Transient stability control method and device for air-fire bundling system

Abstract

The present invention provides a method and device for controlling the transient stability of a wind-fire bundling system. The method comprises: obtaining the terminal voltage of a doubly-fed wind turbine in real time when a wind-fire bundling system fault occurs; if the terminal voltage of the doubly-fed wind turbine is within a first voltage drop range, increasing the reactive current injection coefficient of the doubly-fed wind turbine according to a preset adjustment rule to reduce the swing amplitude of the synchronous generator during the acceleration phase during the fault period; if the terminal voltage of the doubly-fed wind turbine is within a second voltage drop range, increasing the reactive current injection coefficient of the doubly-fed wind turbine according to the adjustment rule to reduce the swing amplitude of the synchronous generator during the acceleration and deceleration phases during the fault period; and if the terminal voltage of the doubly-fed wind turbine is within a third voltage drop range, decreasing the reactive current injection coefficient of the doubly-fed wind turbine according to the adjustment rule to reduce the swing amplitude of the synchronous generator during the deceleration phase during the fault period. The present invention improves the transient stability control effect of the wind-fire bundling system, enhances control efficiency and practicality, and provides a basis for adjusting the transient control parameters of the doubly-fed wind turbine.

Description

Technical Field

[0001] The present invention relates to the technical field of air-fire baling systems, and in particular to a method and device for controlling transient stability of an air-fire baling system. Background Art

[0002] In recent years, with the large-scale development of wind power generation, doubly-fed wind turbines have gradually replaced synchronous turbines, becoming another important power generation unit on the power generation side of power systems. However, the physical structure and operating principle of doubly-fed wind turbines differ significantly from those of traditional synchronous turbines, and their transient characteristics are more complex and flexible. This leads to significant changes in the transient behavior of wind power grid-connected systems, potentially introducing new transient stability issues.

[0003] Currently, research on transient issues in grid-connected doubly-fed wind turbine systems primarily focuses on studying the transient stability of specific power systems through numerical simulation. Numerical simulation methods can consider complex transient models of doubly-fed wind turbines, encompassing multiple aspects such as normal control, transient control, and hardware protection, minimizing and intuitively reflecting the transient processes of various variables in these complex systems. However, research remains limited in its understanding of the impact of transient control parameters (such as the reactive current injection coefficient) on system transient stability.

[0004] Specifically, for example, existing methods obtain the wind farm's fault analysis parameters, calculate the wind farm's grid connection point voltage divider parameters, create a reactive injection proportional coefficient test array and a grid connection point voltage test array, calculate the wind farm's reactive / active current and terminal voltage, determine the output active power for each test value in the reactive injection proportional coefficient test array, and then determine the reactive injection proportional coefficient test value corresponding to the maximum output active power as the optimized parameter for wind farm fault ride-through. This method aims to improve the transient stability of the wind farm after fault recovery, but it cannot improve the transient stability of the system during and after fault recovery. Furthermore, this method requires a large amount of data calculation and processing, resulting in poor control effectiveness, low control efficiency, and low practicality. Summary of the Invention

[0005] In view of the problems existing in the prior art, the main purpose of the embodiments of the present invention is to provide a method and device for transient stability control of a wind and fire baling system, so as to improve the efficiency and practicality of transient stability control of the wind and fire baling system.

[0006] To achieve the above objectives, an embodiment of the present invention provides a method for controlling transient stability of a wind-fire bundling system, the method comprising:

[0007] Real-time acquisition of the voltage at the terminal of the DFIG wind turbine when the wind-thermal bundling system fails;

[0008] If the terminal voltage of the doubly fed wind turbine is in the first voltage drop interval, the reactive current injection coefficient of the doubly fed wind turbine is increased according to a preset adjustment rule to reduce the swing amplitude of the synchronous generator during the acceleration phase during the fault period;

[0009] If the terminal voltage of the doubly fed wind turbine is in the second voltage drop interval, the reactive current injection coefficient of the doubly fed wind turbine is increased according to the adjustment rule to reduce the swing amplitude of the synchronous generator during the acceleration phase and the swing amplitude of the synchronous generator during the deceleration phase during the fault period;

[0010] If the terminal voltage of the doubly fed wind turbine is in the third voltage drop interval, the reactive current injection coefficient of the doubly fed wind turbine is reduced according to the adjustment rule to reduce the swing amplitude of the synchronous generator deceleration stage during the fault period.

[0011] Optionally, in one embodiment of the present invention, the first voltage drop interval is less than the first critical value; the second voltage drop interval is greater than the second critical value and less than the preset voltage upper limit value; the third voltage drop interval is greater than the first critical value and less than the second critical value.

[0012] Optionally, in one embodiment of the present invention, the method further includes:

[0013] Obtain the historical terminal voltage and historical reactive current injection coefficient of the doubly-fed wind turbine when the wind-thermal bundled system fails, and determine the reactive injection current value based on the historical terminal voltage and historical reactive current injection coefficient;

[0014] Obtaining a reactive current value according to a preset maximum capacity of the converter and the reactive injection current value;

[0015] A first critical value is determined according to the maximum capacity of the converter, the reactive injection current value, and the reactive current value.

[0016] Optionally, in one embodiment of the present invention, the method further includes:

[0017] Obtain the historical terminal voltage of the doubly-fed wind turbine when the wind-thermal bundling system fails, and determine the limit value of the low-voltage active power limiting logic based on the historical terminal voltage;

[0018] Obtaining an active current value according to a preset maximum capacity of the converter and a limit value of the low-voltage active power limiting logic;

[0019] The second critical value is determined according to the maximum capacity of the converter, the amplitude limit value of the low-voltage active power limiting logic, and the active current value.

