Transmitting end transient overvoltage control method, device and equipment

Abstract

The invention relates to the technical field of voltage control, in particular to a sending-end transient overvoltage control method, device and equipment, and the method comprises the steps: detecting the deviation between a system voltage value and a rated value, and obtaining the correction of a phase-locked loop angle through the calculation of a proportional link and an amplitude limiting link, thereby indirectly influencing the output of reactive power, and achieving the control of the transient overvoltage. And the problems of overlong control delay and poor voltage suppression effect caused by output reactive power lag in a traditional method of adjusting reactive power are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage control, and in particular to a method, device and equipment for controlling transient overvoltage at a sending end. Background Art

[0002] my country's wind resources are primarily distributed in the "Three Northern" regions, while the load centers are located in the central and eastern regions. This inverse distribution of resources and loads dictates that long-distance UHVDC transmission of wind turbine clusters is the primary method for absorbing this wind power. In recent years, the increasing proportion of wind turbines in the sending-end system has weakened the sending-end grid. Consequently, transient overvoltages caused by typical AC / DC faults, such as commutation failures, can cause large-scale wind turbines to disconnect from the grid, seriously impacting the safe and stable operation of the system.

[0003] Existing analysis of factors affecting wind turbine transient voltage at the sending end is mainly based on electromagnetic transient simulation models and the establishment of transient voltage analytical models. When a commutation failure occurs in the wind power transmission system through DC transmission, the phase-locked deviation caused by the dynamic response of the phase-locked loop (PLL) affects the wind turbine power output, thereby affecting the transient voltage characteristics of the sending end. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a method, device and apparatus for controlling transient overvoltage at a sending end, so as to overcome the problems existing in the current prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present application provides a method for controlling a transient overvoltage at a sending end, comprising:

[0007] Get system parameters;

[0008] Calculate the d-axis modulation and the q-axis modulation according to the system parameters;

[0009] Collect the three-phase grid-connected point voltage of the wind turbine and obtain the phase-locked angle through the phase-locked loop (PLL);

[0010] Calculating a phase-lock angle correction value based on the three-phase grid-connected point voltage of the wind turbine;

[0011] Calculate the transformation angle according to the phase-locking angle and the phase-locking angle correction amount;

[0012] transforming the d-axis modulation amount and the q-axis modulation amount according to the transformation angle using a dq / abc transformation calculation formula to obtain a three-phase modulation amount;

[0013] The three-phase output voltage target value of the converter is controlled according to the three-phase modulation amount.

[0014] Furthermore, in the above method, the system parameters include: an active power reference value, an active output feedback value, a reactive power reference value and a reactive output feedback value.

[0015] Furthermore, in the above method, the step of calculating the d-axis modulation amount according to the system parameters includes:

[0016] The active power reference value is subtracted from the active output feedback value, and the difference is passed through a PI controller to obtain a d-axis current inner loop reference value;

[0017] Subtracting the d-axis current inner loop reference value from the d-axis component of the output current of the grid-side converter GSC, and passing the difference through a PI controller to obtain a d-axis control voltage;

[0018] The d-axis modulation amount is obtained by subtracting the product of the d-axis component of the output current and the connection inductance of the grid-side converter GSC from the d-axis control voltage.

[0019] Furthermore, in the above method, the step of calculating the q-axis modulation value according to the system parameters includes:

[0020] The reactive power reference value is subtracted from the reactive output feedback value, and the difference is passed through a PI controller to obtain a q-axis current inner loop reference value;

[0021] Subtracting the q-axis current inner loop reference value from the q-axis component of the output current of the grid-side converter GSC, and passing the difference through a PI controller to obtain a q-axis control voltage;

[0022] The q-axis modulation amount is obtained by subtracting the product of the q-axis component of the output current and the connection inductance of the grid-side converter GSC from the q-axis control voltage.

