21 is connected to the point M, and the cathode of the reverse-resistance type turn-off device S21 is connected to the point a 2; the anode of the reverse-resistance type turn-off device S24 is connected to the point a2, and the cathode of the reverse-resistance type turn-off device S24 is connected to the point N; the anode of the reverse-resistance type turn-off device S23 is connected to the point M, and the reverse-resistance type turn-off deviceThe cathode of device S23 is connected to point b 2; the anode of the reverse-resistance type turn-off device S26 is connected to the point b2, and the cathode of the reverse-resistance type turn-off device S26 is connected to the point N; the anode of the reverse-resistance type turn-off device S25 is connected to the point M, and the cathode of the reverse-resistance type turn-off device S25 is connected to the point c 2; the anode of the reverse blocking type turn-off capable device S22 is connected to the point c2, and the cathode of the reverse blocking type turn-off capable device S22 is connected to the point N. DC filter inductor L_dcOne end of which is connected to the point P, a DC filter inductor L_dcThe other end of which is connected to point P1. And the point P is used as a high-voltage direct-current output positive connecting terminal of the active phase change type high-voltage direct-current transmission converter, and the point N is used as a high-voltage direct-current output negative connecting terminal of the active phase change type high-voltage direct-current transmission converter. The current flowing from the primary three-phase connection terminal A1 of the first connection transformer 1 to the point A is i_a1The current flowing from the primary three-phase connection terminal B1 to point B of the first connecting transformer 1 is i_b1The current flowing to the point C from the primary three-phase connection terminal C1 of the first connecting transformer 1 is i_c1The current flowing from the primary three-phase connection terminal A2 of the second connection transformer 2 to the point A is i_a2The current flowing to the point B from the primary three-phase connection terminal B2 of the second joint transformer 2 is i_b2The current flowing to the point C from the primary three-phase connection terminal C2 of the second joint transformer 2 is i_c2. The current flowing from the primary three-phase connecting terminal A of the first connecting transformer 1 to the three-phase alternating current power supply of the active phase-change type high-voltage direct-current transmission converter is i_agThe current flowing from the primary three-phase connection terminal B of the first connecting transformer 1 to the three-phase AC power supply is i_bgThe current flowing from the primary three-phase connection terminal C of the first connecting transformer 1 to the three-phase AC power supply is i_cgAnd satisfies the following conditions: i.e. i_ag＝i_a1+i_a2，i_bg＝i_b1+i_b2，i_cg＝i_c1+i_c2. From point P via DC filter inductor L_dcThe current flowing to point P1 is i_dc. The three-phase alternating current power supply voltages connected with the three-phase connecting terminal A, B, C on the alternating current side of the active phase-change type high-voltage direct current transmission converter are respectively u_sa、u_sbAnd u_scAnd u is_sa、u_sbAnd u_scA sine wave of equal voltage amplitude and frequency F, u_saInitial phase angle lead u_sbInitial phase angle of 120 DEG u_sbInitial phase angle lead u_scThe initial phase angle is 120 deg..

The voltages at the sides a1, B1 and C1 of the first connecting transformer 1 have the same phase as the three-phase voltages at the sides A1, B1 and C1, the amplitude ratio is K, and K is a positive number; the voltages at the sides a1, B1 and C1 of the second coupling transformer 2 have the same phase as the three-phase voltages at the sides A1, B1 and C1, and the amplitude ratio is also K.

By adjusting the switching time and the on-time of the reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25 and S26, the current flows through the DC filter inductor L_dcCurrent i of_dcControlling; the switching time and the on-time of the reverse-resistance type turn-off device S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25, S26 are determined as follows:

