Hybrid phase-shifting transformer and control method

Abstract

The invention provides a hybrid phase-shifting transformer and a control method, a circuit comprises an electromagnetic unit, a power electronic unit and an isolation unit, and the electromagnetic unit comprises an excitation winding, an excitation winding tap, a polarity switch, a secondary side winding and a tertiary side winding; the excitation windings are in triangular connection; the secondary side winding and the tertiary side winding are connected in series in the same phase; the excitation winding is connected in parallel with the secondary side winding and the tertiary side winding through a polarity switch; the excitation winding is electrically connected with the input end of the power electronic unit through the excitation winding tap; the excitation winding, the secondary side winding and the tertiary side winding are provided with gears; the secondary side winding and the tertiary side winding are used for inputting the first compensation voltage into the power system and adjusting the power system; the isolation unit is used for inputting the second compensation voltage to the power system. According to the hybrid phase-shifting transformer provided by the invention, continuous and smooth adjustment of the voltage amplitude and phase of the main line can be realized in high-power electric power system scenes such as new energy grid connection and long-distance power transmission.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power grid, in particular to a hybrid phase-shifting transformer and a control method. BACKGROUND

[0002] As the core equipment of power system, the performance of phase-shifting transformer directly affects the stability, flexibility and efficiency of power grid. The traditional phase-shifting transformer generally adopts a pure electromagnetic structure, and the on-load tap changer is used to switch the winding taps to change the voltage amplitude and phase. Although this technology is reliable, the regulation is essentially stepwise and discontinuous. In order to pursue fast and stepless regulation, all-electronic phase-shifting transformer emerges as the times require. This kind of equipment completely uses large-capacity power electronic converters to realize power control and phase regulation, achieving millisecond-level response and completely stepless and smooth control.

[0003] Under the background of the prior art, the existing phase-shifting transformer technology scheme faces the problem that performance and economy are difficult to balance: the traditional pure electromagnetic scheme is reliable, but its regulation is essentially stepwise and discontinuous, and the performance is relatively backward; the all-electronic scheme has superior performance, but the cost is extremely high, and the core converter must bear all the transmission power, which leads to large device capacity, high cost, and significant operating loss. The volume, cost and heat dissipation requirements of the system make it economically poor in most high-power application scenarios, and it is difficult to promote on a large scale. Therefore, how to build a phase-shifting transformer scheme that can fully take advantage of the cost of electromagnetic equipment and has the high-precision continuous regulation capability of power electronic equipment is a technical problem that needs to be solved at present. SUMMARY

[0004] The present application aims to provide a hybrid phase-shifting transformer and a control method to solve the above technical problems, which can realize continuous and smooth regulation of the voltage amplitude and phase of the main line in the high-power power system scenarios such as new energy grid connection and long-distance power transmission.

[0005] In order to solve the above technical problems, the present application provides a hybrid phase-shifting transformer applied to a power system, which comprises an electromagnetic unit, a power electronic unit and an isolation unit, wherein the electromagnetic unit comprises an excitation winding, an excitation winding tap, a polarity switch, a secondary winding and a tertiary winding; wherein: The excitation winding is connected in a delta configuration; the secondary winding and the tertiary winding are independently provided, and the secondary winding and the tertiary winding are connected in series in phase; the excitation winding is connected in parallel with the secondary winding through the polarity switch; the excitation winding is electrically connected with the input end of the power electronic unit through the excitation winding tap; and the excitation winding is also connected in parallel with the tertiary winding through the polarity switch; The excitation winding is provided with a first gear position; the secondary winding is provided with a second gear position; and the tertiary winding is provided with a third gear position. The excitation winding is configured to provide an excitation voltage, and based on the first gear position, obtain an excitation winding access number of turns to phase-adjust the first compensation voltage. The polarity switch is configured to inversely adjust the first compensation voltage. The secondary winding is configured to input the first compensation voltage to the power system, and based on the second gear position, obtain a secondary winding access number of turns to amplitude-adjust the first compensation voltage. The tertiary winding is configured to input the first compensation voltage to the power system, and based on the third gear position, obtain a tertiary winding access number of turns to amplitude-adjust the first compensation voltage. The excitation winding is further configured to provide a power electronic unit input voltage. An output end of the power electronic unit is electrically connected to an input end of the isolation unit. A forward output end of the isolation unit is electrically connected to the tertiary winding, and a reverse output end of the isolation unit is electrically connected to the power system; and the isolation unit is configured to input a second compensation voltage to the power system.

[0006] In the above scheme, by setting the first gear position for the excitation winding, the phase of the first compensation voltage can be coarsely adjusted by changing the access number of turns of the excitation winding; at the same time, the excitation winding provides the power electronic unit input voltage for the power electronic unit, laying a foundation for the subsequent fine adjustment of the second compensation voltage. Then, by setting the second gear position for the secondary winding, the amplitude of the first compensation voltage can be adjusted by changing the access number of turns of the secondary winding; by setting the third gear position for the tertiary winding, the amplitude of the first compensation voltage can be adjusted by changing the access number of turns of the tertiary winding. Moreover, since the secondary winding and the tertiary winding are in-phase series connection and are connected in parallel with the excitation winding through the polarity switch, the amplitude of the first compensation voltage can be controlled in a large range by combining the inverse adjustment function of the polarity switch, so as to cover the voltage amplitude adjustment requirements in the new energy grid connection and long-distance power transmission scenarios. After the power electronic unit receives the power electronic unit input voltage, the amplitude and phase of the power electronic unit input voltage can be finely adjusted by the power electronic unit and input to the isolation unit. Then, the second compensation voltage is output by the conversion of the isolation unit and is input into the power system, which ensures the safe operation of the power electronic unit, and at the same time, the second compensation voltage output after fine adjustment is accurately superimposed into the main line, so as to realize the continuous and smooth adjustment of the amplitude and phase of the main line voltage.

[0007] Further, the excitation winding comprises: A-phase excitation winding, B-phase excitation winding, and C-phase excitation winding. one end of the A-phase field winding is connected with one end of the B-phase field winding; the other end of the A-phase field winding is connected with one end of the C-phase field winding; the other end of the B-phase field winding is connected with the other end of the C-phase field winding; the A-phase field winding and the B-phase field winding are connected to form a first triangular junction, the A-phase field winding and the C-phase field winding are connected to form a second triangular junction, and the B-phase field winding and the C-phase field winding are connected to form a third triangular junction; the A-phase field winding is electrically connected with the polarity switch through the first triangular junction, the second triangular junction and the third triangular junction; the first gear is arranged on the A-phase field winding, the B-phase field winding and the C-phase field winding; the field winding tap is arranged on the A-phase field winding, the B-phase field winding and the C-phase field winding; the first gear of the A-phase field winding is electrically connected with the field winding tap of the A-phase field winding, the first gear of the B-phase field winding is electrically connected with the field winding tap of the B-phase field winding, and the first gear of the C-phase field winding is electrically connected with the field winding tap of the C-phase field winding; the field winding tap of the A-phase field winding is electrically connected with the second input end of the power electronic unit, the field winding tap of the B-phase field winding is electrically connected with the third input end of the power electronic unit, and the field winding tap of the C-phase field winding is electrically connected with the first input end of the power electronic unit.

[0008] In the above scheme, the A-phase field winding, the B-phase field winding and the C-phase field winding are connected in a triangular shape in a head-to-tail manner, and are electrically connected with the polarity switch through three triangular junctions, so that the voltage phases of the three-phase field windings are mutually different by 120°, thereby providing a basic electrical condition for synchronous regulation of the three-phase voltage phases. Then, the first gear and the field winding tap are arranged on the three-phase field windings, and the first gear of the corresponding phase is electrically connected with the field winding tap, and the field winding tap is respectively connected with the three input ends of the power electronic unit, and the first gear of each phase can change the turn number of the connected field winding, thereby adjusting the input voltage amplitude and phase of the power electronic unit, so that the input voltage of the power electronic unit can be flexibly changed according to the adjustment requirement, to provide adaptive input.