[0023] Furthermore, the method described above, wherein the phase-lock angle correction value is calculated based on the three-phase grid connection point voltage of the wind turbine, includes:

[0024] The three-phase grid connection point voltage of the wind turbine is subjected to an effective value RMS calculation link to obtain an RMS value of the grid connection point voltage;

[0025] The difference between the RMS value of the grid connection point voltage and the system rated voltage is calculated, and the difference is passed through a proportional link and a limiting link to obtain a phase-locked angle correction value.

[0026] Furthermore, in the above method, the step of calculating the transformation angle based on the phase-lock angle and the phase-lock angle correction value includes:

[0027] The phase-locking angle and the phase-locking angle correction amount are summed to obtain a transformation angle for controlling transformation.

[0028] Furthermore, in the above method, the dq / abc conversion calculation formula includes:

[0029]

[0030] Among them, m dg is the d-axis modulation, m qg is the q-axis modulation, m ag 、m bg and m cg is the three-phase modulation quantity, and θ is the conversion angle.

[0031] Furthermore, in the above method, controlling the target value of the three-phase output voltage of the converter according to the three-phase modulation amount includes:

[0032] generating a converter trigger pulse by a pulse generator according to the three-phase modulation amount;

[0033] The switching tube of the converter is triggered to be turned on and off according to the converter trigger pulse, thereby controlling the target value of the three-phase output voltage of the converter.

[0034] In a second aspect, the present application provides a sending-end transient overvoltage control device, comprising:

[0035] Parameter acquisition module, used for system parameters;

[0036] A modulation amount calculation module is used to calculate the d-axis modulation amount and the q-axis modulation amount according to the system parameters;

[0037] A transformation angle calculation module is used to collect the three-phase grid-connected point voltage of the wind turbine, obtain a phase-locked angle through a phase-locked loop (PLL), calculate a phase-locked angle correction value based on the three-phase grid-connected point voltage of the wind turbine, and calculate a transformation angle based on the phase-locked angle and the phase-locked angle correction value;

[0038] a conversion module, configured to convert the d-axis modulation amount and the q-axis modulation amount according to the conversion angle using a dq / abc conversion calculation formula to obtain a three-phase modulation amount;

[0039] The converter control module is used to control the converter three-phase output voltage target value according to the three-phase modulation amount.

[0040] In a third aspect, the present application provides a sending-end transient overvoltage control device, comprising a processor and a memory, wherein the processor is connected to the memory:

[0041] The processor is configured to call and execute the program stored in the memory;

[0042] The memory is used to store the program, and the program is used at least to execute any one of the above sending-end transient overvoltage control methods.

[0043] The beneficial effects of the present invention are:

[0044] The present application first obtains the system parameters, calculates the d-axis modulation and q-axis modulation based on the system parameters, then collects the three-phase grid-connected point voltage of the wind turbine, obtains the phase-locked angle through the phase-locked loop (PLL), calculates the phase-locked angle correction based on the three-phase grid-connected point voltage of the wind turbine, calculates the transformation angle based on the phase-locked angle and the phase-locked angle correction, and finally, transforms the d-axis modulation and q-axis modulation based on the transformation angle using the dq / abc transformation calculation formula to obtain the three-phase modulation, and controls the three-phase output voltage target value of the converter based on the three-phase modulation. In the present application, by detecting the deviation between the system voltage value and the rated value, the correction value of the phase-locked loop angle is calculated through the proportional link and the limiter link, thereby indirectly affecting the output of reactive power, avoiding the problem of excessive control delay caused by the traditional method of adjusting reactive power and poor voltage suppression effect caused by output reactive lag. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] 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 use in the embodiments or the description of the prior art. 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.

