Subway flywheel energy storage system with direct current ice melting function and ice melting energy storage method

Abstract

The application discloses a metro flywheel energy storage system with a direct current ice melting function, which comprises a medium voltage looped network, a contact network, a running rail and positive and negative bus lines, and further comprises a metro rectification module and a flywheel energy storage module; the metro rectification module is connected with the positive and negative bus lines; the positive bus line is connected with the contact network, and the negative bus line is connected with the running rail; the flywheel energy storage module is connected with the positive bus line, the negative bus line and the running rail respectively; the flywheel energy storage module is further connected with the contact network through a circuit breaker QF, and the contact network and the running rail are connected through a remote short-circuit switch K3. The application further discloses an ice melting and energy storage method using the metro flywheel energy storage system with the direct current ice melting function. The application has both the direct current ice melting function and the flywheel energy storage charging and discharging function, the two functions are time-multiplexed through switch control, efficient utilization of the equipment is realized, and the performance-price ratio is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of transportation technology, in particular to a subway flywheel energy storage system with direct current ice melting function and an ice melting energy storage method. BACKGROUND

[0002] As a way of daily travel for citizens, the subway has many advantages and thus has developed rapidly. However, the subway also faces some problems. Problem one: how to recycle the regenerative braking energy of the subway, which plays an important role in reducing energy consumption, suppressing catenary voltage fluctuation and improving the stability of the power supply system. In the current mainstream subway regenerative braking energy utilization technology, flywheel energy storage is the optimal solution. Its basic principle is that when the subway braking generates regenerative braking energy and raises the DC catenary voltage, the flywheel energy storage device will store the regenerative braking energy that cannot be absorbed by the adjacent car in mechanical energy, and then convert the stored mechanical energy into electrical energy when the subway traction causes the DC network voltage to drop, thereby achieving energy saving and voltage stabilization. Problem two: when the subway vehicle uses overhead catenary power supply, the influence of rain, snow and ice weather on the catenary is particularly prominent. The catenary is an important power supply facility for subway traction, and when the catenary surface is covered with ice, it will seriously affect the normal current collection of the pantograph and reduce the reliability of subway power supply, thereby threatening the safety of train operation. Small-scale line icing can be removed by artificial or mechanical methods (such as knocking with a wooden hammer), high-pressure steam ice melting, etc., but for large-scale and long-distance lines, such methods are inefficient and have poor ice melting effect. Therefore, it is of great economic and social significance to install advanced and reliable ice melting devices at the traction substation to safely and quickly remove the ice on a large range of catenaries. From the current technical level at home and abroad, direct current ice melting technology is the most mature and feasible ice melting method, and its basic principle is to use the heat generated by the direct current passing through the wire to melt the ice layer.

[0003] Today, flywheel energy storage devices have been researched and applied in urban rail transit systems at home and abroad. Direct current ice melting technology has been maturely applied in power transmission lines, and corresponding research has been carried out on direct current ice melting of electrified railway catenaries. Zhuzhou Electric Locomotive Factory, Xuji Group and other manufacturers have also carried out research on catenary direct current ice melting, but there is no example of using direct current ice melting technology in urban rail transit lines nationwide. In recent years, a direct current ice melting device containing reactive power compensation function (SVG) has attracted attention. It has both reactive power compensation function and direct current ice melting function, is easy to switch, and is economical and effective, and mostly uses half-bridge, full-bridge and hybrid MMC topological structures.

[0004] Existing subway regenerative braking devices and DC de-icing devices have relatively limited functions. For example, the subway regenerative braking device only recovers regenerative braking energy from the subway and stabilizes the DC contact network voltage. The DC de-icing device only has a de-icing function and is only used when the contact network is icy, resulting in long periods of idle time. If a traction substation requires both of these functions, it must be equipped with two sets of equipment, which requires a large footprint and incurs high procurement costs.

[0005] Existing flywheel energy storage devices and DC de-icing devices have relatively limited functions. For example, flywheel energy storage devices only have energy storage and charging / discharging functions, while DC de-icing devices only have de-icing functions, and are only used when the contact wire is covered with ice, resulting in long periods of idle time. If a traction substation requires both of these functions, it must be equipped with two sets of equipment, which requires a large footprint and incurs high procurement costs. Summary of the Invention

[0006] The purpose of this invention is to provide a subway flywheel energy storage system and ice-melting energy storage method that has both DC ice melting and flywheel energy storage charging and discharging functions. The two functions are time-division multiplexed through switch control to achieve efficient utilization of the equipment and improve cost performance.

