A phase feeding converter feedforward method and system

Abstract

A phase power supply converter feedforward method and system, the method comprising detecting grid voltage of M seat and T seat respectively, obtaining voltage amplitude and phase through single-phase phase-locked loop, compensating voltage amplitude and phase, and calculating phase-locked feedforward term according to DC voltage of power unit; after parallel side voltage stabilization of the converter is completed, parallel side compensation phase is reduced to zero at a set rate; the converter parallel side is switched from phase-locked feedforward to instantaneous value feedforward; after grid connection of converter cascade side, cascade side compensation phase is reduced to zero at a set rate; the converter cascade side is switched from phase-locked feedforward to instantaneous value feedforward. The method and system can realize flexible and non-impact grid connection of the converter, reduce transient impact current of the converter caused by grid fluctuation and fault, improve grid adaptation and fault ride-through capability of the converter after grid connection, and realize online smooth switching of phase-locked feedforward and instantaneous value feedforward.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology for rail transit, specifically to a feedforward method and system for a phase-to-phase power supply converter. Background Technology

[0002] Electric locomotives are single-phase electrical loads. To reduce the impact of negative-sequence current on the power system, the traction network power supply adopts measures such as phase-separation and phase sequence rotation, and adds electrical phase-splitting links in the overhead contact line. Automatic phase-splitting devices not only operate frequently, have short lifespans, and low reliability, but also cause losses in train speed and traction. In-phase power supply devices solve problems such as electrical phase-splitting, voltage fluctuations, low power factor, and excessive negative-sequence current in traction substations.

[0003] The in-phase power supply system mainly consists of a traction matching transformer and an in-phase power supply converter. The traction matching transformer is a multi-winding transformer, and the in-phase power supply converter is composed of multiple power units connected in series and parallel, including a parallel side and a cascaded side. The high-voltage side of the traction matching transformer is connected to the M-base of the traction transformer, and the low-voltage side is connected to the parallel side of the in-phase power supply converter. The cascaded side of the converter is connected to the T-base of the traction transformer.

[0004] The in-phase power supply converter first charges the DC bus through the cascade side soft start device, then the parallel side unlocks and connects to the grid and stabilizes the DC voltage. After the DC voltage reaches the set value, the cascade side unlocks and connects to the grid.

[0005] To reduce the inrush current when a converter is connected to the grid, phase-locked loop (PLL) feedforward is generally used. This involves obtaining the amplitude and phase of the grid voltage through a PLL, and then compensating for the amplitude and phase to ensure that the voltage at which the converter unlocks is exactly the same as the grid voltage, resulting in no inrush current during grid connection. While PLL feedforward can achieve inrush-free grid connection for converters, the response speed is slow due to the PLL and filtering stages in the feedforward calculation process. After the converter is connected to the grid, it cannot respond quickly when there are fluctuations in the grid voltage, especially during grid voltage faults, when the transient inrush current of the converter is large and may even trigger overcurrent protection, leading to a shutdown. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a feedforward method and system for in-phase power supply converters, which can improve the grid adaptability and transient performance of the converter after grid connection, reduce transient current surges caused by grid fluctuations and faults, and simultaneously achieve smooth, shock-free grid connection of the converter.

[0007] This invention is achieved using the following technical solution:

[0008] A first aspect of the present invention provides a feedforward method for a co-phase power supply converter, the co-phase power supply converter including a parallel side, a cascaded side, and a starting circuit, wherein the parallel side is connected to a traction transformer M base via a traction matching transformer, and the cascaded side is connected to a traction transformer T base via a starting circuit. The method includes the following steps:

[0009] The grid voltages of M and T are detected separately. The voltage amplitude and phase are obtained through a single-phase phase-locked loop. After compensating for the voltage amplitude and phase, the phase-locked feedforward term is calculated based on the DC voltage of the power unit.

[0010] After the voltage regulation on the parallel side of the converter is completed, the compensation phase on the parallel side decreases to zero at a set rate;

[0011] The converter parallel side is switched from phase-locked feedforward to instantaneous value feedforward;

[0012] After the cascaded converter is connected to the grid, the compensation phase on the cascaded side decreases to zero at a set rate.

