Anti-interference electricity system of powder feeding frequency converter

Abstract

The invention relates to the technical field of frequency converter anti-interference electricity control, in particular to an anti-interference electricity system of a powder feeding frequency converter. Comprising a voltage monitoring module used for monitoring frequency converter bus voltage in real time; the voltage difference control module is used for controlling the system to access the electric equipment according to the frequency converter bus voltage; the boosting module is used for boosting the voltage of the energy storage module and converting direct current into alternating current; the isolation filtering module comprises a high-frequency isolation transformer, a high-frequency rectification filtering circuit and an isolation diode, the high-frequency isolation transformer is used for isolating the input circuit from the output circuit, the high-frequency rectification filtering circuit enables alternating current to become direct current and carries out smooth filtering on the output direct current, and when the isolation diode is in a cut-off state, the high-frequency rectification filtering circuit carries out smooth filtering on the output direct current; the support power supply is isolated from the frequency converter bus power supply. According to the technical scheme, the direct-current load of the anti-interference electricity system can share the existing energy storage battery, the problem of direct-current bus grounding or short-circuit protection is avoided, and the energy storage utilization rate of an industrial site is safely improved.

Description

Technical Field

[0001] The invention relates to the technical field of frequency converter anti-electrical shaking control, in particular to an anti-electrical shaking system for a powder feeding frequency converter. Background Art

[0002] There are many important equipments in chemical enterprises that need frequency conversion speed regulation, such as powder feeder. Due to the strong continuity of its production process, the frequency conversion equipment will stop for a short time when the power grid "shakes", and the whole process will be interrupted, causing huge economic losses to the enterprise. At the same time, during the operation of the low-voltage inverter, the power grid may shake or lose power. The short-term undervoltage caused by the shaking of the power grid will cause the inverter to trip and stop, affecting production.

[0003] In order to solve the above problems, energy storage modules such as independent batteries are generally connected to the inverter. When the inverter fails, the energy storage module instantly supplies power to the inverter to solve the problem of transient voltage in the power network caused by power fluctuations, thereby avoiding interruption of continuous production process and ensuring stable operation of production and equipment.

[0004] Using UPS (uninterruptible power supply) can indeed solve the problem of inverter power swing, but UPS loads are generally computers, communication equipment and electrical control circuits. If the motor is powered directly, there are some problems. When the motor starts, the starting current is generally 5-7 times the rated current, which means that a large-capacity UPS is required, and a large-capacity battery is also required, resulting in expensive investment, batteries needing to be activated every year, short service life, high maintenance costs, etc. And the UPS is connected in series in the circuit, once the UPS fails, it will affect the powder feeding system.

[0005] This solution utilizes existing energy storage modules and realizes DC load sharing of the anti-power sway system through voltage level and power conversion. However, sharing of energy storage by multiple loads also brings about the problem of DC bus grounding or short-circuit protection. Summary of the invention

[0006] The purpose of the present invention is to propose an anti-electrical sway system for a powder feeding inverter. This technical solution can enable the DC load of the anti-electrical sway system to share the existing energy storage battery, avoid the problem of DC bus grounding or short-circuit protection, and safely improve the utilization rate of industrial on-site energy storage.

[0007] To achieve the above purpose, the present invention provides a basic solution: a powder feeding inverter anti-electrical shaking system, comprising: Voltage monitoring module, used to monitor the inverter bus voltage in real time; The pressure difference control module is used to control the access of electrical equipment according to the inverter bus voltage control system; A boost module, used to boost the voltage of the energy storage module and convert direct current into alternating current; The isolation and filtering module includes a high-frequency isolation transformer and a high-frequency rectification and filtering circuit. The high-frequency isolation transformer is used to isolate the input and output circuits. The high-frequency rectification and filtering circuit converts alternating current into direct current and performs smooth filtering on the output direct current.

