Method and system for realizing precise synchronization through cooperation of phase modifier and SFC

Abstract

The invention discloses a method and a system for realizing accurate synchronization through cooperation of a phase modifier and an SFC, and the method comprises the steps: dividing a synchronization rotation speed change curve of a synchronous phase modifier into three stages, obtaining a corresponding time range and a corresponding frequency change rate range, combining a 100% grid connection success rate criterion, and directly setting a frequency difference constant value without calculation. And reversely deducing an initial angle difference range required to be met at the exit moment of the SFC, and adding the angle margin to obtain a final angle difference range. And the SFC drives the rotating speed of the phase modifier to 1.05 times of the rated rotating speed, stably rotates for a period of time and exits from the SFC according to the final angular difference range, and the synchronous phase modifier starts to run down, so that the purpose of reducing the frequency difference constant value is achieved. According to the method, the 100% grid connection success rate is met, frequency difference constant value calculation is not needed, physical communication between the synchronizing device and the SFC is not needed either, the frequency difference constant value can be greatly reduced, the impact of synchronous phase modifier idle speed grid connection synchronization on a power grid is reduced, and accurate synchronization of the synchronous phase modifier is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power system grid-connected control, and specifically relates to a method and system for achieving precise synchronization by cooperating with a phase regulator and an SFC. Background Art

[0002] With the promotion and application of large-capacity, long-distance UHV DC transmission technology, the problem of "strong DC and weak AC" in the power grid has become prominent, especially the lack of dynamic reactive power support during faults has become one of the main problems affecting system stability. In addition, with the large-scale centralized development of new energy sources such as wind power and photovoltaics, the DC sending-end power grid is weak and the short-circuit capacity is insufficient, which may even lead to large-scale grid disconnection. Since the new high-power phase regulator has a strong bidirectional reactive power regulation function, its inherent reactive output characteristics just meet the power grid's demand for dynamic reactive power during faults, and can effectively solve the problems of insufficient dynamic reactive power in the receiving-end power grid and insufficient short-circuit capacity support in the weak sending-end power grid. Therefore, phase regulators have been widely used in new energy fields such as high-voltage UHV DC transmission, wind power, and photovoltaics.

[0003] At present, the commonly used grid connection method for phase regulators is inertial speed reduction. During the startup phase, the phase regulator switches to the starting excitation system for excitation, and uses a static frequency converter (SFC) to drag the phase regulator to accelerate. After the rotor speed rises to 1.05 times the rated speed (3150 rpm), the SFC system is cut off, and the phase regulator loses its driving force and starts inertial speed reduction under no-load state; during the inertial speed reduction period, the starting excitation system exits, the main excitation system is connected and starts to establish the terminal voltage, the synchronization device intervenes, and the system starts synchronously; the synchronization device passively captures the synchronization opportunity, and detects the frequency difference, phase angle difference and voltage difference between the phase regulator and the grid side in real time. After entering the synchronization allowable range, a grid connection command is issued, and the phase regulator is connected to the grid.

[0004] During the above startup process, the rotor of the phase-converter is in a free inertia deceleration state from the time when the SFC system is cut off to the time before the grid connection is completed. Since the rotor speed in this state is uncontrollable and irreversible, once the synchronization fails during the inertia deceleration process, it is necessary to shut down and restart, which will cause a certain waste of resources. Usually, the voltage can be adjusted by excitation during the inertia deceleration process, ignoring the pressure difference factor during the synchronization process; during the inertia deceleration and grid connection process, the conditions for achieving a 100% grid connection success rate are met:

[0005]

[0006] in, is the maximum angular difference, Δf set is the frequency difference constant, D is the frequency change rate, ΔA set is the angular difference constant, The initial angle difference that satisfies the frequency difference qualified window.

