阅读说明：本技术 一种对钢轨电位进行控制的柔性接地装置 (Flexible grounding device for controlling steel rail potential ) 是由 孟献仪 王浩先 苗金元 张洋 张欢 于 2019-10-29 设计创作，主要内容包括：本发明提供一种对钢轨电位进行控制的柔性接地装置,包括与钢轨电位接地体连接的若干功率模块、对功率模块的工作模式进行分配控制的主控制器,所述主控制器通过电压传感器与钢轨电位接地体连接用于采集钢轨电位数据,钢轨电位的采用柔性控制,摒弃钢轨电位传统的分段控制方法,丰富城轨回流系统柔性接地理论；可以使钢轨电位与杂散电流的综合协同控制,避免各参数独立控制的副作用,实现两者并柜控制；控制方法计及多点钢轨电位的耦合作用影响,避免钢轨电位控制的连锁动作；计及回流系统暂态参数对钢轨电位控制时暂态过电压影响,避免出现误动作闭锁情况,同时,降低了回流系统钢轨电位振荡频率；降低了钢轨电位控制时的功率消耗。(The invention provides a flexible grounding device for controlling the potential of a steel rail, which comprises a plurality of power modules connected with a steel rail potential grounding body and a main controller for distributing and controlling the working modes of the power modules, wherein the main controller is connected with the steel rail potential grounding body through a voltage sensor and is used for acquiring steel rail potential data; the comprehensive cooperative control of the steel rail potential and the stray current can be realized, the side effect of independent control of each parameter is avoided, and the cabinet combination control of the steel rail potential and the stray current is realized; the control method takes the coupling effect influence of multipoint steel rail potential into consideration, and avoids the linkage action of steel rail potential control; transient overvoltage influence of transient parameters of the reflux system on steel rail potential control is calculated, misoperation and locking are avoided, and meanwhile, the oscillation frequency of the steel rail potential of the reflux system is reduced; the power consumption during the control of the rail potential is reduced.)

1. The flexible grounding device is characterized by comprising a plurality of power modules connected with a steel rail potential grounding body and a main controller for performing distribution control on the working modes of the power modules, wherein the main controller is connected with the steel rail potential grounding body through a voltage sensor and is used for acquiring steel rail potential data.

2. The flexible grounding device for controlling the potential of the steel rail as claimed in claim 1, wherein the operation modes of the power module include a constant voltage mode, a constant current control mode and a constant resistance mode.

3. The flexible grounding device for controlling the electric potential of the steel rail as claimed in claim 1, wherein the power module comprises a power-on charging current-limiting resistor, a full-wave rectifier bridge connected with the power-on charging current-limiting resistor, a filter capacitor connected with the full-wave rectifier bridge, a power IGBT connected with the filter capacitor, a freewheeling diode connected with the power IGBT, a power inductor connected with the freewheeling diode, a load capacitor connected with the power inductor, and a load resistor connected with the load capacitor.

4. The flexible grounding device for controlling the steel rail potential of claim 3, wherein the power IGBT, the free-wheeling diode, the power inductor and the load capacitor form a three-way parallel Buck circuit, and the output end of the Buck circuit is connected with a load resistor.

5. The flexible grounding device for controlling the potential of the steel rail as claimed in claim 3, wherein the power-on charging current-limiting resistor is formed by connecting a direct current contactor KM and a power resistor Ri in parallel.

6. The flexible grounding device for controlling the potential of the steel rail as claimed in claim 1, wherein the input maximum current of the power unit modules is 100A, and the power modules are connected into the system in parallel.

7. A flexible earthing device for controlling the rail potential according to claim 6, characterized in that the number of parallel power modules is not more than 8.

8. The flexible grounding device for controlling the steel rail potential of claim 1, wherein the main controller controls the output voltage by PWM, so that the input voltage, the output voltage and the input current can be continuously adjusted.

Technical Field

The invention relates to the technical field of steel rail potential control, in particular to a flexible grounding device for controlling the steel rail potential.