[0046] Figure 1 This is a flow chart provided by an embodiment of a method for controlling transient overvoltage at a sending end of the present invention;

[0047] Figure 2 This is a structural diagram of an embodiment of a sending-end transient overvoltage control device provided by the present invention;

[0048] Figure 3 This is a structural diagram of an embodiment of a sending-end transient overvoltage control device provided by the present invention;

[0049] Figure 4 This is a structural diagram of an equivalent system of a fan through a DC transmission system provided by an embodiment of a method for controlling transient overvoltage at a sending end of the present invention;

[0050] Figure 5 This is a main circuit topology diagram of a direct-drive wind turbine grid-connected system provided by an embodiment of a method for controlling transient overvoltage at a sending end of the present invention;

[0051] Figure 6 This is a characteristic diagram of the phase change of the sending-end grid voltage after commutation failure provided by an embodiment of a sending-end transient overvoltage control method of the present invention;

[0052] Figure 7 This is a phase-locked loop control structure diagram provided by an embodiment of a method for controlling transient overvoltage at a sending end of the present invention;

[0053] Figure 8 This is a PLL output waveform diagram under different x and wp conditions during phase step jump provided by an embodiment of a sending-end transient overvoltage control method of the present invention;

[0054] Figure 9 This is a PLL output waveform diagram under different x and wp conditions when the phase is ramped, provided by an embodiment of a method for controlling transient overvoltage at a sending end of the present invention;

[0055] Figure 10 A voltage vector diagram of a coupling point between a synchronous dq coordinate system and a PLL-dq coordinate system is provided in an embodiment of a method for controlling transient overvoltage at a sending end of the present invention;

[0056] Figure 11 This is a diagram showing the effect of phase-locking deviation on wind turbine output power provided by an embodiment of a method for controlling transient overvoltage at a sending end of the present invention;

[0057] Figure 12 The present invention provides a flowchart of a method for controlling transient overvoltage at a sending end based on phase-locked angle correction, according to an embodiment of the method for controlling transient overvoltage at a sending end. DETAILED DESCRIPTION

[0058] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0059] Figure 1 This is a flow chart of an embodiment of a method for controlling transient overvoltage at the sending end of the present invention. Figure 1 , this embodiment may include the following steps:

[0060] S1. Obtain system parameters;

[0061] S2. Calculate the d-axis modulation and the q-axis modulation according to the system parameters;

[0062] S3, collect the three-phase grid connection point voltage of the wind turbine and obtain the phase-locked angle through the phase-locked loop (PLL);

[0063] S4. Calculate the phase-lock angle correction value based on the three-phase grid connection point voltage of the wind turbine;

[0064] S5. Calculate the transformation angle based on the phase-locking angle and the phase-locking angle correction value;

[0065] S6. Transform the d-axis modulation amount and the q-axis modulation amount according to the transformation angle using the dq / abc transformation calculation formula to obtain the three-phase modulation amount;

[0066] S7. Control the three-phase output voltage target value of the converter according to the three-phase modulation amount.

[0067] It is understood that this embodiment first obtains system parameters, calculates the d-axis modulation and q-axis modulation based on the system parameters, then collects the three-phase grid-connected point voltage of the wind turbine, obtains the phase-locked angle through the phase-locked loop (PLL), calculates the phase-locked angle correction based on the three-phase grid-connected point voltage of the wind turbine, and calculates the transformation angle based on the phase-locked angle and the phase-locked angle correction. Finally, the d-axis modulation and q-axis modulation are transformed according to the transformation angle using the dq / abc transformation formula to obtain the three-phase modulation, and the three-phase output voltage target value of the converter is controlled based on the three-phase modulation. In this application, by detecting the deviation of the system voltage value from the rated value, the correction value of the phase-locked loop angle is calculated through the proportional link and the limiter link, thereby indirectly affecting the reactive power output, avoiding the problems of excessive control delay caused by traditional methods of adjusting reactive power and poor voltage suppression caused by output reactive lag.

[0068] It should be noted that, based on existing research, this embodiment first analyzes the mechanism of transient voltage generation at the sending end after commutation failure. Then, based on the dynamic response equation of the phase-locked loop, the main factors affecting the dynamic response characteristics of the phase-locked loop are analyzed, and a wind turbine power output equation considering phase-locked deviation is established. The influence mechanism of phase-locked deviation on the reactive power transient response of the wind turbine is revealed. Finally, the correctness of the conclusions is verified based on the PSCAD / EMPTC simulation platform.