[0020] An embodiment of the present invention further provides a transient stability control device for an air-fire bundling system, the device comprising:

[0021] Terminal voltage module, used to obtain the terminal voltage of the doubly-fed wind turbine in real time when the wind-thermal bundling system fails;

[0022] A first drop interval module is configured to increase the reactive current injection coefficient of the doubly fed wind turbine according to a preset adjustment rule if the terminal voltage of the doubly fed wind turbine is in the first voltage drop interval, so as to reduce the swing amplitude of the synchronous generator during the acceleration phase during the fault period;

[0023] a second drop interval module, configured to increase the reactive current injection coefficient of the doubly fed wind turbine according to an adjustment rule if the terminal voltage of the doubly fed wind turbine is in the second voltage drop interval, so as to reduce the swing amplitude of the synchronous generator in the acceleration phase and the swing amplitude of the synchronous generator in the deceleration phase during the fault period;

[0024] The third drop interval module is used to reduce the reactive current injection coefficient of the doubly fed wind turbine according to the adjustment rule if the terminal voltage of the doubly fed wind turbine is in the third voltage drop interval, so as to reduce the swing amplitude of the synchronous generator in the deceleration stage during the fault period.

[0025] Optionally, in one embodiment of the present invention, the first voltage drop interval is less than the first critical value; the second voltage drop interval is greater than the second critical value and less than the preset voltage upper limit value; the third voltage drop interval is greater than the first critical value and less than the second critical value.

[0026] Optionally, in one embodiment of the present invention, the apparatus further includes:

[0027] A reactive power injection module is used to obtain the historical terminal voltage and historical reactive current injection coefficient of the doubly-fed wind turbine when the wind-thermal bundling system fails, and determine the reactive power injection current value based on the historical terminal voltage and historical reactive current injection coefficient;

[0028] A reactive current value module, configured to obtain a reactive current value according to a preset maximum capacity of the converter and the reactive injection current value;

[0029] The first critical value module is used to determine a first critical value according to the maximum capacity of the converter, the reactive injection current value and the reactive current value.

[0030] Optionally, in one embodiment of the present invention, the apparatus further includes:

[0031] The limit value module is used to obtain the historical terminal voltage of the doubly fed wind turbine when the wind-thermal bundling system fails, and determine the limit value of the low-voltage active power limiting logic based on the historical terminal voltage;

[0032] The active current value module is used to obtain the active current value according to the preset maximum capacity of the converter and the limit value of the low-voltage active current limit logic;

[0033] The second critical value module is used to determine the second critical value according to the maximum capacity of the converter, the limit value of the low-voltage active power limiting logic and the active current value.

[0034] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the above method is implemented when the processor executes the program.

[0035] The present invention also provides a computer-readable storage medium storing a computer program for executing the above method on a computer.

[0036] The present invention also provides a computer program product, comprising a computer program / instructions, which implement the steps of the above method when executed by a processor.

[0037] The present invention determines the influence of the reactive current injection coefficient on the transient stability of the wind-fire bundling system, and performs rapid and effective transient stability control on the wind-fire bundling system of the doubly fed wind turbine reactive injection coefficient, thereby improving the transient stability control effect of the wind-fire bundling system, enhancing the control efficiency and practicality, and providing a basis for adjusting the transient control parameters of the doubly fed wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 This is a flow chart of a method for controlling transient stability of a wind-fire bundling system according to an embodiment of the present invention;

[0040] Figure 2 A flowchart of determining a first critical value in an embodiment of the present invention;

[0041] Figure 3 A flowchart of determining a second critical value in an embodiment of the present invention;

[0042] Figure 4 Schematic diagram of transient current command control of the rotor converter in an embodiment of the present invention;

[0043] Figure 5A and Figure 5B Schematic diagram of the relationship between active / reactive current and terminal voltage of a doubly-fed wind turbine during a fault in an embodiment of the present invention;

[0044] Figure 6 This is a topological diagram of the wind and fire bundling system in an embodiment of the present invention;

[0045] Figure 7 Schematic diagram of the voltage at the doubly-fed wind turbine terminal when wind power is connected to fault location 2 at different reactive current injection coefficients of 50% in an embodiment of the present invention;

[0046] Figures 8A-8C Schematic diagram of the change of the power angle of the synchronous generator set under different reactive current injection coefficients at fault location 1 in an embodiment of the present invention;

[0047] Figures 9A-9C Schematic diagram of the change of the power angle of the synchronous generator set under different reactive current injection coefficients at fault location 2 in an embodiment of the present invention;

[0048] Figures 10A-10C Schematic diagram of the changes in terminal voltage, active current and power angle of the doubly-fed wind turbine under different reactive current injection coefficients at fault location 1 with metal grounding in an embodiment of the present invention;

[0049] Figures 11A-11C Schematic diagram of the changes in terminal voltage, active current and power angle of the doubly-fed wind turbine under different reactive current injection coefficients at fault location 2 with metal grounding in an embodiment of the present invention;

[0050] Figures 12A-12C Schematic diagram of the changes in terminal voltage, active current and power angle of the doubly-fed wind turbine under different reactive current injection coefficients of non-metallic grounding at fault location 1 in an embodiment of the present invention;

[0051] Figure 13 This is a schematic structural diagram of a transient stability control device for an air-fire bundling system according to an embodiment of the present invention;

[0052] Figure 14 It is a schematic structural diagram of a transient stability control device for an air-fire bundling system according to another embodiment of the present invention;

[0053] Figure 15 It is a structural schematic diagram of a transient stability control device for an air-fire bundling system in another embodiment of the present invention;

[0054] Figure 16 A schematic structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] Embodiments of the present invention provide a method and device for controlling transient stability of an air-fire bundling system.

