Input bridge leg common hybrid through traction power supply device and control method thereof

Abstract

The application provides an input bridge arm shared hybrid through traction power supply device and a control method thereof. The device comprises a balanced traction transformer, single-phase multi-tap transformers, a two-phase three-bridge-arm module and an H-bridge module. The primary side of the balanced traction transformer is connected with a three-phase power grid. Two ports of the secondary side of the balanced traction transformer are respectively connected with the primary sides of two single-phase multi-tap transformers. The upper connection points of the secondary sides of the two single-phase multi-tap transformers are respectively connected with the middle points of two-phase bridge arms of the two-phase three-bridge-arm module. The lower connection points are connected with the middle point of the common bridge arm of the two-phase three-bridge-arm module after being collinear. The DC side of the two-phase three-bridge-arm module is connected with the DC side of the H-bridge module. The AC side of the H-bridge module is connected with a traction grid. The application can further reduce the number of active devices required for reconstruction, reduce the system reconstruction and construction cost, and ensure reliable operation of the device by using the method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rail transit system traction power supply, and particularly refers to an input bridge arm shared hybrid through traction power supply device and a control method thereof. BACKGROUND

[0002] In the rail transit system, the through traction power supply device is mainly divided into two types of "three-phase-single-phase" and "two-phase-single-phase". Among them, the three-phase-single-phase through traction power supply scheme must completely rebuild the existing traction substation, and it is difficult to fully utilize the existing two-phase balanced traction transformer, and the three-phase-single-phase through traction power supply device requires more power electronic devices and passive elements, and the cost is higher. In contrast, the two-phase-single-phase through traction power supply device can fully utilize the existing traction transformer and reduce the transformation cost.

[0003] The current typical two-phase-single-phase through traction power supply device is a hybrid through traction power supply device based on a multi-tap transformer as shown in Figure 1 The device is connected with the existing balanced traction transformer through two single-phase multi-tap step-down transformers. Compared with the three-phase-single-phase through traction power supply device, the device has fewer active and passive devices, lower transformation cost, and higher engineering application value. However, the input port of this device is two independent single-phase full-bridge converter structures, and the input bridge arm has not been fully utilized, and there is still a large space for improvement in reducing the number of devices and investment cost. Therefore, how to further optimize the two-phase input port structure of the hybrid through traction power supply device to fully utilize the input port and reduce the number of devices is a difficult problem to be solved at present. SUMMARY

[0004] In order to overcome the shortcomings of the above background technology, the present application provides an input bridge arm shared hybrid through traction power supply device and a control method thereof. The present application is transformed on the basis of the existing hybrid through traction power supply device, and further reduces the number of active devices required for transformation and the system transformation and construction cost through the two-phase input port shared bridge arm mode. At the same time, the present application proposes a control method for the bridge arm shared two-phase input port to ensure reliable operation of the device.

[0005] In order to solve the above technical problems, the present application adopts the following technical method: an input bridge arm shared hybrid through traction power supply device, the device comprising a balanced traction transformer, a single-phase multi-tap transformer, an H-bridge module composed of N H-bridge inverters, the single-phase multi-tap transformer having N taps at the secondary side, characterized in that: the device further comprises a two-phase three-bridge arm module composed of N two-phase three-bridge arm inverters;

[0006] The primary side of the balancing traction transformer is connected to a three-phase power grid. Two ports on the secondary side of the balancing traction transformer are respectively connected to the primary sides of two single-phase multi-tap transformers. The upper connection point of the nth tap on the secondary side of the two single-phase multi-tap transformers is connected to a filter inductor. and Then, connect the two-phase bridge arms of the nth two-phase three-bridge inverter to the midpoint of each bridge arm. The lower terminals of the nth taps on the secondary sides of the two single-phase multi-tap transformers are collinear and then connected to the midpoint of the common bridge arm of the nth two-phase three-bridge inverter. A filter capacitor is connected to the DC side of the nth two-phase three-bridge inverter. Then it is connected to the DC side of the nth H-bridge inverter, and the AC sides of the N H-bridge inverters are connected in series to form the output voltage. Connect to the traction network, where n=1, 2…N.

[0007] Preferably, the switching devices of the H-bridge inverter and the two-phase three-arm inverter are IGBT devices, MOSFET devices, or power electronic devices made of SiC or GaN materials.

[0008] As another aspect of the present invention, the control method of the input bridge arm shared type hybrid through traction power supply device includes DC voltage regulation control of the two-phase three-bridge arm module to stabilize the DC side voltage, while realizing decoupling control of the two-phase voltage and active power sharing; it also includes cascade output control of the H-bridge module to stabilize the traction network voltage or provide stable power to the traction load.