[0007] A subway flywheel energy storage system with DC de-icing capabilities includes:

[0008] The subway rectifier module steps down the medium-voltage ring network AC power and then outputs stable DC power through high-efficiency rectification and voltage regulation technology.

[0009] The flywheel energy storage module serves two purposes. First, it converts regenerative braking energy into DC power via a converter cabinet, driving a permanent magnet synchronous motor. The permanent magnet synchronous motor then accelerates the flywheel rotor, storing this energy as mechanical energy. Second, when the DC grid voltage drops due to subway traction, the flywheel rotor drives the permanent magnet synchronous motor to decelerate, converting the stored mechanical energy into electrical energy. The resulting six-phase AC power is then converted back into DC power via the converter cabinet and released to the contact network.

[0010] The metro rectifier module is connected to the positive and negative busbars; the positive busbar is connected to the overhead contact line, and the negative busbar is connected to the running rail; the flywheel energy storage module is connected to the positive busbar, the negative busbar, and the running rail respectively.

[0011] The flywheel energy storage module is also connected to the contact network via a circuit breaker QF, and the contact network and the running rail are connected via a remote short-circuit switch K3.

[0012] The flywheel energy storage module adopts two sets of three-phase active neutral clamp type three-level topology, in which one phase is connected in series with an inductor and in parallel with a capacitor to form a BUCK type DC / DC circuit; there are six such bridge arms in the converter cabinet to form a six-way BUCK type DC / DC circuit.

[0013] Further, the flywheel energy storage module comprises a switch cabinet K1, an isolating switch cabinet K2, a converter cabinet, a contactor KM and a flywheel cabinet;

[0014] The converter cabinet is connected with the switch cabinet K1 and the negative bus through the isolating switch cabinet K2, and the switch cabinet K1 is further connected with the positive bus;

[0015] The converter cabinet is further connected with the flywheel cabinet through the contactor KM.

[0016] Further, the two groups of three-phase active neutral point clamped three-level topology structures comprise a group A and a group B, and the structures are the same;

[0017] The group A comprises three bridge arms, namely a bridge arm A, a bridge arm B and a bridge arm C, and further comprises an inductor L1, an inductor L2, an inductor L3, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4 and a capacitor C5.

[0018] In the bridge arm A, the collector of the power switch tube Q3 is connected with a DC+ point, the emitter of the power switch tube Q3 and the collector of the power switch tube Q4 are connected, the emitter of the power switch tube Q4 and the collector of the power switch tube Q5 are connected with an a1 point, the emitter of the power switch tube Q5 and the collector of the power switch tube Q6 are connected, the emitter of the power switch tube Q6 is connected with a DC- point, the midpoint of the power switch tube Q3 and the power switch tube Q4 is connected with the collector of the power switch tube Q1, the emitter of the power switch tube Q1 and the collector of the power switch tube Q2 are connected with an a2 point, and the a2 point is connected with the midpoint O of the bus capacitor C1 and the bus capacitor C2; the midpoint of the power switch tube Q5 and the power switch tube Q6 is connected with the emitter of the power switch tube Q2; one end of the capacitor C1 is connected with the DC+ point, and the other end is connected with the neutral point O; one end of the capacitor C2 is connected with the DC- point, and the other end is connected with the neutral point O; the bridge arm A, the bridge arm B and the bridge arm C have the same structure; all the power switch tubes are reversely connected with a diode, the anode of each diode is connected with the emitter of the power switch tube, and the cathode of each diode is connected with the collector of the power switch tube;

[0019] The connection point a1 in the bridge arm A corresponds to b1 in the bridge arm B and c1 in the bridge arm C;

[0020] One end of the inductor L1 is connected with the a1 point in the bridge arm A, and the other end is connected with the capacitor C5 and the contactor KM; one end of the inductor L2 is connected with the b1 point in the bridge arm B, and the other end is connected with the capacitor C4 and the contactor KM; one end of the inductor L3 is connected with the c1 point in the bridge arm C, and the other end is connected with the capacitor C3 and the contactor KM.

[0021] Further, the subway rectification module comprises a step-down transformer, a rectification unit and a plurality of switches.

[0022] The voltage reducing transformer is connected with the medium voltage looped network at one end and with one end of the rectifier set; the other end of the rectifier set is connected with positive and negative bus bars respectively; the positive bus bar is connected with the contact network; and the negative bus bar is connected with the running rail.