[0056] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0057] like Figure 1The flowchart of a method for transient stability control of a wind-fire bundling system according to an embodiment of the present invention is shown. The execution subject of the transient stability control method provided by the embodiment of the present invention includes, but is not limited to, a computer. By determining the influence of the reactive current injection coefficient on the transient stability of the wind-fire bundling system, the present invention performs rapid and effective transient stability control of the wind-fire bundling system with a reactive current injection coefficient of a doubly-fed wind turbine. This improves the transient stability control effect of the wind-fire bundling system, enhances control efficiency and practicality, and provides a basis for adjusting the transient control parameters of the doubly-fed wind turbine. The method shown in the figure includes:

[0058] Step S1, obtaining the terminal voltage of the doubly-fed wind turbine in real time when the wind-thermal bundling system fails;

[0059] Step S2: if the terminal voltage of the doubly-fed wind turbine is in the first voltage drop interval, then according to a preset adjustment rule, the reactive current injection coefficient of the doubly-fed wind turbine is increased to reduce the swing amplitude of the synchronous generator during the acceleration phase during the fault period;

[0060] Step S3: If the voltage at the doubly-fed wind turbine terminal is in the second voltage drop interval, then according to the adjustment rule, the reactive current injection coefficient of the doubly-fed wind turbine is increased to reduce the swing amplitude of the synchronous generator during the acceleration phase and the swing amplitude of the synchronous generator during the deceleration phase during the fault period;

[0061] Step S4: If the terminal voltage of the doubly fed wind turbine is in the third voltage drop interval, the reactive current injection coefficient of the doubly fed wind turbine is reduced according to the adjustment rule to reduce the swing amplitude of the synchronous generator during the deceleration stage during the fault period.

[0062] The reactive injection coefficient is the proportional reactive current injection rate of a doubly-fed wind turbine into the grid, based on the grid voltage drop. Furthermore, during a fault in a wind-thermal bundled system, the active and reactive currents of the doubly-fed wind turbine in the bundled system change with the terminal voltage. Specifically, the terminal voltage drop can be categorized into three scenarios based on the dominant transient control link for active and reactive currents.

[0063] Specifically, when the terminal voltage of the doubly fed wind turbine is in the second voltage drop range, the reactive current is dominated by the reactive proportional injection link and increases as the terminal voltage decreases, and the active current is dominated by the LVPL (low voltage active limiting logic) limiting link and decreases as the terminal voltage decreases, and the converter still has margin.

[0064] Furthermore, when the DFIG terminal voltage is in the third voltage drop range, the reactive current is still dominated by the reactive proportional injection link, but the active current is limited by the reactive current and maximum capacity, decreasing as the terminal voltage decreases. When the DFIG terminal voltage is in the first voltage drop range, the reactive current reaches the maximum capacity of the converter and no longer changes with the terminal voltage, and the active current is zero.

[0065] The reactive current injection coefficient of the doubly-fed wind turbine is adjusted differently in different voltage drop intervals to achieve precise control of transient stability during faults in the wind-thermal bundled system. Specifically, the preset adjustment rules can be set based on actual operating conditions, such as the value of each increase or decrease in the reactive current injection coefficient of the doubly-fed wind turbine, the number of adjustments, and so on.

[0066] Furthermore, when focusing on the first swing amplitude of the synchronous generator in the wind-fire bundled system (the synchronous generator acceleration phase during a fault), analysis of relevant historical data shows that as the reactive current injection coefficient of the doubly-fed wind turbine increases, the first swing amplitude of the synchronous generator decreases, and the transient stability of the wind-fire bundled system improves. Furthermore, when focusing on the second swing amplitude of the synchronous generator in the wind-fire bundled system (the synchronous generator deceleration phase after fault clearance), it is necessary to consider the initial value of the active current ramp during the fault recovery period. Therefore, for different voltage drop intervals (i.e., the first, second, and third voltage drop intervals), the initial value of the active current ramp varies differently with the reactive current injection coefficient of the doubly-fed wind turbine.

[0067] Specifically, within the first voltage drop interval, the active current begins to ramp up from 0 at the initial stage of fault recovery. At this time, the initial value of the active current ramp-up remains unchanged by the DFIG reactive current injection coefficient and remains at 0. The DFIG reactive current injection coefficient has little impact on the transient stability of the wind-fire bundling system. Within the second voltage drop interval, as the DFIG reactive current injection coefficient increases, the amplitude of the second swing decreases, which is beneficial to the transient stability of the wind-fire bundling system. Within the third voltage drop interval, the amplitude of the second swing decreases as the DFIG reactive current injection coefficient increases. However, when the DFIG reactive current injection coefficient increases to a certain value (generally 5) or above, the second swing actually increases with the DFIG reactive current injection coefficient, which is detrimental to the transient stability of the wind-fire bundling system.

[0068] This shows that when using the DFIG reactive current injection coefficient to control the transient stability of a wind-thermal bundled system, the second swing amplitude should be the primary focus. This is because the first swing amplitude decreases as the DFIG reactive current injection coefficient increases. Therefore, when controlling the DFIG reactive current injection coefficient to decrease, it is necessary to do so as slowly as possible to ensure that the second swing amplitude decreases while the first swing amplitude does not increase significantly.