Background

At present, a direct current traction power supply system is generally adopted by urban rail transit lines at home and abroad. The system consists of main equipment such as a traction substation, a traction network and a train, and adopts a power supply mode of return flow of a running rail. The traction substation reduces the voltage of the urban power grid alternating current, rectifies the alternating current into 750V or 1500V direct current, and transmits the direct current to a contact network. The traction current reaches the train through a contact network, and returns to the negative pole of the traction substation through a return system (comprising a running rail, a stray current drainage network, a ground network and the like).

However, in the dc traction power supply system, since the running rail cannot be completely insulated from the ground and has a certain longitudinal resistance, a certain voltage drop is formed on the running rail when the traction current flows back, and a potential difference exists between the running rail and the ground, which is referred to as a rail potential. Therefore, a small amount of current does not return to the negative pole of the traction substation along the traveling return current rail, but flows into a peripheral medium or the ground, and returns to the rail or the negative pole of a rectifier unit of the traction substation through a path with smaller resistance.

The potential rise of the steel rail can endanger the personal safety of passengers and influence the safe operation of trackside equipment. Because the train and the running rail have the same potential, when passengers get on or off the train, if the ground potential of the running rail is too high, the safety of the passengers can be damaged. In addition, the running rail is connected with various trackside equipment, such as a shielding door, a switch machine and the like, and when the potential of the running rail is too high and the trackside equipment has certain insulation weakness, the trackside equipment can be damaged. When a plurality of urban rail transit lines in China operate, phenomena such as ignition of an over-shielding door, burning and melting of a grounding wire of a point switch and the like occur, and great harm is caused to safe operation of the lines.

In order to prevent the damage of the Over-high rail potential to passengers and trackside equipment, an Over Voltage Protection Device (OVPD) is usually installed at the station position of the urban rail transit lines at home and abroad. One end of the OVPD is connected with the walking rail, the other end of the OVPD is connected with a system grounding grid, when the situation that the potential of the steel rail at the position exceeds the personal safety limit value specified by the standard is detected, the OVPD is switched on for a period of time, and the walking rail is in short circuit with the ground, so that the potential level of the steel rail at the position is reduced.

However, the rigid grounding mode of the steel rail potential limiting device has some problems.

1) The safety of the human body and equipment is guaranteed when the steel rail potential device acts on the steel rail potential device, but a large amount of backflow current flows into the grounding grid through the steel rail potential limiting device, stray current is formed, electric corrosion is generated on the grounding grid and structural steel bars in a station and metal materials of connected equipment, the service life of the metal materials is shortened, and the service life of subway engineering is influenced in severe cases.

2) When the potential of the steel rail exceeds a set value, the conventional steel rail potential limiting device shorts a traveling rail with a system grounding grid to reduce the potential of the steel rail at the position, and belongs to rigid grounding. When the rail potential rises, a section of protection action is easy to be grounded frequently, the potential of the running rail fluctuates back and forth, the oscillation amplitude reaches hundreds of volts, the impact on a direct current traction power supply system is large, and the safe operation of personnel and equipment is influenced.

3) The rail potential limiting device of each line with 2-3 stations frequently displays that the rail potential is too high, the action times are multiple, and the phenomenon that the shielding door outer frame structure generates discharge sparks to adjacent metal parts sometimes occurs. Therefore, in operation, the rail potential device should act as little as possible on the premise of playing a role of safety protection.

Disclosure of Invention

In order to solve the above problems completely, and especially to overcome the shortcomings of the prior art, the invention provides a flexible grounding device for controlling the potential of a steel rail. In order to achieve the purpose, the invention adopts the following technical means:

the utility model provides a flexible earthing device that controls rail electric potential, includes a plurality of power modules of being connected with rail electric potential grounding body, carries out distribution control's main control unit to power module's mode, main control unit is connected with rail electric potential grounding body through voltage sensor and is used for gathering rail electric potential data.

Further, the working modes of the power module include a constant voltage mode, a constant current control mode and a constant resistance mode.

Constant voltage mode: different from the traditional terminal voltage control, the device voltage control belongs to the source terminal voltage control, and the purpose of parallel shunt is realized by changing the external port characteristic of a device port voltage-current characteristic adjusting system.

