CN113381422B

CN113381422B - Train ground automatic passing neutral section method, system, terminal equipment and storage medium

Info

Publication number: CN113381422B
Application number: CN202110724101.3A
Authority: CN
Inventors: 于天剑; 刘畅; 唐建湘; 成庶; 伍珣; 李凯迪
Original assignee: Central South University; Zhuzhou CRRC Times Electric Co Ltd
Current assignee: Central South University; Zhuzhou CRRC Times Electric Co Ltd
Priority date: 2021-06-18
Filing date: 2021-06-29
Publication date: 2023-04-07
Anticipated expiration: 2041-06-29
Also published as: CN113381423B; CN113381423A; CN113381422A

Abstract

The invention discloses a method, a system, terminal equipment and a storage medium for automatically passing neutral section on the ground of a train, wherein the method comprises the following steps: the method comprises the steps of acquiring the running position of a train, determining a power supply for supplying power to the train according to the running position, and specifically: when the train is positioned in the transition region, according to the voltage and the current of the transition region and the parameters of the quadruple auxiliary current converting device, determining an output voltage decoupling modulation signal of the quadruple auxiliary current converting device in the transition region and an output voltage modulation signal of a power supply arm corresponding to the transition region; when the train is positioned in the electric isolation area, the voltage amplitude and the phase of the quadruple auxiliary converter device are pre-modulated by taking the voltage of the power supply arm B as a target. The invention can avoid the influence of overvoltage and overcurrent impact of the bow net electric arc on the car net system; the flexible switching of the voltage between the adjacent power supply arms can be realized, and the short circuit and transient impact influence caused by direct voltage switching can be effectively avoided and inhibited; in addition, the alternate transfer of power guarantees the rated operation condition of the train and reduces the speed loss of the train.

Description

Train ground automatic passing neutral section method, system, terminal equipment and storage medium

Technical Field

The invention belongs to the technical field of traction power supply of electrified railways, and particularly relates to a method, a system, terminal equipment and a computer readable storage medium for automatically passing a neutral section on the ground of a train.

Background

Based on the single-phase power supply characteristics of the electrified railway, the traction load is generally characterized by single-phase, random and non-linear characteristics. Therefore, the three-phase load imbalance problem of the power system is usually solved by supplying power to the traction network in sections after the 3/2 system conversion is realized by the traction transformer. However, the electrical isolation section (i.e. the electrical phase separation section) provided for preventing the short circuit between the phases is a weak link of the traction power supply system, and causes a plurality of potential safety hazards. On one hand, when the train runs in an excessive phase separation mode, the continuous and violent electromagnetic transient impact influence can be caused to the pantograph system, and meanwhile, the unbalance of the power system is easily caused by the short-time serious accumulation of transient energy. On the other hand, the train speed loss caused by the power interruption greatly reduces the railway operation efficiency. Therefore, how to realize safe and efficient split-phase operation of the electric locomotive becomes a current research focus.

The vehicle-mounted automatic passing neutral section, the on-column automatic passing neutral section and the ground automatic passing neutral section are three types of train passing neutral sections which are widely applied at present. The first two methods both belong to an idle running split-phase running mode, generally have the defects of large speed loss, serious transient impact and the like, and do not meet the development requirements of high-speed and heavy-load trains, so the schemes are gradually replaced by the latter. However, when the locomotive is in a ground-neutral-section live operation mode, the locomotive is very likely to have serious transient impact influence on the pantograph system during the switching process of the voltages of the adjacent power supply arms. The prior art has adopted various methods to solve the above problems, such as: on the basis of research of a high-speed Vacuum Circuit Breaker (VCB), hybrid phase-controlled circuit breaker topologies aiming at different conditions are provided, and within a dead zone satisfying the limitation of a target action window, uninterrupted operation of an auxiliary power system in a Neutral Section (NSs) can be ensured; by controlling the electronic switch to be switched on or off at the current zero crossing point, the power-off dead zone is greatly shortened, and the influence of transient impact is reduced; a superconducting current limiting limiter (SFCL) is applied to improve a neutral-section passing switch system, and the surge current level is greatly restrained. However, the ground switch passing neutral section method cannot fundamentally eliminate the power failure dead zone, so that the in-phase power supply technology based on the realization of the uninterrupted passing neutral section operation of the train through active power compensation is developed. Research shows that the load power compensation is realized through the balance transformer and the active compensation device, so that harmonic waves and negative sequences can be eliminated, and the in-phase power supply function is realized. On this basis, the prior art discloses various solutions, such as: a parallel VSI STATCOM type balance network scheme capable of eliminating negative sequence current; an Active Power Compensator (APC) and YN, vd balance wiring transformers are adopted to form a balance traction substation, and a single-phase and same-phase power supply scheme is obtained. However, the optimization scheme has special modification requirements on the traditional overhead contact system, and the popularization and application of the traditional overhead contact system are limited.

Generally, by instantaneous power compensation, the influence of reactive power and negative sequence on the power system can be effectively suppressed. However, the energy between the power supply arm and the neutral zone cannot be smoothly transferred through single quantitative compensation, and the residual voltage of the neutral zone is easy to generate electric arcs when the pantograph-catenary is separated, and even a relay protection device is broken down. Aiming at the problem of electromagnetic transient impact, a Direct Power Control (DPC) algorithm is widely applied to the technical field of train passing split-phase. For example, research on Flexible group Automatic routing Technology Base on Voltage Compensation and Simulation of Flexible Automatic routing System Based on RTDS are Based on DPC and Voltage phase modulation Technology, but the single-layer topology circuit has the limitation of insufficient output driving capability. In order to adapt to the practical engineering application background with large capacity, a Virtual co-phase transformation power supply system adapting the cascaded H-bridge multilevel converter adopts a cascaded H-bridge converter to directly drive a load, and simultaneously adopts a modulation method of recent level approximation to realize smooth switching of output voltage, but the cost problem caused by the excessively high number of cascaded modules and the accumulated error generated by an integral algorithm limit the practical engineering application prospect of the method. In order to overcome the defect of complex structure of a Modular Multilevel Converter (MMC), a high-voltage four-leg converter topology based on series-connected IGBTs is provided in Transformarless power divider used as load balancing and uninterrupted power supply for auto-following neutral section, and the power Regulator (RPC) does not contain a matching transformer, so that the specification of the device is reduced by 30%, but the method still generates transient shock wave current of a plurality of cycles in the circuit switching process.

Disclosure of Invention

The invention aims to solve the technical problems that the existing train passing neutral section method has a power supply dead zone and serious transient impact, so that the invention provides a train ground automatic passing neutral section method and terminal equipment based on structure improvement and control algorithm optimization.

The invention discloses a train ground automatic passing neutral section method based on structure improvement and control algorithm optimization, which is applied to a ground automatic passing neutral section system, wherein the system comprises a power supply arm A, a power supply arm B and a quadruple auxiliary converter device, which are used for supplying power to a train, and the train drives to the power supply arm B from the power supply arm A; the method comprises the following steps:

acquiring the running position of a train, wherein the running position comprises a transition region and an electric isolation region;

determining a power supply for supplying power to the train according to the running position, specifically:

when the train is located in the transition region, determining an output voltage decoupling modulation signal of the quadruple auxiliary converter device and an output voltage modulation signal of a power supply arm corresponding to the transition region in the transition region according to the voltage and the current of the transition region and the parameters of the quadruple auxiliary converter device, and realizing dynamic and smooth transfer of energy when the power supply arm corresponding to the transition region and the quadruple auxiliary converter device supply power to the train;

when the train is located in the electric isolation area, the quadruple auxiliary converter device is used for supplying power to the train, and the voltage amplitude and the phase of the quadruple auxiliary converter device are pre-modulated by taking the voltage of the power supply arm B as a target.