[0013] The converter cascade side switches from phase-locked feedforward to instantaneous value feedforward.

[0014] Furthermore, the voltage amplitude and phase of the grid are obtained through a single-phase phase-locked loop. The parallel side of the converter is phase-locked to the grid voltage of M, and the cascaded side is phase-locked to the grid voltage of T.

[0015] The phase-locked feedforward term is obtained by dividing the calculated grid voltage by the DC voltage. The feedforward term on the parallel side of the converter is the grid voltage divided by the DC voltage of the power unit, and the feedforward term on the cascaded side of the converter is the grid voltage divided by the sum of the DC voltages of all power units.

[0016]

[0017]

[0018] In the formula, u f1_Pari Δk is the phase-locked feedforward value for the i-th power unit on the parallel side of the in-phase power supply converter, where i = 1, 2, 3, ..., N, and N is the number of power units; M N is the amplitude compensation coefficient for the parallel side. t For the traction matching transformer ratio, U M The voltage amplitude of the M-base obtained by phase-locked loop, Δθ M For the voltage compensation phase of seat M, U dci The 5ms moving average of the DC voltage of the i-th power unit;

[0019] u f1_Cas Δk is the phase-locked feedforward value on the cascaded side of the in-phase power supply converter. T U is the amplitude compensation coefficient for the cascaded side. TThe amplitude of the voltage at the T-base obtained by phase-locked loop, Δθ T For the voltage compensation phase of the T-type base, ∑U dci This is the sum of the 5ms moving average of the DC voltage of all power units in the converter.

[0020] Furthermore, the instantaneous feedforward value is calculated by the following formula:

[0021]

[0022]

[0023] In the formula, u f2_Pari Δk is the instantaneous feedforward value of the i-th power unit on the parallel side of the in-phase power supply converter, where i = 1, 2, 3, ..., N, and N is the number of power units; M For the parallel side amplitude compensation coefficient, u M The voltage of the M power grids was obtained through sampling;

[0024] u f2_Cas Δk is the instantaneous feedforward value on the cascaded side of the in-phase power supply converter. T U is the amplitude compensation coefficient for the cascaded side. T For the sampled grid voltage at location T, U dci This is the 5ms moving average of the DC voltage of the i-th power unit.

[0025] Furthermore, the completion of voltage regulation on the parallel side of the converter includes: when the error between the DC voltage command and the feedback value is less than a threshold value for a continuous period of time, the voltage regulation of the power unit is completed; the grid connection on the cascade side of the converter includes: when the error between the current command and the feedback value on the cascade side is less than another threshold value for a continuous period of time, the grid connection on the cascade side is completed.

[0026] Furthermore, the phase compensation angle decreases to zero at a set rate, calculated as follows:

[0027] Δθ i =Δθ i_set ×λ (5)

[0028] In the formula, Δθ i_set The compensation phase set for the phase-locked feedforward of the parallel or cascaded side of the in-phase power supply converter, i = M or T, λ is a number that changes from 1 to 0, the change time is settable, Δθ i This refers to the current compensation phase on the parallel or cascaded side of the same-phase power supply converter.

[0029] A second aspect of the present invention provides a feedforward system for a phase-powered converter, the phase-powered converter including a parallel side, a cascaded side, and a starting circuit, wherein the parallel side is connected to a traction transformer M base via a traction matching transformer, and the cascaded side is connected to a traction transformer T base via a starting circuit. The system includes:

[0030] The phase-locked feedforward term calculation module detects the grid voltage of M-base and T-base respectively, obtains the voltage amplitude and phase through a single-phase phase-locked loop, compensates for the voltage amplitude and phase, and calculates the phase-locked feedforward term based on the DC voltage of the power unit.

[0031] The control module, after the voltage stabilization of the parallel side of the converter is completed, reduces the compensation phase of the parallel side to zero at a set rate, and controls the parallel side of the converter to switch from phase-locked feedforward to instantaneous value feedforward; after the cascaded side of the converter is connected to the grid, the compensation phase of the cascaded side reduces to zero at a set rate, and controls the cascaded side of the converter to switch from phase-locked feedforward to instantaneous value feedforward.