[0009] Further, the polarity switch comprises an A-phase first polarity switch, an A-phase second polarity switch, a B-phase first polarity switch, a B-phase second polarity switch, a C-phase first polarity switch and a C-phase second polarity switch. The A-phase field winding and the B-phase field winding are connected to form a first triangular junction, and the first triangular junction connects the intermediate points of the C-phase first polarity switch and the C-phase second polarity switch; The A-phase field winding and the C-phase field winding are connected to form a second triangular junction, and the second triangular junction connects the intermediate points of the B-phase first polarity switch and the B-phase second polarity switch; The B-phase field winding and the C-phase field winding are connected to form a third triangular junction, and the third triangular junction connects the intermediate points of the A-phase first polarity switch and the A-phase second polarity switch.

[0010] In the above scheme, the intermediate points of the first polarity switch and the second polarity switch of each phase are electrically connected to the corresponding triangular junction. When the first polarity switch and the second polarity switch of a certain phase are switched, the phase of the field winding voltage of the phase can be changed, thereby controlling the phase of the compensation voltage of the phase. The independently designed polarity switch of each phase can meet the differentiated needs of the power system for phase phase adjustment, and lay a foundation for fine adjustment of subsequent power electronic units.

[0011] Further, the secondary side winding includes an A-phase source side winding, a B-phase source side winding, and a C-phase source side winding. The A-phase source side winding and the A-phase first polarity switch are connected in series; the B-phase source side winding and the B-phase first polarity switch are connected in series; and the C-phase source side winding and the C-phase first polarity switch are connected in series. One end of the A-phase source side winding is connected to one end of the A-phase first polarity switch; the other end of the A-phase source side winding is connected to the power system; the other end of the A-phase first polarity switch is connected to the B-phase field winding; the other end of the A-phase first polarity switch is also connected to the C-phase field winding; one end of the B-phase source side winding is connected to one end of the B-phase first polarity switch; the other end of the B-phase source side winding is connected to the power system; the other end of the B-phase first polarity switch is connected to the A-phase field winding; the other end of the B-phase first polarity switch is also connected to the C-phase field winding; one end of the C-phase source side winding is connected to one end of the C-phase first polarity switch; the other end of the C-phase source side winding is connected to the power system; the other end of the C-phase first polarity switch is connected to the A-phase field winding; and the other end of the C-phase first polarity switch is also connected to the B-phase field winding. The second gear is arranged on the A-phase source side winding, the B-phase source side winding, and the C-phase source side winding.

[0012] In the above scheme, by connecting the A-phase source-side winding, the B-phase source-side winding and the C-phase source-side winding with the first polarity switch of the corresponding phase in series respectively, and setting the second gear for each source-side winding, the number of turns of the corresponding source-side winding can be changed through the second gear of each source-side winding to adjust the voltage amplitude output by each phase to the power system, thereby accurately matching the differentiated amplitude requirements of each phase voltage in the new energy grid-connected or long-distance power transmission scenario. Then, one end of each source-side winding is connected with the first polarity switch of the corresponding phase in series, which can switch the phase of the voltage of the phase through the first polarity switch, so that each phase can independently adjust the amplitude and cooperatively adjust the phase. Then, each source-side winding is connected with the other two-phase excitation windings through the first polarity switch, which can make the adjustment of the three-phase source-side windings linked with the three-phase excitation windings, so that when a certain phase is adjusted, the other phases can be cooperatively responded through the voltage coupling of the excitation windings, avoiding the imbalance of three-phase voltage caused by independent adjustment of each phase.

[0013] Further, the three-phase load-side windings include an A-phase load-side winding, a B-phase load-side winding and a C-phase load-side winding. The A-phase load-side winding is connected with the A-phase second polarity switch in series; the B-phase load-side winding is connected with the B-phase second polarity switch in series; and the C-phase load-side winding is connected with the C-phase second polarity switch in series. One end of the A-phase load-side winding is connected with one end of the A-phase second polarity switch; the other end of the A-phase load-side winding is connected with the first forward output end of the isolation unit; the other end of the A-phase second polarity switch is connected with the B-phase excitation winding; the other end of the A-phase second polarity switch is also connected with the C-phase excitation winding; one end of the B-phase load-side winding is connected with one end of the B-phase second polarity switch; the other end of the B-phase load-side winding is connected with the second forward output end of the isolation unit; the other end of the B-phase second polarity switch is connected with the A-phase excitation winding; the other end of the B-phase second polarity switch is also connected with the C-phase excitation winding; one end of the C-phase load-side winding is connected with one end of the C-phase second polarity switch; the other end of the C-phase load-side winding is connected with the third forward output end of the isolation unit; the other end of the C-phase second polarity switch is connected with the A-phase excitation winding; the other end of the C-phase second polarity switch is also connected with the B-phase excitation winding. The third gear is arranged on the A-phase load-side winding, the B-phase load-side winding and the C-phase load-side winding.

[0014] In the above scheme, the A-phase load-side winding, the B-phase load-side winding and the C-phase load-side winding are respectively connected in series with the second polarity switch of the corresponding phase, and a third gear position is arranged for each phase. The third gear position can change the turn number of the load-side winding of the corresponding phase, thereby independently adjusting the output voltage of each phase, and complementing the boost regulation of the source-side winding of the corresponding phase to realize full-range adjustment of the voltage amplitude of the power system. At the same time, the second polarity switch connected in series with the load-side winding of each phase can synchronously switch the phase of the voltage of the phase, cooperating with the step-down regulation to accurately match the differentiated voltage regulation requirements in the new energy grid-connected and long-distance power transmission scenarios. Then, the load-side winding of each phase is connected to the excitation windings of the other two phases through the second polarity switch of the corresponding phase, which can ensure that the regulation of the tertiary winding is linked with the excitation winding and the secondary winding, avoiding the imbalance of the three-phase voltage caused by the separate-phase regulation, and ensuring the symmetry and synchronization of the three-phase regulation; and the other end of the load-side winding is electrically connected to the positive output end of the isolation unit, so that the first compensation voltage output by the electromagnetic unit can be superimposed with the second compensation voltage output by the isolation unit, forming a cooperative compensation mechanism of coarse adjustment and fine adjustment, and further improving the accuracy of the voltage regulation of the power system.

[0015] Further, the power electronic unit comprises an AC / DC converter, a filter capacitor and a DC / AC converter; wherein: the first input end of the AC / DC converter is electrically connected to the C-phase excitation winding tap as the first input end of the power electronic unit; the second input end of the AC / DC converter is electrically connected to the A-phase excitation winding tap as the second input end of the power electronic unit; the third input end of the AC / DC converter is electrically connected to the B-phase excitation winding tap as the third input end of the power electronic unit; the first output end of the AC / DC converter is electrically connected to one end of the filter capacitor; the second output end of the AC / DC converter is electrically connected to the other end of the filter capacitor; one end of the filter capacitor is electrically connected to the first input end of the DC / AC converter; the other end of the filter capacitor is electrically connected to the second input end of the DC / AC converter; the first output end of the DC / AC converter is electrically connected to the first input end of the isolation unit; the second output end of the DC / AC converter is electrically connected to the second input end of the isolation unit; the third output end of the DC / AC converter is electrically connected to the third input end of the isolation unit.

[0016] In the above scheme, by connecting the three input ends of the AC / DC converter with the three-phase field winding taps one by one, three-phase alternating current can be directly obtained from the field winding taps, without the need to take power from the power system, only for processing small-capacity power required for compensation, reducing the capacity load and cost of the power electronic unit, adapting to the economic needs of new energy grid connection and long-distance power transmission and other high-power scenarios; and by corresponding input power electronic units, the input voltage of the power electronic unit obtained can be adjusted flexibly in amplitude and phase to follow the field winding gear changes, laying a foundation for adaptability for subsequent conversion. Then, the input three-phase alternating current is converted into direct current by the AC / DC converter, and then the direct current is filtered by the filtering capacitor to filter out harmonics and fluctuations in the current, avoiding distortion of the compensation voltage caused by interference of the clutter, and ensuring the stability of the power quality. Subsequently, the filtered direct current is converted into three-phase alternating current again by the DC / AC converter. Finally, the three output ends of the DC / AC converter are electrically connected one by one with the three input ends of the isolation unit: ensuring that the converted three-phase alternating current can be input to the isolation unit, avoiding phase shift or amplitude loss during transmission. At the same time, with the isolation protection and voltage transformation function of the isolation unit, the power electronic unit can be protected from the impact of power system fluctuations, and the second compensation voltage meeting the adjustment requirements can be output, providing support for the subsequent superposition of the first compensation voltage to the power system, and finally achieving continuous and smooth adjustment of the voltage of the power system.