[0007] Ignoring the voltage difference factor that can be adjusted by excitation during the inertia speed reduction process, the angle difference setting has little effect on the frequency difference setting and the grid connection success rate, and the influence of the angle difference setting can also be ignored. In theory, the larger the frequency difference setting, the easier it is to successfully connect to the grid. However, the inertia speed reduction grid connection process faces the compatibility problem of reliability and success rate. If a larger grid connection frequency difference setting is set to ensure the grid connection success rate, it will cause excessive impact current at the grid connection moment, reduce the service life of the equipment or even directly damage the equipment; if a smaller grid connection frequency difference is set to ensure the reliability of the grid connection, it will cause no grid connection point during the inertia speed reduction period, resulting in grid connection failure. At the moment of closing the phase regulator, the magnitude of the grid connection impact current is related to the frequency difference and angle difference. The larger the frequency difference, the greater the impact. Therefore, it is extremely necessary to ensure that the phase regulator can improve the grid connection success rate under the premise of reliable inertia speed reduction grid connection mode while reducing the frequency difference setting.

[0008] During the inertial speed reduction operation of the synchronous condenser, the initial phase angle of the frequency difference satisfying the window has a great influence on the frequency difference constant. The conventional frequency difference setting calculation method, in order to ensure 100% grid-connected success rate, does not consider the influence of the initial phase angle due to the random initial phase angle. Therefore, the frequency difference constant setting will be relatively large, causing a certain impact on the power grid when the condenser is connected to the grid, and it is impossible to further reduce the frequency difference constant while ensuring 100% grid-connected success. The existing inertial speed reduction point continuously iterates to improve the initial phase angle conditions and improve the grid-connected success rate. In theory, the grid-connected success rate can be improved, but continuous iteration will require the condenser speed to change repeatedly, which greatly increases the performance requirements of the SFC and synchronous condenser, making it difficult to achieve in engineering. Summary of the invention

[0009] In order to solve the deficiencies in the prior art, the present invention provides a method and system for realizing precise synchronization by cooperating with a phase regulator and an SFC. The method and system do not need to perform frequency difference constant calculation, and can significantly reduce the frequency difference constant. Moreover, the synchronization device and the SFC do not need to establish physical communication. After the synchronization device reversely infers the final range of the initial angle difference at the time of SFC exit, it can be displayed, and then the SFC can exit according to the range.

[0010] The present invention adopts the following technical solution.

[0011] The first aspect of the present invention provides a method for achieving precise synchronization by cooperating with a phase regulator and an SFC, comprising:

[0012] The idling process is divided into t 0 ,t 1 ,t 2 ,t 3 During the idling process, t0 At time SFC exits, the phase regulator starts to run at idle speed, t 1 At the moment when the excitation voltage is completed and the synchronization is started, t 0 to 1 Time period Δt 1 =t 1 -t 0 , Δt 1 The internal frequency change rate is D1; ​​t 2 The time is the starting time of the frequency difference qualified window, at which the frequency difference Δf=Δf set , t 1 to 2 Time period Δt 2 =t 2 -t 1 , Δt 2 The internal frequency change rate is D2; t 2 From time to successful synchronous closing time t 3 is the third time period; according to the actual parameters of the phase regulator and the speed change curve of the pseudo-synchronous experiment, obtain Δt 1 , Δt 2 The variation range of and the variation range of D1 and D2;

[0013] Set the ideal frequency difference constant Δf set The angle difference from the ideal value is ΔA set , and combined with the variation range of D2, according to the 100% grid connection success rate criterion, t 2 Angular difference in time Range

[0014] Select as Combination Δt 1 , Δt 2 , D1 and D2, according to t 2 The function expression of the angle difference, frequency change rate and time at the moment is used to calculate t 1 Angular difference in time Range

[0015] Range Combination Δt 1 and D1 range, according to t 1 The function expression of the angle difference, frequency change rate and time at the moment is used to calculate t 0 Initial angle difference at time Range

[0016] Considering the time error of idling process and leading time error, Range Adding the angle margin, we get the final scope;

[0017] After SFC brings the condenser speed to 1.05 times the rated speed, SFC keeps the speed unchanged. When it is within the range, exit SFC immediately and the phase regulator starts idling and synchronization.

[0018] Preferably, the 100% grid connection success rate criterion is:

[0019]

[0020] Preferably, the t 2 The function expression of the angle difference, frequency change rate and time at the moment is:

[0021]

[0022] Δf t1 =Δf 0 -D1*Δt 1

[0023] Where Δf t1 t 1 Time frequency difference, Δf 0 t 0 The initial frequency difference at time .