[0008] Beneficial effects of the basic solution: The high-frequency isolation transformer can electrically isolate the input and output, and the isolation diode can further isolate the supporting power supply from the inverter bus power supply when it is in the cut-off state. No matter which side of the high-frequency isolation transformer fails, it will not affect the other side and the equipment connected to the other side, and will not affect the safe operation of the DC energy storage module. The voltage detection module detects the frequency conversion bus voltage to monitor whether the grid voltage has a power shake event. When the grid shakes, the pressure difference control module can be used to control the system to timely access the required protection device, thereby protecting the powder feeder and other equipment from voltage fluctuations and short circuits.

[0009] By boosting the energy storage module through the boost module and converting DC power into AC power for transmission, it can be more adaptable to long-distance transmission and make full use of the existing energy storage modules. At the same time, it can also reduce voltage loss and realize energy storage sharing among multiple energy storage modules. It can also avoid DC bus grounding or short-circuit protection problems caused by shared energy storage. The high-frequency rectification and filtering circuit can convert AC power into DC power to power the required protection equipment. At the same time, it can also eliminate high-frequency interference and noise and improve signal quality.

[0010] As a preferred solution, the voltage monitoring module includes a power quality monitor, which monitors by collecting DC bus voltage parameters of the inverter.

[0011] The power quality monitor can monitor the DC bus voltage parameters of the inverter in real time, promptly discover and solve the problem of voltage instability, and monitor the DC bus voltage of the inverter instead of directly monitoring the grid voltage. This can avoid the instantaneous grid voltage drop from having a substantial impact on the power supply equipment, but avoid the system misconnection event caused by the voltage change detected by the voltage monitoring module, so that the system can provide support more timely and accurately.

[0012] As a preferred solution, the pressure difference control module includes a switch device, and the access state of the system is controlled by the switch device being in an off state or an on state.

[0013] Using switch devices to control the access status of the system can further isolate and protect both sides of the system and improve the safety of the system.

[0014] As a preferred solution, the boost module includes a full-bridge PWM circuit capable of performing DC / DC conversion.

[0015] The full-bridge PWM circuit can convert DC power into high-frequency AC power and generate a stable output voltage, providing reliable support for the inverter.

[0016] As a preferred solution, it also includes an output protection module, which includes a reverse protection diode and a fuse.

[0017] The output protection module can prevent the system from damaging the protected equipment, the reverse protection diode can avoid damage caused by reverse connection of the line, and the fuse can quickly cut off the circuit when a short circuit, overload or abnormal situation occurs in the circuit to protect the circuit from damage to the protected equipment.

[0018] As a preferred solution, a support timing module is also included, and the support timing module is electrically connected to the pressure difference control module for managing the support time of the system.

[0019] The support timing module manages the support time of the system so that the system can provide support more reasonably, ensuring that the protected equipment can receive effective support and protecting the security of the system itself.

[0020] As a preferred solution, the support timing module includes a shortest support timing sub-module and a longest support timing sub-module. The shortest support timing sub-module is used to set the shortest support timing duration, and the longest timing duration sub-module is used to set the longest support timing duration. The shortest support timing duration and the longest support timing duration form a support timing duration threshold range.

[0021] By setting the shortest support timing duration, it can be ensured that the powder-feeding inverter anti-electrical shaking system can cover the power grid shaking time, avoiding the support equipment from stopping operation when the power grid shaking has not stopped; by setting the longest support timing duration, on the one hand, it can avoid the powder-feeding inverter anti-electrical shaking system providing meaningless support when the power grid has not been restored for a long time, causing other equipment to stop operating; on the other hand, the support time of the powder-feeding inverter anti-electrical shaking system also has requirements for the capacity of the energy storage module. Setting the longest support timing duration can protect the energy storage module, avoid the energy storage module being exhausted due to each support, and reduce the life of the energy storage module. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a circuit diagram of the anti-electrical shaking system of the powder feeding inverter. DETAILED DESCRIPTION

[0023] The technical solution of this application is further described in detail below through specific implementation methods: Embodiment 1 like Figure 1The anti-sway system of the powder feeding inverter shown in the figure maintains the operation of the variable frequency load through the DC power supply circuit. The system includes a pressure difference control module, a voltage detection module, a boost module, an isolation filter module, an energy storage module, and an output protection module.