[0023] The method comprises the following steps:

[0024] When the contactor KM is closed and the circuit breaker QF is opened, the system starts the flywheel energy storage charging and discharging mode; in this mode, when the metro braking generates regenerative braking energy and the DC contact network voltage is raised, the regenerative braking energy that cannot be absorbed by the adjacent vehicle is converted into six-phase alternating current through the converter cabinet, the six-phase alternating current drives the permanent magnet synchronous motor, the flywheel rotor is accelerated, and the energy is stored in the form of mechanical energy; when the metro traction causes the DC network voltage to drop, the flywheel rotor drives the permanent magnet synchronous motor to start deceleration, the stored mechanical energy is converted into electrical energy, the six-phase alternating current generated is converted into DC through the converter cabinet, and the DC is released to the contact network, so that the energy saving and voltage stabilization effects are achieved.

[0025] When the circuit breaker QF is closed and the contactor KM is opened, the system starts the DC deicing mode; in this mode, DC is output to the contact network, the contact network and the far end of the running rail are short-circuited through the switch K3, the switch is in a closed state in the DC deicing mode, a loop is formed between the contact network and the running rail by the output DC, the DC current flows through the contact network to generate Joule heat, and the effect of melting ice is achieved.

[0026] The circuit topology in the converter cabinet of the device realizes time-sharing multiplexing of two functions. In the flywheel energy storage charging and discharging mode, the converter cabinet outputs six-phase alternating current to drive the permanent magnet synchronous motor, the flywheel rotor is accelerated by the permanent magnet synchronous motor, and the electrical energy is stored in the form of mechanical energy; in the flywheel energy storage charging and discharging mode, the converter cabinet converts the six-phase alternating current into DC and releases the DC to the contact network, so that the energy saving and voltage stabilization effects are achieved. In the DC deicing DC / DC working mode, the converter cabinet outputs DC, a current loop is formed between the uplink and downlink contact networks or between the contact network and the running rail, heat is generated to melt the ice on the contact network.

[0027] In the DC deicing DC / DC mode, the device can melt the ice on the running rail and the contact network at the same time, increase the adhesion coefficient of the running rail, and prevent the metro vehicle from slipping. The device adopts two three-phase active neutral point clamped three-level circuits in parallel to realize six-way DC output through switching control. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The system topology of the device Figure 1;

[0029] Figure 2 is the electrical topology of flywheel energy storage module of the present application;

[0030] Figure 3 is the circuit diagram of one phase in DC de-icing mode of the present application. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described with the prior art. Obviously, the described embodiments are only some of the embodiments of the present application, not all.

[0032] As shown in Figure 1 , the metro flywheel energy storage system with DC de-icing function includes a medium-voltage looped network, a catenary, a running rail, and positive and negative busbars, and further includes a metro rectifier module which reduces the voltage of the introduced urban power grid alternating current, and then outputs stable direct current through high-efficiency rectification and voltage regulation technology to meet the power supply demand of a high-power and long-distance metro line. The metro rectifier module includes a step-down transformer, a rectifier unit, and a plurality of switches; one end of the step-down transformer is connected with the medium-voltage looped network, and the other end is connected with one end of the rectifier unit; the other end of the rectifier unit is connected with the positive and negative busbars respectively; the positive busbar is connected with the catenary respectively, and the negative busbar is connected with the running rail.

[0033] As shown in Figure 1 , the metro system introduces medium-voltage 35KV alternating current from the urban power grid, and the introduced alternating current is reduced in voltage by a step-down transformer of a traction substation, and then is input to a rectifier unit to output stable 1500V direct current through high-efficiency rectification and voltage regulation technology to meet the power supply demand of a high-power and long-distance metro line. The positive power supply at the output side of the rectifier unit is connected with the positive busbar, and the negative power supply at the output side of the rectifier unit is connected with the negative busbar, and the voltage level of the positive busbar is 1500V direct current. The positive and negative busbars are connected with the metro catenary and the running rail through switches K4, K5, K6 and K7 to control the on-off of the circuit.