[0017] Further, the isolation unit comprises a first isolation transformer, a second isolation transformer and a third isolation transformer; wherein: The primary side of the first isolation transformer is electrically connected with the first output end of the DC / AC converter as the first input end of the isolation unit; the primary side of the second isolation transformer is electrically connected with the second output end of the DC / AC converter as the second input end of the isolation unit; the primary side of the third isolation transformer is electrically connected with the third output end of the DC / AC converter as the third input end of the isolation unit; The positive output end of the secondary side of the first isolation transformer is electrically connected with the other end of the A-phase load-side winding; the positive output end of the secondary side of the second isolation transformer is electrically connected with the other end of the B-phase load-side winding; the positive output end of the secondary side of the third isolation transformer is electrically connected with the other end of the C-phase load-side winding; The secondary side of the first isolation transformer is electrically connected with the power system; the secondary side of the second isolation transformer is electrically connected with the power system; the secondary side of the third isolation transformer is electrically connected with the power system.

[0018] In the scheme, by adopting the first isolation transformer, the second isolation transformer and the third isolation transformer, and the primary side of each transformer being connected with the three-phase output end of the DC / AC converter one by one, the electrical isolation of the power electronic unit, the power system and the electromagnetic unit is realized, the voltage impact, harmonic interference or short circuit fault of the power system is avoided to be conducted to the power electronic unit, and the damage risk of the high-precision electronic device is reduced. Secondly, by adopting the independent isolation design of each phase, when transient disturbance occurs in a phase line, the normal work of the power electronic units of the other two phases is not affected, and the independence and stability of three-phase regulation are ensured. Then, the positive output end of the secondary side of each isolation transformer is electrically connected with the corresponding phase load side winding, so that the second compensation voltage output by the power electronic unit can be superimposed with the first compensation voltage output by the load side winding, so that the power system can be regulated by the second compensation voltage and the first compensation voltage together, and the regulation precision is improved. Finally, by directly connecting the reverse output end of the secondary side of each isolation transformer to the power system, it is ensured that the superimposed second compensation voltage and the first compensation voltage can be injected into the power system according to the preset phase and amplitude, the phase shift or amplitude loss in the injection process is avoided, and the accuracy of the voltage regulation of the power system is ensured.

[0019] Further, comprising: an A-phase line, a B-phase line and a C-phase line; The A-phase line is composed of the A-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the first isolation transformer, the A-phase load side winding, the A-phase second polarity switch, the A-phase first polarity switch and the A-phase source side winding. The B-phase line is composed of the B-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the second isolation transformer, the B-phase load side winding, the B-phase second polarity switch, the B-phase first polarity switch and the B-phase source side winding. The C-phase line is composed of the C-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the third isolation transformer, the C-phase load side winding, the C-phase second polarity switch, the C-phase first polarity switch and the C-phase source side winding. The field winding voltage of any one phase line is the same or opposite in phase value to the voltage of the same phase load side winding. The voltage of the load side winding of any one phase line is the same in phase value to the voltage of the same phase source side winding.

[0020] In the above scheme, by independently forming complete regulation links for the three-phase lines A, B and C, the voltage fluctuation of the single-phase line can be independently regulated without linkage with other phases, thereby improving the flexibility and accuracy of single-phase regulation. Moreover, since the first compensation voltage and the second compensation voltage of each phase are integrated, the voltage amplitude of the phase can be independently raised or lowered, the phase can be independently switched, and the compensation can be continuously and smoothly implemented, thereby adapting to differentiated regulation requirements. In addition, the three-phase lines adopt a completely symmetrical topology and follow a unified phase matching rule, thereby avoiding the situation that the voltage amplitude difference or phase difference of the three phases is too large when the phases are independently regulated, thereby ensuring that the three-phase voltage regulation is always synchronous and symmetrical, and preventing three-phase imbalance from causing power grid harmonic overruns, equipment overheating or protection device malfunctions. The three-phase independent links can also synchronously respond to overall fluctuations in the power grid, thereby quickly restoring the three-phase voltage to the stable range through collaborative regulation, and improving the anti-disturbance capability and operation stability of the power system.

[0021] Further, the power system compensation voltage is the sum of the first compensation voltage and the second compensation voltage.

[0022] In the above scheme, the first compensation voltage output by the electromagnetic unit can undertake large-range and large-capacity hierarchical coarse adjustment, and the second compensation voltage output by the power electronic unit through the isolation unit can undertake small-range and high-precision continuous fine adjustment. The superposition of the two forms a complementary function, which can first use the first compensation voltage output by the electromagnetic unit for coarse adjustment to quickly pull the voltage to the vicinity of the target range, and then use the second compensation voltage output by the power electronic unit for fine adjustment to compensate for the coarse adjustment error, thereby realizing continuous adjustment of the power system compensation voltage and ensuring that the power system compensation voltage is quickly and stably stabilized to the standard value.

[0023] The application provides a hybrid phase-shifting transformer control method, which is applied to the hybrid phase-shifting transformer described in any one of the above. Obtaining preset phase modulation requirements and preset amplitude modulation requirements to obtain a secondary side winding phase-shifting angle and a tertiary side winding phase-shifting angle; Obtaining an excitation winding ratio based on a first gear position of the excitation winding; Obtaining a secondary side winding ratio and a tertiary side winding ratio based on the excitation winding ratio, the secondary side winding phase-shifting angle and the tertiary side winding phase-shifting angle; Adjusting a second gear position of the secondary side winding and a third gear position of the tertiary side winding based on the secondary side winding ratio and the tertiary side winding ratio; Controlling the hybrid phase-shifting transformer to adjust the first compensation voltage based on the first gear position of the excitation winding, the second gear position of the secondary side winding and the third gear position of the tertiary side winding; Based on the excitation winding ratio, the power electronic unit and the isolation unit, the hybrid phase-shift transformer adjusts the second compensation voltage.

[0024] The hybrid phase-shift transformer control method provided by the application only needs to obtain preset phase modulation requirements and preset amplitude modulation requirements of the power system in actual application, and converts the requirements into phase shift angle parameters of the secondary side winding and the tertiary side winding, so as to avoid adjustment direction deviation, lay a foundation for subsequent accurate adjustment of the secondary side winding ratio and the tertiary side winding ratio, and ensure that the phase modulation and amplitude modulation requirements can be corresponded to the adjustment actions of specific windings. Then, based on the excitation winding ratio determined by the first gear of the excitation winding, the secondary side winding ratio and the tertiary side winding ratio are derived in combination with the secondary side winding phase shift angle and the tertiary side winding phase shift angle, so as to avoid three-phase imbalance or compensation voltage distortion caused by single winding adjustment, and ensure that the adjustment actions of the three are consistent. At the same time, the obtained secondary side winding ratio and tertiary side winding ratio provide a quantitative basis for subsequent gear adjustment, so that the switching of the number of turns of the winding can match the adjustment requirements, and errors caused by blind adjustment can be avoided. Then, the second gear of the secondary side and the third gear of the tertiary side are adjusted according to the secondary side winding ratio and the tertiary side winding ratio, and the first gear of the excitation winding is combined to complete the adjustment of the first compensation voltage. Subsequently, based on the excitation winding ratio, the power electronic unit and the isolation unit, the second compensation voltage is adjusted, and the small error after rough adjustment is continuously corrected through the power electronic unit, so as to form cooperation with the rough adjustment of the first compensation voltage, realize high-precision and continuous smooth output of the compensation voltage of the power system, and meet the requirements of the power grid on power quality. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A hybrid phase-shift transformer circuit structure diagram is provided for an embodiment of the application. Figure 2 A power electronic unit input voltage schematic diagram of a hybrid phase-shift transformer is provided for an embodiment of the application. Figure 3 A schematic diagram of excitation winding gear division of an electromagnetic unit is provided. Figure 4 A power electronic unit input voltage distribution schematic diagram when the number of excitation winding gears of the electromagnetic unit is 6 is provided. Figure 5 A power electronic unit input voltage distribution schematic diagram when the number of excitation winding gears of the electromagnetic unit is 9 is provided. Figure 6 A voltage adjustment schematic diagram of a hybrid phase-shift transformer is provided. DETAILED DESCRIPTION

