CN114937968B - A DC deicing device and control method for electrified railway catenary - Google Patents

Abstract

The invention discloses a direct-current deicing device for an electrified railway overhead line system and a control method thereof. A left converter and a right converter of the direct current ice melting device are connected back to back and are respectively connected to a secondary bus of a traction transformer through an isolation type step-down transformer. The middle direct current sides of the two converters are connected through a breaker. When the device works in a direct-current anti-icing and ice-melting mode, the direct-current ports on the left side and the right side of the device are connected in series through the circuit breakers, and then the anode and the cathode after being connected in series are respectively connected to an alpha uplink contact net and a beta downlink contact net, so that the high-capacity direct-current anti-icing and ice-melting requirements of the contact nets can be met. When the device works in a regenerated energy utilization mode, the direct current ports on the left side and the right side of the device are connected in parallel through the circuit breakers, and the connecting lines are led out to provide grid-connected interfaces for the energy storage and new energy systems, so that the regenerated braking energy of the locomotive can be effectively utilized, and the energy efficiency, the electric energy quality and the reliability of the power supply system of the electrified railway are improved.

Description

A DC deicing device and control method for electrified railway catenary

technical field

The invention relates to the field of electrified railway traction power supply systems, in particular to a DC deicing device and a control method for an electrified railway catenary.

Background technique

At present, in the traction power supply system of electrified railways, electric locomotives/EMUs take power from the catenary to supply energy for themselves. Since the catenary is completely exposed to the external environment, icing is extremely prone to occur in some low temperature, high humidity, and high altitude areas . Catenary icing will affect the normal flow of locomotives, and even cause damage to the power supply network, leading to power interruption, which seriously threatens the normal operation of electrified railways. my country has a vast territory, complex and diverse terrain, and changeable climate. A large number of main railway lines in central China and southwest mountainous areas are facing the threat of catenary icing. For example, in the ice and snow disaster in 2008, many trunk lines in Guizhou, Hunan and other places were interrupted due to icing of catenary lines, which led to outages and huge economic losses.

In recent years, as my country's electrified railway continues to develop towards high speed and heavy load, realizing efficient anti-icing and deicing of catenary has become the focus and technical difficulty of ensuring safe and reliable power supply of electrified railway in harsh environments. At present, the domestic and foreign solutions to the icing of power transmission lines and railway catenary mainly include mechanical deicing and thermal deicing. Among them, the mechanical deicing method is mainly based on scraping and deicing and vibrating wires, which requires a lot of human resources, takes a long time, has low efficiency, and poor on-site operation safety; the thermal deicing method uses Joule's law to circulate The high current raises the temperature of the wire to achieve the purpose of melting and falling off the ice coating. The high current flowing can use AC or DC current. This method is safe, reliable, low in cost, and high in operability, so it has attracted widespread attention.

Among them, DC deicing technology has become the preferred solution to the problem of icing on transmission lines in power systems due to its advantages of no need to consider line reactance, small equipment capacity, and high deicing efficiency. However, since the icing of the line only occurs in severe weather conditions such as winter and spring rain, snow and freezing, and the ice melting device only works during the "skylight" period of railway operation, this will cause the ice melting equipment to be idle most of the time, Utilization is very low.

Contents of the invention

The object of the present invention is to provide a DC deicing device and a control method for an electrified railway catenary.

