A control method and system for a double-axis excitation phase modifier under deep phase advancement

Abstract

The application discloses a control method and system for a double-shaft excitation phase modifier under deep phase advancing, and comprises the following steps: determining the type and operation condition of the double-shaft excitation phase modifier; determining a control strategy according to the type and operation condition of the double-shaft excitation phase modifier; and controlling the double-shaft excitation phase modifier based on the control strategy, so that the double-shaft excitation phase modifier can keep safe and stable operation under the deep phase advancing condition. The application has no special requirement for the original excitation control mode of the phase modifier, is suitable for the double-shaft excitation phase modifier in which the d shaft provides excitation alone and the double-shaft phase modifier in which the d shaft and the q shaft provide excitation together, has better adaptability and robustness of the control system, has perfect theoretical basis, can optimize the excitation control parameters according to different phase modifiers, and can keep the double-shaft excitation phase modifier controllable, safe and stable under the deep phase advancing condition.

Description

Technical Field

[0001] This invention relates to the field of motor and electrical appliance technology, and more specifically, to a control method and system for deep phase advance of a dual-axis excitation camera. Background Technology

[0002] With the successive commissioning of new synchronous condensers, their role in suppressing overvoltage or commutation failure at converter stations and improving UHVDC transmission power is becoming increasingly prominent. However, existing large synchronous condensers are all concentrated in converter stations or substations, which has limited effect on improving the voltage stability of the entire sending and receiving end power grid, especially in areas near renewable energy plants. Furthermore, transient overvoltages and insufficient short-circuit capacity in the vicinity of renewable energy plants have become major factors restricting UHV transmission power and renewable energy absorption. Based on the principle of local reactive power compensation and balancing, small and medium-capacity synchronous condensers configured at renewable energy plants can achieve flexible, distributed reactive power compensation and inertia support. They play a significant role in avoiding transient overvoltages at wind power, photovoltaic, and other renewable energy plants, and improving the voltage and frequency stability of areas where renewable energy plants converge, demonstrating excellent application prospects.

[0003] Compared to traditional small synchronous condensers, the new distributed synchronous condensers used in new energy power plants or aggregation areas, in addition to requiring good transient and subtransient characteristics, should also have stronger leading-phase operation capabilities to ensure effective suppression of overvoltages in the vicinity of the power plant. The leading-phase capability of traditional synchronous condensers or generators is limited by a minimum excitation current of zero, and their maximum short-time leading-phase capability depends entirely on the reactance parameters of the generator itself, which is far less than the late-phase overload capability, making it very unfavorable for suppressing overvoltage levels. Further optimizing the synchronous condenser parameters to improve its leading-phase capability would inevitably lead to a significant increase in cost with limited effectiveness.

[0004] Dual-axis excitation synchronous condensers and their control technology enable them to operate flexibly under single-axis excitation, dual-axis excitation, and alternating positive and negative excitation conditions, overcoming the limitation of zero minimum excitation current. Through coordinated control of d-axis reverse excitation and q-axis excitation, the synchronous condenser achieves short-term phase-leading capability comparable to its late-phase overload capability while maintaining stable operation. This significantly improves the overvoltage suppression effect per unit of installed capacity and effectively enhances the return on investment for the synchronous condenser. Summary of the Invention

[0005] This invention proposes a control method and system for a dual-axis excitation camera under deep phase advance conditions, in order to solve the problem of how to maintain controllable, safe and stable operation of a dual-axis excitation camera under deep phase advance conditions.

[0006] To address the aforementioned problems, according to one aspect of the present invention, a control method for depth-advance phase adjustment of a dual-axis excitation camera is provided, the method comprising:

[0007] Determine the type and operating conditions of the dual-axis excitation synchronous condenser;

[0008] The control strategy is determined based on the type and operating conditions of the dual-axis excitation synchronous condenser;

[0009] The dual-axis excitation camera is controlled based on the aforementioned control strategy to ensure its safe and stable operation under deep phase advance conditions.

[0010] Preferably, the type of the dual-axis excitation camera includes: a dual-axis excitation camera that provides the excitation magnetic field solely on the d-axis and a dual-axis excitation camera that provides the excitation magnetic field jointly on the d and q axes.

[0011] Preferably, determining the control strategy based on the type and operating conditions of the dual-axis excitation phase shifter includes:

[0012] For a dual-axis excitation phase converter that provides the excitation magnetic field solely along the d-axis, when dω < 0, θ ∈ [θ0, π / 2], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the negative direction of the d-axis d Among them, q-axis excitation control is not a mandatory item;

[0013] When dω<0, θ∈[π / 2,π-θ0,], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Or increase the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the negative direction of the d-axis d- Or increase the excitation electromotive force E in the positive d-axis direction. d+ ;

[0014] When dω>0, θ∈[-π / 2, θ0], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Among them, q-axis excitation control is not a mandatory item;

[0015] When dω>0, θ∈[-π-θ0,-π / 2], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ;

[0016] Where θ is the combined induced electromotive force E of the terminal voltage U and the d and q axes. ∑ The angle between them; θ0 is the lead of the terminal voltage U to E. q Angle; I fd E is the d-axis excitation current. q The q-axis magnetizing induced electromotive force is generated by the d-axis current; E d The d-axis excitation induced electromotive force is generated by the q-axis excitation current; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