[0024] The pressure difference control module includes a controller and a switch device, which are used to control the opening and closing of the system.

[0025] The voltage monitoring module is used to monitor the inverter bus voltage in real time. It is preferred to use a power quality monitor to collect the DC bus voltage parameters of the inverter for monitoring.

[0026] The boost module includes a full-bridge PWM circuit and is capable of performing DC / DC conversion.

[0027] The isolation filter module includes a high-frequency isolation transformer, a high-frequency rectifier filter circuit, and an isolation diode. The high-frequency isolation transformer can isolate the input and output circuits to prevent the direct transmission of voltage and current, thereby protecting the powder feeder and other equipment from voltage fluctuations and short circuits. The high-frequency rectifier filter circuit can smooth and filter the input and output voltage and current, converting AC power into DC power, eliminating high-frequency interference and noise, and improving the quality of electric energy. The isolation diode can be in the cut-off state when the anti-sway system of the powder feeder inverter enters the hot standby state, so that the support power supply and the inverter bus power supply are further isolated.

[0028] The output protection module includes a reverse connection protection diode and a fuse. In this embodiment, both the positive and negative electrodes of the system output end are provided with a reverse connection protection diode and a fuse.

[0029] The system output terminal is connected to the terminal of the inverter DC bus on the load side. The inverter is normally powered by three-phase AC. When the three-phase AC voltage is normal, the inverter anti-sway system enters the hot standby state, and the isolation diode in the system is cut off to isolate the support power supply from the inverter bus power supply.

[0030] When the grid voltage drops, the bus voltage on the DC side of the inverter will also decrease.

[0031] When the bus voltage is lower than DC500V, the anti-power sway system of the powder-feeding inverter starts to supply power to the DC bus of the inverter to ensure the normal operation of the inverter part of the inverter, and then to ensure the stable operation of the load it carries, and avoid device shutdown accidents caused by temporary voltage drops.

[0032] When the inverter bus voltage is normal, the boost module PWM signal is turned off, the switch device inside the pressure difference control module is cut off, the device enters the hot standby state, and the inverter is powered normally by three-phase AC or photovoltaic power.

[0033] When the AC voltage drops temporarily, the voltage detection module detects that the inverter bus voltage drops and meets the switch device conduction conditions inside the voltage difference control module. The anti-sway system automatically starts to operate, that is, the boost module PWM signal is turned on, and the DC voltage input by the energy storage module is boosted through the boost module, so that the DC power is inverted into high-frequency AC power, and the stable DC 500V is output in parallel to the DC bus of the inverter to provide voltage support for it, ensuring the normal operation of the inverter part of the inverter, so that the motor at the rear end of the inverter can work normally, and the support timing starts. After the power grid returns to normal, the devices inside the voltage difference control module are turned off, the boost module PWM signal is turned off, and the anti-sway system of the powder inverter automatically exits the support, and the timing ends. It enters the hot standby state again to prepare for the next voltage drop or short interruption in the power grid.

[0034] Embodiment 2 In this embodiment, a support timing module is also included. The support timing module is electrically connected to the pressure difference control module and is used to manage the support time of the anti-electrical shaking system of the powder feeding inverter.

[0035] The support timing module includes a shortest support timing submodule and a longest support timing submodule. The shortest support timing submodule is used to set the shortest support timing duration, and the longest timing duration submodule is used to set the longest support timing duration. The shortest support timing duration and the longest support timing duration form a support timing duration threshold range.