The technical scheme that realizes the object of the present invention is:

A DC deicing device for an electrified railway catenary, including a source storage device; the source storage device includes a left AC/DC converter and a right AC/DC converter, and the AC terminals of the left AC/DC converter pass through the The left inductor and the left step-down transformer are connected to the α-phase bus, and the AC terminal of the right AC/DC converter is connected to the β-phase bus through the right inductor and the right step-down transformer in turn, and the left and right AC/DC The DC side of the converter is also provided with a left capacitor and a right capacitor respectively; the positive pole of the left AC/DC converter is connected to the positive pole of the right AC/DC converter and is connected to the positive pole of the energy storage system through a circuit breaker QF5, and the left AC The /DC converter is connected to the negative pole of the right AC/DC converter and connected to the negative pole of the energy storage system through the circuit breaker QF6; a circuit breaker QF7 is also included so that the positive pole of the left AC/DC converter is connected to the right side through QF7 The positive pole of the AC/DC converter, the positive pole of the left AC/DC converter is connected to the positive pole of the energy storage system through QF5; a circuit breaker QF8 is also included so that the negative pole of the left AC/DC converter is connected to the right AC through QF8 The negative pole of the /DC converter, the negative pole of the right AC/DC converter is connected to the negative pole of the energy storage system through QF6; the positive pole of the left AC/DC converter is also connected to the right AC/DC converter through the circuit breaker QF11 Negative pole; the negative pole of the left AC/DC converter is also connected to the α-phase uplink catenary through the isolating switch QS9 and the circuit breaker QF9 in turn, and the positive pole of the right AC/DC converter is also connected to the β-phase down catenary; when the DC ice-melting device works in DC anti-icing and ice-melting mode, QF5, QF6, QF7, QF8 are disconnected and QS9, QS10, QF9, QF10, QF11 are closed; when the DC melting When the ice device works in regenerative braking energy utilization mode, QS9, QS10, QF9, QF10, QF11 are disconnected and QF7, QF8 are closed.

The control method of the above-mentioned device, comprising,

Step 1: judging whether the catenary is open to traffic, if not, continue;

Step 2: If the ambient temperature outside the catenary is T≤0°C, continue;

Step 3: Make the DC deicing device work in DC anti-icing and deicing mode, specifically:

3.1 Disconnect QF5 and QF6;

3.2 Disconnection: the circuit breaker QF1 from the α-phase busbar to the α-phase downlink catenary, the circuit breaker QF2 from the α-phase busbar to the α-phase uplink catenary, the circuit breaker QF3 from the β-phase busbar to the β-phase uplink catenary, and the β-phase busbar to the Circuit breaker QF4 of β-phase downlink catenary; 3.3 Closing: disconnector QS5 between α-phase uplink and β-phase uplink, α-phase uplink and α-phase downlink QS6, α-phase downlink The isolating switch QS7 for the β-phase downlink catenary, the isolating switch QS8 for the β-phase uplink catenary and the β-phase downlink catenary;

3.4 Disconnect QF7, QF8, close QF11;

3.5 Close QS9, QS10, close QF9, QF10;

3.6 Set the DC side voltage reference value of the left AC/DC converter and the right AC/DC converter as the ice-melting voltage.

Further technical solutions also include,

Step 4: Determine whether the catenary is covered with ice, if so, make the DC deicing device continue to work in the DC anti-icing and deicing mode; if not, make the DC deicing device switch to regenerative braking energy utilization mode;

Step 5: Determine whether the catenary is open to traffic, if not, make the DC deicing device continue to work in the DC anti-icing and deicing mode; if so, make the DC deicing device switch to regenerative braking energy utilization model;

The DC deicing device switches to the regenerative braking energy utilization mode, specifically:

4.1 Disconnect QF9, QF10, disconnect QS5, QS7, QS9, QS10;

4.2 Close QF7, QF8, open QF11;

4.3 Close QF1, QF2, QF3, QF4;

4.4 Set the DC side voltage reference values of the left AC/DC converter and the right AC/DC converter as initial voltages.

A further technical solution, between steps 4.3 and 4.4, also includes step 4.3'; said step 4.3' is: keep QS6, QS8 closed; or, disconnect QS6, QS8, close QF5, QF6; or, keep QS6 and QS8 are closed, and QF5 and QF6 are closed.

Compared with prior art, the beneficial effect of the present invention is:

1. The DC ice-melting device is based on the existing source-storage device of the line. When it works in the DC anti-icing and ice-melting mode, it can meet the large-capacity DC anti-icing and ice-melting requirements of the catenary.