[0069] Under normal operating conditions, the reactive power consumption level of the DC system is about 40% to 60% of the active power transmission level. Almost all of this reactive power is provided by the reactive power compensation device at the commutation busbar. The reactive power exchange between the DC system and the AC system at the sending end is close to zero. Figure 4 As shown, where U s is the bus voltage at the machine end, U g is the commutation bus voltage, P w and Q w are the active and reactive power output of the wind turbine, P d and Q d are the active and reactive power of the DC system, Q f is the reactive power emitted by the filter, and X is the equivalent reactance of the system.

[0070] During the commutation failure period, the DC current will undergo a dynamic process of "rising first and then falling" under the control of the control system, causing the reactive power consumption level of the DC system to increase first and then decrease. During this period, the reactive power balance of the sending-end system is broken, resulting in a transient voltage problem of "low first and then high" at the sending-end commutation bus. The transient voltage change equation at the commutation bus can be approximated as shown in formula (1). In the DC rising stage, Q d Much larger than Q w and Q f , the converter station absorbs reactive power from the AC system (ΔQ<0), at this time the sending end voltage decreases, the wind turbine enters the low voltage ride-through state and generates reactive power to support the transient low voltage; in the DC drop stage, Q d It decreases rapidly. Since the wind turbine's low voltage ride-through control and reactive power compensation device cannot exit in time due to control response delay, the converter station transmits reactive power to the AC system (ΔQ>0). At this time, the sending end voltage increases. After that, the wind turbine enters the high voltage ride-through state and lacks reactive power to suppress transient overvoltage.

[0071]

[0072] Where S ac is the short-circuit capacity at the commutation bus, △U g is the transient voltage change, and △Q is the reactive power change.

[0073] The main circuit topology of the direct-drive wind turbine grid-connected system is as follows: Figure 5 As shown, where L f and C f are filter inductors and capacitors respectively, u abc_g and i abc_g are the three-phase voltage and current on the grid side, R g and L g are the equivalent resistance and inductance of the power grid, e abc is the three-phase voltage of the power grid, q PLL is the voltage phase of the phase-locked loop output, u dq_g and i dq_g are the dq axis components of the grid side voltage and current respectively.

[0074] During steady-state operation, the wind turbine uses grid voltage-oriented control, tracking the grid voltage phase through a phase-locked loop and ensuring that the d-axis voltage is in the same direction as the grid voltage. At this time, the d-axis reference current is given by the voltage outer loop, and the q-axis reference current is 0. In the event of a system fault, the wind turbine uses fault ride-through control, requiring it to output or absorb a certain amount of reactive power to assist the grid operation. The specific requirements are: when the grid connection point voltage is between 20% and 90% of the rated voltage, the wind turbine enters low voltage ride-through control; when the grid connection point voltage is between 110% and 130% of the rated voltage, the wind turbine enters high voltage ride-through control. The current reference values under different control modes are shown in Equation (2).

[0075]

[0076] Where i dref and i qref are respectively the active and reactive current reference values of the fan control system, i dnref is the active current reference value in steady state, I rate is the rated current of the wind farm, and U is the voltage amplitude at the grid connection point.

[0077] When a typical AC / DC fault occurs in the system, the voltage phase at the sending end will change to varying degrees. The phase change characteristics will vary depending on factors such as the fault type, electrical distance, and the magnitude of the active current before and after the fault. The specific differences are manifested in the phase lead and lag changes, the change amplitude, and the change speed. The phase change characteristics of the sending end voltage after commutation failure are as follows: Figure 6 shown.

[0078] according to Figure 6 It can be seen that after a commutation failure occurs in the DC system, the transient change characteristics of the voltage phase at the sending end are specifically manifested as follows: when a commutation failure fault occurs, the voltage phase approximately shows a step jump and leads the change; when the fault is restored, the voltage phase first lags behind the sudden change and then recovers slowly, with a slow recovery speed.

[0079] The phase-locked loop consists of a phase detector, a loop filter and a voltage-controlled oscillator. Taking the classic three-phase synchronous phase-locked loop as an example, its control structure is as follows: Figure 7 As shown in the figure, u α_g and u β_g are the α and β components of the grid-side voltage in the two-phase stationary coordinate system.