Preferably, the quadruple auxiliary converter device includes four groups of converter units connected in parallel, and the converter units include: the system comprises a step-down transformer, a step-up transformer and a single-phase H-bridge converter;

the input end of the single-phase H-bridge converter is coupled with the step-down transformer, and the output end of the single-phase H-bridge converter is coupled with the step-up transformer.

Preferably, the determining, according to the voltage and the current of the transition region and the parameter of the quadruple auxiliary variable current device, the output voltage decoupling modulation signal of the quadruple auxiliary variable current device and the output voltage modulation signal of the power supply arm corresponding to the transition region in the transition region specifically includes:

acquiring voltage and current of the transition region, and determining instantaneous active power, instantaneous reactive power and d-axis voltage fundamental component of the transition region in a d-q coordinate system according to the voltage and the current;

obtaining parameters of the quadruple auxiliary converter device, wherein the parameters comprise an output active power given value and an output reactive power given value;

determining an output voltage decoupling modulation signal of the quadruple auxiliary converter device in the transition region according to the instantaneous active power, the instantaneous reactive power, the d-axis voltage fundamental component, the output active power given value and the output reactive power given value of the transition region;

and determining an output voltage modulation signal of the power supply arm corresponding to the transition region according to the output voltage decoupling modulation signal of the quadruple auxiliary variable current device.

Preferably, the instantaneous active power, the instantaneous reactive power and the d-axis voltage fundamental component of the transition region in the d-q coordinate system are determined according to the voltage and the current, and specifically:

determining the instantaneous active power and the instantaneous reactive power of the transition region under a d-q coordinate system according to a first formula, wherein the first formula is as follows:

wherein P is the instantaneous active power of the transition region, Q is the instantaneous reactive power of the transition region, u _d And u _q The voltage components of the voltage u in the transition region in the d-axis and q-axis, i _d And i _q The current components of the current i in the transition region in the d axis and the q axis respectively.

Preferably, the determining of the output voltage decoupling modulation signal of the quadruple auxiliary variable current device in the transition region specifically includes:

determining an output voltage decoupling modulation signal of the quadruple auxiliary variable current device in the transition region according to a second formula, wherein the second formula is as follows:

in the formula u _abd "and u _abq Is the output voltage of the quadruple auxiliary current transformer on the d axis and the q axis respectively, K _PP ' and K _PI Respectively representing the proportional and integral coefficients, K, of the active PI regulator _QP K and K _QI ' respectively represents the proportional and integral coefficients of the reactive PI regulator; p _c ^* And Q _c ^* Respectively representing the given value of the output active power and the given value of the output reactive power of the quadruple auxiliary converter device, P _c And Q _c Respectively instantaneous active power and instantaneous reactive power of the transition region, wherein P and Q are instantaneous calculated values (formula theoretical values) of power, P _c And Q _c The instantaneous value of the output power of the neutral area network is obtained when the instantaneous power calculation theory is applied to the condition of excessive phase separation. P and P _C Values and meanings are the same, Q and Q _C Is the same as the meaning, S is the input variable of the original formula after Laplace transform, u is the input variable of the original formula _ds "and u _qs Determined according to a third formula:

where k is the transformation ratio of the primary winding and the secondary winding of the step-up transformer, and u is _m Is the fundamental amplitude of the voltage in the transition zone, P and Q being the instantaneous active power in the transition zone and the instantaneous reactive power, ω, in the transition zone, respectively _s Is the voltage angular frequency, R, of the transition region _eq And L _eq Determined according to a fourth formula, which is:

in the formula, L _c And R _c Respectively representing the equivalent inductance and the equivalent resistance, L, of the quadruple auxiliary converter device _f And R _f Respectively representing the equivalent inductance and the equivalent resistance, L, of the filter circuit _s And R _s Respectively representing equivalent inductance and equivalent resistance of the transition region, n is the parallel connection multiple number of the submodules, and k is the transformation ratio of a primary winding and a secondary winding of the booster transformer.

Preferably, the voltage amplitude and the phase of the quadruple auxiliary variable current device are pre-modulated by taking the voltage of the power supply arm B as a target, specifically:

pre-modulating the voltage amplitude and the phase of the quadruple auxiliary variable current device according to a fifth formula, wherein the fifth formula is as follows:

in the formula u _s In order to pre-modulate the voltage,

to the voltage u of the supply arm B _B Voltage u to arm A _A Phase difference between them, U _A And U _B Are respectively a voltage u _A And electricityPress u _B T is time, Δ t is time interval, f ₀ The frequencies of supply arm a and supply arm B.

Preferably, the transition region comprises a transition region A and a transition region B which are positioned at two sides of the electrical isolation region;

correspondingly, when the train is located in the transition zone, according to the voltage and the current of the transition zone and the parameters of the quadruple auxiliary variable current device, determining an output voltage decoupling modulation signal of the quadruple auxiliary variable current device and an output voltage modulation signal of a power supply arm corresponding to the transition zone in the transition zone, so as to realize dynamic and smooth transfer of energy when the power supply arm corresponding to the transition zone and the quadruple auxiliary variable current device supply power to the train, specifically:

when the train is located in the transition area A, according to the voltage and the current of the transition area A and the parameters of the quadruple auxiliary converter device, determining an output voltage decoupling modulation signal of the quadruple auxiliary converter device and an output voltage modulation signal of the power supply arm A in the transition area A, so that the quadruple auxiliary converter device gradually replaces the power supply arm A to supply power to the train;

when the train is located in the transition zone B, according to the voltage and the current of the transition zone B and the pre-modulated parameters of the quadruple auxiliary converter device, determining an output voltage decoupling modulation signal of the quadruple auxiliary converter device and an output voltage modulation signal of the power supply arm B in the transition zone B, so that the power supply arm B replaces the quadruple auxiliary converter device step by step to supply power to the train.

The second aspect of the invention discloses a train ground automatic passing neutral section system, which comprises:

the system comprises a ground position identification unit, a power regulation unit and a control unit, wherein the ground position identification unit is used for acquiring the running position of a train and sending the running position to the power regulation unit, and the running position comprises a transition area A, an electrical isolation area and a transition area B;

the power regulation unit comprises a power supply arm A, a power supply arm B, a quadruple auxiliary converter device and a circuit breaker and is used for realizing dynamic and smooth transfer of energy between adjacent power supply arms and a neutral zone and flexible switching of voltage;

the quadruple auxiliary variable-current device comprises four groups of parallel variable-current units, and each variable-current unit comprises: the system comprises a step-down transformer, a step-up transformer and a single-phase H-bridge converter;

the input end of the single-phase H-bridge converter is coupled with the step-down transformer, and the output end of the single-phase H-bridge converter is coupled with the step-up transformer;

the circuit breaker comprises a first circuit breaker and a second circuit breaker, the first circuit breaker is used for switching the power supply arm A and the quadruple auxiliary converter device according to the operation position, and the second circuit breaker is used for switching the power supply arm B and the quadruple auxiliary converter device according to the operation position.

The third aspect of the invention discloses a terminal device, which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the computer program to realize the steps of the train ground automatic passing neutral section method.

A fourth aspect of the present invention discloses a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of the above-described train ground auto-passing phase-splitting method.

The method has the advantages that the method innovatively explores the train ground automatic passing phase separation method, deeply analyzes the working principle of a single H-bridge converter and the coupling mechanism between a plurality of sub-modules and a matching transformer in a traction power supply system, improves and optimizes the topological structure and the control algorithm of the converter device on the basis, and provides the train ground automatic passing phase separation improvement method based on the transient power and voltage amplitude phase regulation and control algorithm.