[0026] With reference to the drawings and the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0027] The present embodiment provides a hybrid phase-shifting transformer, and a circuit structure diagram thereof is shown in Figure 1 which is applied to a power system and includes an electromagnetic unit, a power electronic unit and an isolation unit, wherein the electromagnetic unit includes an excitation winding, an excitation winding tap, a polarity switch, a secondary winding and a tertiary winding; wherein: the excitation winding is connected in a delta connection; the secondary winding and the tertiary winding are independently arranged, and the secondary winding is connected in series with the tertiary winding in phase; the excitation winding is connected in parallel with the secondary winding through the polarity switch; the excitation winding is electrically connected with an input end of the power electronic unit through the excitation winding tap; the excitation winding is also connected in parallel with the tertiary winding through the polarity switch; the excitation winding is provided with a first gear; the secondary winding is provided with a second gear; and the tertiary winding is provided with a third gear; the excitation winding is configured to provide an excitation voltage and obtain an excitation winding access number of turns based on the first gear to phase-adjust a first compensation voltage; the polarity switch is configured to inversely phase-adjust the first compensation voltage; the secondary winding is configured to input the first compensation voltage to the power system and obtain a secondary winding access number of turns based on the second gear to amplitude-increase-adjust the first compensation voltage; the tertiary winding is configured to input the first compensation voltage to the power system and obtain a tertiary winding access number of turns based on the third gear to amplitude-decrease-adjust the first compensation voltage; the excitation winding is also configured to provide a power electronic unit input voltage; an output end of the power electronic unit is electrically connected with an input end of the isolation unit; a forward output end of the isolation unit is electrically connected with the tertiary winding, and a reverse output end of the isolation unit is electrically connected with the power system; and the isolation unit is configured to input a second compensation voltage to the power system.

[0028] In the above scheme, by setting the first gear for the field winding, the phase of the first compensation voltage can be coarsely adjusted by changing the number of turns of the field winding connected; at the same time, the field winding provides the power electronic unit input voltage for the power electronic unit, laying the foundation for the subsequent fine adjustment of the second compensation voltage. Then, by setting the second gear for the secondary winding, the amplitude of the first compensation voltage can be adjusted by changing the number of turns of the secondary winding connected; by setting the third gear for the tertiary winding, the amplitude of the first compensation voltage can be adjusted by changing the number of turns of the tertiary winding connected. Moreover, since the secondary winding and the tertiary winding are in-phase series connection and are connected in parallel with the field winding through the polarity switch, the amplitude of the first compensation voltage can be controlled in a large range by combining the anti-phase adjustment function of the polarity switch to cover the voltage amplitude adjustment requirements in the new energy grid connection and long-distance power transmission scenarios. After the power electronic unit receives the power electronic unit input voltage, the amplitude and phase of the power electronic unit input voltage can be finely adjusted by the power electronic unit and input to the isolation unit. Subsequently, the second compensation voltage is output by the conversion of the isolation unit and is connected into the power system, ensuring the safe operation of the power electronic unit, and at the same time, the second compensation voltage output after fine adjustment is accurately superimposed into the main line, realizing continuous and smooth adjustment of the amplitude and phase of the main line voltage.

[0029] Further, the field winding comprises: A-phase field winding, B-phase field winding and C-phase field winding; One end of the A-phase field winding is connected to one end of the B-phase field winding; the other end of the A-phase field winding is connected to one end of the C-phase field winding; the other end of the B-phase field winding is connected to the other end of the C-phase field winding; The A-phase field winding and the B-phase field winding form a first triangular junction, the A-phase field winding and the C-phase field winding form a second triangular junction, and the B-phase field winding and the C-phase field winding form a third triangular junction; the A-phase field winding is electrically connected to the polarity switch through the first triangular junction, the second triangular junction and the third triangular junction; The first gear is arranged on the A-phase field winding, the B-phase field winding and the C-phase field winding; The field winding tap is arranged on the A-phase field winding, the B-phase field winding and the C-phase field winding; The first gear of the A-phase field winding is electrically connected to the field winding tap of the A-phase field winding, the first gear of the B-phase field winding is electrically connected to the field winding tap of the B-phase field winding, and the first gear of the C-phase field winding is electrically connected to the field winding tap of the C-phase field winding; The A-phase excitation winding tap is electrically connected with a second input end of the power electronic unit, the B-phase excitation winding tap is electrically connected with a third input end of the power electronic unit, and the C-phase excitation winding tap is electrically connected with a first input end of the power electronic unit.

[0030] In the above scheme, the number of gear positions of each phase excitation winding Ke≥2, the A-phase excitation winding, the B-phase excitation winding and the C-phase excitation winding are connected in a triangular connection mode, and are respectively electrically connected with the polarity switch through three triangular connection points, so as to provide a basic electrical condition for synchronous regulation of three-phase excitation winding voltage phase difference. Then, the first gear position and the excitation winding tap are arranged for the three-phase excitation winding, and the first gear position of the corresponding phase is electrically connected with the excitation winding tap, and the excitation winding tap is respectively connected with the three input ends of the power electronic unit. The first gear position of each phase can change the turn number of the excitation winding, and then adjust the input voltage amplitude and phase of the power electronic unit, so that the input voltage of the power electronic unit can be flexibly changed according to the adjustment requirement, to provide adaptive input. By adjusting the excitation winding tap of the corresponding phase, the excitation winding of the corresponding phase can be divided into two parts, so that the excitation voltage is also divided into two parts, for example, as shown in FIG. 6, taking the A-phase as an example, the input voltage is U Figure 1 SA , the compensation voltage generated by the A-phase source side winding is ΔU SA , the compensation voltage generated by the A-phase load side winding is ΔU LA , the first compensation voltage of the electromagnetic unit is + , the second compensation voltage of the power electronic unit is U PA , the voltage after the adjustment of the power electronic unit is U LA , U LA =U PA +U LA0 , is the third triangular connection point potential, the voltage of the A-phase excitation winding close to the B-phase side is U ea1 , the excitation voltage close to the C-phase side is U ea2 , the total excitation voltage of the A-phase U 23 = U ea1 + U ea2 ; the total excitation voltage of the B-phase U 31 = U eb1 + U eb2 , the total excitation voltage of the C-phase U 12 = U ec1 + U ec2 ; and the three-phase excitation winding gears have the same adjustment rule, which can ensure that the three-phase excitation winding gears are equal. Figure 1 ​The electromagnetic unit, the A-phase excitation winding of the electromagnetic unit is powered from a third delta connection point, and generates a voltage U 23 The excitation winding of the electromagnetic unit is the A-phase (U 23 The voltage U SA The voltage U LA The B-phase excitation winding of the electromagnetic unit is powered from a second delta connection point, and generates a voltage U 31 The excitation winding of the electromagnetic unit is the B-phase (U 31 The voltage U SB The voltage U LB The C-phase excitation winding of the electromagnetic unit is powered from a first delta connection point, and generates a voltage U 12 The excitation winding of the electromagnetic unit is the C-phase (U 12 The voltage U SC The voltage U LC The voltage U

[0031] Further, the polarity switch comprises: an A-phase first polarity switch, an A-phase second polarity switch, a B-phase first polarity switch, a B-phase second polarity switch, a C-phase first polarity switch, and a C-phase second polarity switch. The A-phase excitation winding and the B-phase excitation winding are connected to form a first delta connection point, and the first delta connection point is connected to a middle point of the C-phase first polarity switch and the C-phase second polarity switch. The A-phase excitation winding and the C-phase excitation winding are connected to form a second delta connection point, and the second delta connection point is connected to a middle point of the B-phase first polarity switch and the B-phase second polarity switch. The B-phase excitation winding and the C-phase excitation winding are connected to form a third delta connection point, and the third delta connection point is connected to a middle point of the A-phase first polarity switch and the A-phase second polarity switch.