[0034] The flywheel energy storage module converts the regenerative braking electric energy into six-phase alternating current through a converter cabinet on one hand, and the direct current is converted into six-phase alternating current to drive a permanent magnet synchronous motor, and the permanent magnet synchronous motor drives the flywheel rotor to accelerate to store the part of energy in the form of mechanical energy; on the other hand, when the metro traction causes the direct current network voltage to drop, the flywheel rotor drives the permanent magnet synchronous motor to decelerate to convert the stored mechanical energy into electric energy, and the generated six-phase alternating current is converted into direct current by the converter cabinet and is released to the catenary.

[0035] The flywheel energy storage module comprises a switch cabinet K1, an isolation switch cabinet K2, a converter cabinet, a contactor KM and a flywheel cabinet; the converter cabinet is connected with the switch cabinet K1 and a negative bus through the isolation switch cabinet K2, and the switch cabinet K1 is further connected with a positive bus; the converter cabinet is further connected with the flywheel cabinet through the contactor KM.

[0036] As shown in Figure 2 The flywheel energy storage module is composed of two groups of three-phase active neutral point clamped three-level inverter circuits in parallel, which are group A and group B, and outputs or inputs two groups of three-phase alternating currents. The three-phase active neutral point clamped three-level inverter circuit has three bridge arms, and each bridge arm has six power switching tubes. Due to the clamping effect of the two neutral point clamping switching tubes on the left side of each phase bridge arm, the voltage stress of each switching tube is half of the total voltage of the DC bus.

[0037] Group A comprises three bridge arms, namely bridge arm A, bridge arm B and bridge arm C, and further comprises inductors L1, L2 and L3, capacitors C1, C2, C3 and C4 and C5.

[0038] In the bridge arm A, the collector of the power switching tube Q3 is connected with the DC+ point, the emitter of the power switching tube Q3 and the collector of the power switching tube Q4 are connected, the emitter of the power switching tube Q4 and the collector of the power switching tube Q5 are connected with the a1 point, the emitter of the power switching tube Q5 and the collector of the power switching tube Q6 are connected, the emitter of the power switching tube Q6 is connected with the DC- point, the midpoint of the power switching tube Q3 and the power switching tube Q4 is connected with the collector of the power switching tube Q1; the emitter of the power switching tube Q1 and the collector of the power switching tube Q2 are connected with the a2 point, and the a2 point is connected with the midpoint O of the bus capacitor C1 and the bus capacitor C2; the midpoint of the power switching tube Q5 and the power switching tube Q6 is connected with the emitter of the power switching tube Q2; one end of the capacitor C1 is connected with the DC+ point, and the other end is connected with the neutral point O; one end of the capacitor C2 is connected with the DC- point, and the other end is connected with the neutral point O; the bridge arm A, the bridge arm B and the bridge arm C have the same structure; all the power switching tubes are reversely connected with a diode, and the anode of each diode is connected with the emitter of the power switching tube, and the cathode of each diode is connected with the collector of the power switching tube.

[0039] The connection point a1 in the bridge arm A corresponds to b1 in the bridge arm B and c1 in the bridge arm C.

[0040] One end of the inductor L1 is connected with the a1 point in the bridge arm A, and the other end is connected with the capacitor C5 and the contactor KM; one end of the inductor L2 is connected with the b1 point in the bridge arm B, and the other end is connected with the capacitor C4 and the contactor KM; one end of the inductor L3 is connected with the c1 point in the bridge arm C, and the other end is connected with the capacitor C3 and the contactor KM.

[0041] As shown in Figure 2Group B and Group A have the same structure, and no further description is made.

[0042] The flywheel energy storage module is installed in the traction substation. The input end of the converter cabinet is connected with the positive bus, the input end negative is connected with the negative bus and the running rail, the line in the middle is controlled by the 1500V switch cabinet K1 to control the on-off of the line, and the electrical isolation is realized by the disconnector cabinet K2. The converter cabinet has two outputs. One output six-phase alternating current is controlled by the contactor KM to control the on-off of the flywheel cabinet permanent magnet synchronous motor, and the flywheel rotor drives the permanent magnet synchronous motor or the flywheel rotor drives the permanent magnet synchronous motor; the other output direct current is controlled by the circuit breaker QF to control the on-off of the contact net, and the running rail and the contact net are controlled by the switch K3 to control the short circuit of the remote end. When KM is closed and QF is opened, the device starts the flywheel energy storage charging and discharging mode. In this mode, when the metro braking generates regenerative braking energy and raises the voltage of the direct current contact net, the regenerative braking energy that cannot be absorbed by the adjacent car is converted into six-phase alternating current by the converter cabinet, and the six-phase alternating current drives the permanent magnet synchronous motor, and the flywheel rotor is accelerated to store this part of energy in the form of mechanical energy; when the metro traction causes the voltage of the direct current net to drop, the flywheel rotor drives the permanent magnet synchronous motor to start to slow down, and the stored mechanical energy is converted into electrical energy, and the generated six-phase alternating current is converted into direct current by the converter cabinet and released to the contact net, thereby achieving the effect of energy saving and voltage stabilization. When QF is closed and KM is opened, the device starts the direct current deicing mode. In this mode, the output direct current is output to the contact net, and the contact net and the running rail are short-circuited by the switch K3 at the remote end. In the direct current deicing mode, the switch is in the closed state, and the output direct current forms a loop between the contact net and the running rail, and the direct current flows through the contact net to generate Joule heat, thereby achieving the effect of melting ice.