The method adopts four single-phase H-bridge converters and a matching transformer which are connected in parallel to form a combined auxiliary converter device, and introduces a transformer equivalent conversion principle to correct an instantaneous power regulation and control algorithm on the basis of improvement of a quadruple structure. On one hand, by controlling smooth dynamic transfer of supplied energy between two adjacent power supply arms and a neutral zone, a safe current environment is provided for bow net separation operation, and overvoltage and overcurrent impact influence of bow net electric arcs on a car net system is effectively avoided. On the other hand, through the pre-regulation and control of the amplitude and the phase of the neutral zone voltage, the flexible switching of the voltage between the adjacent power supply arms is realized, and the short circuit and transient impact influence caused by the direct switching of the voltage are effectively avoided and restrained. In addition, the alternate transfer of power ensures the rated operation condition of the locomotive, reduces the speed loss of the train and effectively improves the railway operation efficiency. Compared with the existing automatic switch neutral section passing method, the method provided by the invention has incomparable advantages in the aspects of inhibiting arc net arc, preventing electric quantity mutation and the like. Compared with a single-topology scheme, the method provided by the invention can effectively inhibit transient impact influence, shorten the duration time of a transient process and reduce the transient waveform distortion rate, and is obviously superior to the single-topology scheme in the aspects of improving circuit capacity and system response speed and precision. Finally, the correctness, feasibility and robustness of the method are comprehensively verified from two aspects of the performance advantage and the anti-interference capability of the method through an MATLAB/Simulink full-digital simulation experiment platform.

Drawings

FIG. 1 is a flow chart of the ground automatic passing neutral section method of the train of the present invention;

FIG. 2 is a system diagram of a conventional ground automatic passing neutral section method for a train;

FIG. 3 is a structural diagram of the ground automatic passing neutral section system of the train of the present invention;

FIG. 4 is a resistance-inductance model equivalent circuit for the system of FIG. 3;

FIG. 5 is a system resistance-inductance model equivalent circuit corresponding to each step in the process of passing through the neutral section of the train, wherein, (a) a pre-grid-connection stage, (b) a first power adjustment stage, (c) a voltage pre-modulation stage, (d) a second power adjustment stage, and (e) a neutral section exit standby stage are adopted;

FIG. 6 is an equivalent circuit diagram of a quadruple auxiliary variable current device according to the present invention;

FIG. 7 is an equivalent circuit of the transformer of the present invention, (a) T-type equivalent circuit, (b) Γ -type equivalent circuit, and (c) simplified equivalent circuit;

FIG. 8 is a circuit structure of a transformer based on the principle of equivalent transformation;

FIG. 9 is a diagram of an instantaneous power control algorithm of the grid-connected auxiliary converter after modification in the present invention;

FIG. 10 is a diagram showing the variation of voltage vectors during amplitude-phase modulation according to the present invention;

FIG. 11 is a block diagram of a flexible neutral section passing control system of the grid-connected auxiliary converter according to the present invention;

FIG. 12 is a graph showing the results of an experiment of the method of the present invention;

FIG. 13 is a diagram showing experimental results corresponding to each step in the passing phase separation process of the train according to the present invention;

FIG. 14 is a graph of the results of a comparison experiment of a conventional switching auto-passing phase separation method with the method of the present invention;

FIG. 15 is a graph of the results of a comparison experiment of the single topology method and the method of the present invention;

FIG. 16 is a comparison graph of the frequency domain analysis of the transient process of the neutral zone current of the single topology method and the method of the present invention;

FIG. 17 is a graph showing a comparative analysis of the transient impact of the A/B output current of the power supply arm and the system response speed of the power supply arm A/B output current of the single topology method of the present invention;

FIG. 18 is a diagram of the robustness analysis of the system under variable parameters, variable loads and variable load frequencies.

Detailed Description

As shown in fig. 2, when a train is about to enter a neutral zone, a switch acts to enable a power supply arm a to supply power to the neutral zone; when the train completely enters a neutral zone, the power supply arm B replaces the power supply arm A to supply power to the locomotive after an extremely short dead zone is formed; when the train completely departs from the neutral zone, the switch system is reset to prepare for the next passing of the neutral section.

According to the traditional ground switch automatic passing neutral section method, when a train runs away from a transition area, a contact net containing an inductive element is separated from a pantograph under a high-current environment, so that an arc discharge phenomenon is easily caused, and even the pantograph is burnt. In addition, the electric locomotive with the inductance-resistance load characteristic usually generates surge currents of different degrees under the influence of factors such as voltage residual error, transformer residual magnetism, closing phase angle and the like in the switching process of the neutral section passing circuit, the transient impact influence seriously threatens the safety of a vehicle network system, and meanwhile, the average service life of each line component is reduced.

In order to solve the above problems, the embodiment of the invention discloses a train ground automatic passing neutral section method based on structure improvement and control algorithm optimization, the flow chart of which is shown in fig. 1, the method is applied to a ground automatic passing neutral section system, the system comprises a power supply arm A, a power supply arm B and a quadruple auxiliary converter device, and the train is driven to the power supply arm B from the power supply arm A; the method comprises the following steps:

step1, acquiring the running position of a train, wherein the running position comprises a transition region and an electric isolation region;

step2, determining a power supply for supplying power to the train according to the running position, specifically:

when the train is positioned in the transition region, according to the voltage and the current of the transition region and the parameters of the quadruple auxiliary converter device, determining an output voltage decoupling modulation signal of the quadruple auxiliary converter device in the transition region and an output voltage modulation signal of a power supply arm corresponding to the transition region, and realizing dynamic and smooth transfer of energy when the power supply arm corresponding to the transition region and the quadruple auxiliary converter device supply power to the train;

when the train is positioned in the electrical isolation area, the quadruple auxiliary converter device is used for supplying power to the train, and the voltage amplitude and the phase of the quadruple auxiliary converter device are pre-modulated by taking the voltage of the power supply arm B as a target.

In the embodiment of the present invention, the quadruple auxiliary converter device includes four groups of converter units connected in parallel, each group of converter units includes: the system comprises a step-down transformer, a step-up transformer and a single-phase H-bridge converter;

The determining of the output voltage decoupling modulation signal of the quadruple auxiliary variable current device in the transition region and the output voltage modulation signal of the power supply arm corresponding to the transition region according to the voltage and the current of the transition region and the parameters of the quadruple auxiliary variable current device specifically includes:

acquiring voltage and current of a transition region, and determining instantaneous active power, instantaneous reactive power and d-axis voltage fundamental component of the transition region in a d-q coordinate system according to the voltage and the current;

obtaining parameters of a quadruple auxiliary converter, wherein the parameters comprise a given output active power value and a given output reactive power value;

determining an output voltage decoupling modulation signal of a quadruple auxiliary converter device in the transition region according to the instantaneous active power, the instantaneous reactive power, the d-axis voltage fundamental component, the output active power given value and the output reactive power given value of the transition region;

and determining the output voltage modulation signal of the power supply arm corresponding to the transition region according to the output voltage decoupling modulation signal of the quadruple auxiliary current transformer.

where P is the instantaneous active power of the transition region, Q is the instantaneous reactive power of the transition region, u _d And u _q Voltage components i of the voltage u in the transition region on the d-axis and the q-axis, respectively _d And i _q The current components of the current i in the transition region in the d-axis and q-axis, respectively.