[0024] Preferably, the t 1 The function expression of the angle difference, frequency change rate and time at the moment is:

[0025]

[0026] Where Δf 0 t 0 The initial frequency difference at time .

[0027] Preferably, the final Range is in is the angle margin.

[0028] The second aspect of the present invention provides a system for realizing precise synchronization by cooperating with a phase regulator and an SFC, including a pseudo-synchronization experimental data acquisition module and an initial angle difference range derivation module at the SFC exit time;

[0029] The pseudo-synchronous experiment data acquisition module is used to obtain the time period Δt according to the actual parameters of the phase regulator and the speed change curve of the pseudo-synchronous experiment. 1 , Δt 2 The range of variation and Δt 1, Δt 2 The frequency change rate D1 and D2 within the time period, where Δt 1 =t 1 -t 0 , Δt 2 =t 2 -t 1 , t 0 The moment when SFC exits and the phase regulator starts to run inertially; t 1 The moment when the excitation voltage is built up and synchronization is started; t 2 is the starting time of the frequency difference qualified window;

[0030] The SFC exit time initial angle difference range derivation module is used to set the ideal frequency difference constant Δf set The ideal angle difference is combined with the variation range of D2, and t is obtained according to the 100% grid connection success rate criterion. 2 Angular difference in time Range Select as Combination Δt 1 , Δt 2 , D1 and D2, according to t 2 The function expression of the angle difference, frequency change rate and time at the moment is used to calculate t 1 Angular difference in time Range Combination Δt 1 and D1 range, according to t 1 The function expression of the angle difference, frequency change rate and time at the moment is used to calculate t 0 Initial angle difference at time Range right Range Adding the angle margin, we get the final scope;

[0031] After the SFC brings the condenser speed to 1.05 times the rated speed, the SFC keeps the speed unchanged. When it is within the range, SFC is exited immediately and the phase regulator starts to inertially decelerate and synchronize.

[0032] Preferably, the 100% grid connection success rate criterion adopted by the SFC exit time initial angle difference range derivation module is as follows:

[0033]

[0034] Preferably, the SFC exit time initial angle difference range derivation module uses t 2The function expression of the angle difference, frequency change rate and time at the moment is:

[0035]

[0036] Δf t1 =Δf 0 -D1*Δt 1

[0037] Where Δf t1 t 1 Time frequency difference, Δf 0 t 0 The initial frequency difference at time .

[0038] Preferably, the SFC exit time initial angle difference range derivation module uses t 1 The function expression of the angle difference, frequency change rate and time at the moment is:

[0039]

[0040] Where Δf 0 t 0 The initial frequency difference at time .

[0041] Preferably, the SFC exit time initial angle difference range derivation module is Range Adding angular margin Get the final scope

[0042] Compared with the prior art, the beneficial effects of the present invention include at least:

[0043] The present invention divides the synchronous speed change curve of the synchronous condenser into three stages, obtains the time range and frequency change rate range of the three stages, and combines the 100% grid connection success rate criterion without calculation, directly sets the ideal frequency difference constant and the ideal angle difference constant, and reversely deduces the range of the initial phase angle difference that needs to be met at the SFC exit time from the function expression of the angle difference, the frequency change rate and the time, and adds the angle margin on this basis to obtain the final angle difference range, exits the SFC within the range, and the condenser idles, and controls the exit time of the SFC, thereby achieving the purpose of reducing the frequency difference constant. While meeting the 100% grid connection success rate, the method does not need to calculate the frequency difference constant, and does not need the synchronization device to establish physical communication with the SFC. It can greatly reduce the frequency difference constant, reduce the impact of the synchronous condenser idle speed grid connection synchronization on the power grid, and realize the precise synchronization of the synchronous condenser, which solves the impact of the large frequency difference constant setting on the power grid during the synchronous condenser idle speed reduction grid connection process in the prior art. For SFC equipment with SFC rotor position sensing capability, the engineering implementation is convenient and has good practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the process diagram of the phase regulator's inertia speed reduction operation;