[0032] In the above scheme, the middle points of the first polarity switch and the second polarity switch of each phase are electrically connected to the corresponding delta connection point. When the first polarity switch and the second polarity switch of a certain phase are switched, the phase of the excitation winding voltage of the phase can be changed, so as to control the phase of the compensation voltage of the phase. The independently designed polarity switch of each phase can meet the differentiated needs of the power system for phase adjustment of different phases, and lay a foundation for fine adjustment of subsequent power electronic units.

[0033] Further, the secondary side winding comprises: an A-phase source side winding, a B-phase source side winding, and a C-phase source side winding. The A-phase source side winding and the A-phase first polarity switch are connected in series; the B-phase source side winding and the B-phase first polarity switch are connected in series; and the C-phase source side winding and the C-phase first polarity switch are connected in series. One end of the A-phase source side winding is connected with one end of the A-phase first polarity switch; the other end of the A-phase source side winding is connected with the power system; the other end of the A-phase first polarity switch is connected with the B-phase field winding; the other end of the A-phase first polarity switch is also connected with the C-phase field winding; one end of the B-phase source side winding is connected with one end of the B-phase first polarity switch; the other end of the B-phase source side winding is connected with the power system; the other end of the B-phase first polarity switch is connected with the A-phase field winding; the other end of the B-phase first polarity switch is also connected with the C-phase field winding; one end of the C-phase source side winding is connected with one end of the C-phase first polarity switch; the other end of the C-phase source side winding is connected with the power system; the other end of the C-phase first polarity switch is connected with the A-phase field winding; the other end of the C-phase first polarity switch is also connected with the B-phase field winding. The second gear is arranged on the A-phase source side winding, the B-phase source side winding and the C-phase source side winding.

[0034] In the above scheme, the A-phase source side winding, the B-phase source side winding and the C-phase source side winding in the secondary side winding are connected in a triangle. By connecting the A-phase source side winding, the B-phase source side winding and the C-phase source side winding with the first polarity switch of the corresponding phase in series, and arranging the second gear on each phase source side winding, the turn number of the corresponding phase source side winding can be changed through the second gear of each phase source side winding, so as to adjust the voltage amplitude output to the power system by each phase, thereby accurately matching the differentiated amplitude value requirement of each phase voltage in the new energy grid connection or long distance power transmission scene. Then, one end of each phase source side winding is connected with the first polarity switch of the corresponding phase in series, which can switch the phase of the voltage of this phase through the first polarity switch, so that each phase can independently adjust the amplitude and cooperatively adjust the phase. Then, each phase source side winding is connected with the field windings of the other two phases through the first polarity switch, which can make the adjustment of the three-phase source side windings linked with the three-phase field windings, so as to ensure that when a certain phase is adjusted, the other phases can be cooperatively responded through the voltage coupling of the field windings, thereby avoiding the imbalance of three-phase voltage caused by independent adjustment of each phase.

[0035] Further, the tertiary side winding includes an A-phase load side winding, a B-phase load side winding and a C-phase load side winding. The A-phase load side winding and the A-phase second polarity switch are connected in series; the B-phase load side winding and the B-phase second polarity switch are connected in series; the C-phase load side winding and the C-phase second polarity switch are connected in series. One end of the A-phase load-side winding is connected with one end of the A-phase second polarity switch; the other end of the A-phase load-side winding is connected with the first forward output end of the isolation unit; the other end of the A-phase second polarity switch is connected with the B-phase field winding; the other end of the A-phase second polarity switch is also connected with the C-phase field winding; one end of the B-phase load-side winding is connected with one end of the B-phase second polarity switch; the other end of the B-phase load-side winding is connected with the second forward output end of the isolation unit; the other end of the B-phase second polarity switch is connected with the A-phase field winding; the other end of the B-phase second polarity switch is also connected with the C-phase field winding; one end of the C-phase load-side winding is connected with one end of the C-phase second polarity switch; the other end of the C-phase load-side winding is connected with the third forward output end of the isolation unit; the other end of the C-phase second polarity switch is connected with the A-phase field winding; the other end of the C-phase second polarity switch is also connected with the B-phase field winding. The third gear is arranged on the A-phase load-side winding, the B-phase load-side winding and the C-phase load-side winding.

[0036] In the above scheme, the A-phase load-side winding, the B-phase load-side winding and the C-phase load-side winding are respectively connected in series with the second polarity switch of the corresponding phase, and the third gear is arranged on each phase. The third gear can change the turn number of the corresponding phase load-side winding, thereby independently adjusting the output voltage of each phase, and complementing the amplitude adjustment of the source-side winding of the corresponding phase, to realize full-range adjustment of the voltage amplitude of the power system. At the same time, the second polarity switch connected in series with each phase load-side winding can synchronously switch the voltage phase of the phase, cooperating with the amplitude adjustment to accurately match the differentiated voltage adjustment requirements in the new energy grid-connected and long-distance power transmission scenarios. Then, the load-side winding of each phase is connected with the field windings of the other two phases through the second polarity switch of the corresponding phase, which can ensure that the regulation of the tertiary winding is linked with the field windings and the secondary winding, avoiding the imbalance of three-phase voltage caused by separate-phase regulation, and ensuring the symmetry and synchronization of three-phase regulation; and the other end of the load-side winding is electrically connected with the forward output end of the isolation unit, so that the first compensation voltage output by the electromagnetic unit can be superimposed with the second compensation voltage output by the isolation unit, forming a cooperative compensation mechanism of coarse adjustment and fine adjustment, and further improving the accuracy of voltage regulation of the power system.

[0037] Further, the power electronic unit comprises an AC / DC converter, a filter capacitor and a DC / AC converter; wherein: The first input end of the AC / DC converter is electrically connected with the C-phase excitation winding tap as the first input end of the power electronic unit; the second input end of the AC / DC converter is electrically connected with the A-phase excitation winding tap as the second input end of the power electronic unit; the third input end of the AC / DC converter is electrically connected with the B-phase excitation winding tap as the third input end of the power electronic unit; the first output end of the AC / DC converter is electrically connected with one end of the filter capacitor; and the second output end of the AC / DC converter is electrically connected with the other end of the filter capacitor. One end of the filter capacitor is electrically connected with the first input end of the DC / AC converter; and the other end of the filter capacitor is electrically connected with the second input end of the DC / AC converter. The first output end of the DC / AC converter is electrically connected with the first input end of the isolation unit; the second output end of the DC / AC converter is electrically connected with the second input end of the isolation unit; and the third output end of the DC / AC converter is electrically connected with the third input end of the isolation unit.