2. After the DC deicing device is converted to the regenerative braking energy utilization mode, the regenerative braking energy of the locomotive can be effectively used, which improves the energy efficiency, power quality and reliability of the electrified railway power supply system.

3. The control method of the direct current ice melting device is simple and easy to implement. It can switch between the two working modes in real time on demand, and the equipment utilization rate is high, which saves the floor area and economic cost required for the establishment of a new ice melting device.

Description of drawings

Figure 1 is a schematic diagram of the structure of the DC deicing device installed on the whole line of the traction power supply system.

Fig. 2 is a flow chart of the device switching between two working modes.

Figure 3 is a schematic diagram of the system connection when the device works in the DC anti-icing and ice-melting modes.

Fig. 4 is a schematic diagram of the system connection when the device works in the regenerative braking energy utilization mode.

Fig. 5 is a schematic structural diagram of the data processing and control system of the device.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The DC deicing device for the electrified railway catenary provided by the present invention can not only meet the requirements of large capacity DC deicing and deicing of the catenary, but also can effectively utilize the regenerative braking energy of the electric locomotive, improve the energy efficiency and power supply reliability of the system, improve the The power quality of the system. The device can switch between the DC anti-icing mode, the deicing mode and the regenerative braking energy utilization mode in real time to improve equipment utilization and save investment costs.

As shown in Figure 1, from a global perspective, a set of DC ice-melting devices must be installed in each traction substation. The device takes power from the 27.5kV bus on the secondary side of the traction transformer, and there are partitions between the traction substations. The ice-melting devices of each traction substation operate independently. The device can contain a hybrid energy storage system, and connect new energy resources (such as wind power and photovoltaics) along the line according to the line conditions.

From a single point of view, the ice-melting device in the station can be divided into two identical converters, left and right. Each converter includes an AC side inductor, a DC side capacitor, and a circuit composed of controllable devices (such as IGBT, IGCT). bridge circuit. Among them, the AC side inductor plays the role of filtering, and the DC side capacitor plays the role of voltage stabilization. The bridge circuit composed of controllable devices can be turned on and off through the SPWM control device to form a DC output with a controllable voltage value.

Specifically, the left and right converters of the device are connected back to back, and are respectively connected to the 27.5kV bus on the secondary side of the traction transformer through an isolated step-down transformer. When working, the isolated step-down transformers on both sides of the back-to-back converter step down the 27.5kV single-phase high-voltage AC power to single-phase low-voltage AC power (such as 1500V), and then rectify it into DC power of different voltage levels through the converter. The intermediate DC side is connected through a circuit breaker, and the output of the DC side is connected in parallel with a voltage stabilizing capacitor. When the device works in the DC anti-icing and ice-melting mode, its left and right DC ports are connected in series through a circuit breaker, and then the connected positive and negative poles are connected to the α uplink and β downlink catenary respectively. When the device works in regenerative energy utilization mode, its left and right DC ports are connected in parallel through a circuit breaker, and lead out connecting lines to provide grid-connected interfaces for energy storage and new energy systems; in addition, the upper and lower power supply arms on the left and right sides They are respectively connected to the output feeder of the 27.5kV bus through the isolation switch and the circuit breaker.

In the control method of the above-mentioned device, the data processing and control system controls the corresponding circuit breaker and isolating switch according to the feedback signal of the catenary environmental parameter monitoring unit to make the source-storage-ice-melting device work in different modes. As shown in Figure 2, the specific implementation steps are:

Step 1, judging whether the line is open to traffic in a short period of time according to the positioning device on the vehicle and the driving diagram;

If so, make the device work in the regenerative braking energy utilization mode; otherwise, go to the next step.

Step 2, start the catenary environmental parameter monitoring unit.