[0045] Figure 2 Schematic diagram of the synchronous window to meet the frequency difference setting. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0047] The present invention takes into account that after the inertia deceleration process begins, the initial conditions are determined, so the inertia deceleration process is basically determined and calculable, that is, the frequency difference and angle difference at any time node can be calculated and predicted. Obviously, if the size of the angle difference at the time when the frequency difference qualified window is satisfied can be controlled, the control of the frequency difference constant can be achieved, and the control of the angle difference is key to controlling the moment when the SFC exits. Through strict theoretical derivation and precise calculation, the purpose of reducing the frequency difference constant can be achieved by controlling the exit moment of the SFC, and there is no need to establish physical communication between the synchronization device and the SFC. In order to control the exit moment of the SFC, Example 1 of the present invention provides a method for cooperating with a phase regulator and an SFC to achieve precise synchronization. Through strict theoretical derivation, the range of the initial phase angle difference at the exit moment of the SFC is obtained. The SFC is exited within this range, and the phase regulator is idling, which can greatly reduce the frequency difference constant. The method is simple to calculate, and for SFC equipment with SFC rotor position sensing capability, it is easy to implement in engineering and has good practical value. The method specifically includes:

[0048] Step 1: Reference Figure 1 , the idling process is divided into t 0 ,t 1 ,t 2 ,t 3 The three time stages divided by time, t 0 At time SFC exits, the phase regulator starts to run at idle speed, t 1 At the moment when the excitation voltage is completed and the synchronization is started, the time period Δt 1 =t 1 -t 0 , Δt 1 The frequency change rate within the time period is df / dt=D1; t 2 The time is the starting time of the frequency difference qualified window, at which the frequency difference Δf=Δfset , t 1 to 2 Time period Δt 2 =t 2 -t 1 , Δt 2 The frequency change rate within the time period is df / dt=D2,t 2 From time to successful synchronous closing time t 3 is the third time period. According to the actual parameters of the phase regulator and the speed change curve of the pseudo-synchronous experiment, the time period Δt is obtained. 1 , Δt 2 The range of variation and Δt 1 , Δt 2 The range of frequency change rates D1 and D2 within the time period;

[0049] Step 2: Set the ideal frequency difference constant Δf set The angle difference from the ideal value is ΔA set , and combined with the variation range of D2, according to the 100% grid connection success rate criterion, t 2 Angular difference in time Range

[0050] Step 3: Select as Combination Δt 1 , Δt 2 , D1 and D2, according to t 2 The function expression of the angle difference, frequency change rate and time at the moment is used to calculate t 1 Angular difference in time Range

[0051]

[0052] Step 4: Range Combination Δt 1 and D1 range, according to t 1 The function expression of the angle difference, frequency change rate and time at the moment is used to calculate t 0 Initial angle difference at time Range

[0053]

[0054] Further preferably, the present invention selects an ideal frequency difference value and an ideal angle difference value through a function expression of angle difference and time, combined with a 100% grid connection success rate condition, taking into account the influence of errors in each link, and reversely deduces an initial angle difference range that needs to be satisfied at the SFC exit time, specifically:

[0055] According to the phase condenser idling characteristics, the function expression of the angle difference and time is obtained, and according to this general expression, t 1 ,t 2 The angle difference expression at the moment (the function expression of the angle difference at each stage and the time and frequency change rate) is used to obtain the angle difference calculation process from the SFC exit moment to the frequency difference passing moment. Set the ideal frequency difference constant Δf set Ideal angle difference ΔA set , taking the lead time into consideration, the angular difference range that needs to be met at the SFC exit time is obtained by reverse calculation based on the 100% grid connection success rate condition.

[0056] 1) Assume that the initial angle difference at the SFC exit time, i.e. the idling start time, is (3150 rpm corresponds to 52.5 Hz. 3000 rpm corresponds to 50 Hz, so the initial frequency difference is Δf 0 =2.5Hz), t0=0, then the angle difference at time t is:

[0057]

[0058] 2), according to formula (1), we get t 1 Time and frequency difference qualified time t 2 Angular difference expression.

[0059] t 1 Time angle difference:

[0060] t 1 Time frequency difference: Δf t1 =2.5-D1*Δt 1 (3)

[0061] t 2 Time angle difference:

[0062] 3) Considering the lead time, set the frequency difference constant Δf of the synchronous device set , angle difference constant ΔA set ; and Δf set satisfy

[0063]

[0064] Where ΔA set It is the constant value of the angular difference, and it can be adjusted according to the maximum constant value in engineering in the calculation example.