[0038] In the above scheme, the input line voltage of a phase of the power electronic unit is superposed by two parts of electromagnetic unit excitation winding voltage with a phase difference of 120°, i.e., the three-phase excitation line voltage of the power electronic unit is U ec2 +U ea1 , U ea2 +U eb1 and U eb2 +U ec1 , forming a single-phase input line voltage of the power electronic unit with adjustable amplitude and phase. The input voltage of the power electronic unit is shown in Figure 2 , the total excitation voltage U 23 = U ea1 + U ea2 of the A-phase of the electromagnetic unit; the total excitation voltage U 31 = U eb1 + U eb2 of the B-phase; and the total excitation voltage U 12 = U ec1 + U ec2 of the C-phase; the voltage U p12 = U ec2 + U ea1 between the input ends p1 and p2 of the power electronic unit; the voltage U p23 = U ea2 + U eb1 between the input ends p2 and p3; and the voltage U p31 = U eb2 + U ec1 between the input ends p3 and p1. The gear division of the excitation winding of the electromagnetic unit is shown in Figure 3 As the gear of the excitation winding is changed, the proportion of the two parts of the excitation voltage will change, as shown inFigure 4 As shown, taking phase A as an example, the power electronic unit input voltage U corresponding to different excitation winding positions is... p23 They are: 1st gear U p23-1 , 2nd gear U p23-2 , 3rd gear U p23-3 , 4th gear U p23-4 , 5th gear U p23-5 , 6th gear U p23-6 The input voltage of the power electronic unit corresponding to the six gear positions is in U 23 and U 31 The voltages are uniformly distributed on straight lines with a 30° phase difference. It can be seen that the amplitude and phase of the input voltage of the power electronic unit are different. Therefore, both the amplitude and phase of the input voltage of the power electronic unit are adjustable. The phase range of the input line voltage of the power electronic unit is [0°, 120°]. When the number of excitation winding positions of the electromagnetic unit is even, taking the case with 6 excitation winding positions as an example, ... Figure 4 As shown, taking phase A as an example, the power electronic input voltage amplitude is U. p23-3 and U p23-4 According to geometric relationships, its amplitude can be expressed as ,in, U represents the number of effective turns connected in the excitation winding, and the voltage amplitude with the largest power electronic input voltage is... p23-1 and U p23-6 Its amplitude is equal to the amplitude of the voltage of the excitation winding of the electromagnetic unit, and can be expressed as: or Furthermore, the input voltage of the power electronic unit at different speeds varies from that of U. 23 In phase span to U 31 Since they are in phase, the phase span of the input voltage of the power electronic unit is [0°, 120°]. The maximum amplitude of the input line voltage of the power electronic unit is... When the number of stops in the electromagnetic unit's excitation winding is odd, for example, taking the case where the number of stops in the electromagnetic unit's excitation winding is 9, ... Figure 5 As shown, taking phase A as an example, the power electronic input voltage amplitude is U. p23-5 According to geometric relationships, the minimum input voltage of the power electronic unit is The power electronic input voltage amplitude is U. p23-1 and U p23-9 Its amplitude is equal to the amplitude of the voltage of the excitation winding of the electromagnetic unit, and can be expressed as: or The phase span of the input voltage of the power electronic unit at different taps remains [0°, 120°]. By connecting the three input terminals of the AC / DC converter to the taps of the three-phase excitation winding one by one, three-phase AC power can be directly obtained from the excitation winding taps without drawing power from the power system. This is only used to handle the small capacity power required for compensation, reducing the capacity load and cost of the power electronic unit and adapting to the economic needs of high-power scenarios such as new energy grid connection and long-distance power transmission. Furthermore, by inputting the corresponding power electronic units in separate phases, it is ensured that the obtained input voltage of the power electronic unit can flexibly adjust the amplitude and phase of the input voltage according to the change of the excitation winding tap, laying a foundation for adaptability in subsequent conversions. Next, the AC / DC converter converts the input three-phase AC power into DC power, and then filters the DC power through a filter capacitor to remove harmonics and fluctuations in the current, avoiding compensation voltage distortion caused by noise interference and ensuring the stability of power quality. Subsequently, the DC / AC converter converts the filtered DC power back into three-phase AC power. Finally, the three output terminals of the DC / AC converter are electrically connected one-to-one with the three input terminals of the isolation unit. This ensures that the converted three-phase AC power is input to the isolation unit, avoiding phase shift or amplitude loss during transmission. Simultaneously, in conjunction with the isolation protection and transformation functions of the isolation unit, it protects the power electronic unit from power system fluctuations and outputs a second compensation voltage that meets regulation requirements. This provides support for subsequent superposition of the first compensation voltage onto the power system, ultimately achieving continuous and smooth regulation of the power system voltage.

[0039] Furthermore, the isolation unit includes a first isolation transformer, a second isolation transformer, and a third isolation transformer; wherein: The primary side of the first isolation transformer is electrically connected to the first output terminal of the DC / AC converter as the first input terminal of the isolation unit; the primary side of the second isolation transformer is electrically connected to the second output terminal of the DC / AC converter as the second input terminal of the isolation unit; and the primary side of the third isolation transformer is electrically connected to the third output terminal of the DC / AC converter as the third input terminal of the isolation unit. The positive output terminal of the secondary side of the first isolation transformer is electrically connected to the other end of the load-side winding of phase A; the positive output terminal of the secondary side of the second isolation transformer is electrically connected to the other end of the load-side winding of phase B; and the positive output terminal of the secondary side of the third isolation transformer is electrically connected to the other end of the load-side winding of phase C. The reverse output terminal of the secondary side of the first isolation transformer is electrically connected to the power system; the forward output terminal of the secondary side of the second isolation transformer is electrically connected to the power system; and the forward output terminal of the secondary side of the third isolation transformer is electrically connected to the power system.

[0040] In the scheme, by adopting the first isolation transformer, the second isolation transformer and the third isolation transformer, and the primary side of each transformer being connected with the three-phase output end of the DC / AC converter one by one, the electrical isolation of the power electronic unit, the power system and the electromagnetic unit is realized, the voltage impact, harmonic interference or short-circuit fault of the power system is avoided from being conducted to the power electronic unit, and the damage risk of the high-precision electronic device is reduced. The primary side and the secondary side of the isolation transformer have fixed turns, and only have the function of fixed ratio transformation. Secondly, by adopting the independent isolation design of each phase, it is ensured that when transient disturbance occurs in a phase line, the normal work of the power electronic units of the other two phases is not affected, and the independence and stability of three-phase regulation are ensured. Then, the positive output end of the secondary side of each isolation transformer is electrically connected with the corresponding phase load side winding, so that the second compensation voltage output by the power electronic unit can be superimposed with the first compensation voltage output by the load side winding, so that the power system can be regulated by the second compensation voltage and the first compensation voltage together, and the regulation precision is improved. Finally, by directly connecting the reverse output end of the secondary side of each isolation transformer to the power system, it is ensured that the superimposed second compensation voltage and the first compensation voltage can be injected into the power system according to the preset phase and amplitude, the phase shift or amplitude loss in the injection process is avoided, and the accuracy of the voltage regulation of the power system is ensured.

[0041] Further, comprising: an A-phase line, a B-phase line and a C-phase line; The A-phase line is composed of the A-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the first isolation transformer, the A-phase load side winding, the A-phase second polarity switch, the A-phase first polarity switch and the A-phase source side winding. The B-phase line is composed of the B-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the second isolation transformer, the B-phase load side winding, the B-phase second polarity switch, the B-phase first polarity switch and the B-phase source side winding. The C-phase line is composed of the C-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the third isolation transformer, the C-phase load side winding, the C-phase second polarity switch, the C-phase first polarity switch and the C-phase source side winding. The field winding voltage of any one phase line is the same as or opposite to the phase value of the load side winding voltage of the same phase, and the load side winding voltage of any one phase line is the same as the phase value of the source side winding voltage of the same phase.

[0042] In the above scheme, by forming a complete regulation link for each of the A, B and C three-phase lines independently, the voltage fluctuation of a single-phase line can be independently regulated without the need to link other phases, improving the flexibility and accuracy of single-phase regulation. Moreover, since each phase integrates the first compensation voltage and the second compensation voltage of the corresponding phase, the phase voltage amplitude can be raised or lowered, the phase positive and negative switching can be realized, and the continuous and smooth compensation can be achieved, adapting to differentiated regulation requirements. Secondly, the three-phase line adopts a completely symmetrical topology and follows a unified phase matching rule, which can avoid the situation of excessive three-phase voltage amplitude difference or phase difference when regulating independently, thereby ensuring that the three-phase voltage regulation is always synchronized and symmetrical, preventing three-phase imbalance from causing power grid harmonic overruns, equipment overheating or protection device misoperation. The three-phase independent link can also respond to overall grid fluctuations synchronously, thereby quickly restoring the three-phase voltage to the stable range through coordinated regulation, improving the anti-disturbance ability and operation stability of the power system.

[0043] Further, the power system compensation voltage is the sum of the first compensation voltage and the second compensation voltage.