[0009] Furthermore, the process of DC voltage regulation control for the two-phase three-bridge arm module is as follows:

[0010] S1, Acquiring and determining relevant parameters of the device: Real-time acquisition of two-phase voltage on the AC side of the two-phase three-arm inverter. , With two-phase current , and DC side voltage Determine the active power outer loop control parameters of the device. and Filter capacitor Filter inductor and Switching frequency Set the reference value for the DC side voltage of the two-phase three-arm inverter. H-bridge inverter AC side output power reference value and the reactive power reference value at the input port of the device. ;

[0011] S2, inner and outer loop control of two-phase three-bridge arm module;

[0012] S201, inputting the angular frequency obtained by the phase-locked loop into a two-phase voltage , and a two-phase current , , transforming to obtain a voltage active component , a voltage reactive component , a current active component , and a current reactive component in a dq coordinate system

[0013] S202, inputting , , into an active outer loop to obtain a d-axis active reference current , and the calculation formula of the active outer loop is:

[0014] (1)

[0015] wherein is a complex frequency variable, and represents an integral element

[0016] S203, inputting into a reactive outer loop to obtain a q-axis reactive reference current , and the calculation formula of the reactive outer loop is:

[0017] (2)

[0018] S204, inputting into a double-frequency notch filter for filtering, and then inputting , 、 、 、 together into a current inner loop controller to obtain dq-axis reference modulation voltages , ; then , are transformed to obtain phase reference modulation voltages , ,

[0019] S3, two-phase three-bridge-arm module vector decoupling modulation

[0020] S301, inputting ​Phase reference modulation voltage , After adding, divide by 2 again, get two-phase common voltage vector ;

[0021] S302, respectively , Subtract two-phase common voltage vector , get two-phase independent voltage vector , ;

[0022] S303, respectively , , Input into SPWM modulator, get corresponding two-phase independent voltage vector modulation signal , , and two-phase common voltage vector modulation signal , send , And To two-phase three-bridge arm inverter for PWM tracking.

[0023] Further, combined with PQ control and carrier phase shift modulation, the H-bridge module is cascaded output control.

[0024] Compared with the prior art, the beneficial effects of the present application are as follows:

[0025] (1) The input bridge arm shared hybrid through traction power supply device provided by the present application has all the advantages of traditional hybrid through traction power supply device, including making full use of existing traction transformer, low cost and other advantages. Compared with the traditional hybrid through traction power supply device, the number of active devices required by the two-phase input port of the device provided by the present application can be reduced by 16.7%, further reducing the equipment investment cost.

[0026] (2) The control method of the input bridge arm shared hybrid through traction power supply device provided by the present application can realize input two-phase power sharing, DC side double frequency ripple cancellation and other functions under the premise of ensuring two-phase input control decoupling, solve the problem of traction network power negative sequence and harmonic quality, and provide the operation reliability of the device. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Is the topology diagram of the traditional hybrid through traction power supply device;

[0028] Figure 2 Is the topology diagram of the input bridge arm shared hybrid through traction power supply device provided by the present application;

[0029] Figure 3This is a block diagram of the DC voltage regulation control of the two-phase three-bridge arm module in this invention;

[0030] Figure 4 This is the decomposition diagram of the two-phase vector synthesis in this invention;

[0031] Figure 5 This is a topology diagram of a hybrid through-type traction power supply device based on single-phase back-to-back modules;

[0032] Figure 6 This is a simulation waveform diagram of the input arm shared type hybrid through traction power supply device in the embodiment of the present invention (in the figure, (a) is the waveform diagram of two-phase input power and single-phase output power; (b) is the waveform diagram of positive, negative and zero sequence current on the grid side; (c) is the waveform diagram of two-phase three-arm inverter). (d) is the DC-side voltage waveform diagram; (d) is the two-phase three-arm inverter. of Phase voltage and current waveforms; (e) shows a two-phase three-arm inverter. of Phase voltage and current waveforms; (f) shows a two-phase three-arm inverter. (Common arm current waveform diagram). Detailed Implementation

[0033] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0034] The input arm shared type hybrid through-type traction power supply device provided by this invention includes a balanced traction transformer, two single-phase multi-tap transformers, 2N filter inductors, a two-phase three-arm module composed of N two-phase three-arm inverters, N filter capacitors, and an H-bridge module composed of N H-bridge inverters. The wiring method is as follows: Figure 2 As shown:

[0035] First, the primary side of the balancing traction transformer is connected to the three-phase power grid, transforming the 110 / 220 kV three-phase voltage into a 27.5 kV two-phase traction grid voltage. , The two phase voltages are 90° out of phase; the two ports on the secondary side of the balancing traction transformer are respectively connected to the primary side of two single-phase multi-tap transformers, and the two single-phase multi-tap transformers respectively deliver 27.5 kV voltage ( , The voltage is stepped down, and then N single-phase voltages with an effective value of 27.5 / N kV are output from the secondary side. That is, the voltages output from the secondary side of the two single-phase multi-tap transformers are respectively Figure 2 In , (n=1, 2…N), and Their phases are also 90° apart.