In the embodiment of the present invention, determining an output voltage decoupling modulation signal of a quadruple auxiliary converter device in a transition region specifically includes:

determining an output voltage decoupling modulation signal of the quadruple auxiliary current transformer in the transition region according to a second formula, wherein the second formula is as follows:

in the formula u _abd "and u _abq "is the output voltage of quadruple auxiliary current transformer on d axis and q axis, K _PP K and K _PI Respectively representing the proportional and integral coefficients, K, of the active PI regulator _QP ' and K _QI ' respectively represents the proportional and integral coefficients of the reactive PI regulator; p _c ^* And Q _c ^* Respectively represents the given value of the output active power and the given value of the output reactive power of the quadruple auxiliary converter device, P _c And Q _c Respectively instantaneous active power and instantaneous reactive power of the transition region, wherein P and Q are instantaneous calculated values (formula theoretical values) of power, P _c And Q _c The instantaneous value of the output power of the neutral area network is obtained when the instantaneous power calculation theory is applied to the condition of excessive phase separation. P and P _C Values and meanings are the same, Q and Q _C Is the same as the meaning, S is the input variable of the original formula after Laplace transform, u is the input variable of the original formula _ds "and u _qs Determined according to a third formula:

where k is the transformation ratio of the primary winding and the secondary winding of the step-up transformer, and u is _m The fundamental wave amplitude of the voltage in the transition region, P and Q are the instantaneous active power and the instantaneous reactive power, omega, respectively _s Is the voltage angular frequency, R, of the transition region _eq And L _eq Determined according to a fourth formula:

in the formula, L _c And R _c Respectively representing the equivalent inductance and the equivalent resistance, L, of a quadruple auxiliary converter _f And R _f Respectively representing the equivalent inductance and resistance, L, of the filter circuit _s And R _s Respectively representing equivalent inductance and equivalent resistance of the transition region, n is the parallel connection multiple number of the submodules, and k is the transformation ratio of a primary winding and a secondary winding of the booster transformer.

The pre-modulating the voltage amplitude and the phase of the quadruple auxiliary current transformer by using the voltage of the power supply arm B as the target specifically comprises:

in the formula u _s In order to pre-modulate the voltage,

voltage u of supply arm a _A Is in phase (4)>

Voltage u for supply arm B _B Phase of (1), U _A And U _B Are respectively a voltage u _A And voltage u _B T is time, Δ t is time interval, f ₀ The frequencies of supply arm a and supply arm B.

correspondingly, when the train is positioned in the transition area, according to the voltage and the current of the transition area and the parameters of the quadruple auxiliary converter device, determining an output voltage decoupling modulation signal of the quadruple auxiliary converter device in the transition area and an output voltage modulation signal of the power supply arm corresponding to the transition area, and realizing dynamic and smooth transfer of energy when the power supply arm corresponding to the transition area and the quadruple auxiliary converter device supply power to the train, specifically:

when the train is positioned in the transition area A, according to the voltage and the current of the transition area A and the parameters of the quadruple auxiliary converter, determining an output voltage decoupling modulation signal of the quadruple auxiliary converter and an output voltage modulation signal of the power supply arm A in the transition area A, so that the quadruple auxiliary converter gradually replaces the power supply arm A to supply power to the train;

when the train is located in the transition area B, according to the voltage and the current of the transition area B and the parameters of the premodulated quadruple auxiliary converter device, an output voltage decoupling modulation signal of the quadruple auxiliary converter device in the transition area B and an output voltage modulation signal of the power supply arm B are determined, so that the power supply arm B replaces the quadruple auxiliary converter device step by step to supply power to the train.

the ground position identification unit is used for acquiring the running position of the train and sending the running position to the power regulation unit, wherein the running position comprises a transition area A, an electrical isolation area and a transition area B;

the power regulating unit comprises a power supply arm A, a power supply arm B, a quadruple auxiliary converter device and a circuit breaker, and is used for realizing dynamic and smooth transfer of energy between adjacent power supply arms and a neutral zone and flexible switching of voltage;

the converter comprises four groups of converter units connected in parallel, wherein each group of converter units comprises: the system comprises a step-down transformer, a step-up transformer and a single-phase H-bridge converter;

The third aspect of the invention discloses a terminal device, which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the computer program to realize the steps of the train ground automatic passing phase separation method.

In a fourth aspect of the present invention, a computer readable storage medium is disclosed, wherein a computer program is stored in the computer readable storage medium, and when the computer program is executed by a processor, the steps of the above-mentioned train ground automatic passing neutral section method are realized.

The ground automatic neutral-section passing system and method for the train proposed by the present invention will be described in detail below.

The structure schematic diagram of the train ground automatic passing neutral section system is shown in figure 3. The system comprises three main parts, namely a neutral area quadruple auxiliary converter device (hereinafter referred to as an auxiliary converter), a track circuit auxiliary device and an electric locomotive load. Wherein the neutral section is divided into two transition areas A/B and an electrical isolation area, QF ₁ 、QF ₂ The main circuit breaker is used for realizing the switching of the power supply arm; t is ₁ 、T ₂ The matching transformer is used for realizing quadruple parallel expansion of each single submodule; t is ₃ The secondary side is a synthesized output winding and is used for guaranteeing the driving capability of the single module; p is ₁ ～P ₅ The ground position sensor is used for realizing the real-time positioning of the train.

The voltage in the neutral zone is quantitatively controlled by adopting an auxiliary converter, and train position information acquired by an auxiliary ground sensor is matched with the opening and closing of a main breaker, so that the voltage in the neutral zone can be in a transition section (P) ₂ And P ₄ ) The smooth transfer of the system supply energy between the adjacent power supply arm and the neutral zone is realized; while in electrically isolated sections (P) ₃ ) Realizing adjacent power supply arm A/B voltage u _A And u _B The flexible switching between the two modes is realized through power and voltage matching control, so that the problem of train speed loss caused by power failure or degraded operation is avoided while the influence of transient impact is restrained.

For convenient quantitative analysis, the output voltages of the power supply arm A/B and the auxiliary converter and the equivalent resistance-inductance loads of the line and the locomotive are taken as quantitative parameters, the system shown in FIG. 3 is subjected to equivalent conversion, and the equivalent resistance-inductance model of the passing neutral section system shown in FIG. 4 can be obtainedAn electrical circuit. Wherein, K ₁ ～K ₃ The equivalent switch is used for simulating a dynamic passing neutral section process; u. of _ab 、u _A And u _B Respectively representing the output voltages of the auxiliary converter and the tail end of the power supply arm A/B; r _i And X _i Respectively, the equivalent resistance and reactance of the line or locomotive load (i = a, B, C or L; in turn representing the supply arm a/B, the neutral line and the locomotive load).

As analyzed with reference to fig. 3 and 4, assuming that the train moves from the power supply arm a to the power supply arm B in a single-bow mode (a → B), the system operation process can be roughly divided into the following 5 steps according to the electric quantity control requirement of the train operation position and the corresponding time period. By controlling K ₁ K to simulate real-time switching of circuit topology, 5-step equivalent circuits of resistance-inductance model are obtained as shown in (a) to (e) of FIG. 5, where u is close to _ab The dashed box on the side represents the supply loop of the auxiliary converter, close to u _A The dotted line of (c) represents the supply loop of the supply arm A, close to u _B The dashed box represents the supply loop of the supply arm B.

(1) Step1: and a pre-grid connection stage. When the train is about to enter the neutral section (P) as analyzed in conjunction with FIGS. 3 and 4 ₁ )，QF ₁ Closed, QF ₂ The state is disconnected and maintained, and the auxiliary converter is controlled to ensure that when the train drives into a neutral zone, u _A And u all have the same amplitude and phase. Closed K ₁ ，K ₂ Opening K ₃ The equivalent circuit of the pre-networking stage is shown in fig. 5 (a), and the locomotive is independently powered by the power supply arm A (P) _A ＝P _L ，Q _A ＝Q _L ，P _A Active power, Q, for supply arm A _A Reactive power, P, for the supply arm A _L Active power, Q, for train loads _L Reactive power for train load), the output power of the auxiliary converter is approximately equal to 0 (P) _C ＝Q _C ≈0，P _C For assisting the output active power, Q, of the converter _C To the output reactive power of the auxiliary converter).