[0044] In the above scheme, as shown in Figure 6 , taking phase A as an example, the input voltage is U SA , the voltage after electromagnetic unit regulation is U LA0 , the first compensation voltage of the electromagnetic unit is + , and the compensation phase angle of the electromagnetic unit is ; the second compensation voltage of the power electronic unit is U PA , the voltage after power electronic unit regulation is U LA , U LA =U PA +U LA0 , and the compensation phase angle of the power electronic unit is ; then the power system compensation voltage is the sum of the first compensation voltage and the second compensation voltage: + , and the total compensation phase angle is The power electronic unit has continuous regulation capability, and the regulation characteristic of the power electronic unit can be represented by a circle, i.e., the second compensation voltage (UPA) generated by the power electronic unit can be adjusted to any point in the circle; in addition, the radius of the circle is adjustable within the capacity range. The first compensation voltage output by the electromagnetic unit can undertake a large range and large capacity of hierarchical coarse adjustment; and the second compensation voltage output by the power electronic unit through the isolation unit can undertake small range and high precision continuous fine adjustment. Through the superposition of the two, the two complement each other to be able to quickly pull the voltage to the vicinity of the target range through the first compensation voltage output by the electromagnetic unit for coarse adjustment, and then compensate the coarse adjustment error through the second compensation voltage output by the power electronic unit for fine adjustment, so as to realize the continuous regulation of the compensation voltage of the power system, ensure that the compensation voltage of the power system is quickly and stably regulated to the standard value, solve the hierarchical regulation problem, and further realize the line flow regulation, node voltage out-of-limit suppression and distribution network closing loop impact current suppression and other functions.

[0045] The application provides a hybrid phase-shifting transformer control method, which is applied to the hybrid phase-shifting transformer described in any one of the preceding methods. Obtaining preset phase modulation requirements and preset amplitude modulation requirements to obtain a secondary side winding phase-shifting angle and a tertiary side winding phase-shifting angle; Obtaining a magnetizing winding variable ratio based on a first gear of the magnetizing winding; Obtaining a secondary side winding variable ratio and a tertiary side winding variable ratio based on the magnetizing winding variable ratio, the secondary side winding phase-shifting angle and the tertiary side winding phase-shifting angle; Adjusting a second gear of the secondary side winding and a third gear of the tertiary side winding based on the secondary side winding variable ratio and the tertiary side winding variable ratio; Controlling the hybrid phase-shifting transformer to adjust the first compensation voltage based on the first gear of the magnetizing winding, the second gear of the secondary side winding and the third gear of the tertiary side winding; Controlling the hybrid phase-shifting transformer to adjust the second compensation voltage based on the magnetizing winding variable ratio, the power electronic unit and the isolation unit.

[0046] The application provides a mixed phase-shifting transformer control method, in actual application, preset phase modulation requirements and preset amplitude modulation requirements of a power system are only needed to be acquired first, and are converted into phase-shifting angle parameters of secondary side windings and tertiary side windings, so as to avoid adjustment direction deviation, lay a foundation for subsequent accurate adjustment of the secondary side winding ratio and the tertiary side winding ratio, and ensure that the phase modulation and amplitude modulation requirements can correspond to specific winding adjustment actions respectively. Then, based on the excitation winding ratio determined by the first gear of the excitation winding, in combination with the secondary side winding phase-shifting angle and the tertiary side winding phase-shifting angle, the secondary side winding ratio and the tertiary side winding ratio are derived, taking the A phase as an example, the total number of turns of the A phase excitation winding is , the effective number of turns of the A phase source side series winding in the line is , the effective number of turns of the A phase load side series winding in the line is , and the following relationship is ; the source side series winding and the load side series winding have independent adjustment capability, that is, the gears of the two can be different or the same, and then a first compensation voltage with adjustable phase and amplitude can be output. An embodiment is provided, as shown in Figure 6 , taking the A phase as an example, the electromagnetic unit input voltage is U SA , that is, the voltage before adjustment, it is assumed that the source side series winding and the load side series winding are both 4 gears (0, 1, 2 and 3 gears respectively), the source side series winding is hung with 2 gears, and the load side series winding is hung with 3 gears, then the source side series winding adjustment voltage phase is , the load side series winding adjustment voltage phase is . Due to the different gears of the two series windings, the , ; the voltage after adjustment of the two series windings is U LA0 , then after adjustment of the electromagnetic unit, the voltage amplitude adjustment amount is , and the voltage phase adjustment amount is . Through derivation of the secondary side winding ratio and the tertiary side winding ratio, three-phase imbalance or compensation voltage distortion caused by single winding adjustment can be avoided, and the adjustment actions of the three are ensured to be consistent; at the same time, the obtained secondary side winding ratio and tertiary side winding ratio provide a quantitative basis for subsequent gear adjustment, the winding turn switching can be matched with the adjustment requirements, and errors caused by blind adjustment can be avoided. Then, according to the secondary side winding ratio and the tertiary side winding ratio, the second gear of the secondary side and the third gear of the tertiary side are adjusted, and in combination with the first gear of the excitation winding, adjustment of the first compensation voltage is completed, taking the A phase as an example, the compensation voltage generated by the source side series winding is ΔU SA , the compensation voltage generated by the load side series winding is ΔU LA , and then the first compensation voltage U com1 generated by the electromagnetic unit and input into the power system can be represented as Then, based on the excitation winding variable ratio, the power electronic unit and the isolation unit, the second compensation voltage is adjusted, and the small error after coarse adjustment is continuously corrected by the power electronic unit, thereby cooperating with the coarse adjustment of the first compensation voltage to realize high-precision and continuous smooth output of the power system compensation voltage, and meet the requirements of the power grid on power quality.

[0047] The embodiment fuses electromagnetic technology and power electronic technology, the electromagnetic unit undertakes wide-range coarse adjustment, and the small-capacity power electronic unit completes fine and continuous compensation adjustment, so that the capacity and cost of the power electronic unit can be controlled at a low level while realizing smooth control, thereby balancing between technology and economy.

[0048] The above is the preferred embodiment of the present application, and it should be pointed out that, for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements are also considered to be within the scope of protection of the present application.

Claims

1. A hybrid phase-shifting transformer, characterized by Be applied to power system, including electromagnetic unit, power electronic unit and isolation unit, wherein the electromagnetic unit includes field winding, field winding tap, polarity switch, secondary winding and tertiary winding; The field winding is connected in a triangle;The secondary winding and the tertiary winding are independently arranged, and the secondary winding is connected in series with the tertiary winding in phase;The field winding is connected in parallel with the secondary winding through the polarity switch;The field winding is electrically connected with the input end of the power electronic unit through the field winding tap;The field winding is also connected in parallel with the tertiary winding through the polarity switch; The field winding is provided with a first gear;The secondary winding is provided with a second gear;The tertiary winding is provided with a third gear; The field winding is used to provide field voltage, and based on the first gear, the number of turns of the field winding is obtained to phase-adjust the first compensation voltage; The polarity switch is used to inverse-adjust the first compensation voltage; The secondary winding is used to input the first compensation voltage to the power system, and based on the second gear, the number of turns of the secondary winding is obtained to amplitude-adjust the first compensation voltage; The tertiary winding is used to input the first compensation voltage to the power system, and based on the third gear, the number of turns of the tertiary winding is obtained to amplitude-adjust the first compensation voltage; The field winding is also used to provide power electronic unit input voltage; The output end of the power electronic unit is electrically connected with the input end of the isolation unit; The forward output end of the isolation unit is electrically connected with the tertiary winding, and the reverse output end of the isolation unit is electrically connected with the power system;The isolation unit is used to input the second compensation voltage to the power system.

2. A hybrid phase shifting transformer as claimed in claim 1, characterized in that The field winding includes: A-phase field winding, B-phase field winding and C-phase field winding; One end of the A-phase field winding is connected with one end of the B-phase field winding;The other end of the A-phase field winding is connected with one end of the C-phase field winding;The other end of the B-phase field winding is connected with the other end of the C-phase field winding; The A-phase field winding and the B-phase field winding form a first triangular junction, the A-phase field winding and the C-phase field winding form a second triangular junction, and the B-phase field winding and the C-phase field winding form a third triangular junction;The A-phase field winding is electrically connected with the polarity switch through the first triangular junction, the second triangular junction and the third triangular junction; The A-phase field winding, the B-phase field winding and the C-phase field winding are all provided with the first gear; The A-phase field winding, the B-phase field winding and the C-phase field winding are all provided with the field winding tap; The first gear of the A-phase field winding is electrically connected with the field winding tap of the A-phase field winding, the first gear of the B-phase field winding is electrically connected with the field winding tap of the B-phase field winding, and the first gear of the C-phase field winding is electrically connected with the field winding tap of the C-phase field winding; The A-phase excitation winding tap is electrically connected with a second input end of the power electronic unit, the B-phase excitation winding tap is electrically connected with a third input end of the power electronic unit, and the C-phase excitation winding tap is electrically connected with a first input end of the power electronic unit.