[0017] Preferably, determining the control strategy based on the type and operating conditions of the dual-axis excitation phase shifter includes:

[0018] For a dual-axis excitation phase converter where the d and q axes jointly provide the excitation magnetic field, when dω < 0 and δ ∈ [-π / 2, π / 2], the control strategy is determined as follows: by increasing the excitation current I in the opposite direction of the q axis. fq- Or reduce the excitation current I in the positive q-axis direction. fq+ Increase the excitation electromotive force E in the positive direction of the d-axis d+ Or reduce the excitation electromotive force E in the negative d-axis direction. d- ;

[0019] When dω>0 and δ∈[-π / 2, π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ;

[0020] When dω < 0 and δ ∈ [π / 2, π]U[-π, -π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Among them, q-axis excitation control is not a mandatory item;

[0021] When dω>0 and δ∈[π / 2,π]U[-π,-π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction.d- ;

[0022] Where δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

[0023] Preferably, the method further includes:

[0024] A sign coefficient cosδ is introduced into the amplification factor of the transfer function of the q-axis excitation regulator to ensure the accuracy of q-axis excitation current control. Under any circumstances, the torque generated by the q-axis excitation system is a positive damping torque. Here, δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation.

[0025] According to another aspect of the present invention, a control system for a dual-axis excitation-adjusting camera under depth advance is provided, the system comprising:

[0026] Operating condition determination unit, used to determine the type and operating condition of dual-axis excitation synchronous condenser;

[0027] The control strategy determination unit is used to determine the control strategy based on the type and operating conditions of the dual-axis excitation synchronous condenser.

[0028] The control unit is used to control the dual-axis excitation camera based on the control strategy, so that the dual-axis excitation camera can maintain safe and stable operation under deep phase advance conditions.

[0029] Preferably, the type of the dual-axis excitation camera includes: a dual-axis excitation camera that provides the excitation magnetic field solely on the d-axis and a dual-axis excitation camera that provides the excitation magnetic field jointly on the d and q axes.

[0030] Preferably, the control strategy determination unit determines a control strategy based on the type and operating conditions of the dual-axis excitation phase shifter, including:

[0031] For a dual-axis excitation phase converter that provides the excitation magnetic field solely along the d-axis, when dω < 0, θ ∈ [θ0, π / 2], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the negative direction of the d-axis d Among them, q-axis excitation control is not a mandatory item;

[0032] When dω<0, θ∈[π / 2,π-θ0,], and Ifd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Or increase the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the negative direction of the d-axis d- Or increase the excitation electromotive force E in the positive d-axis direction. d+ ;

[0033] When dω>0, θ∈[-π / 2, θ0], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Among them, q-axis excitation control is not a mandatory item;

[0034] When dω>0, θ∈[-π-θ0,-π / 2], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ;

[0035] Where θ is the combined induced electromotive force E of the terminal voltage U and the d and q axes. ∑ The angle between them; θ0 is the lead of the terminal voltage U to E. q Angle; I fd E is the d-axis excitation current. q The q-axis magnetizing induced electromotive force is generated by the d-axis current; E d The d-axis excitation induced electromotive force is generated by the q-axis excitation current; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

[0036] Preferably, the control strategy determination unit determines a control strategy based on the type and operating conditions of the dual-axis excitation phase shifter, including:

[0037] For a dual-axis excitation phase converter where the d and q axes jointly provide the excitation magnetic field, when dω < 0 and δ ∈ [-π / 2, π / 2], the control strategy is determined as follows: by increasing the excitation current I in the opposite direction of the q axis. fq- Or reduce the excitation current I in the positive q-axis direction. fq+ Increase the excitation electromotive force E in the positive direction of the d-axis d+Or reduce the excitation electromotive force E in the negative d-axis direction. d- ;

[0038] When dω>0 and δ∈[-π / 2, π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ;

[0039] When dω < 0 and δ ∈ [π / 2, π]U[-π, -π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Among them, q-axis excitation control is not a mandatory item;

[0040] When dω>0 and δ∈[π / 2,π]U[-π,-π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ;

[0041] Where δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

[0042] Preferably, the control strategy determination unit further includes:

[0043] A sign coefficient cosδ is introduced into the amplification factor of the transfer function of the q-axis excitation regulator to ensure the accuracy of q-axis excitation current control. Under any circumstances, the torque generated by the q-axis excitation system is a positive damping torque. Here, δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation.

[0044] This invention provides a control method and system for a dual-axis excitation phase-adjusting camera under deep phase-adjustment conditions, comprising: determining the type and operating conditions of the dual-axis excitation phase-adjusting camera; determining a control strategy based on the type and operating conditions of the dual-axis excitation phase-adjusting camera; and controlling the dual-axis excitation phase-adjusting camera based on the control strategy to ensure safe and stable operation of the dual-axis excitation phase-adjusting camera under deep phase-adjustment conditions. This invention does not impose special requirements on the original excitation control mode of the phase-adjusting camera, and is suitable for dual-axis excitation phase-adjusting cameras where the d-axis provides excitation alone and dual-axis excitation phase-adjusting cameras where the d and q axes provide excitation together. The control system exhibits good adaptability and robustness; it has a sound theoretical basis, and the excitation control parameters can be optimized according to different phase-adjusting cameras, enabling the dual-axis excitation phase-adjusting camera to maintain controllable, safe, and stable operation under deep phase-adjustment conditions. Attached Figure Description