[0032] Furthermore, the voltage amplitude and phase of the grid are obtained through a single-phase phase-locked loop. The parallel side of the converter is phase-locked to the grid voltage of M, and the cascaded side is phase-locked to the grid voltage of T.

[0033] The phase-locked feedforward term is obtained by dividing the calculated grid voltage by the DC voltage. The feedforward term on the parallel side of the converter is the grid voltage divided by the DC voltage of the power unit, and the feedforward term on the cascaded side of the converter is the grid voltage divided by the sum of the DC voltages of all power units.

[0034]

[0035]

[0036] In the formula, u f1_Pari Δk is the phase-locked feedforward value for the i-th power unit on the parallel side of the in-phase power supply converter, where i = 1, 2, 3, ..., N, and N is the number of power units; M N is the amplitude compensation coefficient for the parallel side. t For the traction matching transformer ratio, U M The voltage amplitude of the M-base obtained by phase-locked loop, Δθ M For the voltage compensation phase of seat M, U dci The 5ms moving average of the DC voltage of the i-th power unit;

[0037] u f1_Cas Δk is the phase-locked feedforward value on the cascaded side of the in-phase power supply converter. T U is the amplitude compensation coefficient for the cascaded side. T The amplitude of the voltage at the T-base obtained by phase-locked loop, Δθ T For the voltage compensation phase of the T-type base, ∑U dci This is the sum of the 5ms moving average of the DC voltage of all power units in the converter.

[0038] Furthermore, the instantaneous feedforward value is calculated by the following formula:

[0039]

[0040]

[0041] In the formula, u f2_Pari Δk is the instantaneous feedforward value of the i-th power unit on the parallel side of the in-phase power supply converter, where i = 1, 2, 3, ..., N, and N is the number of power units; M For the parallel side amplitude compensation coefficient, u M The voltage of the M power grids was obtained through sampling;

[0042] u f2_Cas Δk is the instantaneous feedforward value on the cascaded side of the in-phase power supply converter. T U is the amplitude compensation coefficient for the cascaded side. T For the sampled grid voltage at location T, U dci This is the 5ms moving average of the DC voltage of the i-th power unit.

[0043] Furthermore, the completion of voltage regulation on the parallel side of the converter includes: when the error between the DC voltage command and the feedback value is less than a threshold value for a continuous period of time, the voltage regulation of the power unit is completed; the grid connection on the cascade side of the converter includes: when the error between the current command and the feedback value on the cascade side is less than another threshold value for a continuous period of time, the grid connection on the cascade side is completed.

[0044] Furthermore, the phase compensation angle decreases to zero at a set rate, calculated as follows:

[0045] Δθ i =Δθ i_set ×λ (5)

[0046] In the formula, Δθ i_set The compensation phase set for the phase-locked feedforward of the parallel or cascaded side of the in-phase power supply converter, i = M or T, λ is a number that changes from 1 to 0, the change time is settable, Δθ i This refers to the current compensation phase on the parallel or cascaded side of the same-phase power supply converter.

[0047] In summary, this invention provides a feedforward method and system for in-phase power supply converters. The method includes a parallel-side feedforward method and a cascade-side feedforward method. Before the parallel-side voltage stabilization of the converter is completed, phase-locked loop (PLL) feedforward is used. This involves obtaining the amplitude and phase of the grid voltage using a PLL, compensating for the amplitude and phase, and then dividing by the moving average of the DC voltage to obtain the feedforward term. After the parallel-side voltage stabilization of the converter is completed, the compensated phase of the PLL feedforward is reduced to zero at a set rate. Then, the PLL feedforward is switched to instantaneous value feedforward, which uses the actual collected grid voltage, after amplitude compensation, divided by the moving average of the DC voltage, as the feedforward term. Before the cascade-side converter is unlocked and connected to the grid, PLL feedforward is used. After grid connection, the compensated phase is reduced to zero at a set rate, and then the instantaneous value feedforward is switched. This method and system can achieve flexible, shock-free grid connection of converters, reduce transient inrush currents of converters caused by grid fluctuations and faults, improve the grid adaptability and fault ride-through capability of converters after grid connection, and simultaneously enable smooth online switching between phase-locked feedforward and instantaneous value feedforward. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating the in-phase power supply converter feedforward method according to an embodiment of the present invention.