[0043] Figure 3 The circuit diagram of one phase of the six-phase direct current output of the system in the direct current deicing mode. The circuit is actually one phase of the three-phase active neutral point clamped (ANPC) three-level circuit, a inductor is connected in series, and a capacitor is connected in parallel, forming a BUCK type DC / DC circuit. There are six such bridge arms in the converter cabinet, which form six BUCK type DC / DC circuits, and the parallel output direct current is connected to the contact net. The short-circuit switch K3 of the remote end of the contact net and the running rail is closed, forming a current loop, thereby achieving the effect of melting ice on the contact net.

[0044] The application utilizes a set of circuit topologies of a system to realize two functional modes, which can solve the problem of utilization of metro regenerative braking energy, achieve the effect of energy saving and voltage stabilization, increase equipment utilization, and improve economy. The metro flywheel energy storage device with the functions of direct current ice melting has the characteristics of convenience, speediness and high efficiency. The device is used as a flywheel energy storage device in normal times to realize real-time power compensation function, and can also be used as a direct current ice melting device to play an important role in the case of contact net icing in extreme environment, and prevent the metro from losing power due to poor contact between the pantograph and the contact net. The two modes often do not need to be performed at the same time, so two switches need to be arranged on the output side to control the selection of the modes, and the switching is convenient, simple and efficient.

[0045] The active neutral point clamped three-level circuit used in the converter cabinet has many advantages. Compared with the two-level circuit, the voltage stress of each switch tube is only half of the DC bus voltage, and under the same voltage level of the DC bus, a switch tube with a smaller voltage resistance level can be selected; due to the significant reduction of dv / dt in the switching process of each switch tube, the system electromagnetic interference is improved. Compared with the neutral point clamped (NPC) three-level circuit, the clamping diode is replaced by a switch tube, which solves the problem of uneven heat distribution.

[0046] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A metro flywheel energy storage system with direct current ice melting function, comprising a medium voltage looped network, a catenary, a running rail, and positive and negative busbars, characterized in that, Also include: The subway rectifier module, the medium voltage ring network AC voltage is reduced, and then the high efficiency rectification and voltage regulation technology outputs stable DC power; The flywheel energy storage module includes a converter cabinet, a contactor KM and a flywheel cabinet; the converter cabinet is connected with the flywheel cabinet through the contactor KM; the flywheel energy storage module is connected with the positive bus, the negative bus and the running rail respectively; the flywheel energy storage module converts the regenerative braking power into six-phase AC power through the converter cabinet, and converts the DC power into six-phase AC power to drive the permanent magnet synchronous motor; on the other hand, when the DC network voltage drops due to subway traction, the flywheel rotor drives the permanent magnet synchronous motor to slow down, and the stored mechanical energy is converted into electrical energy, and the generated six-phase AC power is converted into DC power by the converter cabinet and released to the catenary; The subway rectifier module is connected with the positive bus and the negative bus; the positive bus is connected with the catenary, and the negative bus is connected with the running rail; The converter cabinet is also connected with the catenary through a circuit breaker QF; the catenary is connected with the running rail through a remote short-circuit switch K3; The converter cabinet adopts two groups of three-phase active neutral point clamped three-level topology structure, one inductor in series and one capacitor in parallel, forming a BUCK type DC / DC circuit; the converter cabinet has six such bridge arms to form a six-way BUCK type DC / DC circuit; The converter cabinet has two output paths, one outputting six-phase AC power to control the on-off of the permanent magnet synchronous motor in the flywheel cabinet through the contactor KM; the other outputting six-phase DC power to control the on-off of the catenary through the circuit breaker QF; When the circuit breaker QF is closed, the contactor KM is turned off; When the circuit breaker QF is turned off, the contactor KM is closed.