Step 3, according to the temperature sensor feedback signal in the catenary environment parameter monitoring unit, judge the external environment temperature T at this time;

If T≤0℃, go to the next step; otherwise, continue to compare the ambient temperature.

Step 4: Detect the opening and closing status of each circuit breaker and isolating switch in the device, and switch them to the DC anti-icing and ice-melting mode. The specific process of switching operation is as follows:

4.1 If the new energy system and the energy storage system are in the grid-connected operation state, disconnect the circuit breakers QF5 and QF6 on the outgoing connection line of the intermediate DC side, and the new energy system and the energy storage system will be out of operation;

4.2 Disconnect the output feeder circuit breakers QF1, QF2, QF3, QF4 of the traction substation;

4.3 Close the isolating switches QS5, QS6, QS7, and QS8 to form an uplink and downlink parallel DC ice melting circuit;

4.4 Disconnect the DC side circuit breakers QF7 and QF8 in the middle of the back-to-back converter, close the circuit breaker QF11, and change the DC ports of the single-phase converters on both sides of the back-to-back converter from parallel to series;

4.5 Close the isolating switches QS9 and QS10, close the circuit breakers QF9 and QF10, and supply power to the catenary from the DC series ports of the back-to-back converters.

Step 5, start the data processing and control system, set the DC side voltage reference value of the back-to-back converter as the ice-melting voltage U _dc0 , and the device works in the catenary DC anti-icing and ice-melting mode.

Step 6, according to the sensor feedback signal in the catenary environmental parameter monitoring unit, combined with the network meteorological data information and the catenary state video camera to judge the icing condition of the catenary. If the catenary is covered with ice, the state of each circuit breaker and isolating switch remains unchanged, and the device continues to work in the DC anti-icing and ice-melting mode; otherwise, go to step eight.

Step 7, judging whether the line is open to traffic in a short period of time according to the positioning device on the vehicle and the driving diagram. If not, the state of each circuit breaker and isolating switch remains unchanged, and the device continues to work in the DC anti-icing and ice-melting mode; if yes, go to step eight.

Step 8: Detect the opening and closing status of each circuit breaker and isolating switch in the device, and switch them to the regenerative braking energy utilization mode. The specific process of switching operation 2 is as follows:

8.1 Turn off the circuit breakers QF9 and QF10, disconnect the isolating switches QS5, QS7, QS9 and QS10, and separate the α power supply arm and the β power supply arm by means of electrical splitting;

8.2 Close the intermediate DC side circuit breakers QF7 and QF8 of the back-to-back converters, open the circuit breaker QF11, and connect the DC ports of the single-phase converters on both sides of the back-to-back converters in parallel;

8.3 Close the output feeder circuit breakers QF1, QF2, QF3, QF4 of the traction substation;

8.4 This step can be performed selectively: keep the isolating switches QS6 and QS8 where the partitions are closed, and run in parallel at the ends of the upstream and downstream lines, which can reduce the fluctuation of the network voltage at the end of the power supply arm; or, disconnect the isolating switches QS6 and QS8 where the partitions are located, and close them. The circuit breakers QF5 and QF6 on the connection line leading out from the intermediate DC side realize the grid-connected operation of the new energy system and the energy storage system; or, keep the isolating switches QS6 and QS8 where the partitions are closed, close the circuit breakers QF5 and QF6, and the ends of the uplink and downlink lines Parallel operation, while realizing grid-connected operation of new energy systems and energy storage systems.

Step 9: start the data processing and control system, set the reference value of the intermediate DC side voltage of the back-to-back converter as the initial voltage U _dc1 , and the device works in the regenerative braking energy utilization mode.

Figure 3 is a schematic diagram of the system connection when the device works in the DC anti-icing and ice-melting modes.