[0049] Figure 2 This is a topology diagram of the in-phase power supply device according to an embodiment of the present invention;

[0050] Figure 3 This is a diagram of the in-phase power supply converter control system according to an embodiment of the present invention;

[0051] Figure 4 This is a feedforward control diagram of the parallel side of the in-phase power supply converter according to an embodiment of the present invention;

[0052] Figure 5 This is a feedforward control diagram for the cascaded power supply converter of an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0054] The first aspect of the present invention provides a feedforward method for a non-phase power supply converter, the non-phase power supply converter including a parallel side, a cascaded side, and a starting circuit, wherein the parallel side is connected to a traction transformer M base through a traction matching transformer, and the cascaded side is connected to a traction transformer T base through a starting circuit, where M and T are natural numbers. The method includes the following steps, as follows: Figure 1 As shown:

[0055] In step S100, the grid voltage of M-base and T-base are detected respectively. The voltage amplitude and phase are obtained through a single-phase phase-locked loop. After compensating the voltage amplitude and phase, the phase-locked feedforward term is calculated based on the DC voltage of the power unit.

[0056] The voltage amplitude and phase of the grid are obtained through a single-phase phase-locked loop. The parallel side of the converter is phase-locked to the grid voltage of M, and the cascaded side is phase-locked to the grid voltage of T.

[0057] The phase-locked feedforward term is obtained by dividing the calculated grid voltage by the DC voltage. The feedforward term on the parallel side of the converter is the grid voltage divided by the DC voltage of the power unit, and the feedforward term on the cascaded side of the converter is the grid voltage divided by the sum of the DC voltages of all power units.

[0058] The voltage amplitude and phase of the M-base are obtained through a single-phase phase-locked loop on the parallel side. Combined with amplitude and phase compensation, the grid voltage of the M-base is calculated. Dividing this voltage by the transformer turns ratio yields the parallel-side port voltage of the power unit. Dividing this by the DC voltage of the power unit then yields its feedforward term. Since the DC voltage of the power unit fluctuates by 100Hz, a 5ms moving average filter is applied. The specific calculation formula is as follows:

[0059]

[0060] In the formula, u f1_Pari Δk is the phase-locked feedforward value for the i-th power unit on the parallel side of the in-phase power supply converter, where i = 1, 2, 3, ..., N, and N is the number of power units; M N is the amplitude compensation coefficient for the parallel side. t For the traction matching transformer ratio, U M The voltage amplitude of the M-base obtained by phase-locked loop, Δθ M For the voltage compensation phase of seat M, U dci This is the 5ms moving average of the DC voltage of the i-th power unit.

[0061] The voltage amplitude and phase of the T-base are obtained through a single-phase phase-locked loop on the cascaded side. Combined with amplitude and phase compensation, the grid voltage of the T-base is calculated. Dividing this voltage by the sum of the DC voltages of all power units in the converter yields its feedforward term. The specific calculation formula is as follows:

[0062]

[0063] In the formula, u f1_Cas Δk is the phase-locked feedforward value on the cascaded side of the in-phase power supply converter. T U is the amplitude compensation coefficient for the cascaded side. T The amplitude of the voltage at the T-base obtained by phase-locked loop, Δθ T For the voltage compensation phase of the T-type base, ∑U dciThis is the sum of the 5ms moving average of the DC voltage of all power units in the converter.

[0064] In step S200, after the voltage stabilization on the parallel side of the converter is completed, the compensation phase on the parallel side decreases to zero at a set rate.

[0065] Specifically, the phase compensation angle decreases to zero at a set rate, calculated using the following formula:

[0066] Δθ i =Δθ i_set ×λ (3)

[0067] In the formula, Δθ i_set The compensation phase set for the phase-locked feedforward of the parallel or cascaded side of the in-phase power supply converter, i = M or T, λ is a number that changes from 1 to 0, the change time is settable, Δθ i This refers to the current compensation phase on the parallel or cascaded side of the same-phase power supply converter.