[0069] Specifically, the increase in the DFIG's reactive current injection coefficient within the first and second voltage drop intervals helps ensure the transient stability of the wind-fire bundling system. Furthermore, as the DFIG's reactive current injection coefficient increases, the first swing amplitude also decreases. Therefore, when setting the adjustment rule, the increment of the DFIG's reactive current injection coefficient can be set to 0.5 or 1, significantly improving the efficiency of transient stability control for the wind-fire bundling system. Furthermore, the increment of the DFIG's reactive current injection coefficient can be adjusted based on actual conditions and is not limited here.

[0070] Furthermore, because reducing the reactive current injection coefficient of the doubly-fed wind turbine increases the amplitude of the first swing, within the third voltage drop interval, the corresponding decrease in the reactive current injection coefficient of the doubly-fed wind turbine in the adjustment rule is smaller than the increase. For example, the decrease is 0.2 at a time. This appropriately reduces the reactive current injection coefficient of the doubly-fed wind turbine, ensuring that the amplitude of the first swing is not excessive while reducing the amplitude of the second swing and improving the transient stability of the wind-fire bundling system.

[0071] As an embodiment of the present invention, the first voltage drop interval is less than the first critical value; the second voltage drop interval is greater than the second critical value and less than the preset voltage upper limit; the third voltage drop interval is greater than the first critical value and less than the second critical value.

[0072] When setting the first, second and third voltage drop intervals, it is necessary to determine the upper and lower limits of each interval. t1 is the dividing value between the first voltage drop interval and the third voltage drop interval, the second critical value U t2 The voltage upper limit value U1 is the upper limit value of the second voltage drop interval. Specifically, the voltage upper limit value can be adjusted and set according to actual working conditions.

[0073] In this embodiment, if Figure 2 As shown, the method further includes:

[0074] Step S21, obtaining the historical terminal voltage and historical reactive current injection coefficient of the doubly-fed wind turbine when the wind-thermal bundling system fails, and determining the reactive injection current value based on the historical terminal voltage and the historical reactive current injection coefficient;

[0075] Step S22, obtaining a reactive current value according to a preset maximum capacity of the converter and a reactive injection current value;

[0076] Step S23 , determining a first critical value according to the maximum capacity of the converter, the reactive injection current value, and the reactive current value.

[0077] Among them, the boundary value of each voltage drop range is determined based on the historical data of the wind and fire bundling system failure. Figure 4 The schematic diagram of the transient current command control for the rotor converter shown in FIG. shows that the reactive injection current is derived from the terminal voltage and reactive current injection coefficient of the doubly-fed wind turbine. The reactive injection current value is then determined using the historical terminal voltage and reactive current injection coefficient. Furthermore, the reactive current value can be derived from the reactive injection current value and the preset maximum converter capacity. The process for obtaining the reactive injection current value and the reactive current value can be conventionally performed and will not be further elaborated here.

[0078] Furthermore, the reactive injection current value is determined based on different historical terminal voltages and historical reactive current injection coefficients, i.e. p rq_inj +i p rq_ctrl_10 , and the reactive current value i p rq like Figure 5A As shown, combined with the maximum capacity of the converter I rmax , the intersection of these three lines is the first critical value U t1 .

[0079] In this embodiment, if Figure 3 As shown, the method further includes:

[0080] Step 31, obtaining the historical terminal voltage of the doubly-fed wind turbine when the wind-thermal bundling system fails, and determining the limit value of the low-voltage active power limiting logic based on the historical terminal voltage;

[0081] Step S32, obtaining the active current value according to the preset maximum capacity of the converter and the limit value of the low-voltage active power limiting logic;

[0082] Step S33 , determining a second critical value according to the maximum capacity of the converter, the amplitude limit value of the low-voltage active power limiting logic, and the active current value.

[0083] Among them, similar to the first critical value, such as Figure 4 As shown, the historical terminal voltage of the doubly-fed wind turbine during a wind-thermal bundled system failure can be used to determine the low-voltage active power limiting logic limit value, i.e., the LVPL limit. The active current value can be determined using the low-voltage active power limiting logic limit value and the preset maximum converter capacity. The process of determining the active current value and the low-voltage active power limiting logic limit value can be conventionally performed and will not be further described here.

[0084] Furthermore, the limit value i of the low voltage active power limiting logic is determined according to different historical terminal voltages. p rdmax2 , and the active current value i p rd like Figure 5BAs shown, combined with the maximum capacity of the converter I rmax , the intersection of these three lines is the second critical value U t2 .

[0085] The present invention determines the influence of the reactive current injection coefficient on the transient stability of the wind-fire bundling system, and performs rapid and effective transient stability control on the wind-fire bundling system of the doubly fed wind turbine reactive injection coefficient, thereby improving the transient stability control effect of the wind-fire bundling system, enhancing the control efficiency and practicality, and providing a basis for adjusting the transient control parameters of the doubly fed wind turbine.

[0086] In a specific embodiment of the present invention, the transient control strategy of the doubly fed wind turbine rotor side converter is as follows: Figure 4 As shown in Figure 1, during the transient control action, all the integrators of the normal control are frozen and maintain the pre-fault steady-state value. To control the reactive current output normally, It is the active current for normal control output.

[0087] Among them, in the reactive branch, the steady-state value before the fault is The injected current obtained from the reactive injection link After the converter capacity is limited i rmax After constraint, the actual reactive current instruction is obtained U t is the voltage amplitude at the terminal voltage, U tref is the terminal voltage reference value, k qv is the reactive injection coefficient.