[0045] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0046] Figure 1 This is a flowchart of a control method 100 for depth advance of a dual-axis excitation camera according to an embodiment of the present invention;

[0047] Figure 2 To adjust the camera's electrical phasor diagram;

[0048] Figure 3 For the dual-axis excitation adjustment camera E according to an embodiment of the present invention q Schematic diagram of electromagnetic torque when >0;

[0049] Figure 4 For the dual-axis excitation adjustment camera E according to an embodiment of the present invention q Schematic diagram of electromagnetic torque when <0;

[0050] Figure 5 (a) and (b) are schematic diagrams of the electromagnetic torque of the synthesized magnetic field of the dual-axis excitation phase modulator at any initial position according to an embodiment of the present invention.

[0051] Figure 6 This is a block diagram of the transfer function of the q-axis excitation regulator according to an embodiment of the present invention;

[0052] Figure 7 The additional control damping function K for q-axis excitation according to an embodiment of the present invention Efq A schematic diagram of the phase-amplitude frequency response (cosδ≈1);

[0053] Figure 8 The additional control damping coefficient K for q-axis excitation according to an embodiment of the present invention D (cosδ≈1) Schematic diagram;

[0054] Figure 9The additional control damping function K for q-axis excitation according to an embodiment of the present invention Efq A schematic diagram of the phase-amplitude frequency response (cosδ=-0.5);

[0055] Figure 10 This is a schematic diagram of the control system 1100 for depth advance of a dual-axis excitation camera according to an embodiment of the present invention. Detailed Implementation

[0056] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0057] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0058] Figure 1 This is a flowchart of a control method 100 for depth-advancing camera adjustment according to an embodiment of the present invention. Figure 1 As shown, the control method for a dual-axis excitation phase-advancing camera under deep phase-advancing conditions provided by the embodiments of the present invention has no special requirements on the original excitation control mode of the phase-advancing camera. It is suitable for dual-axis excitation phase-advancing cameras that provide excitation only on the d-axis and dual-axis phase-advancing cameras that provide excitation jointly on the d and q axes. The control system has good adaptability and robustness; it has a sound theoretical basis and can optimize the excitation control parameters according to different phase-advancing cameras, enabling the dual-axis excitation phase-advancing camera to maintain controllable, safe, and stable operation under deep phase-advancing conditions. The control method 100 for a dual-axis excitation phase-advancing camera under deep phase-advancing conditions provided by the embodiments of the present invention starts from step 101, in which the type and operating conditions of the dual-axis excitation phase-advancing camera are determined.

[0059] Preferably, the type of the dual-axis excitation camera includes: a dual-axis excitation camera that provides the excitation magnetic field solely on the d-axis and a dual-axis excitation camera that provides the excitation magnetic field jointly on the d and q axes.

[0060] In step 102, the control strategy is determined based on the type and operating conditions of the dual-axis excitation synchronous condenser.

[0061] Preferably, determining the control strategy based on the type and operating conditions of the dual-axis excitation phase shifter includes:

[0062] For a dual-axis excitation phase converter that provides the excitation magnetic field solely along the d-axis, when dω < 0, θ ∈ [θ0, π / 2], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the negative direction of the d-axis d Among them, q-axis excitation control is not a mandatory item;

[0063] When dω<0, θ∈[π / 2,π-θ0,], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Or increase the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the negative direction of the d-axis d- Or increase the excitation electromotive force E in the positive d-axis direction. d+ ;

[0064] When dω>0, θ∈[-π / 2, θ0], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Among them, q-axis excitation control is not a mandatory item;

[0065] When dω>0, θ∈[-π-θ0,-π / 2], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ;

[0066] Where θ is the combined induced electromotive force E of the terminal voltage U and the d and q axes. ∑ The angle between them; θ0 is the lead of the terminal voltage U to E. q Angle; I fd E is the d-axis excitation current. q The q-axis magnetizing induced electromotive force is generated by the d-axis current; E d The d-axis excitation induced electromotive force is generated by the q-axis excitation current; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

[0067] Preferably, determining the control strategy based on the type and operating conditions of the dual-axis excitation phase shifter includes:

[0068] For a dual-axis excitation phase converter where the d and q axes jointly provide the excitation magnetic field, when dω < 0 and δ ∈ [-π / 2, π / 2], the control strategy is determined as follows: by increasing the excitation current I in the opposite direction of the q axis. fq- Or reduce the excitation current I in the positive q-axis direction. fq+ Increase the excitation electromotive force E in the positive direction of the d-axis d+ Or reduce the excitation electromotive force E in the negative d-axis direction. d- ;

[0069] When dω>0 and δ∈[-π / 2, π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ;

[0070] When dω < 0 and δ ∈ [π / 2, π]U[-π, -π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Among them, q-axis excitation control is not a mandatory item;

[0071] When dω>0 and δ∈[π / 2,π]U[-π,-π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ;

[0072] Where δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

[0073] Preferably, the method further includes:

[0074] A sign coefficient cosδ is introduced into the amplification factor of the transfer function of the q-axis excitation regulator to ensure the accuracy of q-axis excitation current control. Under any circumstances, the torque generated by the q-axis excitation system is a positive damping torque. Here, δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation.