[0068] In step S300, the parallel side of the converter is switched from phase-locked feedforward to instantaneous value feedforward.

[0069] Specifically, the instantaneous value feedforward includes parallel-side instantaneous value feedforward and cascade-side instantaneous value feedforward. The parallel-side instantaneous value feedforward term is obtained by dividing the sampled M-base grid voltage by the corresponding power unit DC voltage after amplitude compensation. The converter cascade-side instantaneous value feedforward term is obtained by dividing the sampled T-base grid voltage by the sum of the DC voltages of all power units after amplitude compensation. The specific calculation formula is as follows:

[0070]

[0071]

[0072] In the formula, u f2_Pari Δk is the instantaneous feedforward value of the i-th power unit on the parallel side of the in-phase power supply converter, where i = 1, 2, 3, ..., N, and N is the number of power units; M For the parallel side amplitude compensation coefficient, u M The voltage of the M grid units obtained from sampling; u f2_Cas Δk is the instantaneous feedforward value on the cascaded side of the in-phase power supply converter. T U is the amplitude compensation coefficient for the cascaded side. T For the sampled grid voltage at location T, U dci This is the 5ms moving average of the DC voltage of the i-th power unit.

[0073] During the voltage regulation period on the parallel side of the in-phase power supply converter, the parallel side is in phase-locked feedforward mode. After voltage regulation is completed, the phase compensation angle Δθ MThe value decreases to zero at a set rate, then switches to instantaneous value feedforward; before unlocking on the cascaded side, it uses phase-locked feedforward, and after unlocking, the phase compensation angle Δθ is adjusted. T It decreases to zero at the set rate, then switches to instantaneous value feedforward and begins to respond to current commands.

[0074] In step S400, after the cascaded converter is connected to the grid, the compensation phase on the cascaded side decreases to zero at a set rate. Calculations are performed according to the above formula (3).

[0075] In step S500, the converter cascade side switches from phase-locked feedforward to instantaneous value feedforward. Calculations are performed according to the above formula (5).

[0076] Furthermore, the completion of voltage regulation on the parallel side of the converter includes: when the error between the DC voltage command and the feedback value is less than a threshold value for a continuous period of time, the voltage regulation of the power unit is considered complete; the grid connection on the cascaded side of the converter includes: when the error between the current command and the feedback value on the cascaded side is less than another threshold value for a continuous period of time, the grid connection on the cascaded side is considered complete. Specifically, after the parallel side of the same-phase power supply converter is unlocked and voltage regulation is completed, if the error between the DC voltage command and the feedback value is less than 3% for 2 consecutive seconds, the voltage regulation of the power unit is considered complete; after the cascaded side is unlocked, there is no response to the current command, and if the error between the current command and the feedback value on the cascaded side is less than 1% for 1 consecutive second, the grid connection on the cascaded side of the converter is considered complete.

[0077] A second aspect of the present invention provides a feedforward system for a phase-connected power converter. The phase-connected power converter includes a parallel side, a cascaded side, and a starting circuit. The parallel side is connected to M power grids via a traction matching transformer, and the cascaded side is connected to T power grids via a starting circuit. M and T are natural numbers. The system includes: a phase-locked feedforward term calculation module, which detects the grid voltages of M and T respectively, obtains the voltage amplitude and phase through a single-phase phase-locked loop, compensates the voltage amplitude and phase, and calculates the phase-locked feedforward term based on the DC voltage of the power unit; and a control module, which, after the parallel side of the converter completes voltage stabilization, reduces the compensated phase of the parallel side to zero at a set rate, and controls the parallel side of the converter to switch from phase-locked feedforward to instantaneous value feedforward; and, after the cascaded side of the converter is connected to the grid, reduces the compensated phase of the cascaded side to zero at a set rate, and controls the cascaded side of the converter to switch from phase-locked feedforward to instantaneous value feedforward.

[0078] The in-phase power supply device provided in this embodiment includes a traction matching transformer and an in-phase power supply converter. The in-phase power supply converter mainly consists of 18 power units connected in series and parallel, including a parallel side, a series side, an output reactor, and a starting circuit. Figure 2 As shown.

