197results about How to "Reduce Harmonic Pollution" patented technology

This invention discloses a inversion method for photovoltaic parallel in network, which uses digital signal processor (DSP) as core, the power factor is one and having small harmonic pollution to electric network, said method is a high efficiency and high reliability inversion method.

The invention provides a triphase variable-frequency power supply with high power and an operating method thereof, belonging to the technical field of variable-frequency power supplies. The variable-frequency power supply comprises a triphase grid input circuit, a rectifying circuit, an inverter unit, an output transformer, a direct-current (DC) bus monitoring circuit, an inverter driving circuit, an inverter output monitoring circuit, a transformer output monitoring circuit, an output switch driving circuit, a variable-frequency power supply output monitoring circuit, a digital signal processor (DSP), a keyboard and display circuit, a communication circuit, a vibration detection circuit and a protection circuit, wherein the triphase grid input circuit is connected with the rectifying circuit; the rectifying circuit is connected with the inverter unit; the inverter unit is connected with the output transformer and the DSP by the inverter driving circuit; the output transformer is connected with an output end of the power supply; and an input end and an output end of the output transformer, the output end of the power supply and the output switch are connected with the DSP. The variable-frequency power supply operates under the control of software.

The invention discloses a reactive power control circuit of a single-phase photovoltaic inverter. The reactive power control circuit comprises a bus voltage supporting capacitor, a single-phase full-bridge inversion circuit, a filtering inductor, an EMC (Electro Magnetic Compatibility) filtering circuit, a sampling circuit, a power switch pipe driving circuit and a DSP (Digital Signal Processor), wherein the DSP consists of a PLL (Phase Locked Loop) control module, a voltage outer ring PI control module, a current inner ring PI feedforward control module and a sinusoidal PWM (Pulse-Width Modulation) wave sending control module, and an input signal of the sinusoidal PWM wave sending control module of the DSP further includes a current inner ring current given amount Ig. The invention further provides a reactive power control method of the single-phase photovoltaic inverter. The method not only can be used for judging whether the voltage Uac of a power grid is larger than zero, and comparing the absolute value of a PWM wave sending control input modulation wave Upwm with a given triangular carrier wave Uc, but also can be used for judging whether the given current inner ring current amount Ig is larger than zero. Not only can the conduction loss of a power switching tube be reduced, and the conversion efficiency of the inverter is improved, but also the current waveform can be continuous, an output harmonic wave is reduced, and the pollution on a harmonic wave of a power grid is reduced.

The invention relates to the technical field of wind power generation, in particular to a wind power generation-combined ordered charge and discharge coordinated control system of a pure electric vehicle. The system is characterized in that: information of each charging station is transmitted to a power grid dispatching center, the power grid dispatching center judges the state of the current power system to generate a corresponding charging control mode, and then, the information is transmitted to a charging station concentrated coordination monitoring system to carry out information interaction; the power gird dispatching center transmits a pitch peak instruction to each dynamic battery, namely a dynamic battery group, through a communication network of the charging station concentrated coordination monitoring system; and the dynamic battery group receives the pitch peak instruction to realize pitch peak and feeds back residual electric quantity to a power grid at the same time. According to the system disclosed by the invention, an advantage complementation relation among wind power generation, charge and discharge of the electric vehicle and power gird stabilization is realized and coordinated; the acceptability of wind and electricity is improved; the harmonic pollution caused by disordered charge of the pure electric vehicles and the adverse influence on the power grid are reduced to the greatest extent, and the utilization efficiency of wind and electricity and the stabilization level of the power grid are improved.

The invention is an energy feedback power unit used in series power unit-type high voltage inverter and implementing four-quadrant operating ability, and its control circuit comprises: filter circuit composed of three-phase capacitors and three-phase reactors, three-phase synchronous rectifier bridge composed of IGBTs, DC filter circuit composed of capacitors, unit inverter bridge composed of IGBTs, and synchronous rectification control circuit and unit inversion control circuit controlling the operating states of the three-phase synchronous rectifier bridge and unit inverter bridge, respectively. And it has rectifying and energy feedback functions, and simple structure, low losses, easy to implement, low-cost, having high power factor but no harmonic pollution to electric network. And the high voltage transformer composed by it has all functional characteristics of common high voltage transformers and ability to convert kinetic energy or potential energy into electric power to feed back to the electric network on the conditions of fast system braking or weight dropping.