[0075] In step 103, the dual-axis excitation camera is controlled based on the control strategy to ensure safe and stable operation of the dual-axis excitation camera under deep phase advance conditions.

[0076] A dual-axis synchronous condenser can achieve short-term phase advance capability comparable to its late-phase overload capability by applying reverse excitation to its d-axis winding. However, as the excitation current becomes negative, the electromagnetic torque changes from driving torque to braking torque, causing the rotor to continuously decelerate and enter asynchronous operation. At this time, the active and reactive power of the synchronous condenser will experience uncontrollable and severe oscillations. The purpose of this invention is to propose a coordinated control strategy and implementation method for a dual-axis synchronous condenser during deep phase advance, enabling the dual-axis synchronous condenser to maintain controllable, safe, and stable operation under deep phase advance conditions.

[0077] A synchronous condenser operates as an unloaded synchronous motor during normal operation, and its electrical phasor diagram is shown in Figure 2. Assuming the d-axis excitation current is positive, the excitation induced electromotive force E... q The direction is defined as the positive q-axis. In this paper, the power angle δ is defined as the angle between the terminal voltage U and the positive q-axis. δ is positive when the positive q-axis leads U, and negative when the positive q-axis lags U. θ is the combined induced electromotive force E of the terminal voltage U and the d- and q-axis axes. ∑ The angle between them, E ∑ When θ is positive, E leads U. ∑ When lag is U, θ is negative.

[0078] 1) Dual-axis excitation phase-shifting control strategy with separate excitation magnetic field provided on the d-axis

[0079] Assuming the no-load loss of the synchronous condenser is P0 (based on generator inertia, electromagnetic power is braking power, and P0 is a negative value), for a dual-axis excitation synchronous condenser that is only powered by the d-axis excitation winding during normal operation, the synthesized induced electromotive force E during steady-state operation is... ∑ E coincides with the positive direction of the q-axis ∑ =E q At this time, the terminal voltage U leads E. q A very small angle θ0, such as Figure 3 As shown. According to the definition of θ, θ0 is negative, and since E ∑ It coincides with the positive direction of the q-axis, δ=θ0.

[0080] When the q-axis excitation current is not zero, the induced electromotive force of the synchronous condenser is d, and the combined induced electromotive force of the q-axis is E. ∑ If E ∑ lie in Figure 2 green region, then E ∑ the included angle θ with U is between [-π / 2, π / 2], and this interval is the stable interval. When E ∑ the angle θ relative to U is in the interval [-π / 2, θ0] (E ∑ is located in the green lattice region), P<P0, the rotor of the synchronous condenser accelerates (P is the braking torque, so the rotor will accelerate when P<P0), θ will increase. According to P=UE ∑ sinθ / X c (X c is the synchronous reactance of the synchronous condenser), it can be known that P increases with the increase of θ until reaching the stable point where θ≈θ0 and P=P0; when E ∑ the included angle θ relative to U0 is in the interval [θ0, π / 2] (E ∑ is located in the green hatched region), P>P0, the rotor of the synchronous condenser decelerates, θ will decrease, and P decreases with the decrease of θ until reaching the stable point where θ≈θ0 and P=P0.

[0081] When E ∑ is located Figure 3 in the upper left region, the synchronous condenser is in the unstable operation region. If E ∑ the angle relative to U0 is in the interval [-π-θ0, -π / 2] (E ∑ is located in the lower left lattice region), P<P0, the rotor of the synchronous condenser accelerates, θ increases. According to P=UE ∑ sinθ / X c it can be known that when θ is in this interval, P decreases as θ increases, which causes the synchronous condenser to accelerate further, cross the boundary of θ=-π / 2 and enter the stable region corresponding to the lower right lattice, and finally reach the stable point where θ≈θ0 and P=P0; if E ∑ the angle relative to U0 is in the interval [π / 2, π-θ0] (E ∑ is located in the upper left hatched region), P>P0, the rotor of the synchronous condenser decelerates, θ decreases, P increases as θ decreases, which causes the rotor to decelerate further until it crosses the boundary of θ=π / 2 and enters the upper right hatched region, and finally reaches the stable point where θ≈θ0 and P=P0.

[0082] In an actual system, since P0 is unknown and θ is difficult to measure, it is impossible to directly judge the magnitude of P relative to P0 and the interval where θ is located. Therefore, ω is usually used as a criterion. dω>0 indicates P<P0, at this time E ∑ is located Figure 3 in the lower left or lower right lattice acceleration region, θ∈[-π-θ0, θ0]; dω<0 indicates P>P0, corresponding to the Figure 2 upper left or upper right hatched deceleration region, at this time θ∈[θ0, π-θ0].

[0083] When the phase shifter is operating in a delayed or normal leading phase state, the induced electromotive force E ∑ =E q lie in Figure 3 Within the upper right region of the image, a small change in θ will not cause instability in the synchronous condenser, and no adjustment is needed from the q-axis excitation system. However, when the system voltage suddenly increases and the d-axis excitation current of the dual-axis excitation synchronous condenser changes from positive to negative, E... q <0, E q It will fall into the unstable upper left region, such as Figure 4 As shown.