[0079] The control system of the in-phase power supply converter, such as Figure 3As shown, the system consists of a central controller, parallel-side module controllers, and cascade-side module controllers. The central controller enables system start-up, shutdown, protection, and control of the cascaded converter side. The parallel-side module controllers control and protect the DC voltage on the parallel side of the power units, and the cascade-side module controllers provide protection for the cascaded power units. The central controller, parallel-side module controllers, and cascade-side module controllers communicate with each other via optical fiber.

[0080] After receiving the start command, the in-phase power supply converter first performs a soft start, closing contactor KM1 to charge the DC side of the power unit. After the DC voltage reaches the set value, contactor KM2 closes, and then contactors KM3_1 to KM3_18 close. At this time, both the parallel side and the cascade side of the converter are phase-locked feedforward. The feedforward term on the parallel side is implemented in the parallel side module controller, and the feedforward term on the cascade side is implemented in the central controller.

[0081] The grid voltage u required for the parallel phase-locked connection of the power unit M and the voltage compensation phase setting value Δθ of seat M M_set The central controller sends data to the parallel-side module controllers, which calculate the 5ms moving average of the DC voltage of their own power units and then compare it with the grid voltage u. M Phase-locked loop (PLL) is performed. Based on the voltage amplitude and phase of the M-base obtained from the PLL, the PLL feedforward term on the parallel side of the power unit is calculated. The specific calculation formula is as shown in formula (1) above.

[0082] The central controller uses the collected grid voltage u T Phase-locked loop (PLL) is performed. Based on the DC voltage uploaded by the parallel-side module controller of the 18 power units and the amplitude and phase of the T-base voltage obtained by PLL, the PLL feedforward term of the converter cascade side is obtained. The amplitude and phase compensation amount is obtained from the background. The specific calculation formula is as shown in formula (2) above.

[0083] After the converter soft start is completed, the central controller sends an unlock command to the parallel-side module controller. The parallel-side module controller then triggers an unlock pulse and controls the DC voltage to the set value according to the set slope. When the error between the DC voltage set value and the feedback value of the power unit is less than 3% for 2 consecutive seconds, the parallel-side module controller sends feedback to the central controller that the DC bus voltage regulation of the power unit is complete, and reduces the phase compensation angle Δθ at the set rate. M After the compensation angle decreases to zero, the phase-locked feedforward is switched to instantaneous value feedforward, such as... Figure 4 As shown.

[0084] After the central controller receives feedback from the 18 power units and completes the DC bus voltage stabilization, it unlocks the cascaded converter side. At this time, the converter does not respond to the current command. The error between the cascaded side current command and the feedback value is less than 3% for 1 second, and the grid connection on the cascaded side is completed. The central controller then reduces the phase compensation angle Δθ at the set rate. T After reducing it to zero, the cascaded side is switched from phase-locked feedforward to instantaneous value feedforward, such as... Figure 5 As shown.

[0085] After the feedforward switching is completed on both the parallel and cascaded sides of the converter, the grid connection is completed.

[0086] In summary, this invention provides a feedforward method and system for in-phase power supply converters. The method includes a parallel-side feedforward method and a cascade-side feedforward method. Before the parallel-side voltage stabilization of the converter is completed, phase-locked loop (PLL) feedforward is used. This involves obtaining the amplitude and phase of the grid voltage using a PLL, compensating for the amplitude and phase, and then dividing by the moving average of the DC voltage to obtain the feedforward term. After the parallel-side voltage stabilization of the converter is completed, the compensated phase of the PLL feedforward is reduced to zero at a set rate. Then, the PLL feedforward is switched to instantaneous value feedforward, which uses the actual collected grid voltage, after amplitude compensation, divided by the moving average of the DC voltage, as the feedforward term. Before the cascade-side converter is unlocked and connected to the grid, PLL feedforward is used. After grid connection, the compensated phase is reduced to zero at a set rate, and then the instantaneous value feedforward is switched. This method and system can achieve flexible, shock-free grid connection of converters, reduce transient current surges in converters caused by grid fluctuations and faults, improve the grid adaptability and fault ride-through capability of converters after grid connection, and simultaneously enable smooth online switching between phase-locked feedforward and instantaneous value feedforward.