[0036] Secondly, construct the common bridge arm connection point. Connect the upper connection point of the nth tap on the secondary side of the two single-phase multi-tap transformers to the filter inductor respectively. and Then, connect to the midpoint of each of the two phase arms of the nth two-phase three-arm inverter, i.e. Figure 2 Medium-duration two-phase three-bridge inverter The two-phase voltages on the AC side are respectively , Furthermore, the lower connection points of the nth taps on the secondary side of two single-phase multi-tap transformers are connected to form a common voltage point, which is then connected to the midpoint of the nth common arm of a two-phase three-bridge transformer. Figure 2 Two-phase three-bridge inverter The common voltage on the AC side is By adopting the approach of common vector synthesis, the number of bridge arms at the two-phase input ports is reduced, further decreasing the number of components in the traditional hybrid through-type traction power supply device.

[0037] Finally, the two-phase three-bridge inverter DC side connected filter capacitor Then connect with the H-bridge inverter The DC side is connected, and each H-bridge inverter (O1, O2, ... O) is connected to the DC side. n …,O N The output voltage is formed by connecting the AC side of the circuit in series. Connect to the traction network.

[0038] Preferably, the switching devices of the H-bridge module and the two-phase three-arm module in this invention are IGBT devices, MOSFET devices, or power electronic devices made of SiC or GaN materials.

[0039] The control section of the aforementioned input arm shared type hybrid through-type traction power supply device mainly includes DC voltage regulation control of two-phase three-arm modules and cascaded output control of H-bridge modules. Among them, the two-phase three-arm inverter in the two-phase three-arm module... Responsible for stabilizing DC side voltage Simultaneously achieve two-phase voltage and The decoupling control and active power distribution are implemented; the H-bridge module stabilizes the traction network voltage or provides stable power to the traction load through cascaded output. Specifically, in this embodiment, the H-bridge module is cascaded output controlled by combining PQ control and carrier phase-shift modulation.

[0040] Preferred, such as Figure 3 As shown, the process of DC voltage regulation control for the two-phase three-arm bridge module is as follows:

[0041] S1, Acquiring and determining relevant parameters of the device: Real-time acquisition of two-phase three-arm inverter. AC side two-phase voltage , With two-phase current , and DC side voltage Determine the active power outer loop control parameters of the device. and Filter capacitor Filter inductor and Switching frequency Set the reference value for the DC side voltage of the two-phase three-arm bridge module. H-bridge module AC side output power reference value and the reactive power reference value at the input port of the device. .

[0042] S2, inner and outer loop control of the two-phase three-bridge arm module.

[0043] S201, Angular frequency is obtained by inputting a phase-locked loop (PLL). Based on angular frequency For two-phase voltage , With two-phase current , conduct Transformation yields the voltage active component in the dq coordinate system. Voltage reactive component Active component of current reactive component of current .

[0044] S202, will , , The active reference current along the d-axis is obtained by inputting it into the active outer loop. The formula for calculating the active power outer loop is:

[0045] (1)

[0046] In the formula, For complex frequency variables, Indicates the integration process;

[0047] S203, The q-axis reactive reference current is obtained by inputting it into the reactive outer loop. The formula for calculating the reactive power outer loop is:

[0048] (2)

[0049] S204, the input into the filter after the double frequency trap, and , 、 、 、 together into the current inner loop controller (dq axis current inner loop controller has been more common, not in detail here), get the dq axis reference modulation voltage , ; then , transform, get phase reference modulation voltage , .

[0050] S3, two phase three bridge arm module vector decoupling modulation. Based on the common vector synthesis idea, the existing phase voltage vector is decomposed, which is constructed as two phase common voltage vector and two phase independent voltage vector , two parts. The common voltage vector is tracked by the common bridge of the two phase three bridge arm module, and the two phase independent voltage vector is tracked by the remaining bridge. Based on the vector sharing idea, the number of bridges can be further reduced without affecting the two phase decoupling control. The specific vector synthesis and decomposition scheme is shown in Figure 4 .