Among them, taking the CTMH-150 type contact wire and JTMH-120 type catenary cable as an example, based on the calculation of a single power supply arm length of 25km, when the up and down contact wires are connected in series as the ice-melting circuit, the equivalent DC resistance of the line is about 5Ω. At this time, the ice-melting current required to achieve DC ice-melting is 1000A, so the series-connected ice-melting voltage is 5000V. Because the structure of the left and right converters is symmetrical, the DC side voltage reference value in the middle of the back-to-back converter is set as the ice-melting voltage If the voltage U _dc0 = 2500V, the device works in catenary DC anti-icing and ice-melting mode. During work, the ice-melting current and voltage can be controlled in real time according to the external environment, so as to achieve effective anti-icing under low temperature conditions and efficient ice-melting under ice-covered conditions.

Since the device works in the DC anti-icing and ice-melting mode, the energy storage system and the new energy system are out of operation. Therefore, when the internal source ice storage-melting device of the traction substation does not include an energy storage system or a new energy system, the device can still be used for DC anti-icing and ice melting.

Fig. 4 is a schematic diagram of the system connection when the device works in the regenerative braking energy utilization mode.

Among them, set the DC side voltage reference value of the back-to-back converter as the initial voltage _Udc1 = 3600V, detect the voltage and current values on the α and β power supply arms in real time, calculate the instantaneous power on both sides of the power supply arms, and control The four-quadrant operation of the back-to-back converter realizes the power interaction of the two arms, balances the active power of the two arms, and reduces the negative sequence of the system.

According to the system energy management strategy, the regenerative braking energy on one side of the power supply arm is transferred to the traction locomotive on the other side of the power supply arm, and the remaining regenerative braking energy is stored in the energy storage system, or during the intensive operation of the line , control the energy storage system to release energy to the power supply arm, control the new energy system to provide energy to the power supply arm, realize energy saving and consumption reduction of the traction power supply system, and improve energy utilization efficiency.

If the capacity of the back-to-back converter is remaining, the reactive power and negative sequence compensation function is activated, and the comprehensive management of power quality is realized through the output of the converter and the current with the same amplitude and opposite phase as the reactive power and harmonic current measured by the power supply arm.

Fig. 5 is a schematic structural diagram of the data processing and control system of the device.

Among them, according to the sensor feedback signal in the catenary environmental parameter monitoring unit, it is judged whether to start the DC anti-icing and ice-melting functions, specifically:

1) The catenary environmental parameter monitoring unit includes a temperature sensor, a humidity sensor, and a wind speed sensor, and the three sensors detect the temperature, humidity, and wind speed conditions in the environment where the catenary is located;

2) The sensor detection results are converted into specified signals and fed back to the data processing and control system. The data processing and control system combines the networked meteorological data information and the catenary status video camera to judge the icing status of the catenary and issue corresponding control commands.

3) Because the voltage of the DC output terminal of the back-to-back converter is controllable, the ice-melting voltage can be controlled and adjusted according to the ice-covered state of the line, so that the line can pass through short-circuit currents of different sizes to achieve effective anti-icing under low temperature conditions and high efficiency under ice-covered conditions. melting ice.

Claims (4)