The invention discloses a traction power supply device based on the PWM rectifier. The device comprises a transformer, a rectifier, a control panel, a host computer and a switching power supply. The invention is characterized in that: the rectifier is a PWM rectifier, the switching power supply employs an intelligent power module with high integration degree, the control panel utilizes CPLD for failure predication and pulse blocking protection and sends six paths of PWM pulses via optical fiber interfaces to actuate power switching tubes inside the PWM rectifier, the host computer is connected with the control panel via Ethernet network and serves for the state monitoring and fault diagnosis of the rectifier, the rectifier is conducted under the current decoupling control based on the synchronously-rotating dq coordinate system, utilizes the phase-locked loop to obtain power voltage synchronizing angles and then performs PI regulation of the d-axis current and the q-axis current respectively, and generates six paths of PWM pulses by means of space vector pulse-width modulation.

The invention provides a power electronic rectification transformer. An input is a three-phase or single-phase alternating current, and an output is a direct current. Each phase on the input side is formed by connecting a plurality of same power units in series, so that the requirement of different voltage levels can be met; and the output side is a three-phase or single-phase parallel output of all modules. Each power unit consists of four parts, namely a full control rectification circuit of an input level, a middle inversion circuit, a high-frequency transformer and a non-control rectification circuit of an output level. The power electronic rectification transformer can replace the conventional rectification transformer and the backward stage rectification device, has the characteristics of improving the quality of the power of electric distribution network, along with low cost, and can be widely used in fields of electrochemical electrolysis, traction, transmission, electroplating, charging, excitation, static electricity dust removal and the like.

The invention relates to a three-phase-to-five-phase double-stage matrix converter based on a Z source, which belongs to the technical field of power electronic converters and aims to overcome the problems that the traditional five-phase voltage source inverter is large in size, low in input side power factor and limited in service life of a frequency converter and causes serious pollutions to power grid harmonic waves and the existing matrix type converter is low in voltage transmission ratio. The matrix converter provided by the invention comprises a double-stage matrix type converter and a Z source network, wherein the double-stage matrix type converter is composed of a rectifier stage circuit and an inverter stage circuit; the Z source network is connected in series between the rectifier stage circuit and the inverter stage circuit; one end of a first capacitor of the Z source network is connected with one end of a first inductor to serve as a first input end; the other end of the first inductor is connected with one end of a second capacitor to serve as a first output end; the other end of the second capacitor is connected with one end of a second inductor to serve as a second input end; and the other end of the second inductor is connected with the other end of the first capacitor to serve as a second output end. The matrix converter provided by the invention is suitable for driving a five-phase motor.

The invention discloses a super-fast operating mechanism for a high-voltage switch, which comprises a permanent magnetic position-keeping auxiliary drive device (3) and a buffer and energy storage device (4), wherein, one end of a movable core push rod (36) of the permanent magnetic position-keeping auxiliary drive device (3) is connected with a tube-type push rod of the buffer and energy storage device (4); the super-fast operating mechanism is characterized in that the other end of the movable core push rod (36) of the permanent magnetic position-keeping auxiliary drive device (3) is connected with an electromagnetic eddy current repulsion main drive device (2) which is used for providing initial operating force for operating the switch; the permanent magnetic position-keeping auxiliary drive device is used for providing stable and reliable power when a switch contact moves to the position of 5mm and keeping the switch contact in position when the movement of the switch is over; the buffer and energy storage device is used for reducing the impact of the operating mechanism to the shell of the mechanism and the switch contact during the operating process and storing the energy in the form of spring energy for next switching operation .

A multi-object comprehensive control energy conservation device of a subway power supply system adopts a plurality of AC / DC converter modules with the controllable high power factor rectification to replace the conventional rectification circuit, so as to realize the bidirectional energy flow and effectively suppress the harmonic wave of the device by utilizing the high power factor rectification technique, wherein the plurality of AC / DC converter modules are further connected in parallel, so as to expand the capacity of the entire device. At the same time, one or more DC / DC converter modules which are connected in parallel are arranged at the part of the DC traction bus, so that the electric energy generated during the braking process of the train can be partially fed back to the electric network through the AC / DC converter module, and part of the electric energy can be stored in the independent condenser bank through the pressure boost of the DC / DC converter module. The device can fully recover and utilize the braking energy and overcome the shock to the electric network caused by the energy fed back instantaneously through part of the absorbed energy and the feedback energy.