(2) Step2: a first power adjustment phase. With reference to figure 3 of the drawings,when the train enters the transition area A (P) ₂ ) The power supply arm is suspended in parallel with the neutral section, and the locomotive pantograph is simultaneously connected across two lines in the area, and the equivalent circuit is shown as (b) in fig. 5. In order to avoid bow-net arcs when the train leaves the transition zone, the alternating transfer of the supply energy must be carried out in step2, i.e. the output power P driving the auxiliary converter follows the set value P by the slope k _P Linearly increasing to the rated power value of the locomotive, and under the premise of keeping the voltage of the load end unchanged, the output power P of the power supply arm A _A Will be given a value of-k _P Passively decreases to near 0. And the rated operating power of the locomotive remains substantially unchanged during this energy transfer.

(3) Step3: a voltage pre-modulation stage. When the train completely enters the electric isolation area (P) ₃ )，QF ₁ And QF ₂ The state is switched on and the equivalent circuit is shown as (c) in fig. 5. Due to u _A And u _B There is usually a certain difference between them, so u (u = u) needs to be controlled _A ) By u _B The target is dynamically modulated. The flexible switching of the voltage avoids the short circuit and the electric impact influence caused by voltage residual.

(4) Step4: and a second power adjustment stage. After the train enters the transition zone B (P) ₄ ) The equivalent circuit is shown in fig. 5 (d). The transfer trend of the supplied energy is symmetrical to the first power adjustment stage, and the analysis method is just like step 2.

(5) Step5: and (4) a phase separation standby stage. After the train has completely moved out of the neutral zone (P) ₅ )，QF ₁ And QF ₂ Are open and the equivalent circuit is shown in fig. 5 (e). When the train enters the section B of the power supply arm, the system is reset and waits for the next train passing through the split-phase operation.

The control algorithm used in the above step2 and step4 is specifically:

the input end of the single-phase H-bridge converter is a four-quadrant pulse rectifying circuit matched with the step-down transformer, and the input end of the single-phase H-bridge converter is mainly used for providing a stable direct current source for the inverting input end. The invention adopts a transient current control algorithm and realizes the voltage-stabilizing output function at the direct current side based on the feedforward control strategy of voltage and current double closed loops.

1.1 instantaneous Power control of grid-connected auxiliary Converters

1.1.1 equivalent decoupling mathematical model of grid-connected auxiliary converter

The non-periodic variation rule of the electric quantity in the transient process enables the traditional average power control algorithm not to be applicable to the over-phase condition any more, so the decoupling type transient power improvement control algorithm applicable to the parallel quadruple inverter circuit structure is provided on the basis of the transient power control algorithm by combining with the transformer coupling topological structure. The auxiliary converter is considered as a whole (including the transformer), and the equivalent circuit of the combined system is shown in fig. 6. Wherein u is _ab Is the output voltage of the grid-connected auxiliary converter; l is _C And R _C Respectively representing the equivalent inductance and resistance of the circuit; u and i represent neutral zone grid voltage and current, respectively.

From KVL

Let u and i have fundamental amplitude u _m And i _m ，

Is the power factor angle. To facilitate the decoupling control, the fundamental components of u and i in the synchronously rotating d-q coordinate system are obtained as follows.

u＝u _m sin(ω _s t) (2)

Wherein

In the same way, u _ab Can be decoupled as

Wherein

In the formula (I), the compound is shown in the specification,

is u _ab Angle, omega, with voltage u at the grid connection _s Is the grid-connected voltage angular frequency.

Substituting the formulas (2), (3) and (5) into the formula (1) and obtaining the final product based on the differential partial derivative algorithm

The formula (7) contains sin (omega) _s t)) and cos (ω) _s And t) separating and simplifying the items, and obtaining a decoupling mathematical model of the grid-connected auxiliary converter system as follows.

1.1.2 mathematical model correction based on coupling transformer equivalent circuit

In the auxiliary converter devices of the parallel structure, the control object of the algorithm must be specific to each single submodule circuit. Therefore, based on the research method in the previous section with the combined converter system as the target, the influence of the matching transformer on the circuit structure and the control algorithm must be further considered, and the algorithm is further modified accordingly. It is worth pointing out that, inside the auxiliary converter device, the output voltages of the submodules connected in parallel are the same, the total output current of the system is the sum of the output currents of the submodules, and the control algorithms of the submodules are completely consistent. Therefore, on the premise of satisfying the correction of the current superposition multiple n (ideally, n is equal to the circuit weight), the equivalent circuit analysis method and the decoupling mathematical model represented by fig. 6 and the formula (8) are also suitable for the single topology circuit with the transformer.

For the convenience of mathematical analysis, equivalent transformation is required to be performed on the transformer module. Setting transformer primary winding (N) ₁ ) Secondary winding (N) ₂ ) Has a transformation ratio of k, E ₂ "and I ₂ Respectively converting the secondary side winding into the equivalent voltage value and the equivalent current value of the primary side, the following equivalent relation should be satisfied

According to the principle of invariance of copper loss and the principles of invariance of magnetic leakage and reactive loss of the primary winding and the secondary winding before and after conversion, the equivalent conversion relations of resistance, reactance and impedance of the secondary winding can be respectively obtained as follows

From the conversion result, a T-type equivalent circuit of the transformer is obtained as shown in (a) of FIG. 7, in which X is _m 、R _m And Z _L "is the excitation reactance, excitation resistance and load impedance of the transformer, respectively. Moving the excitation branch to the left to the power supply end, the Γ -type equivalent circuit of the transformer can be further obtained as shown in (b) of fig. 7.

In general, i is usually satisfied in a Γ -type equivalent circuit ₀ <<i ₁ Therefore, the influence of the excitation branch can be ignored, resulting in a simplified equivalent circuit as shown in (c) in fig. 7. For convenience of illustration, the resistance-inductance series elements indicated by the broken lines in (c) of fig. 7 are combined as follows

A simplified equivalent circuit of the transformer indicated by a solid line in (c) in fig. 7 can be obtained.

Combining the above equivalent principles, one can use the graph of FIG. 8The single converter grid-connected model circuit shown in (a) of (a) is converted into a simplified equivalent circuit shown in (b) of fig. 8. Wherein L is _f 、R _f Respectively representing equivalent resistance and inductance of the filter circuit; u. of _ab And' is the inversion output voltage corrected by the algorithm. In order to simplify the analysis, the research only considers the inductance resistance characteristic of the line, so that the reactance value only needs to analyze the inductance parameter.

The transformer equivalent circuit included in the dashed line frame in (b) of fig. 8 should satisfy the following relationship

Wherein n is the number of parallel connection multiples of the submodules, and is used for correcting the current value of the single circuit (in the invention, n = 4). Referring to the analysis methods in sections (b) and 1.1.1 of FIG. 8, u can be established _ab ' and u _ab Is as follows

From (a) in FIG. 8, it can be seen

The system-level decoupling mathematical model expressed by the equation (8) is corrected in consideration of k and n, and the corrected decoupling mathematical model obtained by the equations (9) to (14) is as follows

For convenience of presentation, the following definitions are made

The decoupling mathematical model of the grid-connected auxiliary converter corrected based on the transformer equivalent transformation principle can be obtained as follows:

1.1.3 instantaneous power calculation for grid-connected auxiliary converter

In the d-q coordinate system, the instantaneous power of the single-phase system is only 1/3 of that of the three-phase system. So that the expressions of instantaneous active and reactive power can be obtained as follows

Positioning the d-axis to the u position has

Substitution of formula (19) into (18) gives

Simple mathematical processing is carried out on the expression of i and u to obtain

Based on equation (21), u, i and u can be established by filtering out the high frequency component with a low pass filter _m 、i _m Thereby realizing the calculation of the instantaneous power.