[0065] correspond Figure 2 The ideal synchronization time when the intermediate frequency difference Δf=0.

[0066] 4) According to the 100% grid connection success rate condition (5), set Δf set and ΔA set , find Specifically, let Δf set =0.2Hz, then equation (6) holds true. According to the range of D2, we can get Range

[0067]

[0068] 5) Take Substituting into equation (4), according to Δt 2 and D2 range, calculate Range

[0069] 6), according to Δt 1 and D1 value range, substitute into formula (2) and calculate Range

[0070] in,

[0071] Step 5: Calculated according to step 4 range, taking into account the idling process time error and the leading time error, Value range Add an angle margin Get the final scope

[0072] Further preferably, according to 6) calculated The value range takes into account the time error of the inertia deceleration process and the leading time error. Add an angle margin to the value range For example, 10°, the final scope.

[0073] Step 6: After SFC brings the condenser speed to 1.05 times the rated speed (3150 rpm), SFC maintains the speed at 3150 rpm and waits for the SFC rotation angle difference to enter the final When it is within the range, SFC is exited immediately, the phase regulator starts the inertial deceleration process and completes the synchronous operation.

[0074] Further preferably, according to the initial angle difference range obtained in step 5, the SFC is exited, and the phase regulator starts to inertially decelerate and synchronize. Specifically, after the SFC drag speed rises to 3150 rpm, the speed is kept unchanged and stabilized for a short period of time. During this period of time, when the angle difference enters The SFC is exited immediately within the range, and the phase regulator starts the inertial deceleration process.

[0075] In summary, the present invention divides the synchronous phase speed change curve of the synchronous condenser into three stages, and uses the function expression of angle difference, frequency change rate and time to obtain the time range and frequency change rate range of the three stages according to the pseudo-synchronous experiment and the speed change curve. Set the ideal frequency difference constant and angle difference constant, combined with the 100% grid connection success rate criterion The initial angle difference range that needs to be met when SFC exits can be inferred from the function expression of angle difference, frequency change rate and time. Considering the time error of the phase regulator inertia deceleration process and the leading time error, The range of values ​​plus an angle margin Get the final scope SFC brings the condenser speed to 1.05 times the rated speed, and then rotates steadily for a period of time. The scope exits SFC, and the synchronous condenser starts to coast, achieving the purpose of reducing the frequency difference constant. The complete implementation process is as follows:

[0076] Step 1: Obtain Δt based on the actual parameters of the phase regulator and the pseudo-synchronous experimental curve 1 , Δt 2 The range of change, and the range of change of the frequency change rate D1 and D2 within this time range.

[0077] Step 2: Let Δf set =0.2Hz, ΔA set =1°, according to the 100% grid connection success rate formula, the following formula is established. According to the D2 range in step 1, we can get Range

[0078] Step 3: Get Substitute into the following formula, according to Δt in step 1 2 and D2 range, calculate Range

[0079]

[0080] t 1 Time angle difference:

[0081] t 1 Time frequency difference: Δf t1 =2.5-D1*Δt 1

[0082] t 2 Time angle difference:

[0083] Step 4: According to Δt in step 1 1 and D1 value range, substitute into the above formula, calculate Range in,

[0084] Step 5: Calculated according to step 4 The value range takes into account the time error of the inertia deceleration process and the leading time error. The range of values ​​plus an angle margin For example, 10°, the final scope.

[0085] Step 6: After the SFC drag speed rises to 3150 rpm, the SFC keeps the speed constant and stabilizes for a short period of time. During this period, the angle difference enters The SFC is exited immediately within the range, and the phase regulator starts the inertial deceleration process.