[0080] Phase-locked loop input grid point voltage u abc_g The voltage dq component in the dq coordinate system is obtained by coordinate transformation, and u q_g Input into the PI controller to get the angular frequency ω of the phase-locked loop voltage PLL , after integration, the phase-locked loop output phase θ can be obtained PLL .

[0081] according to Figure 7 The PLL control structure shown in FIG1 can obtain the transfer function equation of the PLL output phase, as shown in equation (3).

[0082]

[0083] Where, E s is the voltage amplitude at the grid connection point, K ppll and K ipll is the PI controller parameter, s is the Laplace operator, ξ is the damping ratio of PLL, ω p is the control bandwidth of the PLL, and its specific expression is shown in formula (4):

[0084]

[0085] If the voltage phase jumps suddenly from θ0 to θ0+Δθ, the phase change Δθ is substituted into equation (3) as the step response to obtain the phase change Δθ of the phase-locked loop output: PLL , as shown in formula (5).

[0086]

[0087] When E s 2 K ppll 2 -4E s K ipll When <0, the root is the conjugate complex number of the negative real part. After the Laplace inverse transform of formula (5), the time domain equation of the phase change of the phase-locked loop output can be obtained, as shown in formula (6):

[0088]

[0089] According to formula (6), when the phase changes suddenly, the phase-locked deviation is a quantity with a non-zero initial value and changes with time. Therefore, due to the phase jump caused by the fault occurrence and recovery, the phase-locked loop needs a period of time to complete the phase lock. During this period, the phase-locked loop cannot achieve complete phase lock, and the phase-locked deviation is the largest in the initial stage after the phase change.

[0090] According to the analysis of the phase characteristics of the voltage at the grid connection point after the phase commutation failure, it can be seen that the voltage phase suddenly changes when the fault occurs, and at the end of the fault, the voltage gradually ramps back to the original operating state after a small sudden change. Therefore, let the phase sudden change and ramp change be 1rad respectively, and substitute them into formula (3) to calculate the phase output waveform of the phase-locked loop under different phase change trends and different damping ratios and bandwidths, as shown below: Figure 8 and Figure 9 shown.

[0091] according to Figure 8 It can be seen that after the phase step jump, the phase-locked loop needs about 100ms to track the actual phase. During this period, there is a large phase-locked deviation between the phase output of the phase-locked loop and the actual phase; and different ξ and ω p Affects the phase tracking characteristics of the PLL, as ξ and ω p As the phase shift decreases, the PLL tracking becomes slower in the initial stage, which will lead to a larger phase deviation and have a greater impact on the fault ride-through characteristics of the wind turbine.

[0092] according to Figure 9 It can be seen that when the phase changes in a ramp response, there is only a small deviation between the phase-locked loop output phase and the actual phase under different PLL damping ratios and bandwidths in the initial stage, which can be ignored.

[0093] The phase-locked loop mainly affects the synchronous coordinate rotation transformation (Park transformation), so the phase-locked deviation will affect the voltage and current dq components of the input fan control system. Figure 10 The space vector transformation diagram of the αβ-dq coordinate system is given, where V is the composite vector of the three-phase power grid voltage, q real and q pll are the angles between the actual d-axis position and the PLL phase-locked d-axis position and the αβ coordinate system, respectively.

[0094] In steady state, the wind turbine adopts the d-axis voltage orientation strategy, V δ Coincident with the d-axis, the q-axis component is 0; when the grid voltage phase suddenly changes, the phase deviation at this time makes the d-axis orientation invalid, V δ A corresponding component will be generated on the q-axis.