[0084] At this time E q The angle θ between the rotor and the terminal voltage U is approximately π + θ0. If there is no q-axis excitation current, the synchronous condenser will decelerate, and the rotor will rotate clockwise by approximately π electrical degrees relative to the terminal voltage until E... q The angle between the rotor and the terminal voltage U is approximately θ0. At this point, the positive directions of the rotor's d and q axes will be perpendicular to the terminal voltage U. Figure 4 The opposite is shown. During this process, as the rotor rotates relative to the synchronous magnetic field, the active and reactive power of the synchronous condenser will experience uncontrollable and significant fluctuations. When the rotor rotates clockwise relative to the synchronous magnetic field by approximately π electrical degrees, E q When the system reaches near the terminal voltage U0, if the overvoltage has not yet disappeared, the excitation current will reverse and become forward excitation again. At this time, the E generated by the forward excitation current... q The process advances U0 by approximately π + θ0, and then repeats the previous process.

[0085] The function of a dual-axis excitation phase converter is to... q <0, after the phase advance of the synchronous condenser, the active power of the synchronous condenser is controlled by the q-axis excitation current, so that the terminal voltage U and the synthesized induced electromotive force E are equal. ∑ The included angle θ is maintained near π-θ0 (or -π-θ0) to ensure P≈P0, keeping the synchronous condenser rotor in dynamic equilibrium without magnetic pole reversal. After the overvoltage disappears, the reverse d-axis excitation current is reduced while the q-axis excitation current is controlled, allowing the synchronous condenser to smoothly return to normal operation. It should be noted that due to changes in the terminal voltage and excitation induced electromotive force, the dynamic equilibrium point is not strictly θ=π-θ0 (or θ=-π-θ0), and the stable equilibrium point θ0 is not a constant, but a very small angle related to the terminal voltage and excitation induced electromotive force.

[0086] To achieve the above objective, when the external voltage increases, E q When the current is less than 0, a reverse excitation current should be applied to the q-axis winding. This current generates a positive d-axis induced electromotive force E. d When U is combined with E ∑ When the included angle θ is close to π-θ0 (or -π-θ0), the camera is basically balanced. When dω>0, it indicates that E ∑In the acceleration region, E should be reduced by appropriately decreasing the q-axis reverse excitation current. d When dω < 0, it indicates that E ∑ In the deceleration region, the q-axis reverse excitation current should be appropriately increased to increase E. d The control strategies for the q-axis excitation winding under different operating conditions of the synchronous condenser are shown in Table 1.

[0087] Table 1 shows the control strategy for a dual-axis excitation phase-shifting camera that provides a separate excitation magnetic field for the d-axis.

[0088]

[0089] In Table 1, Δ indicates that the synchronous condenser is operating in the stable region and q-axis excitation control is not required, while √ indicates that q-axis excitation control is mandatory; otherwise, the synchronous condenser will lose synchronization. As shown in the table, the increase or decrease of the q-axis excitation current depends only on the sign of dω and is related to the d-axis excitation current, E. q The positive or negative sign is irrelevant.

[0090] 2) Dual-axis excitation phase-shifting control strategy where the d and q axes jointly provide the excitation magnetic field.

[0091] When the d-axis and q-axis jointly provide the excitation magnetic field, excitation currents of any magnitude on the d-axis and q-axis can synthesize a composite magnetic field that is relatively stationary relative to the rotor, achieving stable operation. At this time, the composite induced electromotive force E during steady-state operation... ∑ The angle leading U is θ0 (θ0 is negative during normal operation), and the synthesized induced electromotive force E is assumed to be... ∑ If the angle leading the positive q-axis is δ+θ0, then the angle by which U leads the positive q-axis is δ. Then, as... Figure 5 As shown.

[0092] exist Figure 5 In (a), when E ∑ In the acceleration region, due to the negative E d The switching of the camera produces a braking effect (negative E). d (U0 is ahead, generating braking torque), therefore E in the opposite direction should be increased. d Or reduce E in the positive direction d This corresponds to increasing the q-axis current in the positive direction or decreasing the q-axis current in the negative direction. When E ∑ In the deceleration zone, the reverse direction E should be reduced. d Or increase the positive direction E d This corresponds to decreasing the q-axis current in the positive direction or increasing the q-axis current in the opposite direction.

[0093] exist Figure 5 In (b), when E ∑ In the acceleration region, due to the negative E d The generated torque is driving torque, therefore E in the opposite direction should be reduced. dOr increase E in the positive direction d . When E ∑ In the deceleration zone, E in the opposite direction should be increased. d Or reduce E in the positive direction d .

[0094] Further analysis shows that when the phase-shifting camera is in steady-state operation, the angle δ between the terminal voltage U and the positive direction of the q-axis is within the range of [-π / 2, π / 2], i.e., when cosδ>0, E d What is generated is driving torque; therefore, when the synchronous condenser dω>0, E should be reduced. d (or add E in the opposite direction) d When dω < 0, E should be increased. d (or reduce E in the opposite direction) d When the angle δ between the terminal voltage U and the positive direction of the q-axis is within the range of [π / 2, π] or [-π, -π / 2], i.e., cosδ < 0, E d The generated torque is braking torque, therefore E should be increased when dω>0. d (or reduce E in the opposite direction) d When dω < 0, E should be reduced. d (or add E in the opposite direction) d As shown in Table 2.