2. The metro flywheel energy storage system with DC de-icing function according to claim 1, characterized in that, The flywheel energy storage module further includes a switch cabinet K1 and a disconnector cabinet K2, the converter cabinet is connected with the switch cabinet K1 and the negative bus through the disconnector cabinet K2, and the switch cabinet K1 is also connected with the positive bus.

3. The metro flywheel energy storage system with DC de-icing function according to claim 2, characterized in that, The two groups of three-phase active neutral point clamped three-level topology structure include group A and group B, which have the same structure; Group A includes three bridge arms, namely bridge arm A, bridge arm B and bridge arm C; it also includes inductors L1, L2 and L3, capacitors C1, C2, C3, C4 and C5. In the bridge arm A, the collector of the power switch Q3 is connected with the DC+ point, the emitter of the power switch Q3 and the collector of the power switch Q4 are connected, the emitter of the power switch Q4 and the collector of the power switch Q5 are connected with the a1 point, the emitter of the power switch Q5 and the collector of the power switch Q6 are connected, the emitter of the power switch Q6 is connected with the DC- point, the midpoint of the power switch Q3 and the power switch Q4 is connected with the collector of the power switch Q1; the emitter of the power switch Q1 and the collector of the power switch Q2 are connected with the a2 point, and the a2 point is connected with the midpoint O of the bus capacitor C1 and the bus capacitor C2; the midpoint of the power switch Q5 and the power switch Q6 is connected with the emitter of the power switch Q2; one end of the capacitor C1 is connected with the DC+ point, and the other end is connected with the neutral point O; one end of the capacitor C2 is connected with the DC- point, and the other end is connected with the neutral point O; the bridge arm A, the bridge arm B and the bridge arm C have the same structure; all the power switches are reversely connected with a diode, and the anode of each diode is connected with the emitter of the power switch, and the cathode of each diode is connected with the collector of the power switch; The connection point a1 in the bridge arm A corresponds to b1 in the bridge arm B, and corresponds to c1 in the bridge arm C; One end of the inductor L1 is connected with the a1 point in the bridge arm A, and the other end is connected with one end of the capacitor C5 and the contactor KM; one end of the inductor L2 is connected with the b1 point in the bridge arm B, and the other end is connected with one end of the capacitor C4 and the contactor KM; one end of the inductor L3 is connected with the c1 point in the bridge arm C, and the other end is connected with one end of the capacitor C3 and the contactor KM, and the other end of the capacitor C3, the other end of the capacitor C4 and the other end of the capacitor C5 are connected to a point.

4. The metro flywheel energy storage system with DC de-icing function according to claim 1, characterized in that, The subway rectification module comprises a step-down transformer, a rectification unit and a plurality of switches; One end of the step-down transformer is connected with a medium-voltage looped network, and the other end is connected with one end of the rectification unit; the other end of the rectification unit is connected with a positive bus and a negative bus respectively; the positive bus is connected with a contact network, and the negative bus is connected with a running rail.

5. An ice-melting energy storage method applied to the metro flywheel energy storage system with DC ice-melting function in claim 1, characterized in that, The method comprises the following steps: When the KM is closed and the QF is opened, the system starts the flywheel energy storage charging and discharging mode; in this mode, when the subway braking generates regenerative braking energy and the DC contact network voltage is raised, the regenerative braking energy that cannot be absorbed by adjacent vehicles is converted into six-phase alternating current through the converter, the DC power is converted into six-phase alternating current to drive the permanent magnet synchronous motor, and the flywheel rotor is accelerated to store the part of energy in the form of mechanical energy; when the subway traction causes the DC network voltage to drop, the flywheel rotor drives the permanent magnet synchronous motor to start to decelerate, the stored mechanical energy is converted into electrical energy, the generated six-phase alternating current is converted into DC power through the converter, and the DC power is released to the contact network, so that the energy-saving and voltage-stabilizing effects are achieved; When the QF is closed and the KM is opened, the system starts the DC ice melting mode; in this mode, the output DC power is output to the contact network, the contact network and the far end of the running rail are short-circuited through the switch K3, the switch is in a closed state in the DC ice melting mode, a loop is formed between the contact network and the running rail by the output DC power, the DC current flows through the contact network to generate Joule heat, and the effect of melting ice is achieved.

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