Multiplying both ends of the formula (17) by u _m Can obtain the product

By bringing the formula (20) into (22)

For convenience of presentation, the following definitions are made

By bringing formula (24) into (23)

The formula (25) is converted into a PI control form as follows

Wherein, K _PP `、K _PI ' and K _QP `、K _QI Respectively representing the proportional and integral coefficients of the active PI regulator and the reactive PI regulator; p _c * And Q _c * Respectively representing the given values of the active power and the reactive power output by the auxiliary converter. In summary, a modified instantaneous power control algorithm block diagram of the grid-connected auxiliary converter is shown in fig. 9.

As shown in fig. 9, the feedback values P of the output power of u and i fed back in real time from the neutral region grid-connected position are calculated by the instantaneous power module _c 、Q _c And d-axis voltage fundamental component u _m In combination with P _c *、Q _c * As an input to the instantaneous power decoupling module. Meanwhile, parameter correction is carried out on the decoupling algorithm through introducing k and n transformer equivalent transformation correction modules to obtain an output voltage decoupling modulation signal u of the grid-connected auxiliary converter _abd "and u _abq Then, a modulation signal u of the SPWM module under a three-phase coordinate system is obtained through coordinate transformation _A And controlling inversion output, and finally achieving the aim of instantaneous power dynamic regulation.

1.2 Voltage amplitude-phase modulation

The invention adopts a voltage pre-modulation algorithm to realize u _A And u _B Flexible switching of (3). Neutral section reference voltage u _s Is defined as follows

u _s ＝U _s sin(ω ₁ t) (27)

Let u _A/B Are all at a frequency of f ₀ Changing u during the voltage premodulation phase _s Has a frequency of f ₁ Then Δ f will be converted to u via Δ t accumulation _A And u _B Phase difference between

While taking the voltage amplitude difference into consideration, it can be obtained from equation (27)

Equation (28) is u in the voltage pre-modulation process _s Applied to Step3: a voltage pre-modulation stage. u. of _s The vector regulation process is shown in fig. 10.

In step3, u is _B The voltage reference value is input, and flexible switching and smooth transition of the amplitude and the phase of the neutral region voltage can be realized.

In summary, by combining the corrected instantaneous power decoupling control algorithm and the voltage premodulation algorithm, the flexible passing neutral-section control system of the grid-connected auxiliary converter can be obtained as shown in fig. 11.

2 test verification

The proposed circuit is tested by simulating the automatic neutral section passing operation of the train in the neutral zone. Based on an MATLAB/Simulink simulation experiment platform, a dynamic switching process of an equivalent circuit is simulated through a switch logic circuit, and the method is verified in the following aspects:

(1) Verifying the feasibility of the method;

(2) Compared with the prior method, the optimization effect is verified in a comparison mode;

(3) And (5) verifying the robustness of the system.

The circuit key parameter settings are shown in table 1, and for simplicity of analysis, the locomotive load (7800 kW) was replaced with an equivalent resistive-inductive load, and the carrier frequency of the inverter was 3.75kHz.

TABLE 1 Key parameters in an Autopassing neutral System

The speed of the train passing through the neutral section is 160km/h, the total length of the neutral section is about 230m, the two transition sections respectively occupy 75m, and the electrically isolated section occupies about 80m. The timing of each operating phase is shown in table 2. Wherein, T _A/B And E _I Respectively representing transition regions a/B and electrically isolated regions.

TABLE 2 timing of various operating phases of the Autopassing neutral section System

2.1 method feasibility verification

Based on the circuit key parameters and the train dynamic operation time sequence in tables 1 and 2, referring to the flexible neutral-section passing process (a → B) shown in fig. 3, the experimental results of the main electrical parameters can be obtained as shown in fig. 12.

As shown in fig. 12 (a), U _dc Jump and fall quickly at 0.1s, and the whole process is stabilized at about 1.8kV, which shows that the transient current control algorithm has better direct current voltage stabilization capability.

i、i _A&B And i _L Waveforms of (c) are shown in (b) to (d) of fig. 11. Because the rated value of the voltage of the load end is clamped at about 25kV by the power supply arm, the output power of each module is in direct proportion to the current change, and under the mutual cooperation of the active adjustment of the output power of the converter and the passive change of the output power of the power supply arm, the smooth dynamic transfer of the supply energy between two adjacent power supply arms and a neutral zone is realized, and the problems of overvoltage and overcurrent impact generated by bow net electric arc are effectively solved. The power dynamics situation is shown in (e) of fig. 12, which includes the output active power P of the auxiliary converter and a given reference value P, corresponding to the output active power P of the auxiliary converterAs can be seen from the partial enlarged views of the three waveforms from step2 to step4, P can quickly respond to the change of P in two power adjustment stages, and can be stably kept at about 7800kW in the voltage pre-modulation stage, so that the rated operation condition of the train in a neutral zone is ensured.

On the basis of the qualitative analysis, the preset function of the method is further verified from the perspective of quantitative analysis. Referring to the equivalent circuit in fig. 5, the experimental results corresponding to step1 to step5 are shown in fig. 13. Wherein, device output current represents i, supply arm A output current represents i _A Load current represents i _L . As shown in (a) of FIG. 13, u is expressed as u within 0.1s to 0.6s _A The train is independently powered by a power supply arm A for modulation of the reference value. After 0.6s, the train enters a neutral zone, and due to the voltage matching effect of pre-grid modulation, i does not have a large jump phenomenon, and recovers to a normal value close to 0A again only after a plurality of periods of small fluctuation, so that the current impact influence on the train when entering a phase splitting zone is effectively inhibited. As shown in FIG. 13 (b), i linearly increases at a rate of 400A/s as P changes within 1s to 2s, since i _L The rated value at 410A is basically kept unchanged, so i _A The decrease is passively linear with a change in P, at a rate of about-395A/s. At the end of step2, a smooth transfer of the load current supply from the supply arm a to the auxiliary converter can be substantially completed. When the train leaves the transition area A at 2.3s, i is approximately equal to i _L ，i _A Approaching 0, at which point the parallel suspended pantograph system begins to separate, but due to i _A The value of (a) is extremely low (≈ 0A), and thus generation of bow-net arc is maximally avoided. As shown in fig. 13 (c), the three partial enlarged views correspond to voltage waveforms at timings of 2.7s, 3.2s, and 3.7s in order from left to right. In the range of 2.7s to 3.7s, u gradually changes from u _A Flexible switching to u _B (25 kV/0 ° → 26kV/60 °), at the end of step3, the amplitude and phase of u and u _B Basically, it is identical, this has avoided the short circuit that voltage residual error brought and transient state impact problem effectively. As shown in fig. 13 (d), the train enters the transition zone B after 4.1s, the pantograph system enters the parallel suspension state again, and the voltage pre-adjustment is completedOn the premise of system i _B The phenomenon of large-amplitude jump is not generated, the small value which is close to 0A is quickly recovered only after a plurality of small transient fluctuations, and meanwhile, i is kept in stable transition, and the phenomenon of large-amplitude fall is not generated. Within 4.4 s-5.4 s, the current change law is symmetrical to step2, i is linearly reduced to be close to 0 at the rate of-405A/s _B Then the current is increased linearly to 410A at a rate of 400A/s to preset a safe current environment for the second bow net separation process.

As shown in fig. 13 (e), the pantograph leaves the neutral zone at 5.8s, i _B Is approximately equal to i _L And i approaches to 0, the train is independently powered by the power supply arm B, and the bow net system realizes safe separation. The passing neutral section system is reset within 5.8-6.4 s to prepare for the next passing neutral section operation of the train.