[0086] Embodiment 2 of the present invention provides a system for realizing precise synchronization by cooperating with a phase regulator and an SFC, including:

[0087] The pseudo-synchronous experiment data acquisition module is used to obtain the time period Δt according to the actual parameters of the phase regulator and the speed change curve of the pseudo-synchronous experiment. 1 , Δt 2 The range of variation and Δt 1 , Δt 2 The frequency change rate D1 and D2 within the time period, where Δt 1 =t 1 -t 0 , Δt 2 =t 2 -t 1 , t 0 The moment when SFC exits and the phase regulator starts to run inertially; t 1 The moment when the excitation voltage is built up and synchronization is started; t 2 is the starting time of the frequency difference qualified window;

[0088] The module for deriving the initial angle difference range at the time of SFC exit is used to set the ideal frequency difference constant Δf set The angle difference from the ideal value is ΔA set , and combined with the variation range of D2, according to the 100% grid connection success rate criterion, t 2 Angular difference in time Range Select as Combination Δt 1 , Δt2 , D1 and D2, according to t 2 The function expression of the angle difference, frequency change rate and time at the moment is used to calculate t 1 Angular difference in time Range Range Combination Δt 1 and D1 range, according to t 1 The function expression of the angle difference, frequency change rate and time at the moment is used to calculate t 0 Initial angle difference at time Range right Range Adding angular margin Get the final scope Synchronous device obtained After the range is set, it can be displayed, and then SFC can exit according to this angle range. The synchronous device does not need to establish communication with SFC.

[0089] Further preferably, the 100% grid connection success rate criterion adopted by the SFC exit time initial angle difference range derivation module is as follows:

[0090]

[0091] The adopted 2 The function expression of the angle difference, frequency change rate and time at the moment is:

[0092]

[0093] Δf t1 =Δf 0 -D1*Δt 1

[0094] Where Δf t1 t 1 Time frequency difference, Δf 0 t 0 The initial frequency difference at time .

[0095] The adopted 1 The function expression of the angle difference, frequency change rate and time at the moment is:

[0096]

[0097] Where Δf 0 t 0 The initial frequency difference at time .

[0098] right Range Adding angular margin Get the final scope

[0099]

[0100] After SFC brings the condenser speed to the set speed, SFC keeps the speed unchanged. When it is within the range, SFC is exited immediately and the phase regulator starts to inertially decelerate and synchronize.

[0101] Embodiment 3 of the present invention provides a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the method.

[0102] Embodiment 4 of the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the method when executed by a processor.

[0103] Compared with the prior art, the beneficial effects of the present invention include at least:

[0104] The present invention divides the synchronous speed change curve of the synchronous condenser into three stages, obtains the time range and frequency change rate range of the three stages, and combines the 100% grid connection success rate criterion without calculation, directly sets the ideal frequency difference constant and the ideal angle difference constant, and reversely infers the range of the initial phase angle difference that needs to be met at the SFC exit time from the function expression of the angle difference, the frequency change rate and the time, and adds the angle margin on this basis to obtain the final angle difference range, and exits the SFC within the range, and the condenser idles, and the purpose of reducing the frequency difference constant is achieved by controlling the exit time of the SFC. While meeting the 100% grid connection success rate, this method does not require the calculation of the frequency difference constant, and does not require the synchronization device to establish physical communication with the SFC. The frequency difference constant can be greatly reduced, and the impact of the synchronous condenser idle speed grid connection synchronization on the power grid can be reduced, and the precise synchronization of the synchronous condenser can be achieved, which solves the impact of the large frequency difference constant setting on the power grid during the inertia speed reduction grid connection process of the synchronous condenser in the prior art. For SFC equipment with SFC rotor position sensing capability, the engineering implementation is convenient and has good practical value.

[0105] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0106] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0107] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0108] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for achieving precise synchronization by cooperating with a phase regulator and an SFC, characterized in that: include: The idling process is divided into three time periods divided by t0, t1, t2, and t3. During the idling process, at t0, the SFC exits and the phase regulator starts idling. At t1, the excitation voltage is completed and the synchronization is started. From t0 to t1, Δt1 = t1-t0, and the frequency change rate within Δt1 is D1. At t2, the starting time of the frequency difference qualified window, at which the frequency difference Δf = Δf set , the time period from t1 to t2 Δt2 = t2-t1, the frequency change rate within Δt2 is D2; the time from t2 to the successful synchronous closing time t3 is the third time period; according to the actual parameters of the phase regulator and the speed change curve of the false synchronization experiment, the change range of Δt1, Δt2 and the change range of D1, D2 are obtained; Set the ideal frequency difference constant Δf set The angle difference from the ideal value is ΔA set , and combined with the variation range of D2, the angle difference at time t2 is obtained according to the 100% grid connection success rate criterion Range Select as Combined with the variation range of Δt1, Δt2, D1 and D2, the angle difference at time t2, the frequency change rate and the function expression of time are used to calculate the angle difference at time t1. Range Range Combined with the variation range of Δt1 and D1, the initial angle difference at time t0 is calculated based on the function expression of the angle difference at time t1, the frequency change rate and time. Range Considering the idling process time error and the leading time error, Range Adding the angle margin, we get the final scope; After SFC brings the condenser speed to 1.05 times the rated speed, SFC keeps the speed unchanged. When it is within the range, exit SFC immediately and the phase regulator starts idling and synchronization.