[0095] Table 2d shows the dual-axis excitation phase condenser control strategy where the d and q axes jointly provide the excitation magnetic field.

[0096]

[0097] As can be seen from the above analysis, for a dual-axis excitation phase converter that provides the excitation magnetic field solely along the d-axis, its initial power angle δ = θ0. Since θ0 is in the range of [-π / 2, π / 2], the control strategy shown in Table 1 is a special case of Table 2.

[0098] Based on the above analysis, the transfer function of the q-axis excitation controller can be designed as follows: Figure 6 As shown.

[0099] exist Figure 6 The key to the transfer function shown is the introduction of a sign coefficient of cosδ in the amplification factor, which is used to ensure that the q-axis excitation current control strategy is always consistent with that shown in Table 2.

[0100] Since the q-axis excitation regulator directly controls the excitation voltage, the conversion of the excitation voltage into excitation magnetomotive force (or excitation current) via the excitation winding will have an inertial delay. Therefore, when the slip signal Δω is a low-frequency periodic signal, its contribution to the electromagnetic torque increment ΔT after passing through the q-axis excitation control, excitation winding, and other stages will be significant. eq There will be a phase lag, if ΔT eqIf the phase of the lag Δω is in the range [0, π / 2], then ΔT eq This manifests as a positive damping torque. That is, when Δω increases (ω decreases), the additional electromagnetic torque generated by the q-axis excitation control acts to prevent the increase of Δω, which is exactly what the q-axis excitation control is intended to achieve. Therefore, when designing the q-axis excitation controller, the optimized settings of the control parameters should ensure that the additional electromagnetic torque related to the q-axis excitation control produces positive damping. See the application examples for details.

[0101] The following specific examples illustrate the embodiments of the present invention.

[0102] When the camera rotation speed is disturbed, the electromagnetic torque increment ΔT generated by the q-axis excitation regulation eq As shown in (1)

[0103]

[0104] in

[0105] T qs =T′ q0 T″ q0 s 2 +(X′ q T′ q0 / X″ q +(X q -X″ q )T″ q0 / (X′ q -X″ q ))s+X q / X″ q (2)

[0106] In equation (1), g(s) represents the q-axis transfer function, X″ q X represents the subtransient reactance of the q-axis of the condenser, u is the extreme voltage, and δ is the electrical angle of the terminal voltage relative to the positive direction of the q-axis of the condenser; in equation (2), X q X′ is the quadrature axis synchronous reactance; q Quadrature-axis transient reactance; T′ q0 、T″ q0 Let K be the q-axis transient and subtransient open-circuit time constants, respectively. Define the damping function K. Efq Electromagnetic torque increment ΔT eq The partial derivative with respect to the speed increment Δω is shown in equation (3).

[0107]

[0108] As the previous analysis shows, the q-axis excitation system aims to ensure that the synchronous condenser operates near its equilibrium point without losing synchronization, i.e., maintaining the synchronous condenser at synchronous speed. Therefore, the goal of q-axis excitation control is to generate a large positive damping torque in the synchronous condenser. When the damping function K... Efq When the projection onto Δω is positive, the q-axis excitation winding generates a positive damping torque; conversely, it generates a negative damping torque.

[0109] For a dual-axis excitation phase-modulator that provides a separate excitation magnetic field for the d-axis, under normal operation, δ=θ0≈0. Under typical q-axis excitation control parameters (Kq=800; Kv=1; TA1=1; TA2=10; TA3=0.05; TA4=0.03), the damping function K of a certain dual-axis excitation phase-modulator is... Efq Phase-amplitude frequency characteristics such as Figure 7 As shown, the parameters of the dual-axis excitation camera are: X d =1.5, X′ d =0.14, X″ d =0.11, T′ d0 =8.8, T″ d0 =0.042, X q =1.5, X′ q =0.27, X″ q =0.12, T′ q0 =0.98, T″ q0 =0.078.

[0110] Depend on Figure 7 It can be seen that the damping function K Efq In the low-frequency range, the gain is relatively high and the phase lag angle is small. However, when the frequency reaches 2-3 Hz, the phase lag angle exceeds 90 degrees, and the gain drops significantly. At this point, the additional electromagnetic torque corresponding to the q-axis excitation control will generate negative damping. According to the damping function K... Efq The phase-amplitude frequency characteristics can be used to obtain the damping coefficient K generated by the q-axis excitation additional control. D like Figure 8 As shown.

[0111] For a dual-axis excitation phase condenser that provides excitation magnetic fields along both the d and q axes, if the angle between the system voltage phasor and the positive direction of the q-axis is large during normal operation, assuming δ = -2π / 3, then cosδ = -0.5. Since... Figure 6 The transfer function shown includes a cosδ sign determination step, at which point the excitation phase-adjusting damping function K... Efq Phase-amplitude frequency characteristics such as Figure 9 As shown.

[0112] Therefore, it can be concluded that the adoption Figure 6The q-axis excitation control transfer function shown guarantees that the torque generated by the q-axis excitation system is a positive damping torque under all conditions. However, during normal operation, if the d and q axes jointly provide the excitation current, the damping torque coefficient provided by the q-axis excitation is relatively small during the deep phase advance period because cosδ < 1. In other words, the q-axis excitation control has a slightly weaker effect on damping torque.