[0051] First, according to the vector synthesis relationship, add phase reference modulation voltage , and then divide by 2, get two phase common voltage vector .

[0052] Second, subtract , from two phase common voltage vector , get two phase independent voltage vector , .

[0053] Finally, input , , into the SPWM modulator, get the corresponding two phase independent voltage vector modulation signal , , and two phase common voltage vector modulation signal​ , Vdc1 and Vdc2 are sent to the two-phase three-bridge arm module for PWM tracking. , and are sent to the two-phase three-bridge arm module for PWM tracking.

[0054] To further verify the economy and superiority of the input bridge arm shared hybrid through traction power supply device and the control method thereof, the following three schemes are compared. Scheme 1: hybrid through traction power supply device based on single-phase back-to-back module, as shown in Figure 5 ; Scheme 2: hybrid through traction power supply device with common DC side, as shown in Figure 1 ; Scheme 3: input bridge arm shared hybrid through traction power supply device of the present application, as shown in Figure 2 . The comparison table of the number of active and passive devices required by the three schemes is shown below.

[0055] Table 1 Comparison of the present application and existing hybrid through traction power supply device

[0056] ;

[0057] According to the comparison results in Table 1, under the same IGBT device selection, compared with Scheme 1, the present application can reduce 37.5% of the number of IGBTs and 50% of the number of capacitors; compared with Scheme 2, the present application can reduce 16.7% of the number of IGBTs under the premise of realizing all functions such as power sharing, ripple cancellation and harmonic transmission suppression of Scheme 2. Therefore, the present application can significantly reduce the cost of traction system transformation and improve the economy of the system compared with the prior art.

[0058] Further, based on the MATLAB / Simulink simulation platform, a simulation model of the input bridge arm shared hybrid through traction power supply device of the present application is built to verify the effectiveness of the proposed topology structure and control method. The simulation parameters are shown in Table 2.

[0059] Table 2 Simulation parameters of input bridge arm shared hybrid through traction power supply device

[0060] ;

[0061] The simulation results are shown in Figure 6 . Among them, the single-phase output power waveform is shown as the blue curve in Figure 6 (a), the traction network load is 17.5 MW at 0-0.2s, suddenly rises to 25 MW at 0.2s, and reduces to 10 MW at 0.4s; the two-phase input power waveform of the input bridge arm shared hybrid through traction power supply device is shown as the red and green curves in Figure 6 (a); the positive, negative and zero sequence currents of the three-phase power grid side are shown in Figure 6 (b). From Figure 6 (a) andFigure 6 As can be seen from the simulation waveform in (b), under the proposed control method, The two-phase input power is always evenly distributed, and no negative sequence current is generated on the grid side.

[0062] Since the DC-side voltage waveforms and AC-side voltage and current waveforms of all two-phase three-arm inverters are basically similar, only the waveforms of one two-phase three-arm inverter are shown here. DC side voltage waveform as follows Figure 6 As shown in (c), AC side , The phase voltage and current waveforms are as follows: Figure 6 (d) and Figure 6 As shown in (e), the common arm current waveform is as follows: Figure 6 As shown in (f). Figure 6 (d) Figure 6 (e) and Figure 6 As can be seen from the simulation waveform in (f), under the proposed control method, the DC side voltage is always stable at the set target value of 2400V, the AC side current and voltage remain in phase, and there are no obvious harmonic components.

[0063] In summary, through Figure 1 Simulation results show that the input arm shared type hybrid through traction power supply device and its control method proposed in this invention fully take into account... ​ The device demonstrates all the functions of a traditional hybrid through-type traction power supply unit, including two-phase input power sharing, second-harmonic ripple transmission suppression, and rapid DC voltage stabilization. Furthermore, compared to traditional hybrid through-type traction power supply units, it further reduces the number of active devices by 16.7%, lowering retrofit costs.

[0064] It is worth noting that this invention is only analyzed using a single device parameter as an example. This invention can also be applied to power electronic devices of different types, capacities, and withstand voltage levels. In actual engineering applications, the number of device ports can be adjusted according to the actual situation of device selection.

[0065] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present technical solution are within the protection scope of the present invention.

[0066] To facilitate understanding by those skilled in the art of the improvements of this invention over the prior art, some of the accompanying drawings and descriptions have been simplified, and for clarity, some other elements have been omitted from this application. Those skilled in the art should realize that these omitted elements may also constitute the content of this invention.