2. The method for realizing precise synchronization by cooperating a phase regulator and an SFC according to claim 1, characterized in that: The 100% grid connection success rate criterion is:

3. The method for realizing precise synchronization by cooperating a phase regulator and an SFC according to claim 1, characterized in that: The function expression of the angle difference, frequency change rate and time at the time t2 is: Δf t1 =Δf0-D1*Δt1 Where Δf t1 is the frequency difference at time t1, and Δf0 is the initial frequency difference at time t0.

4. The method for achieving precise synchronization by cooperating with a phase regulator and an SFC according to claim 1, characterized in that: The function expression of the angle difference, frequency change rate and time at the time t1 is: Among them, Δf0 is the initial frequency difference at time t0.

5. The method for realizing precise synchronization by cooperating a phase regulator and an SFC according to claim 1, characterized in that: The final Range is in is the angle margin.

6. A system for achieving precise synchronization by cooperating with a phase regulator and an SFC, characterized in that: The system includes a pseudo-synchronous experimental data acquisition module and an SFC exit time initial angle difference range derivation module; The pseudo-synchronous experiment data acquisition module is used to obtain the variation range of time periods Δt1 and Δt2 and the variation range of frequency change rates D1 and D2 in the time periods Δt1 and Δt2 according to the actual parameters of the phase regulator and the speed variation curve of the pseudo-synchronous experiment, wherein Δt1=t1-t0, Δt2=t2-t1, t0 is the moment when the SFC exits and the phase regulator starts inertial speed reduction operation; t1 is the moment when the excitation voltage is completed and synchronization is started; t2 is the starting time of the frequency difference qualified window; The SFC exit time initial angle difference range derivation module is used to set the ideal frequency difference constant Δf set The ideal angle difference is combined with the variation range of D2, and the angle difference at time t2 is obtained according to the 100% grid connection success rate criterion. Range Select as Combined with the variation range of Δt1, Δt2, D1 and D2, the angle difference at time t2, the frequency change rate and the function expression of time are used to calculate the angle difference at time t1. Range Combined with the variation range of Δt1 and D1, the initial angle difference at time t0 is calculated based on the function expression of the angle difference at time t1, the frequency change rate and time. Range right Range Adding the angle margin, we get the final scope; After the SFC brings the condenser speed to 1.05 times the rated speed, the SFC keeps the speed unchanged. When it is within the range, SFC is exited immediately and the phase regulator starts to inertially decelerate and synchronize.

7. A system for realizing precise synchronization by cooperating with a phase regulator and an SFC according to claim 6, characterized in that: The 100% grid connection success rate criterion adopted by the SFC exit initial angle difference range derivation module is as follows:

8. The system for realizing precise synchronization by cooperating with a phase regulator and an SFC according to claim 6, characterized in that: The function expression of the angle difference, frequency change rate and time at time t2 adopted by the SFC exit initial angle difference range derivation module is: Δf t1 =Δf0-D1*Δt1 Where Δf t1 is the frequency difference at time t1, and Δf0 is the initial frequency difference at time t0.

9. The system of realizing precise synchronization by cooperating with a phase regulator and an SFC according to claim 6, characterized in that: The function expression of the angle difference, frequency change rate and time at time t1 adopted by the SFC exit initial angle difference range derivation module is: Among them, Δf0 is the initial frequency difference at time t0.

10. A system for realizing precise synchronization by cooperating with a phase regulator and an SFC according to claim 6, characterized in that: The SFC exit time initial angle difference range derivation module is Range Adding angular margin Get the final scope

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