[0095] The phase-locked loop output phase angle θ PLL Substitute into the abc-dq transformation matrix, as shown in formula (7):

[0096]

[0097] The grid voltage u abc_g After coordinate transformation, the dq axis voltage equation including phase-locked deviation can be obtained, as shown in equation (8):

[0098]

[0099] Where Δθ PLL is the difference between the actual voltage phase and the phase-locked loop output phase, and its value decays from Δθ to 0 over time. Without considering the phase-locked deviation, the power output equation of the wind turbine is shown in formula (9):

[0100]

[0101] Substituting equations (2) and (8) into equation (9) yields the wind turbine power output equation considering phase-locked deviation during a fault, as shown in equation (10):

[0102]

[0103] Where, E sf is the grid side voltage after the fault, P wf and Q wf are respectively the active and reactive power output by the fan during the fault period, K L is the low voltage ride through reactive gain coefficient.

[0104] Assume that the grid voltage drops by 0.5pu after the fault, and the wind turbine low-through reactive current gain coefficient K L=1.5, according to formula (2), the dq axis current reference value after the wind turbine enters the low-break state can be obtained. Substituting the grid voltage and dq axis current reference value into formula (10), the influence of different phase-locking deviations on the active and reactive power output characteristics of the wind turbine can be obtained, as shown in Figure 11 shown.

[0105] according to Figure 11 It can be seen that when a fault occurs, the voltage phase suddenly changes forward. Due to the dynamic response of the phase-locked loop, there is a positive phase deviation at this time, and the wind turbine will increase its reactive power generation, which can better support the transient low voltage. On the contrary, when the grid voltage phase lags behind the phase-locked loop output phase, the wind turbine will under-generate reactive power, which will worsen the low voltage.

[0106] Preferably, the system parameters include: an active power reference value, an active output feedback value, a reactive power reference value, and a reactive output feedback value.

[0107] Preferably, the d-axis modulation amount is calculated according to the system parameters, including:

[0108] The difference between the active power reference value and the active output feedback value is calculated and the difference is passed through the PI controller to obtain the d-axis current inner loop reference value;

[0109] The d-axis current inner loop reference value is subtracted from the d-axis component of the output current of the grid-side converter GSC, and the difference is passed through the PI controller to obtain the d-axis control voltage;

[0110] The d-axis modulation amount is obtained by subtracting the product of the d-axis component of the output current and the connection inductance of the grid-side converter GSC from the d-axis control voltage.

[0111] Preferably, the q-axis modulation amount is calculated according to the system parameters, including:

[0112] The reactive power reference value is subtracted from the reactive output feedback value, and the difference is passed through the PI controller to obtain the q-axis current inner loop reference value;

[0113] The q-axis current inner loop reference value is subtracted from the q-axis component of the grid-side converter GSC output current, and the difference is passed through the PI controller to obtain the q-axis control voltage;

[0114] The q-axis modulation amount is obtained by subtracting the product of the q-axis component of the output current and the connection inductance of the grid-side converter GSC from the q-axis control voltage.

[0115] Preferably, step S4 includes:

[0116] The three-phase grid-connected point voltage of the wind turbine is subjected to the RMS calculation link to obtain the RMS value of the grid-connected point voltage;

[0117] The difference between the RMS value of the grid connection point voltage and the rated voltage of the system is passed through the proportional link and the limiting link to obtain the phase-locked angle correction value.

[0118] Preferably, step S5 includes:

[0119] The phase-locking angle and the phase-locking angle correction amount are summed to obtain the transformation angle used to control the transformation.

[0120] Preferably, the dq / abc conversion calculation formula includes:

[0121]

[0122] Among them, m dg is the d-axis modulation, m qg is the q-axis modulation, m ag 、m bg and m cg is the three-phase modulation quantity, and θ is the conversion angle.

[0123] Preferably, step S7 includes:

[0124] According to the three-phase modulation amount, a converter trigger pulse is generated by a pulse generator;

[0125] The converter trigger pulse triggers the opening and closing of the converter switch tube, thereby controlling the converter three-phase output voltage target value.

[0126] In specific practice, such as Figure 12 As shown, Figure 12 The present invention provides a flowchart of a method for controlling transient overvoltage at a sending end based on phase-locked angle correction, according to an embodiment of the method for controlling transient overvoltage at a sending end.