The invention discloses a method for smoothing output power of a wind power station by utilizing an energy storage system. In the method, not only wind power is introduced to predict or rectify the output power of the wind power station, but an improved self-adaptive filtering algorithm is applied. Since the output power of the wind power station is rectified by predicting the wind power, the change rate of the output power of the wind power station is decreased, and the output power of the wind power station can meet standards to inject into a power grid. By employing the self-adaptive filtering algorithm, regarding to the input power in different time, time weight coefficient in an adaptive filtering structure can be automatically calculated according to the input, so that the defect that different input cannot correspond to different filtering time constant by utilizing a low pass filter smoothing method in the past can be overcome. After the smoothing method is employed to smooth the output power of the wind power station, the output voltage of the wind power station is kept stable, fluctuation and flicker of the power grid voltage is reduced, harmonic pollution is reduced and accidents are reduced.

The invention discloses an accumulator formation charging / discharging main circuit structure which can improve power factor and reduce the harmonic pollution to power network. The invention comprises a power supply which is a reversible DC power supply with an anode and a cathode respectively connected with a positive DC bus and a negative DC bus which are connected with at least one charging / discharging unit; each charging / discharging unit comprises a charging circuit which is connected with a reversible LED in parallel and a discharging circuit; the input terminal of the charging circuit is connected with the positive DC bus; the output terminal of the discharging circuit and the cathode output terminal of the charging / discharging unit are both connected with the negative DC bus; the output terminal of the charging circuit is connected with the input terminal of the discharging circuit and then connected with the anode output terminal of the charging / discharging unit. The power factor of the invention is close to 1; the invention greatly reduces the harmonic pollution to power network and saves energy resource.

The invention relates to a method and a device for controlling voltage zero crossing point current distortion of a totem-pole PFC. Input and output voltage information and inductance current information are sampled through a sampling module; error signals are compensated and adjusted through a voltage outer loop adjusting unit and a current inner loop adjusting unit; and finally the processed error signals are sent to a PWM modulator to generate a gating signal. The zero crossing point state of the input voltage of each half of the power frequency period is detected to be inserted into dead zone control and bipolar control; soft start of a main switch tube of a high-frequency bridge arm in the dead zone control stage is completed, and the inductance current is constrained without generating a pulse peak; and in the bipolar control stage, the current constraint condition also can be established under the condition that the input voltage is relatively low, so that the input current can be more effectively corrected to enable the input current to follow the input voltage. The device can be stably operated in a CCM control mode, and the problem of zero crossing point pulse is solved, so that the overall power factor value is improved, and the total harmonic distortion amount of the whole system is reduced.

The invention relates to a hybrid energy storage topological structure on the basis of an MMC (modular multilevel converter). The structure comprises a positive bridge arm and a negative bridge arm; the positive bridge arm is formed by sequentially connecting power conversion subunits 1 to n in series; one end of the positive bridge arm is connected with a high-voltage DC (Direct Current) positive bus bar and the other end of the positive bridge arm is connected to a high-voltage three-phase AC (Alternating Current) power grid by a current limiting reactor; the negative bridge arm is formed by sequentially connecting power conversion subunits n+1 to 2n in series; one end of the negative bridge arm is connected with a high-voltage DC negative bus bar and the other end of the negative bridge arm is connected to the high-voltage three-phase AC power grid by a current limiting reactor; each functional conversion subunit is formed by connecting a power conversion module, a potential isolation module and an energy storage module in series. According to the invention, various energy storage bodies are flexibly switched into a power system and an energy storage function and a service which are uninterrupted, high in quality, flexible to control and safe to operate are provided for the power system.

The invention discloses an electrostatic-precipitation pulse power supply control system, which comprises a major loop, a controller and a trigger driving sampling loop, wherein the major loop comprises a first loop which provides a continuous fundamental wave voltage for a dust remover, and a second loop which provides a discontinuous pulse voltage for the dust remover; the controller controls the fundamental wave voltage to be lower than full breakdown voltage of spark discharge inside the electric field of the dust remover; and the controller controls the pulse voltage to be 3-5 times of the fundamental wave voltage. The voltage output by the system is large; when the dust remover performs spark discharge, the turn-off time is not required; the field energy is quickly recovered; the back corona site can be overcome; the dust collection effect is obvious, in particular to small dust in the electrostatic precipitator; the working frequency is high; the power factor is large; a three-phase power supply is used for supplying power; the three-phase power grid is balanced, so that the harmonic pollution to the power grid is low, the volume and the weight of a transformer are reduced, and the consumable is saved.