[0113] Figure 10 This is a schematic diagram of the control system 1000 for depth-advancing camera adjustment according to an embodiment of the present invention. Figure 10 As shown, the control system 1000 for depth-advancing phase adjustment of the dual-axis excitation camera provided in this embodiment of the invention includes: an operating condition determination unit 1001, a control strategy determination unit 1002, and a control unit 1003.

[0114] Preferably, the operating condition determination unit 1001 is used to determine the type and operating condition of the dual-axis excitation synchronous condenser.

[0115] Preferably, the type of the dual-axis excitation camera includes: a dual-axis excitation camera that provides the excitation magnetic field solely on the d-axis and a dual-axis excitation camera that provides the excitation magnetic field jointly on the d and q axes.

[0116] Preferably, the control strategy determination unit 1002 is used to determine the control strategy based on the type and operating conditions of the dual-axis excitation phase shifter.

[0117] Preferably, the control strategy determination unit 1002 determines a control strategy based on the type and operating conditions of the dual-axis excitation synchronous condenser, including:

[0118] For a dual-axis excitation phase converter that provides the excitation magnetic field solely along the d-axis, when dω < 0, θ ∈ [θ0, π / 2], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the negative direction of the d-axis d Among them, q-axis excitation control is not a mandatory item;

[0119] When dω<0, θ∈[π / 2,π-θ0,], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Or increase the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the negative direction of the d-axis d- Or increase the excitation electromotive force E in the positive d-axis direction. d+ ;

[0120] When dω>0, θ∈[-π / 2, θ0], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Among them, q-axis excitation control is not a mandatory item;

[0121] When dω>0, θ∈[-π-θ0,-π / 2], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ;

[0122] Where θ is the combined induced electromotive force E of the terminal voltage U and the d and q axes. ∑ The angle between them; θ0 is the lead of the terminal voltage U to E. q Angle; I fd E is the d-axis excitation current. q The q-axis magnetizing induced electromotive force is generated by the d-axis current; E d The d-axis excitation induced electromotive force is generated by the q-axis excitation current; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

[0123] Preferably, the control strategy determination unit 1002 determines a control strategy based on the type and operating conditions of the dual-axis excitation synchronous condenser, including:

[0124] For a dual-axis excitation phase converter where the d and q axes jointly provide the excitation magnetic field, when dω < 0 and δ ∈ [-π / 2, π / 2], the control strategy is determined as follows: by increasing the excitation current I in the opposite direction of the q axis. fq- Or reduce the excitation current I in the positive q-axis direction. fq+ Increase the excitation electromotive force E in the positive direction of the d-axis d+ Or reduce the excitation electromotive force E in the negative d-axis direction. d- ;

[0125] When dω>0 and δ∈[-π / 2, π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction.d- ;

[0126] When dω < 0 and δ ∈ [π / 2, π]U[-π, -π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Among them, q-axis excitation control is not a mandatory item;

[0127] When dω>0 and δ∈[π / 2,π]U[-π,-π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ;

[0128] Where δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

[0129] Preferably, the control strategy determination unit further includes:

[0130] A sign coefficient cosδ is introduced into the amplification factor of the transfer function of the q-axis excitation regulator to ensure the accuracy of q-axis excitation current control. Under any circumstances, the torque generated by the q-axis excitation system is a positive damping torque. Here, δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation.

[0131] Preferably, the control unit 1003 is used to control the dual-axis excitation camera based on the control strategy, so that the dual-axis excitation camera can maintain safe and stable operation under deep phase advance conditions.

[0132] The control system 1100 of the dual-axis excitation camera under depth advance in an embodiment of the present invention corresponds to the control method 100 of the dual-axis excitation camera under depth advance in another embodiment of the present invention, and will not be described again here.

[0133] The invention has been described with reference to a few embodiments. However, as will be known to those skilled in the art, and as defined in the appended claims, other embodiments besides those disclosed above fall equivalently within the scope of the invention.

[0134] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the art, unless otherwise expressly defined herein. All references to “a / the / the [device, component, etc.]” ​​are openly interpreted as at least one instance of said device, component, etc., unless otherwise expressly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed unless explicitly stated otherwise.