[0127] Active power reference value P * The difference between the active output feedback value P and the PI controller is used to obtain the d-axis current inner loop reference value I gd * , and the d-axis component I of the output current of the grid-side converter GSC gd The d-axis control voltage V is obtained by the PI controller. gd , d-axis control voltage V gd Subtract the output current d-axis component I gd The d-axis modulation value M is obtained by multiplying it with the inductance connected to the grid-side converter GSC. dg ;

[0128] Reactive power reference value Q * The difference between the reactive output feedback value Q and the PI controller is used to obtain the q-axis current inner loop reference value I gq * , and the q-axis component I of the output current of the grid-side converter GSC gq The q-axis control voltage V is obtained by the PI controller. gq , q-axis control voltage V gqSubtract the output current q-axis component I gd The product of the connection inductance of the grid-side converter GSC is the q-axis modulation quantity M qg ;

[0129] Collect the three-phase grid-connected voltage V of the fan ga， V gb， V gc , the phase-locked angle θ1 is obtained through the phase-locked loop PLL;

[0130] Grid connection point voltage V ga， V gb， V gc , after the effective value RMS calculation link, the grid voltage RMS value V grms , and the difference between it and the system rated voltage is obtained through the proportional link and the limit link to obtain the phase-locked angle correction value △θ1;

[0131] The phase-locking angle and the phase-locking angle correction amount are summed to obtain a transformation angle for controlling transformation;

[0132] d-axis modulation M dg and q-axis modulation M qg The three-phase modulation quantity is obtained by dq / abc conversion, and then the converter trigger pulse is generated by the pulse generator;

[0133] The converter trigger pulse triggers the on and off of the converter switch tube, thereby controlling the converter three-phase output voltage target value.

[0134] The present invention also provides a sending-end transient overvoltage control device for implementing the above method embodiment. Figure 2 This is a structural diagram of an embodiment of a sending-end transient overvoltage control device provided by the present invention. Figure 2 As shown, this embodiment includes:

[0135] Parameter acquisition module 1, used for system parameters;

[0136] Modulation calculation module 2, used to calculate the d-axis modulation and q-axis modulation according to system parameters;

[0137] The conversion angle calculation module 3 is used to collect the three-phase grid-connected point voltage of the wind turbine, obtain the phase-locked angle through the phase-locked loop PLL, calculate the phase-locked angle correction value based on the three-phase grid-connected point voltage of the wind turbine, and calculate the conversion angle based on the phase-locked angle and the phase-locked angle correction value;

[0138] The conversion module 4 is used to convert the d-axis modulation amount and the q-axis modulation amount according to the conversion angle using the dq / abc conversion calculation formula to obtain the three-phase modulation amount;

[0139] The converter control module 5 is used to control the converter three-phase output voltage target value according to the three-phase modulation amount.

[0140] Regarding the apparatus in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0141] The present invention also provides a sending-end transient overvoltage control device for implementing the above method embodiment. Figure 3 This is a structural diagram of an embodiment of a sending-end transient overvoltage control device provided by the present invention. Figure 3 As shown, the sending-end transient overvoltage control device of this embodiment includes a processor 21 and a memory 22, wherein the processor 21 is connected to the memory 22. The processor 21 is used to call and execute the program stored in the memory 22; the memory 22 is used to store the program, which is used to at least execute the sending-end transient overvoltage control method of the above embodiment.

[0142] The specific implementation scheme of the sending-end transient overvoltage control device provided in the embodiments of the present application can refer to the implementation scheme of the sending-end transient overvoltage control method in any of the above embodiments, and will not be repeated here.

[0143] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0144] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is at least two.

[0145] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention pertain.

[0146] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0147] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0148] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing module, or each unit may exist physically separately, or two or more units may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or in the form of software functional modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.

[0149] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0150] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0151] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for controlling transient overvoltage at a sending end, characterized in that: include: Get system parameters; Calculate the d-axis modulation and the q-axis modulation according to the system parameters; Collect the three-phase grid-connected point voltage of the wind turbine and obtain the phase-locked angle through the phase-locked loop (PLL); Calculating a phase-lock angle correction value based on the three-phase grid-connected point voltage of the wind turbine; Calculate the transformation angle according to the phase-locking angle and the phase-locking angle correction amount; transforming the d-axis modulation amount and the q-axis modulation amount according to the transformation angle using a dq / abc transformation calculation formula to obtain a three-phase modulation amount; The three-phase output voltage target value of the converter is controlled according to the three-phase modulation amount.