The experimental results show that the method provided by the invention is identical with theoretical analysis, can realize a preset function, inhibit transient impact influence and guarantee safe and efficient passing neutral section operation of a train.

2.2 comparison of optimization results with existing methods

Under the same experimental conditions, the method is compared with the two existing main excessive phase separation methods through transverse tests, and the superiority of the method in the aspects of suppressing transient impact influence, improving system response speed and accuracy and the like is verified.

2.2.1 comparative experiment with conventional automatic switching over phase scheme

Referring to fig. 2, in the conventional switching auto-passing neutral mode, the neutral zone and the supply arm current i _switch And i _{switch_A&B} Waveforms (c) are shown in fig. 14 (a) and (b), respectively. Since such schemes do not have power and voltage regulation functions, i is the time of circuit switching _switch And i _{switch_A&B} A transient sudden change (jump or fall) occurs which will have a severe impact on the pantograph system. The results of the comparative experiments are shown in (c) to (e) of FIG. 14, in which the solid curve with a larger amplitude and the solid curve with a smaller amplitude represent i and i, respectively _A&B The dotted lines each represent i _switch And i _{switch_A&B} . As shown in (c) and (e) of FIG. 14, when step2 and step4 are completed, i is _switch And i _{switch_A&B} The arc discharge phenomenon is generated in the pantograph system under the high-current environment at the two pantograph separation times corresponding to 2.3s and 5.8s because the arc discharge phenomenon is kept in the numerical range of 200A-300A. In addition, referring to (d) of fig. 14, the direct voltage switching operation of the switching neutral-section system at 3s will cause a transient serious distortion of the voltage and current waveforms.

From the above experimental results, it can be seen that the proposed method has its incomparable advantages in suppressing the effects of bow net arcing and transient impact compared to the conventional switching over-phasing method.

2.2.2 comparative experiments with the Single topology protocol

The existing single topology scheme is limited by the structure and has the limitations of small circuit capacity, insufficient output driving capability and the like. The results of the comparative experiments are shown in FIGS. 15 to 17. The waveforms of i and P are shown in (a) and (b) of fig. 15, and it can be seen from the comparison of the current waveforms that the output driving capability and the response speed of the circuit of the single topology scheme are obviously lower than those of the method provided by the present invention, and in addition, the disturbance resistance of the single topology scheme is poor, and the output current i of the single topology scheme is output _s And power P _s Obvious fluctuation exists in the circuit switching process, especially when a 4.1s pantograph system is secondarily connected to the power grid _s And P _s A large drop occurred. As shown in (b) and (d) of fig. 15, the single topology scheme is P at the time of grid connection _s Fall values of [ delta ] DSP (≈ 6600 k) and [ I ] _s The falling values Δ DSI (142) are much larger than the falling values Δ DQP (1100 k) and Δ DQI (30) of the method of the invention. As shown in (c) of fig. 15, since the output value of the single topology is greatly dropped during grid connection, i is also increased _s Degree of transient distortion.

In fig. 15 (c), i is paired in 3 system cycles (4.1 s to 4.16 s) after the secondary grid connection _s And performing fast Fourier analysis on the transient waveform of the sum i to obtain i _s The results of the frequency domain analysis of i and i are shown in fig. 16 (a) and (b), respectively. As can be seen from the above, it is shown that,i _s the total harmonic distortion rate THD of (a) reaches 56.18%, whereas the THD value of i is only 8.88%, which is much lower than the waveform distortion rate of the single topology solution. Furthermore, as can be seen from the partial enlargement of the transient waveform, the transient recovery period of i is also much shorter than i _s The recovery period of (1).

Similarly, the results of the comparative experiment of the output currents of the power supply arms A/B are shown in FIG. 17, in which the two curves represent i _A/B And i _AS/BS And I is the effective value of the current. As can be seen from (a) in fig. 17, at the time of 4.1s grid connection, i _BS Reaches 0.88s, and i _B Is only 0.58s, and furthermore, as can be seen from the partial enlargement, i _B Is also much lower than i _BS . Similar to the analysis method of the neutral zone current, it can be seen from (b) in fig. 17 that I is at the time of 4.1s grid connection _BS The jump value delta RSI (approximatively 360) is also much larger than I _B The jump value Δ RQI (≈ 50). In addition, as can be seen from (a), (c) and (d) in fig. 17, the parameter control precision and the system dynamic response capability of the method provided by the invention are both significantly better than those of the single topology scheme.

The comparison and analysis results are combined, so that compared with a single-topology scheme, the method provided by the invention has obvious improvement effects in the aspects of improving circuit capacity and output driving capability, preventing transient impact and drop, shortening transient recovery time, improving system control accuracy and dynamic response speed and the like.

2.3 System robustness analysis

To highlight the engineering practice of the method of the present invention, u will be given in this section _A/B The phase difference and the amplitude difference, the converter carrier frequency and the locomotive rated operating power are research objects, and the anti-interference capability of the method is comprehensively tested and verified in the aspects of line conditions, circuit parameters and load level.

(1) And the capability of resisting voltage phase difference fluctuation. Set u _A Has the parameters of 25kV/0 degrees and fixed u _B Is 26kV, the phases of the three are sequentially set to 60 degrees, 75 degrees, 90 degrees and 120 degrees, and i under the condition of different phases are obtained _A&B The waveform of (a) is shown in fig. 18. After 2.7s, a slight difference in current value occurred under different conditions, and a maximum fluctuation value occurred when the phase difference was 90 °. However, through comparative analysis, the method provided by the invention has better current regulation and dynamic response capabilities under the condition of lines with different voltage phase differences.

(2) And the capability of resisting voltage amplitude difference fluctuation. The same experiment method as in (1) was used. Set u _A Has a parameter of 25kV/0 DEG, fixed u _B Was 60 °, and the rated values thereof were set to 26kV, 27kV, 28kV, and 29kV in this order, and the experimental results under different conditions were obtained as shown in (b) of fig. 18. It can be seen that as the voltage amplitude modulation range is gradually increased, the fluctuation range of the current at the grid-connected moment is also increased, and reaches the maximum value at 29 kV. However, compared with the large fluctuation situation in the single topology scheme, the fluctuation range does not cause great impact on the pantograph system, and the transient fluctuation amplitude can be recovered to a normal value in a very short time, so that the influence on the subsequent second power adjustment is small. The experimental results of the sections (1) and (2) show that the method provided by the invention is suitable for the condition of passing through neutral section of the train with different line conditions.

(3) Resistance to load fluctuations. The load rated powers of the locomotives were adjusted to 7200kW, 7800kW, and 8400kW in sequence while keeping the initial line conditions unchanged, and the experimental results under different load conditions are shown in (c) of fig. 18. 7200kW corresponds to a local maximum range of current fluctuations. When the system outputs in a steady state, i increases along with the increase of P; in the dynamic P transfer process, i can still respond to feedback change quickly and accurately. Experimental results show that the method provided by the invention is suitable for the situation of passing through the neutral section of the train with different load levels.

(4) Carrier frequency ripple immunity. While the initial conditions of the line and the load were kept constant, the carrier frequencies of the auxiliary inverter were changed to 2kHz, 3kHz, 3.75kHz, and 5kHz in this order, and the experimental results under different carrier conditions are shown in (d) of fig. 18. The maximum time of the current fluctuation corresponding to 3kHz shows that the method provided by the invention is suitable for the passing split-phase auxiliary variable current circuit with different carrier frequencies from the high fitting degree of each waveform.