3. A hybrid phase shifting transformer as claimed in claim 2, characterized in that The polarity switch comprises an A-phase first polarity switch, an A-phase second polarity switch, a B-phase first polarity switch, a B-phase second polarity switch, a C-phase first polarity switch and a C-phase second polarity switch. The A-phase excitation winding and the B-phase excitation winding are connected to form a first delta connection point, and the first delta connection point is connected to a middle point of the C-phase first polarity switch and the C-phase second polarity switch. The A-phase excitation winding and the C-phase excitation winding are connected to form a second delta connection point, and the second delta connection point is connected to a middle point of the B-phase first polarity switch and the B-phase second polarity switch. The B-phase excitation winding and the C-phase excitation winding are connected to form a third delta connection point, and the third delta connection point is connected to a middle point of the A-phase first polarity switch and the A-phase second polarity switch.

4. A hybrid phase shifting transformer as claimed in claim 3, characterized in that The secondary side winding comprises an A-phase source side winding, a B-phase source side winding and a C-phase source side winding. The A-phase source side winding and the A-phase first polarity switch are connected in series, the B-phase source side winding and the B-phase first polarity switch are connected in series, and the C-phase source side winding and the C-phase first polarity switch are connected in series. One end of the A-phase source side winding is connected to one end of the A-phase first polarity switch, the other end of the A-phase source side winding is connected to the power system, the other end of the A-phase first polarity switch is connected to the B-phase excitation winding, the other end of the A-phase first polarity switch is further connected to the C-phase excitation winding, one end of the B-phase source side winding is connected to one end of the B-phase first polarity switch, the other end of the B-phase source side winding is connected to the power system, the other end of the B-phase first polarity switch is connected to the A-phase excitation winding, the other end of the B-phase first polarity switch is further connected to the C-phase excitation winding, one end of the C-phase source side winding is connected to one end of the C-phase first polarity switch, the other end of the C-phase source side winding is connected to the power system, the other end of the C-phase first polarity switch is connected to the A-phase excitation winding, and the other end of the C-phase first polarity switch is further connected to the B-phase excitation winding. The second gear is arranged on the A-phase source side winding, the B-phase source side winding and the C-phase source side winding.

5. A hybrid phase shifting transformer as claimed in claim 4, characterized in that The tertiary side winding comprises an A-phase load side winding, a B-phase load side winding and a C-phase load side winding. The A-phase load side winding and the A-phase second polarity switch are connected in series, the B-phase load side winding and the B-phase second polarity switch are connected in series, and the C-phase load side winding and the C-phase second polarity switch are connected in series. One end of the A-phase load-side winding is connected to one end of the A-phase second polarity switch; the other end of the A-phase load-side winding is connected to the first forward output end of the isolation unit; the other end of the A-phase second polarity switch is connected to the B-phase field winding; the other end of the A-phase second polarity switch is also connected to the C-phase field winding; one end of the B-phase load-side winding is connected to one end of the B-phase second polarity switch; the other end of the B-phase load-side winding is connected to the second forward output end of the isolation unit; the other end of the B-phase second polarity switch is connected to the A-phase field winding; the other end of the B-phase second polarity switch is also connected to the C-phase field winding; one end of the C-phase load-side winding is connected to one end of the C-phase second polarity switch; the other end of the C-phase load-side winding is connected to the third forward output end of the isolation unit; the other end of the C-phase second polarity switch is connected to the A-phase field winding; the other end of the C-phase second polarity switch is also connected to the B-phase field winding. The third gear is arranged on the A-phase load-side winding, the B-phase load-side winding and the C-phase load-side winding.

6. A hybrid phase shifting transformer as claimed in claim 5, characterized in that The power electronic unit comprises an AC / DC converter, a filter capacitor and a DC / AC converter; wherein: The first input end of the AC / DC converter is electrically connected to the C-phase field winding tap as the first input end of the power electronic unit; the second input end of the AC / DC converter is electrically connected to the A-phase field winding tap as the second input end of the power electronic unit; the third input end of the AC / DC converter is electrically connected to the B-phase field winding tap as the third input end of the power electronic unit; the first output end of the AC / DC converter is electrically connected to one end of the filter capacitor; the second output end of the AC / DC converter is electrically connected to the other end of the filter capacitor; One end of the filter capacitor is electrically connected to the first input end of the DC / AC converter; the other end of the filter capacitor is electrically connected to the second input end of the DC / AC converter; The first output end of the DC / AC converter is electrically connected to the first input end of the isolation unit; the second output end of the DC / AC converter is electrically connected to the second input end of the isolation unit; the third output end of the DC / AC converter is electrically connected to the third input end of the isolation unit.

7. A hybrid phase shifting transformer as claimed in claim 6, characterized in that The isolation unit comprises a first isolation transformer, a second isolation transformer and a third isolation transformer; wherein: The primary side of the first isolation transformer is electrically connected to the first output end of the DC / AC converter as the first input end of the isolation unit; the primary side of the second isolation transformer is electrically connected to the second output end of the DC / AC converter as the second input end of the isolation unit; the primary side of the third isolation transformer is electrically connected to the third output end of the DC / AC converter as the third input end of the isolation unit; The other end of the A-phase load-side winding is electrically connected with a positive output end of a secondary side of the first isolation transformer; the other end of the B-phase load-side winding is electrically connected with a positive output end of a secondary side of the second isolation transformer; and the other end of the C-phase load-side winding is electrically connected with a positive output end of a secondary side of the third isolation transformer. The negative output end of the secondary side of the first isolation transformer is electrically connected with the power system; the positive output end of the secondary side of the second isolation transformer is electrically connected with the power system; and the positive output end of the secondary side of the third isolation transformer is electrically connected with the power system.

8. A hybrid phase shifting transformer as claimed in claim 7, characterized in that The application relates to a hybrid phase-shifting transformer and a control method thereof. A-phase line, B-phase line and C-phase line; The A-phase line is composed of the A-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the first isolation transformer, the A-phase load-side winding, the A-phase second polarity switch, the A-phase first polarity switch and the A-phase source-side winding. The B-phase line is composed of the B-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the second isolation transformer, the B-phase load-side winding, the B-phase second polarity switch, the B-phase first polarity switch and the B-phase source-side winding. The C-phase line is composed of the C-phase field winding, the AC / DC converter, the filter capacitor, the DC / AC converter, the third isolation transformer, the C-phase load-side winding, the C-phase second polarity switch, the C-phase first polarity switch and the C-phase source-side winding. The voltage of the field winding of any one phase line is the same as or opposite to the voltage of the load-side winding of the same phase; and the voltage of the load-side winding of any one phase line is the same as the voltage of the source-side winding of the same phase.

9. A hybrid phase shifting transformer according to any one of claims 1 to 8, characterised in that, The power system compensation voltage is the sum of the first compensation voltage and the second compensation voltage.

10. A hybrid phase-shift transformer control method, characterized by, The application relates to a hybrid phase-shifting transformer and a control method thereof. Obtaining preset phase modulation requirements and preset amplitude modulation requirements to obtain a secondary-side winding phase-shifting angle and a tertiary-side winding phase-shifting angle; Obtaining a field winding variable ratio based on a first gear position of the field winding; Obtaining a secondary-side winding variable ratio and a tertiary-side winding variable ratio based on the field winding variable ratio, the secondary-side winding phase-shifting angle and the tertiary-side winding phase-shifting angle; Adjusting a second gear position of the secondary-side winding and a third gear position of the tertiary-side winding based on the secondary-side winding variable ratio and the tertiary-side winding variable ratio; Controlling the hybrid phase-shifting transformer to adjust the first compensation voltage based on the first gear position of the field winding, the second gear position of the secondary-side winding and the third gear position of the tertiary-side winding; Controlling the hybrid phase-shifting transformer to adjust the second compensation voltage based on the field winding variable ratio, the power electronic unit and the isolation unit.

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