[0087] The above provides specific embodiments of the present invention, but the present invention is not limited to the described embodiments. Following the ideas presented in this invention, the technical means in the above embodiments can be transformed, replaced, or modified in ways easily conceived by those skilled in the art, and the resulting technical solutions are essentially the same as the corresponding technical means in this invention, achieving essentially the same inventive purpose. Such technical solutions are formed by fine-tuning the above embodiments, and these solutions still fall within the protection scope of this invention.

Claims

1. A feedforward method for a non-phase power supply converter, characterized in that, The in-phase power supply converter includes a parallel side, a cascaded side, and a starting circuit. The parallel side is connected to the traction transformer M base through a traction matching transformer, and the cascaded side is connected to the traction transformer T base through a starting circuit. The method includes the following steps: The grid voltages of M and T are detected separately. The voltage amplitude and phase are obtained through a single-phase phase-locked loop. After compensating for the voltage amplitude and phase, the phase-locked feedforward term is calculated based on the DC voltage of the power unit. After the voltage regulation on the parallel side of the converter is completed, the compensation phase on the parallel side decreases to zero at a set rate; The converter parallel side is switched from phase-locked feedforward to instantaneous value feedforward; After the cascaded converter is connected to the grid, the compensation phase on the cascaded side decreases to zero at a set rate. The converter cascade side switches from phase-locked feedforward to instantaneous value feedforward; Among them, the voltage amplitude and phase of the grid are obtained through a single-phase phase-locked loop. The parallel side of the converter is phase-locked to the grid voltage of M, and the cascaded side is phase-locked to the grid voltage of T. The phase-locked feedforward term is obtained by dividing the calculated grid voltage by the DC voltage. The feedforward term on the parallel side of the converter is the grid voltage divided by the DC voltage of the power unit, and the feedforward term on the cascaded side of the converter is the grid voltage divided by the sum of the DC voltages of all power units. （1） （2） In the formula, For the parallel side of the same-phase power supply converter i The phase-locked feedforward values ​​for each power unit are i = 1, 2, 3, ..., N, where N is the number of power units; This is the amplitude compensation coefficient for the parallel side. To match the transformer turns ratio for traction, The voltage amplitude of the M-base obtained by phase-locked loop. For the voltage compensation phase of seat M, For the first i The 5ms moving average of the DC voltage of each power unit; This refers to the phase-locked feedforward value on the cascaded side of the in-phase power supply converter. This is the amplitude compensation coefficient for the cascaded side. The voltage amplitude of the T-type base obtained by phase-locked loop. For the voltage compensation phase of the T-type base, This is the sum of the 5ms moving average of the DC voltage of all power units in the converter.

2. The feedforward method for a co-phase power supply converter according to claim 1, characterized in that, The instantaneous feedforward value is calculated by the following formula: （3） （4） In the formula, For the parallel side of the same-phase power supply converter i Instantaneous feedforward values ​​for each power unit, i = 1, 2, 3, ..., N, where N is the number of power units; This is the amplitude compensation coefficient for the parallel side. The voltage of the M power grids was obtained through sampling; This represents the instantaneous feedforward value on the cascaded side of the in-phase power supply converter. This is the amplitude compensation coefficient for the cascaded side. The voltage of the power grid at location T was obtained through sampling. For the first i The 5ms moving average of the DC voltage of each power unit.

3. The feedforward method for a co-phase power supply converter according to claim 1, characterized in that, The completion of voltage regulation on the parallel side of the converter includes: when the error between the DC voltage command and the feedback value is less than a threshold value for a certain period of time, the voltage regulation of the power unit is completed; the completion of grid connection on the cascade side of the converter includes: when the error between the current command and the feedback value on the cascade side is less than another threshold value for a certain period of time, the grid connection on the cascade side is completed.