Claims

1. A hybrid through-type traction power supply device for shared input bridge arms, comprising a balanced traction transformer, a single-phase multi-tap transformer, and an H-bridge module composed of N H-bridge inverters, wherein the single-phase multi-tap transformer has N taps on its secondary side, characterized in that: The device also includes a two-phase three-bridge module consisting of N two-phase three-bridge inverters; The primary side of the balancing traction transformer is connected to the three-phase power grid. Two ports on the secondary side of the balancing traction transformer are respectively connected to the primary sides of two single-phase multi-tap transformers. The upper connection points of the nth taps on the secondary sides of the two single-phase multi-tap transformers are connected to the midpoints of the two-phase arms of the nth two-phase three-bridge inverter. The lower connection points are collinear and connected to the midpoint of the common arm of the nth two-phase three-bridge inverter. The DC side of the nth two-phase three-bridge inverter is connected to the DC side of the nth H-bridge inverter. The AC sides of the N H-bridge inverters are connected in series to form the output voltage. Connect to the traction network, where n=1, 2…N.

2. The input bridge arm shared type hybrid through traction power supply device according to claim 1, characterized in that: The upper connection points of the nth tap on the secondary side of two single-phase multi-tap transformers are respectively connected to filter inductors. and Then, connect the two-phase bridge arms of the nth two-phase three-bridge inverter to the midpoint of each bridge arm. The lower terminals of the nth taps on the secondary sides of the two single-phase multi-tap transformers are collinear and then connected to the midpoint of the common bridge arm of the nth two-phase three-bridge inverter. A filter capacitor is connected to the DC side of the nth two-phase three-bridge inverter. Then it is connected to the DC side of the nth H-bridge inverter.

3. The input bridge arm shared type hybrid through traction power supply device according to claim 2, characterized in that: The switching devices of the H-bridge module and the two-phase three-arm module are all IGBT devices, MOSFET devices, or power electronic devices made of SiC or GaN materials.

4. The control method for the input bridge arm shared type hybrid through traction power supply device as described in claim 1, 2, or 3, characterized in that: This includes DC voltage regulation control of the two-phase three-arm module to stabilize the DC side voltage, while also achieving decoupling control of the two-phase voltage and equal distribution of active power; it also includes cascaded output control of the H-bridge module to stabilize the traction network voltage or provide stable power to the traction load.

5. The control method for the input bridge arm shared type hybrid through traction power supply device according to claim 4, characterized in that: The process of DC voltage regulation control for a two-phase three-bridge arm module is as follows: S1, Acquiring and determining relevant parameters of the device: Real-time acquisition of two-phase voltage on the AC side of the two-phase three-arm inverter. , With two-phase current , and DC side voltage ; Determine the active power outer loop control parameters of the device. and Filter capacitor Filter inductor and Switching frequency ; Setting the DC-side voltage reference value for a two-phase three-arm inverter H-bridge inverter AC side output power reference value and the reactive power reference value at the input port of the device. ; S2, inner and outer loop control of two-phase three-bridge arm module; S201, Angular frequency is obtained by inputting a phase-locked loop. Based on angular frequency For two-phase voltage , With two-phase current , conduct Transformation yields the voltage active component in the dq coordinate system. Voltage reactive component Active component of current reactive component of current ; S202, , , The active reference current along the d-axis is obtained by inputting it into the active outer loop. The formula for calculating the active power outer loop is: (1) In the formula, For complex frequency variables, Indicates the integration process; S203, The q-axis reactive reference current is obtained by inputting it into the reactive outer loop. The formula for calculating the reactive power outer loop is: (2) S204, After being filtered by a frequency-doubled notch filter, it is then combined with... , 、 、 、 The input current is fed into the inner loop controller to obtain the dq-axis reference modulation voltage. , Next, , conduct Transformation, to obtain Phase reference modulation voltage , ; S3, vector decoupling modulation of two-phase three-bridge arm module; S301, Phase reference modulation voltage , After adding them together, divide by 2 to obtain the common voltage vector of the two phases. ; S302, , With the common voltage vector of the two phases respectively Subtraction yields two independent voltage vectors. , ; S303, , , The signals are input into the SPWM modulator respectively to obtain the corresponding two-phase independent voltage vector modulation signals. , and two-phase common voltage vector modulation signal ,Will , and The signal is sent to a two-phase three-bridge inverter for PWM tracking.

6. The control method for the input bridge arm shared type hybrid through traction power supply device according to claim 5, characterized in that: The H-bridge module is cascaded and output controlled by combining PQ control and carrier phase-shift modulation.

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