the three-phase AC power voltage u connected with the AC side three-phase connection terminal A, B, C of the active phase-change HVDC converter is 1/F in each period_saAnd u_scAre all positive and u_sa＝u_scIs defined as T₀. The switching frequencies of the reverse-resistance type turn-off devices S11, S12, S13, S14, S15, S16, S21, S22, S23, S24, S25 and S26 are all F, the on-angle in each period of 1/F is 1/F/3, and the off-time in each period of 1/F is 2/F/3; defining the adjustment time T_R，T_RIs a positive number, and 0 is more than or equal to T_RLess than or equal to 1/F/2, and the turn-on time of the reverse resistance type turn-off device S11 is T₀-T_RThe turn-off time is T₀-T_R+ 1/F/3; the turn-on time of the reverse-resistance type turn-off device S12 is T₀-T_R+1/F/6, turn-off time T₀-T_R+ 1/F/2; the turn-on time of the reverse-resistance type turn-off device S13 is T₀-T_R+1/F/3, turn-off time T₀-T_R+ 2/F/3; the turn-on time of the reverse-resistance type turn-off device S14 is T₀-T_R+1/F/2, turn-off time T₀-T_R+ 5/F/6; reverse blocking type turn-off deviceThe opening time of the element S15 being T₀-T_R+2/F/3, turn-off time T₀-T_R+ 1/F; the turn-on time of the reverse-resistance type turn-off device S16 is T₀-T_R+5/F/6, turn-off time T₀-T_R+ 7/F/6; the turn-on time of the reverse-resistance type turn-off device S21 is T₀+T_RThe turn-off time is T₀+T_R+ 1/F/3; the turn-on time of the reverse-resistance type turn-off device S22 is T₀+T_R+1/F/6, turn-off time T₀+T_R+ 1/F/2; the turn-on time of the reverse-resistance type turn-off device S23 is T₀+T_R+1/F/3, turn-off time T₀+T_R+ 2/F/3; the turn-on time of the reverse-resistance type turn-off device S24 is T₀+T_R+1/F/2, turn-off time T₀+T_R+ 5/F/6; the turn-on time of the reverse-resistance type turn-off device S25 is T₀+T_R+2/F/3, turn-off time T₀+T_R+ 1/F; the turn-on time of the reverse-resistance type turn-off device S26 is T₀+T_R+5/F/6, turn-off time T₀+T_R+ 7/F/6; if the condition of more than 1/F occurs in the moment of the switching-on or switching-off, subtracting 1/F from the moment of the switching-on or switching-off to be used as the actual moment of the switching-on or switching-off; if the on or off time is less than 0, the on or off time plus 1/F is used as the actual on or off time.

By adjusting said adjustment time T_RTo the current-flowing DC filter inductance L_dcCurrent i of_dcControlling; when the average voltage value between the direct current side connecting terminals P and N of the active phase-change type high-voltage direct-current transmission converter is positive, if the current i of the direct current filter inductor is positive_dcIs less than i_dcAt the reference value of (1), the adjustment time T is reduced_ROtherwise, increase the adjustment time T_R(ii) a When the average voltage value between the direct current side connecting terminals P and N of the active phase-conversion type high-voltage direct-current transmission converter is negative, if the current i of the direct current filter inductor is negative_dcIs less than i_dcAt the reference value of (1), the adjustment time T is increased_ROtherwise, the regulation time T is reduced_R。

In the active phase-change type high-voltage direct-current transmission converter, alternating current i_a1，i_b1，i_c1The fundamental wave components of (1) are all ahead of respective alternating three-phase voltage u_sa，u_sb，u_sc(ii) a Alternating current i_a2，i_b2，i_c2The fundamental wave components of (1) are all lagged by respective AC three-phase voltages u_sa，u_sb，u_sc(ii) a Alternating current i_ag，i_bg，i_cgThe fundamental wave components of (a) are all connected with respective alternating three-phase voltages u_sa，u_sb，u_scThe phases are the same.

Fig. 2 is a simulation waveform diagram of a three-phase alternating-current side a-phase voltage and current when the active phase-change type high-voltage direct-current transmission converter adopts the control method. As shown in fig. 2, the effective value of the three-phase ac power line voltage is 1000V, the frequency is 50Hz, the amplitudes and phases of the primary and secondary voltages of the three-phase connection transformer T1 and the three-phase connection transformer T2 are the same, the transformation ratios of the three-phase connection transformer T1 and the three-phase connection transformer T2 are all K1, and the dc current i is 1_dcAdjust time T1000A_RSet to 1 ms. As can be seen from the simulation results, i_a1Fundamental wave component lead u_sa，i_a2Lag u of fundamental component_sa，i_agFundamental component and u_saThe phases are almost the same. The fundamental power factor for a three-phase ac power supply is almost 1. According to the active phase-change type high-voltage direct-current transmission converter, when the control method is adopted, the high-power-factor operation is realized without additional reactive compensation equipment. Meanwhile, all the reverse-resistance type turn-off devices in the invention can be actively turned off, so that the problem of commutation failure in the thyristor-based power grid commutation converter can be solved, and the thyristor-based power grid commutation converter is safer and more economical.