4. The feedforward method for a co-phase power supply converter according to claim 1, characterized in that, The phase compensation angle decreases to zero at a set rate, calculated using the following formula: （5） In the formula, The compensation phase set for the phase-locked feedforward of the parallel or cascaded side of the in-phase power supply converter, i=M or T. For numbers that change from 1 to 0, the change time can be set. This refers to the current compensation phase on the parallel or cascaded side of the same-phase power supply converter.

5. A feedforward system for a non-phase power supply converter, characterized in that, The in-phase power supply converter includes a parallel side, a cascaded side, and a starting circuit. The parallel side is connected to the traction transformer M base via a traction matching transformer, and the cascaded side is connected to the traction transformer T base via a starting circuit. The system includes: The phase-locked feedforward term calculation module detects the grid voltage of M-base and T-base respectively, obtains the voltage amplitude and phase through a single-phase phase-locked loop, compensates for the voltage amplitude and phase, and calculates the phase-locked feedforward term based on the DC voltage of the power unit. The control module, after the voltage stabilization of the parallel side of the converter is completed, reduces the compensation phase of the parallel side to zero at a set rate, and controls the parallel side of the converter to switch from phase-locked feedforward to instantaneous value feedforward; after the cascaded side of the converter is connected to the grid, the compensation phase of the cascaded side reduces to zero at a set rate, and controls the cascaded side of the converter to switch from phase-locked feedforward to instantaneous value feedforward. Among them, the voltage amplitude and phase of the grid are obtained through a single-phase phase-locked loop. The parallel side of the converter is phase-locked to the grid voltage of M, and the cascaded side is phase-locked to the grid voltage of T. The phase-locked feedforward term is obtained by dividing the calculated grid voltage by the DC voltage. The feedforward term on the parallel side of the converter is the grid voltage divided by the DC voltage of the power unit, and the feedforward term on the cascaded side of the converter is the grid voltage divided by the sum of the DC voltages of all power units. （1） （2） In the formula, For the parallel side of the same-phase power supply converter i The phase-locked feedforward values ​​for each power unit are i = 1, 2, 3, ..., N, where N is the number of power units; This is the amplitude compensation coefficient for the parallel side. To match the transformer turns ratio for traction, The voltage amplitude of the M-base obtained by phase-locked loop. For the voltage compensation phase of seat M, For the first i The 5ms moving average of the DC voltage of each power unit; This refers to the phase-locked feedforward value on the cascaded side of the in-phase power supply converter. This is the amplitude compensation coefficient for the cascaded side. The voltage amplitude of the T-type base obtained by phase-locked loop. For the voltage compensation phase of the T-base, This is the sum of the 5ms moving average of the DC voltage of all power units in the converter.

6. The in-phase power supply converter feedforward system according to claim 5, characterized in that, The instantaneous feedforward value is calculated by the following formula: （3） （4） In the formula, For the parallel side of the same-phase power supply converter i Instantaneous feedforward values ​​for each power unit, i = 1, 2, 3, ..., N, where N is the number of power units; This is the amplitude compensation coefficient for the parallel side. The voltage of the M power grids was obtained through sampling; This represents the instantaneous feedforward value on the cascaded side of the in-phase power supply converter. This is the amplitude compensation coefficient for the cascaded side. The voltage of the power grid at location T was obtained through sampling. For the first i The 5ms moving average of the DC voltage of each power unit.

7. The in-phase power supply converter feedforward system according to claim 5, characterized in that, The completion of voltage regulation on the parallel side of the converter includes: when the error between the DC voltage command and the feedback value is less than a threshold value for a certain period of time, the voltage regulation of the power unit is completed; the completion of grid connection on the cascade side of the converter includes: when the error between the current command and the feedback value on the cascade side is less than another threshold value for a certain period of time, the grid connection on the cascade side is completed.

8. The in-phase power supply converter feedforward system according to claim 5, characterized in that, The phase compensation angle decreases to zero at a set rate, calculated using the following formula: （5） In the formula, The compensation phase set for the phase-locked feedforward of the parallel or cascaded side of the in-phase power supply converter, i=M or T. For numbers that change from 1 to 0, the change time can be set. This refers to the current compensation phase on the parallel or cascaded side of the same-phase power supply converter.

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