CN114649795A - Fault protection method and control system for input side of frequency converter system - Google Patents
Fault protection method and control system for input side of frequency converter system Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1216—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for AC-AC converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/34—Snubber circuits
Abstract
The invention discloses a fault protection method and a control system for an input side of a frequency converter system, wherein the fault protection method adopts a breaking fault frequency converter and a fault unit according to different fault types when partial fault occurs on the input side of the frequency converter system, so that the normal operation of the system is ensured; when the system is necessary to stop due to the fault, the operation parameters when the fault occurs are stored, and all frequency converters in the system are coordinated and associated to stop. The converter system input side fault protection control system includes: the system comprises a protection system communication unit, a fault detection unit, a logic control unit and a fault protection execution unit; the components in the fault protection system can be configured according to actual needs, and the fault protection system is convenient and flexible. Compared with the prior art, the invention has the beneficial effects that: the method has the advantages that the fault at the input side of the frequency converter system is effectively protected and processed, the requirement of the frequency converter system is better met, and the safety of the frequency converter system and the reliability of the system operation are improved.
Description
Technical Field
The invention relates to the field of frequency converters, in particular to a fault protection method and a control system for an input side of a frequency converter system.
Background
Currently, frequency converter systems composed of multiple frequency converters are becoming more and more widespread in practical applications. The process requirements of a complex production field can be completed through the cooperative associated control of a plurality of frequency converters. The power supply of the frequency converter system can be independent power supply of each frequency converter or unified power supply, so that when faults at the input side of the processing system are processed, different conditions need to be distinguished for fault processing.
In the normal operation process of the frequency converter, a three-phase power frequency power supply is adopted, when the power grid fluctuates, such as sudden power loss in a short time of voltage or transient voltage reduction caused by sudden input of a large load, if no measures are taken, energy on a capacitor can be consumed quickly due to the load at the motor side and the loss of the frequency converter, so that the voltage of the capacitor is reduced quickly, and when the bus voltage is lower than the undervoltage point of the frequency converter, the frequency converter can be caused to enter an uncontrolled shutdown mode.
At this time, if the shutdown process of different frequency converters in the frequency converter system is not controlled due to power failure, the actions of the different frequency converters do not keep coordination relevance, the overall operation of the frequency converter system is affected, and further accidents may occur.
After confirming that the power supply voltage reaches the starting voltage again, the frequency converter system enters a restarting state, and for some industrial production occasions needing continuous operation, the normal production operation of the frequency converter system can be influenced and unnecessary economic loss is caused due to the fact that the frequency converter system is stopped and restarted caused by the fluctuation of a power grid, so that some measures need to be taken to avoid the situations.
In summary, the input side fault protection method and the control system for the entire frequency converter system are becoming more and more concerned.
Disclosure of Invention
The invention aims to provide a fault protection method and a control system for an input side of a frequency converter system, which are used for solving the problem of protection when a fault occurs on the input side in the operation process of the frequency converter system consisting of a plurality of frequency converters. The main function of the input side of the frequency converter system is to supply power to the whole frequency converter system, and the frequency converter system can supply power to each frequency converter in the system independently or select uniform power supply. When the fault of the input side of the frequency converter system occurs, the type of the fault of the input side of the frequency converter system is determined by detecting external voltage and current data of the frequency converter system and voltage and current data of a direct current bus inside the frequency converter.
Referring to fig. 1, for each frequency converter 10 in the frequency converter system, a frequency converter system input side fault detection unit 20 and a frequency converter system input side fault protection unit 40 are connected thereto; and communicate with the systematic input side trouble communication unit 30 of the frequency converter, for when the systematic input side trouble of the frequency converter happens later, in the course of confirming the fault type, the fault detection data of the frequency converter oneself and systematic input side trouble detection unit of the frequency converter detect the data to provide the systematic input side trouble of the frequency converter to protect the logic control unit at the same time, increase the accuracy of the fault detection, avoid the misoperation; meanwhile, each unit of the fault protection system at the input side of the frequency converter system can be increased according to the condition of the frequency converter in the frequency converter system, so that the flexibility of the system is improved.