[0036] Setting the shortest support timing duration can ensure that the anti-power swing system of the powder feeding inverter can cover the power grid power swing time, avoiding the support equipment from stopping operation when the power grid power swing has not stopped.

[0037] Setting the maximum support timing duration can, on the one hand, avoid meaningless support for the powder inverter anti-power swing system when other equipment stops operating due to long-term failure of power grid restoration; on the other hand, the support duration of the powder inverter anti-power swing system also has requirements on the capacity of the energy storage module. Setting the maximum support timing duration can protect the energy storage module, avoid energy depletion of the energy storage module due to each support, and reduce the life of the energy storage module.

[0038] Embodiment 3 The support timing module will use the real-time data collected by the voltage detection module to accurately determine the start and end time of the power grid power fluctuation, and record the duration of the power grid power fluctuation. The shortest support timing submodule will obtain the reference benchmark value of the shortest support timing duration based on the historical power grid power fluctuation duration.

[0039] The support timing module will also collect the energy storage capacity and efficiency of the energy storage module, and set the energy storage impact weight value accordingly; at the same time, it will also collect the temperature of the energy storage module and set the temperature impact weight value accordingly; in addition, it will also set the aging impact weight value according to the historical support times and support duration of the energy storage module. The longest support timing submodule will weight the energy storage impact weight value, temperature impact weight value and aging impact weight value to obtain the reference benchmark value of the longest support timing duration.

[0040] When the next power grid shake occurs, the shortest support timing submodule and the longest support timing submodule can quickly calculate the shortest support time and the longest support time according to the shortest support timing duration reference benchmark value and the longest support timing duration reference benchmark value respectively, and combine the actual detection value of the voltage detection module, thereby providing more accurate support timing information for the entire system.

[0041] The above contents are only embodiments of the present invention. The common sense such as the known specific structures and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field to which the invention belongs before the application date or the priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for the ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to explain the content of the claims.

Claims

1. The anti-sway system of the powder feeding inverter is characterized by: include: Voltage monitoring module, used to monitor the inverter bus voltage in real time; The pressure difference control module is used to control the access of electrical equipment according to the inverter bus voltage control system; A boost module is used to boost the voltage of the energy storage module and convert direct current into alternating current; The isolation and filtering module includes a high-frequency isolation transformer, a high-frequency rectification and filtering circuit and an isolation diode. The high-frequency isolation transformer is used to isolate the input and output circuits. The high-frequency rectification and filtering circuit converts AC power into DC power and smoothes and filters the output DC power. When the isolation diode is in a cut-off state, the supporting power supply is isolated from the inverter bus power supply.

2. The anti-electrical shaking system of the powder feeding inverter according to claim 1 is characterized in that: The voltage monitoring module includes a power quality monitor, which monitors by collecting the DC bus voltage parameters of the inverter.

3. The anti-electrical shaking system of the powder feeding inverter according to claim 1 is characterized in that: The pressure difference control module includes a switch device, and the access state of the system is controlled by the switch device being in an off state or an on state.

4. The anti-electrical shaking system of the powder feeding inverter according to claim 1 is characterized in that: The boost module includes a full-bridge PWM circuit and is capable of performing DC / DC conversion.

5. The anti-electrical shaking system of the powder feeding inverter according to claim 1 is characterized in that: It also includes an output protection module, which includes a reverse connection protection diode and a fuse.

6. The anti-electrical shaking system of the powder feeding inverter according to claim 1 is characterized in that: It also includes a support timing module, which is electrically connected to the pressure difference control module and is used to manage the support time of the system.

7. The anti-electrical shaking system of the powder feeding inverter according to claim 6 is characterized in that: The support timing module includes a shortest support timing submodule and a longest support timing submodule. The shortest support timing submodule is used to set the shortest support timing duration, and the longest timing duration submodule is used to set the longest support timing duration. The shortest support timing duration and the longest support timing duration form a support timing duration threshold range.

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