[0135] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0136] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0137] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0138] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A control method for a dual-axis excitation camera under depth-advance phase conditions, characterized in that, The method includes: Determine the type and operating conditions of the dual-axis excitation synchronous condenser; The control strategy is determined based on the type and operating conditions of the dual-axis excitation synchronous condenser. The dual-axis excitation camera is controlled based on the aforementioned control strategy to ensure its safe and stable operation under deep phase advance conditions. The step of determining the control strategy based on the type and operating conditions of the dual-axis excitation synchronous condenser includes: For a dual-axis excitation phase converter that provides the excitation magnetic field solely along the d-axis, when dω < 0, θ ∈ [θ0, π / 2], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the negative direction of the d-axis d ; When dω<0, θ∈[π / 2,π-θ0,], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Or increase the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the negative direction of the d-axis d- Or increase the excitation electromotive force E in the positive d-axis direction. d+ ; When dω>0, θ∈[-π / 2, θ0], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ; When dω>0, θ∈[-π-θ0,-π / 2], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ; Where θ is the combined induced electromotive force E of the terminal voltage U and the d and q axes. ∑ The angle between them; θ0 is the lead of the terminal voltage U to E. q Angle; I fd E is the d-axis excitation current. q The q-axis magnetizing induced electromotive force is generated by the d-axis current; E d The d-axis excitation induced electromotive force is generated by the q-axis excitation current; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis; For a dual-axis excitation phase-modulator where the d and q axes jointly provide the excitation magnetic field, when dω < 0 and δ ∈ [-π / 2, π / 2], the control strategy is determined as follows: by increasing the excitation current I in the opposite direction of the q axis. fq- Or reduce the excitation current I in the positive q-axis direction. fq+ Increase the excitation electromotive force E in the positive direction of the d-axis d+ Or reduce the excitation electromotive force E in the negative d-axis direction. d- ; When dω>0 and δ∈[-π / 2, π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ; When dω < 0 and δ ∈ [π / 2, π]U[-π, -π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ; When dω>0 and δ∈[π / 2,π]U[-π,-π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ; Where δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

2. The method according to claim 1, characterized in that, The types of dual-axis excitation camera include: dual-axis excitation camera that provides the excitation magnetic field solely on the d-axis and dual-axis excitation camera that provides the excitation magnetic field jointly on the d and q axes.

3. The method according to claim 1, characterized in that, The method further includes: A sign coefficient cosδ is introduced into the amplification factor of the transfer function of the q-axis excitation regulator to ensure the accuracy of q-axis excitation current control. Under any circumstances, the torque generated by the q-axis excitation system is a positive damping torque. Here, δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation.

4. A control system for a dual-axis excitation camera under depth-advance phase, characterized in that, The system includes: Operating condition determination unit, used to determine the type and operating condition of dual-axis excitation synchronous condenser; The control strategy determination unit is used to determine the control strategy based on the type and operating conditions of the dual-axis excitation synchronous condenser. The control unit is used to control the dual-axis excitation camera based on the control strategy, so that the dual-axis excitation camera can maintain safe and stable operation under deep phase advance conditions. The control strategy determination unit determines the control strategy based on the type and operating conditions of the dual-axis excitation synchronous condenser, including: For a dual-axis excitation phase converter that provides the excitation magnetic field solely along the d-axis, when dω < 0, θ ∈ [θ0, π / 2], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the negative direction of the d-axis d ; When dω<0, θ∈[π / 2,π-θ0,], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the positive q-axis direction. fq+ Or increase the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the negative direction of the d-axis d- Or increase the excitation electromotive force E in the positive d-axis direction. d+ ; When dω>0, θ∈[-π / 2, θ0], and I fd >0 or E q When the value is greater than 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ; When dω>0, θ∈[-π-θ0,-π / 2], and I fd <0 or E q When I < 0, the control strategy is determined as follows: reduce the excitation current I in the negative q-axis direction. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ; Where θ is the combined induced electromotive force E of the terminal voltage U and the d and q axes. ∑ The angle between them; θ0 is the lead of the terminal voltage U to E. q Angle; I fd E is the d-axis excitation current. q The q-axis magnetizing induced electromotive force is generated by the d-axis current; E d The d-axis excitation induced electromotive force is generated by the q-axis excitation current; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis; For a dual-axis excitation phase-modulator where the d and q axes jointly provide the excitation magnetic field, when dω < 0 and δ ∈ [-π / 2, π / 2], the control strategy is determined as follows: by increasing the excitation current I in the opposite direction of the q axis. fq- Or reduce the excitation current I in the positive q-axis direction. fq+ Increase the excitation electromotive force E in the positive direction of the d-axis d+ Or reduce the excitation electromotive force E in the negative d-axis direction. d- ; When dω>0 and δ∈[-π / 2, π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ; When dω < 0 and δ ∈ [π / 2, π]U[-π, -π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Reduce the excitation electromotive force E in the positive direction of the d-axis d+ ; When dω>0 and δ∈[π / 2,π]U[-π,-π / 2], the control strategy is determined as follows: by reducing the excitation current I in the opposite direction of the q-axis. fq- Or increase the excitation current I in the positive q-axis direction. fq+ Reduce the excitation electromotive force E in the positive direction of the d-axis d+ Or increase the excitation electromotive force E in the negative d-axis direction. d- ; Where δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation; E d- E represents the excitation induced electromotive force in the negative d-axis direction. d+ I is the magnetoinduced electromotive force in the positive direction of the d-axis; fq- The excitation current is in the negative q-axis direction; I fq+ The excitation current is in the positive direction of the q-axis.

5. The system according to claim 4, characterized in that, The types of dual-axis excitation camera include: dual-axis excitation camera that provides the excitation magnetic field solely on the d-axis and dual-axis excitation camera that provides the excitation magnetic field jointly on the d and q axes.

6. The system according to claim 4, characterized in that, The control strategy determination unit further includes: A sign coefficient cosδ is introduced into the amplification factor of the transfer function of the q-axis excitation regulator to ensure the accuracy of q-axis excitation current control. Under any circumstances, the torque generated by the q-axis excitation system is a positive damping torque. Here, δ is the angle between the terminal voltage U of the synchronous condenser and the positive direction of the q-axis during steady-state operation.

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