[0088] Furthermore, for the active branch part, the steady-state value before the fault After the converter capacity is limited and LVPL clipping After common constraints, the actual active current command is obtained The LVPL limiting link is based on the terminal voltage U t Calculate the active current limit value of the doubly fed wind turbine in the event of a drop When U t >U1, active current has no limit, when U0<U t <U1, the active current limit value is linearly related to the voltage. The lower the voltage, the smaller the active current limit value. When U t When <U0, the active current limit value is 0.

[0089] Reactive current of doubly fed wind turbine under transient control From the steady-state value before the fault With reactive current injection The sum of the converter capacity limit i rmax The minimum value of Among them, the pre-fault steady-state value and the converter capacity limit i rmax are independent of the fault degree. Only the reactive current injection is related to the terminal voltage amplitude U t during the fault and the reactive current injection coefficient k qv . Therefore, for a system with the same structure and operating conditions, the reactive current during the fault depends on the terminal voltage U t and the reactive current injection coefficient k qv , that is The active current is limited by LVPL and the converter capacity limit constraint together constitute Among them, the LVPL limit is related to the terminal voltage amplitude U t and the slope k of the LVPL limit curve d . The converter capacity limit constraint is related to the reactive current , and the reactive current depends on the terminal voltage amplitude U t . Therefore, the active current depends on the terminal voltage amplitude U t , the slope k of the LVPL limit curve d and the reactive current injection coefficient k qv are related, that is

[0090] Among them Figure 5A and Figure 5B respectively show the variation laws of F irq (U t ,k qv ) and F ird (U t ,k d ,k qv ) with the terminal voltage U t . According to the different dominant transient control links of the active current and the reactive current, the degree of terminal voltage drop can be divided into three cases. The third voltage drop interval: U t2 <U t <U1, the reactive current is dominated by the reactive proportion injection link and increases with the decrease of the terminal voltage. The active current is dominated by the LVPL limit link and decreases with the decrease of the terminal voltage. The converter still has a margin. The second voltage drop interval: U t1 <U t <U t2When the reactive current is still dominated by the reactive proportional injection link, the active current is limited by the reactive current and the maximum capacity, and decreases as the terminal voltage decreases. t t1 , the reactive current reaches the maximum capacity of the converter and no longer changes with the decrease of terminal voltage, and the active current is 0.

[0091] In this embodiment, relevant historical data is used to determine the influence of different wind power access ratios and reactive current injection coefficients under different fault conditions on system transient stability.

[0092] Among them, the reactive current injection coefficient dominates the transient characteristics of the doubly fed wind turbine during faults. Taking the wind-fire bundled transmission system as the research object, the power angle of the synchronous generator set is used to reflect the transient stability of the system. The influence of the reactive current injection coefficient on the transient stability of the system is studied, and the mechanism explanation is given.

[0093] Furthermore, the topology of the wind and fire bundling system is as follows Figure 6 As shown in the figure, the doubly fed wind turbine and synchronous unit are connected to the infinite power grid through three double-circuit transmission lines. The capacity of the synchronous unit is 4000MW. The doubly fed wind turbine units are set to 4000MW, 1714.29MW, and 444.44MW according to different access ratios of 50%, 30%, and 10%, respectively. The fault is set to a three-phase ground fault with a fault duration of 0.1s. The fault locations include (1) Fault_1 at the busbar and (2) Fault_2, Fault_3, and Fault_4 in the middle of a circuit of the double-circuit line. In the figure, DFIG is a doubly fed wind turbine and SG is a synchronous generator.

[0094] Under the conditions of 50%, 30% and 10% wind power access ratio and different fault locations, the reactive current injection coefficient k is changed. qv , the power angle waveform of the synchronous generator is obtained (the reference phase is the infinite power supply 1 voltage phase), and the power angle of the synchronous generator is used as a standard to measure the transient stability of the system.

[0095] Among them, when focusing on the first swing amplitude (the acceleration stage of the synchronous generator during the fault), it can be seen that the reactive current injection coefficient k of the doubly fed wind turbine is qv Increase, the first swing amplitude of the synchronous generator decreases, and the transient stability of the system is enhanced, such as Figures 8A-8C and Figures 9A-9C As shown, Figure 8A and Figure 9A The wind power access ratio is 50%, Figure 8B and Figure 9B The wind power access ratio is 30%, Figure 8C and Figure 9C The wind power access ratio is 10%. This is because as k qv ​Increases, and the doubly-fed wind turbine can output more reactive power during a fault, with stronger voltage support ability, and the voltage drop at the fault point decreases (as Figure 7 shown), the active power output of the synchronous machine increases, the unbalanced power (the difference between the input mechanical power and the output electromagnetic power) received by the synchronous machine decreases, and the transient stability is improved.

[0096] Furthermore, when focusing on the swing amplitude of the second swing (the deceleration stage of the synchronous generator after fault clearing), it is necessary to consider the starting value of the active current ramp during fault recovery, which is divided into the following three cases:

[0097] 1) During the fault, U t < U t1 , as Figure 10A shown, the limited value of the active current obtained by LVPL is 0 (a three-phase metallic ground fault occurs at the busbar). At the beginning of fault recovery, the active current ramps up from 0, as Figure 10B shown. At this time, the starting value of the active current ramp does not change with k qv , and is all 0. k qv has little impact on the system transient stability. The power angle of the synchronous machine is as Figure 10C shown.