2. The method according to claim 1, characterized in that The system parameters include: active power reference value, active output feedback value, reactive power reference value and reactive output feedback value.

3. The method according to claim 2, characterized in that The calculating the d-axis modulation amount according to the system parameters includes: The active power reference value is subtracted from the active output feedback value, and the difference is passed through a PI controller to obtain a d-axis current inner loop reference value; Subtracting the d-axis current inner loop reference value from the d-axis component of the output current of the grid-side converter GSC, and passing the difference through a PI controller to obtain a d-axis control voltage; The d-axis modulation amount is obtained by subtracting the product of the d-axis component of the output current and the connection inductance of the grid-side converter GSC from the d-axis control voltage.

4. The method according to claim 3, characterized in that The calculating and obtaining the q-axis modulation amount according to the system parameters includes: The reactive power reference value is subtracted from the reactive output feedback value, and the difference is passed through a PI controller to obtain a q-axis current inner loop reference value; Subtracting the q-axis current inner loop reference value from the q-axis component of the output current of the grid-side converter GSC, and passing the difference through a PI controller to obtain a q-axis control voltage; The q-axis modulation amount is obtained by subtracting the product of the q-axis component of the output current and the connection inductance of the grid-side converter GSC from the q-axis control voltage.

5. The method according to claim 4, characterized in that The step of calculating the phase-lock angle correction value based on the three-phase grid-connected point voltage of the wind turbine includes: The three-phase grid connection point voltage of the wind turbine is subjected to an effective value RMS calculation link to obtain an RMS value of the grid connection point voltage; The difference between the RMS value of the grid connection point voltage and the system rated voltage is calculated, and the difference is passed through a proportional link and a limiting link to obtain a phase-locked angle correction value.

6. The method according to claim 5, characterized in that The step of calculating the transformation angle according to the phase-locking angle and the phase-locking angle correction value includes: The phase-locking angle and the phase-locking angle correction amount are summed to obtain a transformation angle for controlling transformation.

7. The method according to claim 6, characterized in that The dq / abc conversion calculation formula includes: Among them, m dg is the d-axis modulation, m qg is the q-axis modulation, m ag 、m bg and m cg is the three-phase modulation quantity, and θ is the conversion angle.

8. The method according to claim 7, characterized in that The controlling of the three-phase output voltage target value of the converter according to the three-phase modulation amount includes: generating a converter trigger pulse by a pulse generator according to the three-phase modulation amount; The switching tube of the converter is triggered to be turned on and off according to the converter trigger pulse, thereby controlling the target value of the three-phase output voltage of the converter.

9. A sending-end transient overvoltage control device, characterized in that: include: Parameter acquisition module, used for system parameters; A modulation amount calculation module is used to calculate the d-axis modulation amount and the q-axis modulation amount according to the system parameters; A transformation angle calculation module is used to collect the three-phase grid-connected point voltage of the wind turbine, obtain a phase-locked angle through a phase-locked loop (PLL), calculate a phase-locked angle correction value based on the three-phase grid-connected point voltage of the wind turbine, and calculate a transformation angle based on the phase-locked angle and the phase-locked angle correction value; a conversion module, configured to convert the d-axis modulation amount and the q-axis modulation amount according to the conversion angle using a dq / abc conversion calculation formula to obtain a three-phase modulation amount; The converter control module is used to control the converter three-phase output voltage target value according to the three-phase modulation amount.

10. A sending-end transient overvoltage control device, characterized in that: The device comprises a processor and a memory, wherein the processor is connected to the memory: The processor is configured to call and execute the program stored in the memory; The memory is used to store the program, and the program is at least used to execute the sending-end transient overvoltage control method according to any one of claims 1 to 8.

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