The invention relates to storage battery charge and discharge circuit topology which comprises a first stage of circuit, a second stage of circuit and a digital signal processor (DSP) controller; the first stage of circuit comprises three phases of alternating current power grids and an inverter circuit; the inverter circuit is provided with six transistors of a three-phase bridge, and the second stage of circuit comprises a first conversion circuit, a transformer, a second conversion circuit and a battery; and the DSP controller controls the output voltage, the output current and the switching direction of the inverter circuit and two direct current-direct current (DC-DC) conversion circuits so as to control the charge or the discharge of the whole circuit. After the device is adopted, charge and discharge with unit power factor can be realized for a power grid side; the pollution to the power grid is little; through a certain control method, a pulse width modulation (PWM) rectifier can realize a scalable vector graphics (SVG) function; the output of a wide voltage scope can be realized; and the charge and discharge efficiency is higher.

The invention discloses a highly-reliable main circuit topological structure of a railway ground deflector. The highly-reliable main circuit topological structure comprises a rectification unit, an intermediate DC link and an inversion unit, wherein the rectification unit comprises a single-phase input multi-winding isolation transformer and N power modules on the rectification side. The primary side of the single-phase input multi-winding isolation transformer is connected with a railway traction network, and the secondary side of the single-phase input multi-winding isolation transformer is a plurality of electrically isolated multi-winding coils. Each multi-winding coil is connected with the AC input side of a rectification-side power module, the positive DC bus of the power module is in parallel with the positive DC bus of the intermediate DC link, and the negative DC bus of the power module is in parallel with the negative DC bus of the intermediate DC link. M electrical isolation converter sub-systems can be designed according to system power transformation requirements, power modules in the converter sub-systems are controlled through a carrier phase-shift PWM modulation strategy, cascade operation is carried out through the magnetic field of an isolation transformer, and the reliability of a converter is improved.

The invention discloses a mining high-voltage frequency converter with an explosion-proof type. The frequency converter comprises a phase-shifting transformer unit explosion-proof box and a power unit explosion-proof box; a phase-shifting isolation transformer and a heat radiation system are arranged in the phase-shifting transformer unit explosion-proof box; and a plurality of sets of power units, a control unit and a heat radiation system are arranged in the power unit explosion-proof box, wherein the plurality of sets of power units are in series connection. A high-tension side of the phase-shifting isolation transformer is in series connection with a three phase high voltage power network; the plurality of sets of power units are respectively connected with a low tension side of the phase-shifting isolation transformer; and the power units and the control unit are connected by a fiber. According to the invention, all assembling combination surfaces of the phase-shifting transformer unit explosion-proof box and the power unit explosion-proof box are constructed into sealing structures, so that an external environment is isolated from the phase-shifting transformer unit explosion-proof box and the power unit explosion-proof box; therefore, it can be avoided that corresponding chain explosions happen at high-risk occasions including a coal mine and the like and an explosion-proof effect is good. Besides, a control signal is transmitted by a fiber, so that an electrical isolation capability and an anti-electromagnetic interference performance are good.

The invention discloses a unipolar and bipolar hybrid modulation method for a single-phase voltage type PWM rectifier. By the adoption of the hybrid modulation manner with unipolar modulation and bipolar modulation combined, the problem that zero crossing point current distorts in the unipolar modulation process is solved, the sine degree of current is improved, and the problem of large switching losses in the bipolar modulation process is also solved. The purpose that harmonic pollution on a power grid from net-side unit power factors is low is achieved, and meanwhile the efficiency of the PWM rectifier can be improved.

The invention relates to a control device and a control method for the feedback device of a drive motor, in particular to a current vector control device and a control method driving a motor to return power. The current vector control device comprises an inverter circuit, a clarke converter module, a phase position and amplitude calculation module, a Park converter module, a PI adjuster, an anti-Park converter module, a space voltage vector modulation module and a driving circuit. The invention has the advantages that the invention realizes independent control of active current and reactive current, has short current response time and high control precision and power factor, can accurately track power grid voltage, has small pollution to power grid harmonic wave and the like.