Under this kind of mode, based on traditional inductive current inner loop, output voltage outer loop's basis, increase source end voltage control, the outermost ring is source end voltage control, and the control output is as giving of terminal voltage. The control strategy is equivalent to that variable reference is added on the basis of the traditional voltage control closed loop, namely a source end voltage-output voltage-inductive current three-closed-loop control system is established.

Constant current control mode: the control strategy is similar to the constant-voltage control of the source end and is a three-closed-loop control system of source end current-output voltage-inductive current. Different from the prior art, the nonlinear coupling relationship exists between the source end current and the source end voltage, and the source end voltage is easy to fluctuate along with the current control, so that the source end voltage is required to be introduced as feedforward in the control strategy.

Constant resistance mode: the control strategy is an improvement of a flow mode, is still source end current-output voltage-inductive current three-closed-loop control, and only maintains V/I at a constant value under different voltage conditions. In the control process, the controlled current of the source end is always kept at V/R, and the characteristic of the outer port is ensured to be the constant resistance value characteristic.

Under the normal operation condition, the device works in a constant voltage mode, and when the rail potential leakage current exceeds the allowable output current of the device, the device is automatically switched into a constant current mode to operate at full power.

Further, the power module comprises a startup charging current-limiting resistor, a full-wave rectifier bridge connected with the startup charging current-limiting resistor, a filter capacitor connected with the full-wave rectifier bridge, a power IGBT connected with the filter capacitor, a freewheeling diode connected with the power IGBT, a power inductor connected with the freewheeling diode, a load capacitor connected with the power inductor, and a load resistor connected with the load capacitor.

Furthermore, the power IGBT, the freewheeling diode, the power inductor and the load capacitor form a three-way Buck circuit in parallel, the output end of the Buck circuit is connected with the load resistor and is controlled by an automatic control algorithm of the controller to obtain stable direct current voltage, and the direct current voltage passes through the load resistor to obtain constant direct current.

Furthermore, the starting-up charging current-limiting resistor is formed by connecting a direct-current contactor KM and a power resistor Ri in parallel, when the device is started up, KM is disconnected, Ri is connected in series to a loop, charging current of a filter capacitor is limited 203, and the function of protecting a rectifier bridge is also achieved.

Furthermore, the maximum input current of the power unit modules is 100A, and all the power modules are connected into the system in parallel.

Further, the number of the power modules connected in parallel is not more than 8.

Furthermore, the main controller controls the output voltage by adopting PWM, so that the input voltage, the output voltage and the input current can be continuously adjusted.

The invention has the beneficial effects that: the steel rail potential is flexibly controlled, a traditional segmented control method of the steel rail potential is abandoned, and the flexible grounding theory of an urban rail reflux system is enriched; the comprehensive cooperative control of the steel rail potential and the stray current can be realized, the side effect of independent control of each parameter is avoided, and the cabinet combination control of the steel rail potential and the stray current is realized; the control method takes the coupling effect influence of multipoint steel rail potential into consideration, and avoids the linkage action of steel rail potential control; transient overvoltage influence of transient parameters of the reflux system on steel rail potential control is calculated, misoperation and locking are avoided, and meanwhile, the oscillation frequency of the steel rail potential of the reflux system is reduced; the power consumption during the control of the rail potential is reduced.

Drawings

FIG. 1 is a schematic diagram of the main structure of the grounding device of the present invention;

FIG. 2 is a schematic circuit diagram of a power module of the present invention;

fig. 3 is a block diagram of the source-side constant voltage control strategy of the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

As shown in fig. 1 to 3, the present embodiment provides a flexible grounding device for controlling a rail potential, including a plurality of power modules connected to a rail potential grounding body, and a main controller for performing distribution control on operating modes of the power modules, where the main controller is connected to the rail potential grounding body through a voltage sensor for acquiring rail potential data, and the main controller controls output voltage by using PWM, so as to achieve continuous adjustability of input voltage, output voltage, and input current.

The maximum input current of the power unit modules is 100A, the power modules are connected into the system in parallel, and the number of the power modules which are installed in parallel is at most 8.