[0098] 2) During the fault, U t2 < U t < U1, as Figure 11A shown is the schematic diagram of the terminal voltage of the doubly-fed wind turbine under different reactive current injection coefficients for the metal ground fault at fault location 2. The limited value of the active current is linearly related to the voltage, but is not limited by the converter capacity (a three-phase metal ground fault occurs in the middle of one of the double-circuit lines). At this time, the larger k qv is, the stronger the voltage support ability, the higher the terminal voltage of the doubly-fed wind turbine, the larger the limited value of the active current obtained by LVPL, and the larger the starting value of the active current ramp at the beginning of fault recovery. As Figure 11B shown is the schematic diagram of the active current under different reactive current injection coefficients for the metal ground fault at fault location 2, and it is easier to recover. As Figure 11C shown is the schematic diagram of the power angle change of the synchronous generator unit under different reactive current injection coefficients for the metal ground fault at fault location 2. It can be seen that as k qv increases, the swing amplitude of the second swing decreases, which is beneficial to the system transient stability.

[0099] 3) During the fault, U t1 < U t < U t2 , as Figure 12A shown is the schematic diagram of the terminal voltage under different reactive current injection coefficients for the non-metal ground fault at fault location 1, which is limited by the converter capacity (a three-phase non-metal ground fault occurs at the busbar).

[0100] Among them, when k qvAfter increasing to a certain extent, limited by the capacity of the converter, the amplitude limit value of the active current decreases or even becomes 0, and the initial value of the active current ramp decreases or even becomes 0. As Figure 12B shown in the schematic diagram of the active current under different reactive current injection coefficients for non-metallic grounding at fault location 1. Because the ramp coefficient is the same, the recovery after the fault is slow, and the amplitude of the second swing becomes larger, which is not conducive to the transient stability of the system. As Figure 12C shown in the variation of the power angle of the synchronous generator under different reactive current injection coefficients for non-metallic grounding at fault location 1. It can be seen that the amplitude of the second swing decreases with the increase of k qv , but when k qv increases to 5 or more, the second swing increases with the increase of k qv , which is not conducive to the transient stability of the system.

[0101] In this embodiment, taking the power system shown in Figure 6 as an example, a method for improving the transient stability of the system by adjusting the reactive injection coefficient of the doubly-fed wind turbine is described.

[0102] When a deep fault occurs in the power grid, the terminal voltage of the doubly-fed wind turbine during the fault is monitored in real time, and the magnitude of the reactive injection coefficient is determined according to the degree of voltage drop at the machine terminal:

[0103] 1) When U t <U t1 during the fault, that is, the terminal voltage of the doubly-fed wind turbine is in the first voltage drop interval, increase the reactive current injection coefficient k qv of the doubly-fed wind turbine to reduce the amplitude of the first swing of the synchronous generator, while the amplitude of the second swing is hardly affected, thereby enhancing the transient stability of the system.

[0104] 2) When U t2 <U t <U1 during the fault, that is, the terminal voltage of the doubly-fed wind turbine is in the second voltage drop interval, increase the reactive current injection coefficient k qv of the doubly-fed wind turbine, which can reduce the amplitudes of the first and second swings of the synchronous generator at the same time, thereby enhancing the transient stability of the system.

[0105] 3) When U t1 <U t <U t2 during the fault, that is, the terminal voltage of the doubly-fed wind turbine is in the third voltage drop interval, appropriately reduce the reactive current injection coefficient k qv of the doubly-fed wind turbine to reduce the amplitude of the second swing of the synchronous generator, and at the same time prevent the amplitude of the first swing from being too large, thereby enhancing the transient stability of the system.

[0106] Among them, both the increase and decrease of the reactive current injection coefficient of the doubly-fed wind turbine can be adjusted according to the pre-set adjustment rules according to the actual working conditions, which will not be elaborated here.

[0107] At the same time, the impact of the synchronous generator acceleration stage (first swing amplitude) during the fault period and the generator deceleration stage (second swing amplitude) after the fault is cleared on the transient stability of the system is considered.

[0108] The present invention has learned through theoretical and simulation analysis that, in the initial stage of fault recovery, when the active current climbing coefficient is the same, the second swing amplitude is affected by the starting value of the active current climbing. Therefore, according to the terminal voltage amplitude during the fault period, the starting value of the active current climbing is divided into three cases, as shown in the following formula:

[0109]

[0110] In particular, when the fault period U t1 t t2 , the active current is limited by the converter capacity and changes with k qv As the active current increases, the initial value of the active current ramp decreases, which is not conducive to the transient stability of the system. The conclusion is opposite to that of focusing only on the first swing amplitude. Therefore, it is necessary to comprehensively consider the impact of the two stages of synchronous generator acceleration during the fault period and generator deceleration during fault clearance.

[0111] Furthermore, the proposed method for improving transient stability of a wind-thermal bundled system based on the reactive current injection coefficient of a doubly-fed wind turbine, based on theoretical and simulation analysis, demonstrates that, when not limited by wind turbine capacity, increasing the reactive current injection coefficient is beneficial to system transient stability; when limited by wind turbine capacity, appropriately reducing the reactive current injection coefficient is beneficial. This effect is also greater with a higher proportion of wind power.

[0112] The present invention determines the influence of the reactive current injection coefficient on the transient stability of the wind-fire bundling system, and performs rapid and effective transient stability control on the wind-fire bundling system of the doubly fed wind turbine reactive injection coefficient, thereby improving the transient stability control effect of the wind-fire bundling system, enhancing the control efficiency and practicality, and providing a basis for adjusting the transient control parameters of the doubly fed wind turbine.