1. A direct-current deicing device for an electrified railway contact network comprises a source storage device; the source storage device comprises a left AC/DC converter and a right AC/DC converter, the alternating current end of the left AC/DC converter is connected to the alpha-phase bus through a left inductor and a left step-down transformer in sequence, the alternating current end of the right AC/DC converter is connected to the beta-phase bus through a right inductor and a right step-down transformer in sequence, and the direct current ends of the left AC/DC converter and the right AC/DC converter are respectively provided with a left capacitor and a right capacitor; the anodes of the left AC/DC converter and the right AC/DC converter are connected and connected to the anode of the energy storage system through a breaker QF5, and the cathodes of the left AC/DC converter and the right AC/DC converter are connected and connected to the cathode of the energy storage system through a breaker QF6; the circuit breaker QF7 is further included, so that the anode of the left AC/DC converter is connected to the anode of the right AC/DC converter through the QF7, and the anode of the left AC/DC converter is connected to the anode of the energy storage system through the QF 5; the breaker QF8 is further included, so that the negative electrode of the left AC/DC converter is connected to the negative electrode of the right AC/DC converter through the QF8, and the negative electrode of the right AC/DC converter is connected to the negative electrode of the energy storage system through the QF6; the anode of the left AC/DC converter is also connected to the cathode of the right AC/DC converter through a breaker QF11; the negative electrode of the left AC/DC converter is also connected to an alpha-phase uplink contact network through an isolating switch QS9 and a breaker QF9 in sequence, and the positive electrode of the right AC/DC converter is also connected to a beta-phase downlink contact network through an isolating switch QS10 and a breaker QF10 in sequence; when the direct-current ice melting device works in a direct-current anti-icing and ice melting mode, QF5, QF6, QF7 and QF8 are disconnected, and QS9, QS10, QF9, QF10 and QF11 are closed; when the direct current ice melting device works in a regenerative braking energy utilization mode, QS9, QS10, QF9, QF10 and QF11 are disconnected, and QF7 and QF8 are closed.

2. The control method of the direct-current deicing device for the overhead contact system of the electrified railway of claim 1, comprising,

step 1: judging whether the contact network is on traffic or not, if not, continuing;

step 2: if the external environment temperature T of the contact net is less than or equal to 0 ℃, continuing;

and 3, step 3: the direct-current ice melting device works in a direct-current anti-icing and ice melting mode, and the method specifically comprises the following steps:

3.1 cutting off QF5 and QF6;

3.2, disconnection: a circuit breaker QF1 from an alpha-phase bus to an alpha-phase downlink contact network, a circuit breaker QF2 from the alpha-phase bus to an alpha-phase uplink contact network, a circuit breaker QF3 from a beta-phase bus to a beta-phase uplink contact network, and a circuit breaker QF4 from the beta-phase bus to a beta-phase downlink contact network;

3.3, closing: an isolating switch QS5 of the alpha-phase uplink contact network and the beta-phase uplink contact network, an isolating switch QS6 of the alpha-phase uplink contact network and the alpha-phase downlink contact network, an isolating switch QS7 of the alpha-phase downlink contact network and the beta-phase downlink contact network, and an isolating switch QS8 of the beta-phase uplink contact network and the beta-phase downlink contact network;

3.4 opening QF7 and QF8 and closing QF11;

3.5 close QS9, QS10, close QF9, QF10;

and 3.6 setting the direct-current side voltage reference values of the left AC/DC converter and the right AC/DC converter as the ice melting voltage.

3. The control method of the device for melting ice in a direct current of an overhead contact system of an electrified railway of claim 2, further comprising,

and 4, step 4: judging whether the overhead contact system is iced, if so, enabling the direct-current deicing device to continuously work in a direct-current anti-icing and deicing mode; if not, the direct current ice melting device is switched to a regenerative braking energy utilization mode;

and 5: judging whether the overhead contact system is on the bus or not, if not, enabling the direct-current ice melting device to continuously work in a direct-current anti-icing and ice melting mode; if yes, the direct current ice melting device is switched to a regenerative braking energy utilization mode;

the direct-current ice melting device is converted into a regenerative braking energy utilization mode, and the method specifically comprises the following steps:

4.1 turn off QF9, QF10, turn off QS5, QS7, QS9, QS10;

4.2, closing QF7 and QF8 and opening QF11;

4.3 closed QF1, QF2, QF3, QF4;

4.4 setting the DC side voltage reference value of the left side AC/DC converter and the right side AC/DC converter as the initial voltage.

4. The control method of the device for melting ice in a direct current of an overhead contact system of an electrified railway according to claim 3, characterized in that between the steps 4.3 and 4.4, the method further comprises the step 4.3';

the step 4.3' is as follows: maintaining QS6, QS8 closed; or, QS6, QS8 is opened, and QF5, QF6 are closed; or,

keep QS6, QS8 closed, close QF5, QF6.

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