In order to improve the reliability of the device and simultaneously reduce the voltage and current stress of devices in the converter, the power module adopts a modularized structure, each module has 20kW, a three-way Buck circuit parallel connection mode is adopted in the power module, each branch has 6.7kW, parameters and sizes of rear-end filter elements are reduced by utilizing staggered parallel connection, and the rail potential limiting device is designed into modularized staggered parallel Buck circuits which are used for current equalization and are mutually standby. When one branch fails, the system alarms, the other two branches work normally and share the power of the failed branch, and different control strategies are respectively designed according to different control modes.

The working modes of the power module comprise a constant voltage mode, a constant current control mode and a constant resistance mode.

Constant voltage mode: different from the traditional terminal voltage control, the device voltage control belongs to the source terminal voltage control, and the purpose of parallel shunt is realized by changing the external port characteristic of a device port voltage-current characteristic adjusting system.

Under this kind of mode, based on traditional inductive current inner loop, output voltage outer loop's basis, increase source end voltage control, the outermost ring is source end voltage control, and the control output is as giving of terminal voltage. The control strategy is equivalent to that variable reference is added on the basis of the traditional voltage control closed loop, namely a source end voltage-output voltage-inductive current three-closed-loop control system is established.

Constant current control mode: the control strategy is similar to the constant-voltage control of the source end and is a three-closed-loop control system of source end current-output voltage-inductive current. Different from the prior art, the nonlinear coupling relationship exists between the source end current and the source end voltage, and the source end voltage is easy to fluctuate along with the current control, so that the source end voltage is required to be introduced as feedforward in the control strategy.

Constant resistance mode: the control strategy is an improvement of a flow mode, is still source end current-output voltage-inductive current three-closed-loop control, and only maintains V/I at a constant value under different voltage conditions. In the control process, the controlled current of the source end is always kept at V/R, and the characteristic of the outer port is ensured to be the constant resistance value characteristic.

Under the normal operation condition, the device works in a constant voltage mode, and when the rail potential leakage current exceeds the allowable output current of the device, the device is automatically switched into a constant current mode to operate at full power.

The power module comprises a startup charging current-limiting resistor 201, a full-wave rectifier bridge 202 connected with the startup charging current-limiting resistor 201, a filter capacitor 203 connected with the full-wave rectifier bridge 202, a power IGBT204 connected with the filter capacitor 203, a freewheeling diode 205 connected with the power IGBT204, a power inductor 206 connected with the freewheeling diode, a power inductor 206, a load capacitor 207 and a load resistor 208 connected with the load capacitor 207

The power IGBT, the freewheeling diode, the power inductor and the load capacitor form a three-way Buck circuit in parallel, the output end of the Buck circuit is connected with the load resistor and is controlled by an automatic control algorithm of the controller to obtain stable direct current voltage, and the direct current voltage passes through the load resistor to obtain constant direct current.

The starting-up charging current-limiting resistor is formed by connecting a direct-current contactor KM and a power resistor Ri in parallel, when the device is started up, KM is disconnected, Ri is connected in series to a loop, charging current of a filter capacitor is limited 203, and the function of protecting a rectifier bridge is also achieved.

The steel rail potential is flexibly controlled, a traditional segmented control method of the steel rail potential is abandoned, and the flexible grounding theory of an urban rail reflux system is enriched; the comprehensive cooperative control of the steel rail potential and the stray current can be realized, the side effect of independent control of each parameter is avoided, and the cabinet combination control of the steel rail potential and the stray current is realized; the control method takes the coupling effect influence of multipoint steel rail potential into consideration, and avoids the linkage action of steel rail potential control; transient overvoltage influence of transient parameters of the reflux system on steel rail potential control is calculated, misoperation and locking are avoided, and meanwhile, the oscillation frequency of the steel rail potential of the reflux system is reduced; the power consumption during the control of the rail potential is reduced.

The present invention is illustrated by way of example and not by way of limitation. It will be apparent to those skilled in the art that other variations and modifications may be made in the foregoing disclosure without departing from the spirit or essential characteristics of all embodiments, and that all changes and modifications apparent from the above teachings are within the scope of the invention.