[0113] like Figure 13 FIG2 is a schematic diagram of a transient stability control device for a wind-fire bundling system according to an embodiment of the present invention. The device shown in the figure includes:

[0114] The terminal voltage module 10 is used to obtain the terminal voltage of the doubly-fed wind turbine in real time when the wind-thermal bundling system fails;

[0115] A first drop interval module 20 is configured to increase the reactive current injection coefficient of the doubly fed wind turbine according to a preset adjustment rule if the terminal voltage of the doubly fed wind turbine is in the first voltage drop interval, so as to reduce the swing amplitude of the synchronous generator during the acceleration phase during the fault period;

[0116] ​​a second voltage drop interval module 30 for increasing the reactive current injection coefficient of the doubly fed wind turbine according to an adjustment rule if the terminal voltage of the doubly fed wind turbine is in the second voltage drop interval, so as to reduce the swing amplitude of the synchronous generator during the acceleration phase and the swing amplitude of the synchronous generator during the deceleration phase during the fault period;

[0117] The third drop interval module 40 is configured to reduce the reactive current injection coefficient of the doubly fed wind turbine according to the adjustment rule if the terminal voltage of the doubly fed wind turbine is in the third voltage drop interval, so as to reduce the swing amplitude of the synchronous generator during the deceleration stage during the fault period.

[0118] As an embodiment of the present invention, the first voltage drop interval is less than the first critical value; the second voltage drop interval is greater than the second critical value and less than the preset voltage upper limit; the third voltage drop interval is greater than the first critical value and less than the second critical value.

[0119] In this embodiment, if Figure 14 As shown, the device also includes:

[0120] The reactive power injection module 21 is used to obtain the historical terminal voltage and historical reactive current injection coefficient of the doubly-fed wind turbine when the wind-thermal bundling system fails, and determine the reactive power injection current value based on the historical terminal voltage and historical reactive current injection coefficient;

[0121] The reactive current value module 22 is used to obtain the reactive current value according to the preset maximum capacity of the converter and the reactive injection current value;

[0122] The first critical value module 23 is configured to determine a first critical value according to the maximum capacity of the converter, the reactive injection current value, and the reactive current value.

[0123] In this embodiment, if Figure 15 As shown, the device also includes:

[0124] The limit value module 31 is used to obtain the historical terminal voltage of the doubly fed wind turbine when the wind-thermal bundling system fails, and determine the limit value of the low-voltage active power limiting logic based on the historical terminal voltage;

[0125] The active current value module 32 is used to obtain the active current value according to the preset maximum capacity of the converter and the limit value of the low-voltage active power limiting logic;

[0126] The second critical value module 33 is configured to determine a second critical value according to the maximum capacity of the converter, the amplitude limit value of the low-voltage active power limiting logic, and the active current value.

[0127] Based on the same application concept as the aforementioned method for controlling transient stability of a wind and fire baling system, the present invention also provides the aforementioned device for controlling transient stability of a wind and fire baling system. Because the principles underlying the device for controlling transient stability of a wind and fire baling system are similar to those of the method for controlling transient stability of a wind and fire baling system, the implementation of the device for controlling transient stability of a wind and fire baling system can be referenced to the implementation of the method for controlling transient stability of a wind and fire baling system, and any repetitions will not be repeated.

[0128] The present invention determines the influence of the reactive current injection coefficient on the transient stability of the wind-fire bundling system, and performs rapid and effective transient stability control on the wind-fire bundling system of the doubly fed wind turbine reactive injection coefficient, thereby improving the transient stability control effect of the wind-fire bundling system, enhancing the control efficiency and practicality, and providing a basis for adjusting the transient control parameters of the doubly fed wind turbine.

[0129] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the above method is implemented when the processor executes the program.

[0130] The present invention also provides a computer program product, comprising a computer program / instructions, which implement the steps of the above method when executed by a processor.

[0131] The present invention also provides a computer-readable storage medium storing a computer program for executing the above method on a computer.

[0132] like Figure 16 As shown, the electronic device 600 may further include: a communication module 110, an input unit 120, an audio processor 130, a display 160, and a power supply 170. It is worth noting that the electronic device 600 does not necessarily have to include Figure 16 In addition, the electronic device 600 may also include all components shown in Figure 16 For components not shown, reference may be made to the prior art.

[0133] like Figure 16 As shown, the central processing unit 100 is sometimes also referred to as a controller or an operation control unit, and may include a microprocessor or other processor device and / or logic device. The central processing unit 100 receives inputs and controls the operations of various components of the electronic device 600 .

[0134] Memory 140 may be, for example, one or more of a cache, flash memory, hard drive, removable media, volatile memory, non-volatile memory, or other suitable devices. It may store the aforementioned failure-related information and may also store programs that execute the relevant information. The CPU 100 may execute the programs stored in memory 140 to implement information storage or processing.

[0135] The input unit 120 provides input to the CPU 100. The input unit 120 may be, for example, a keypad or touch input device. The power supply 170 is used to provide power to the electronic device 600. The display 160 is used to display objects such as images and text. The display may be, for example, an LCD display, but is not limited thereto.

[0136] The memory 140 may be a solid-state memory, such as a read-only memory (ROM), a random access memory (RAM), or a SIM card. Alternatively, it may be a memory that retains information even when power is off, can be selectively erased, and is provided with more data. Examples of such memory are sometimes referred to as EPROMs. The memory 140 may also be some other type of device. The memory 140 includes a buffer memory 141 (sometimes referred to as a buffer). The memory 140 may include an application / function storage unit 142 for storing application programs and function programs or processes for executing the operations of the electronic device 600 via the central processing unit 100.

[0137] The memory 140 may also include a data storage unit 143 for storing data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 144 of the memory 140 may include various driver programs for communication functions of the electronic device and / or for executing other functions of the electronic device (such as messaging applications, address book applications, etc.).