The experimental results comprehensively verify that the method provided by the invention has strong capacity of resisting line conditions, circuit parameters and load level disturbance, can be suitable for ground automatic neutral section passing situations under different conditions, and has strong robustness.

The invention innovatively explores an automatic train ground passing neutral section method, deeply analyzes the working principle of a single H-bridge converter and the coupling mechanism between a plurality of sub-modules and a matching transformer in a traction power supply system, improves and optimizes the topological structure and the control algorithm of a converter device on the basis, and provides the automatic train ground passing neutral section improving method based on a transient power and voltage amplitude phase regulation and control algorithm.

The method adopts four single-phase H-bridge converters and a matching transformer to be connected in parallel to form a combined auxiliary converter device, and introduces the transformer equivalent conversion principle to correct the instantaneous power regulation and control algorithm on the basis of improvement of a quadruple structure. On one hand, by controlling smooth dynamic transfer of supplied energy between two adjacent power supply arms and a neutral zone, a safe current environment is provided for pantograph and catenary separation operation, and overvoltage and overcurrent impact influence of pantograph and catenary electric arcs on a car net system is effectively avoided. On the other hand, through the pre-regulation and control of the amplitude and the phase of the neutral zone voltage, the flexible switching of the voltage between the adjacent power supply arms is realized, and the short circuit and transient impact influence caused by the direct switching of the voltage are effectively avoided and restrained. In addition, the alternate transfer of power ensures the rated operation condition of the locomotive, reduces the speed loss of the train and effectively improves the railway operation efficiency. Compared with the existing automatic switch neutral section passing method, the method provided by the invention has incomparable advantages in the aspects of inhibiting arc net arc, preventing electric quantity mutation and the like. Compared with a single-topology scheme, the method provided by the invention can effectively inhibit transient impact influence, shorten the duration time of a transient process and reduce the transient waveform distortion rate, and is obviously superior to the single-topology scheme in the aspects of improving circuit capacity and system response speed and precision. Finally, the correctness, feasibility and robustness of the method are comprehensively verified from the two aspects of performance advantage and anti-interference capability of the method through an MATLAB/Simulink all-digital simulation experiment platform.

Claims

1. The ground automatic passing neutral section method of the train is characterized by being applied to a ground automatic passing neutral section system, wherein the system comprises a power supply arm A, a power supply arm B and a quadruple auxiliary converter device, the power supply arm A, the power supply arm B and the quadruple auxiliary converter device are used for supplying power to the train, the quadruple auxiliary converter device comprises four groups of converter units connected in parallel, and each group of converter units comprises: the system comprises a step-down transformer, a step-up transformer and a single-phase H-bridge converter; the input end of the single-phase H-bridge converter is coupled with the step-down transformer, the output end of the single-phase H-bridge converter is coupled with the step-up transformer, and the train runs from a power supply arm A to a power supply arm B; the method comprises the following steps:

when the train is located in the transition region, according to the voltage and the current of the transition region and the parameters of the quadruple auxiliary converter device, determining an output voltage decoupling modulation signal of the quadruple auxiliary converter device and an output voltage modulation signal of a power supply arm corresponding to the transition region in the transition region, and realizing dynamic and smooth transfer of energy when the power supply arm corresponding to the transition region and the quadruple auxiliary converter device supply power to the train;

when the train is located in the electric isolation area, the quadruple auxiliary converter device is used for supplying power to the train, and the voltage amplitude and the phase of the quadruple auxiliary converter device are pre-modulated by taking the voltage of the power supply arm B as a target;

the determining of the output voltage decoupling modulation signal of the quadruple auxiliary converter device in the transition region specifically includes:

in the formula u _abd "and u _abq Is the output voltage of the quadruple auxiliary current transformer on the d axis and the q axis respectively, K _PP ' and K _PI Respectively representing the proportional and integral coefficients, K, of the active PI regulator _QP K and K _QI ' respectively represents the proportional and integral coefficients of the reactive PI regulator; p is _c ^* And Q _c ^* Respectively representing the given value of the output active power and the given value of the output reactive power of the quadruple auxiliary converter device, wherein P and Q are respectively the instantaneous active power and the instantaneous reactive power of the transition region, u _ds "and u _qs Determined from a third formula:

where k is the transformation ratio of the primary winding and the secondary winding of the step-up transformer, u _m Is the fundamental amplitude of the voltage in the transition zone, P and Q being the instantaneous active power in the transition zone and the instantaneous reactive power, ω, in the transition zone, respectively _s Is the voltage angular frequency, R, of the transition region _eq And L _eq Determined according to a fourth formula, which is:

2. The method as claimed in claim 1, wherein the determining, according to the voltage and the current in the transition region and the parameters of the quadruple auxiliary variable current device, the output voltage decoupling modulation signal of the quadruple auxiliary variable current device and the output voltage modulation signal of the power supply arm corresponding to the transition region in the transition region specifically includes:

3. The method according to claim 2, characterized in that the instantaneous active power, the instantaneous reactive power and the d-axis voltage fundamental component of the transition zone in the d-q coordinate system are determined from the voltage and the current, in particular:

determining instantaneous active power and instantaneous reactive power of the transition region under a d-q coordinate system according to a first formula, wherein the first formula is as follows:

4. A method according to any of claims 1-3, characterized in that said voltage amplitude and phase of said quadruple auxiliary variable current device is pre-modulated with respect to the voltage of said supply arm B, in particular:

in the formula u _s In order to pre-modulate the voltage,

for the voltage u of the supply arm A _A Is in phase (4)>

To the voltage u of the supply arm B _B Phase of (1), U _A And U _B Are respectively a voltage u _A And voltage u _B T is time, Δ t is time interval, f ₀ The frequencies of supply arm a and supply arm B.

5. The method of claim 1, wherein said transition region comprises transition region a and transition region B on either side of said electrically isolated region;

when the train is located in the transition area A, according to the voltage and the current of the transition area A and the parameters of the quadruple auxiliary converter device, determining an output voltage decoupling modulation signal of the quadruple auxiliary converter device and an output voltage modulation signal of the power supply arm A in the transition area A, and enabling the quadruple auxiliary converter device to gradually replace the power supply arm A to supply power to the train;

6. An automatic neutral section passing system for a train ground, the system comprising:

the train power control device comprises a ground position identification unit, a power regulation unit and a control unit, wherein the ground position identification unit is used for acquiring the running position of a train and sending the running position of the train to the power regulation unit, and the running position comprises a transition area A, an electrical isolation area and a transition area B;

the quadruple auxiliary converter device comprises four groups of converter units connected in parallel, and each group of converter units comprises: the system comprises a step-down transformer, a step-up transformer and a single-phase H-bridge converter;

the circuit breaker comprises a first circuit breaker and a second circuit breaker, the first circuit breaker is used for switching the power supply arm A and the quadruple auxiliary converter device according to the operation position, and the second circuit breaker is used for switching the power supply arm B and the quadruple auxiliary converter device according to the operation position;

the specific working process of the power regulating unit is as follows:

in the formula u _abd "and u _abq Is the output voltage of the quadruple auxiliary current transformer on the d axis and the q axis respectively, K _PP ' and K _PI Respectively representing the proportion and integral coefficient of the active PI regulator, K _QP K and K _QI ' respectively represents the proportional and integral coefficients of the reactive PI regulator; p _c ^* And Q _c ^* Respectively representing the given value of output active power and the given value of output reactive power of the quadruple auxiliary converter device, P and Q are respectively the instantaneous active power and the instantaneous reactive power of the transition region, u _ds "and u _qs "according toDetermining by a third formula:

7. A terminal device comprising a memory, a processor and a computer program stored in said memory and executable on said processor, characterized in that said processor implements the steps of the method according to any of claims 1 to 5 when executing said computer program.

8. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 5.