The invention relates to a pulsed power supply for electrosparking in the machining field, in particular to a pulsed power supply with parallel high-energy capacitors for the electrosparking. The power supply comprises a rectification circuit (1), a power factor correction circuit (2), a voltage regulator circuit (3), a high-energy capacitor charge and discharge circuit (4), a voltage and current detection circuit (6), a machining control module circuit (7) and a PWM (Pulse-Width Modulation) control circuit (8). The pulsed power supply can provide approximately 150 V no-load breakdown voltages and 100-500 J discharge energy for an electrical discharge machining gap (5) in a single discharge process. The power supply adopts an accumulator structure, the parallel large-capacity capacitors are charged and discharged independently; the high energy stored in the capacitors is directly released to a discharge gap without passing through a current-limiting resistor, so that high instantaneous discharge energy and a strong discharge explosive force can be achieved; the power supply is applicable to difficult-to-machine materials such as ceramics and polycrystalline diamonds in the machining engineering; the current-limiting resistor with serious energy consumption is removed thoroughly; and the utilization rate of electrical energy can be increased by 2-3 times.

The invention relates to an automatic conversion device of an alternating current power supply, which belongs to the field of power electronics and aims to solve the problems that the requirement of power supply parameters of the power supply cannot be completely satisfied by the traditional converter, the output voltage stability is poor, and harmonic pollution to a power grid and magnetic pollution to an environment are easily caused due to potential safety hazard existing in manual operation of voltage ratio. The automatic conversion device comprises two stages of circuits, wherein the front stage is a Boost circuit having active power factor correction (APFC) function, the rear stage is a full-bridge inversion circuit, the full-bridge inversion circuit can be used for automatically switching output according to the grade of an input voltage, the Boost circuit can be used for boosting a wide-range alternating current into 400V direct current for output, and the full-bridge inversion circuit is used for automatically switching output voltage and frequency according to the input voltage. By the automatic conversion device, automatic switching of sine alternating current voltage between 220V / 50Hz and 110V / 60Hz can be achieved. The automatic conversion device is used for automatic switching of normal mains supply between 110V / 60Hz and 220V / 50Hz.

The invention discloses a control method for an aging power supply device, and belongs to the field of power electronic system control. The method comprises a control method of a single-phase AC / DC converter circuit, an open-loop control method adopted by an LLC resonant converter, and a control method of a bidirectional BUCK-BOOST converter circuit. Through the control method of the single-phaseAC / DC converter circuit, the DC bus voltage is kept constant, fluctuation of the power grid frequency and distortion of the grid connection current at the non-fundamental frequency are suppressed, andharmonic pollution to the power grid is reduced. Through the adoption of the open-loop control method, the series LLC resonant converter can work in an intermittent mode, the switching loss of the circuit is reduced, and meanwhile, the requirement of boosting between a direct-current bus and the input of the BUCK-BOOST converter circuit is also met. Through the control method of the bidirectionalBUCK-BOOST converter circuit, power sharing by a host and a slave in a constant-current mode is realized, switching tube driving signals of two BUCK-BOOST converters are subjected to phase shifting by 180 degrees to realize interleaved parallel connection, ripples of the current on the output side are reduced, and the quality of the output current is improved.

The invention discloses a high-power modular battery formation charging / discharging system, belonging to the field of battery formation charge / discharge. The system comprises an invertible DC (direct current) power module, a DC bus, a conversion charging / discharging module and a central control unit. The invertible DC power module adopts an automatic master-slave current sharing technology, can automatically configure the module number according to the system capacity, realizes automatic current sharing among the modules, and can inversion-feed the redundant electric energy back to the power grid so as to realize master-slave redundant invertible DC power module design; the DC bus transmits electric energy in the system; the conversion charging / discharging module is directly connected with the DC bus; by adopting the automatic master-slave current sharing technology, each module can form a loop independently for production, or multiple modules are freely connected in parallel to form a loop for production; and the central control unit is connected with the invertible DC power module and the conversion charging / discharging module through the bus, and can realize the functions of operation data acquisition, system resource allocation, module alternation coordination, system capacity reduction protection and the like.

The invention provides a vehicle-mounted charger control circuit and method, a charger and an electric vehicle. The vehicle-mounted charger control circuit comprises a filtering and rectification module, a power factor correction module, a half-bridge LLC resonant conversion module and a main control module, wherein the filtering and rectification module is used for converting an input alternating-current electric signal into a direct-current signal after filtering out an electromagnetic interference signal; the half-bridge LLC resonant conversion module is used for enabling switching tubes tooperate in a zero-voltage state so as to realize zero-voltage switching when the charger is charged; and the main control module is used for acquiring a resonant current zero-crossing point of the half-bridge LLC resonant conversion module and a voltage zero-crossing point of mid-point voltage of the half-bridge LLC resonant conversion module in real time. By comparing the potential difference between the two zero-crossing points, resonant network input impedance of the half-bridge LLC resonant conversion module is detected to ensure that the half-bridge LLC resonant conversion module works in an inductive area, and it is ensured that the charger works in a zero-voltage working area no matter load changes or the input voltage changes, thereby reducing harmonic pollution during charging ofthe charger.