[0138] The communication module 110 is a transmitter / receiver 110 that transmits and receives signals via an antenna 111. The communication module (transmitter / receiver) 110 is coupled to the central processor 100 to provide input signals and receive output signals, which may be the same as in a conventional mobile communication terminal.

[0139] Based on different communication technologies, multiple communication modules 110 may be provided in the same electronic device, such as a cellular network module, a Bluetooth module, and / or a wireless local area network module. The communication module (transmitter / receiver) 110 is also coupled to a speaker 131 and a microphone 132 via an audio processor 130 to provide audio output via the speaker 131 and receive audio input from the microphone 132, thereby implementing common telecommunication functions. The audio processor 130 may include any suitable buffer, decoder, amplifier, etc. Furthermore, the audio processor 130 is also coupled to the central processing unit 100, enabling local recording via the microphone 132 and playback of stored audio via the speaker 131.

[0140] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0141] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts 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, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0142] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0143] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0144] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A transient stability control method for an air-fire bundling system, characterized in that: The method comprises: Real-time acquisition of the voltage at the terminal of the DFIG wind turbine when the wind-thermal bundling system fails; If the terminal voltage of the doubly fed wind turbine is in the first voltage drop interval, then according to a preset adjustment rule, the reactive current injection coefficient of the doubly fed wind turbine is increased to reduce the swing amplitude of the synchronous generator during the acceleration phase during the fault period; If the terminal voltage of the doubly fed wind turbine is in the second voltage drop interval, increasing the reactive current injection coefficient of the doubly fed wind turbine according to the adjustment rule to reduce the swing amplitude of the synchronous generator in the acceleration phase and the swing amplitude of the synchronous generator in the deceleration phase during the fault period; If the terminal voltage of the doubly fed wind turbine is in the third voltage drop interval, the reactive current injection coefficient of the doubly fed wind turbine is reduced according to the adjustment rule to reduce the swing amplitude of the synchronous generator in the deceleration stage during the fault period.

2. The method according to claim 1, characterized in that The first voltage drop interval is less than a first critical value; the second voltage drop interval is greater than a second critical value and less than a preset voltage upper limit; the third voltage drop interval is greater than the first critical value and less than the second critical value.

3. The method according to claim 2, characterized in that The method further comprises: Obtaining a historical terminal voltage and a historical reactive current injection coefficient of the doubly-fed wind turbine when the wind-thermal bundled system fails, and determining a reactive injection current value based on the historical terminal voltage and the historical reactive current injection coefficient; Obtaining a reactive current value according to a preset maximum capacity of the converter and the reactive injection current value; A first critical value is determined according to the maximum capacity of the converter, the reactive injection current value, and the reactive current value.

4. The method according to claim 2, characterized in that The method further comprises: Obtaining the historical terminal voltage of the doubly-fed wind turbine when the wind-thermal bundling system fails, and determining the limit value of the low-voltage active power limiting logic based on the historical terminal voltage; Obtaining an active current value according to a preset maximum capacity of the converter and a limit value of the low-voltage active power limiting logic; The second critical value is determined according to the maximum capacity of the converter, the amplitude limit value of the low-voltage active power limiting logic, and the active current value.

5. A transient stability control device for an air-fire baling system, characterized in that: The device comprises: Terminal voltage module, used to obtain the terminal voltage of the doubly-fed wind turbine in real time when the wind-thermal bundling system fails; a first drop interval module, configured to increase the reactive current injection coefficient of the doubly fed wind turbine according to a preset adjustment rule if the terminal voltage of the doubly fed wind turbine is in the first voltage drop interval, so as to reduce the swing amplitude of the synchronous generator in the acceleration phase during the fault period; a second drop interval module, configured to increase the reactive current injection coefficient of the doubly fed wind turbine according to the adjustment rule if the terminal voltage of the doubly fed wind turbine is in the second voltage drop interval, so as to reduce the swing amplitude of the synchronous generator in the acceleration phase and the swing amplitude of the synchronous generator in the deceleration phase during the fault period; The third drop interval module is used to reduce the reactive current injection coefficient of the doubly fed wind turbine according to the adjustment rule if the terminal voltage of the doubly fed wind turbine is in the third voltage drop interval, so as to reduce the swing amplitude of the synchronous generator in the deceleration stage during the fault period.

6. The device according to claim 5, characterized in that The first voltage drop interval is less than a first critical value; the second voltage drop interval is greater than a second critical value and less than a preset voltage upper limit; the third voltage drop interval is greater than the first critical value and less than the second critical value.

7. The device according to claim 6, characterized in that The device further comprises: A reactive power injection module is used to obtain the historical terminal voltage and the historical reactive current injection coefficient of the doubly-fed wind turbine when the wind-thermal bundling system fails, and determine the reactive power injection current value according to the historical terminal voltage and the historical reactive current injection coefficient; A reactive current value module, configured to obtain a reactive current value according to a preset maximum capacity of the converter and the reactive injection current value; The first critical value module is used to determine a first critical value according to the maximum capacity of the converter, the reactive injection current value and the reactive current value.

8. The device according to claim 6, characterized in that The device further comprises: A limit value module is used to obtain the historical terminal voltage of the doubly fed wind turbine when the wind-thermal bundling system fails, and determine the limit value of the low-voltage active power limiting logic based on the historical terminal voltage; An active current value module, configured to obtain an active current value according to a preset maximum capacity of the converter and a limit value of the low-voltage active power limiting logic; The second critical value module is used to determine the second critical value according to the maximum capacity of the converter, the limit value of the low-voltage active power limiting logic and the active current value.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 4 is implemented.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program for causing a computer to execute the method according to any one of claims 1 to 4.

11. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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