The invention discloses a high-efficiency energy-saving charger, which is formed by sequentially connecting an input electromagnetic interference (EMI) module, a rectification filtering module 1, an active power factor corrector (APFC), a direct current (DC) / DC regulation module, a rectification filtering module 2 and an output EMI module. An over-voltage and over-current detector is connected between the rectification filtering module 1 and the APFC. A voltage and current power factor detector is connected between the rectification filtering module 2 and the output EMI module. A protection control circuit is also connected to the DC / DC regulation module, and is also connected with the over-voltage and over-current detector and the voltage and current power factor detector respectively. The high-efficiency energy-saving charger has the remarkably advantages of increasing a power factor of electrical equipment and reducing harmonic pollutions to a power grid.

The invention relates to a double PWM inverter with energy capable of bidirectionally flowing, which comprises an AC / DC module, a DC_Bus module, a DC / AC module and a new energy access unit, wherein the AC / DC module, the DC / AC module and the new energy access unit are connected with the DC_Bus module respectively. Compared with the prior art, the double PWM inverter has high power factor and low harmonic pollution, particularly the bidirectional flowing characteristic of the energy, and is suitable to be used in solar grid connection; and the novel power electronic technology can effectively reduce the device loss, improve the electric energy conversion efficiency of an electric energy transducer, inhibit most electric energy quality problems of a low-voltage distribution network, improve the power supply quality and the operation stability of the low-voltage distribution network, and provides satisfactory power supply sources, power supply stability and power supply electric energy quality for power supply users.

The invention discloses an integrated control system of an elevator, which comprises a master control module, an external signal module and a motor, wherein the external signal module and the motor are respectively and electrically connected with the master control module. The integrated control system is characterized in that the master control module comprises a logic control module and a drive control module; the logic control module is used for receiving and processing a signal from the external signal module; the drive control module is used for controlling the operation of the motor; and the master control module further comprises a power-off automatic flat-layer module used for controlling the elevator to be operated to the flat-layer position under emergency circumstances. The integrated control system with the technical scheme has the benefits that the logic control and the drive control to the elevator are organically combined, high integration is achieved, and the function of driving the elevator by a frequency converter is optimized fully.

The invention discloses an aging power supply device with parallel input and series output and belongs to the field of power electronic system control. The device is mainly composed of a host, a slave, a power supply module, a load device, a display panel, a control panel, a first fan, a second fan, a first thermistor and a second thermistor module, wherein the host is connected with an input endof the slave in parallel, the host is then connected with a power grid of the power supply module, the output of the host and the output of the slave are connected in series and then connected with the load device, and the outputs are connected in series and then connected with the load device as an output end of the aging power supply device, and thereby input-parallel output-series is realized.The aging power supply device is advantaged in that internal topological structures of the host and the slave are the same, the internal topological structures of the host and the slave respectively comprise three control circuits including a single-phase AC / DC converter circuit, an isolation LLC resonant converter circuit and a bidirectional BUCK-BOOST converter circuit, energy can flow in two directions, a power grid is not polluted, loss is small, cost is low, and reliability and practicability are good.

The invention provides an overhead contact system intelligent ice melting system. The overhead contact system intelligent ice melting system comprises an ice melting control device and N converters; one end of each converter is connected with a direct current overhead contact system, and the other end of each converter is connected with an alternating current network; the converters are used for entering rectification working conditions according to a first control signal and entering inversion working conditions according to a second control signal; the ice melting control device is used for obtaining the first control signal and the second control signal and sending the first control signal and the second control signal to the converter corresponding to an section needing ice melting, wherein the first control signal and the second control signal both include ice melting current values. Thus, energy circulation is formed among the converters in the rectification working conditions, the section needing ice melting of the direct current overhead contact system and the converters in the inversion working conditions and Between corresponding sections of the alternating current network, and current of the section needing ice melting of the direct current overhead contact system is not less than the ice melting current values.