The fault protection method for the input side of the frequency converter system comprises the following steps of: when the frequency converter system is electrified, the basic resource table of each frequency converter in the frequency converter system is recorded to the fault protection logic control unit at the input side of the frequency converter system through the communication between the fault protection communication unit at the input side of the frequency converter system and the frequency converter system, and the basic resource table is used as a basis for the fault protection logic control unit at the input side of the frequency converter system to execute protection actions when a fault occurs; when the frequency converter system normally operates, the fault protection detection unit at the input side of the frequency converter system detects the operation state of each frequency converter in real time, and when the frequency converter system has an input side fault, the fault protection logic control unit at the input side of the frequency converter system analyzes the fault state and the number of the frequency converters with the fault, analyzes according to a frequency converter system basic resource table stored in the early stage, and determines the protection measures to be taken; the protection measures are executed by a fault protection execution unit at the input side of the frequency converter system, the current operation data of the frequency converter system is stored to a fault protection logic control unit at the input side of the frequency converter system, and meanwhile, an alarm is given to the outside; and after the fault is eliminated, the fault protection logic control unit on the input side of the frequency converter system recovers the frequency converter system on site and continues to operate.
The fault detection unit at the input side of the frequency converter system can perform fault detection on faults at the input side in the frequency converter system, and the fault detection comprises the following steps:
1) for a single frequency converter, the fault detection of the input side comprises input power supply voltage amplitude detection, input three-phase power supply open-phase detection, input power supply three-phase unbalance detection, direct-current bus voltage limit detection and direct-current bus current detection;
2) for a frequency converter system, the fault detection of the input side comprises the detection of the voltage of an inlet wire power supply and the detection of the inlet wire current of the input side; the number of the detection units actually included is increased or decreased according to the actual requirement of the frequency converter system, so that the running state of the input side of the system is ensured to be detected in real time.
The fault detection of the frequency converter system and the fault detection of the fault protection system at the input side of the frequency converter system can mutually verify, and as shown in fig. 3, the accuracy of fault judgment can be improved, and false operation is avoided.
Faults targeted by fault protection on the input side of the frequency converter system can be divided into short-time voltage sag faults and power failure faults. The protection measures taken against the short-time voltage drop fault mainly ensure that the frequency converter can normally operate without being influenced; for power failure, the adopted protection measures mainly ensure that the frequency converters in the frequency converter system can be in orderly shutdown or synchronous shutdown in mutual coordination and association, and adverse effects on the system caused by uncontrolled shutdown of the frequency converters in the system are avoided.
Under the condition that the frequency converter system needs to be stopped, the operation data of the frequency converter system during fault should be stored, and reference is provided for the recovery operation after the fault of the system is eliminated in the later period. The method for ensuring the frequency converter system to stop coordinately by adopting a common direct current bus system in the frequency converter system comprises the following steps: firstly, determining that a frequency converter system has power failure or short-time power failure, and forming a common direct current bus running system according to actual conditions by using a contactor between direct current bus capacitors of each frequency converter through a fault protection execution unit at the input side of the frequency converter system; secondly, reasonably avoiding unnecessary energy loss is considered, all unnecessary loss circuits are broken at the front end and the rear end of the circuit of the direct current bus capacitor in the main energy storage link according to actual needs, so that the frequency converter system only completes necessary operation when an input side fault occurs in a common direct current bus system, and other energy losses are reduced; furthermore, after the total energy storage of the direct-current bus of the frequency converter system is determined, the time for the frequency converter system to normally operate when a power failure occurs can be determined; and finally, after reserving corresponding allowance for the upper limit according to the running time, setting shutdown parameters of each frequency converter in the system, and ensuring that each frequency converter in the frequency converter system is shut down or enters a protection state according to the system instruction requirement. And meanwhile, alarming is carried out externally, the field operation data of the frequency converter system is stored, and data support is provided for the frequency converter system to recover operation.
The invention also provides a fault protection control system of the input side of the frequency converter system, which comprises the following units: the system comprises a communication unit of a protection system at the input side of a frequency converter system, a fault detection unit at the input side of the frequency converter system, a logic control unit of fault protection at the input side of the frequency converter system and a fault protection execution unit at the input side of the frequency converter system; the fault detection unit at the input side of the frequency converter system comprises fault detection at the input side inside the frequency converter and fault detection at the input side outside the frequency converter system; the input side fault protection logic control unit of the frequency converter system comprises a logic control system, a storage system and a peripheral operation unit; the fault protection execution unit at the input side of the frequency converter system executes fault protection on the frequency converter and the frequency converter system; and the fault protection communication unit at the input side of the frequency converter system is responsible for communication between the fault protection system at the input side of the frequency converter system and the frequency converter system.
Has the advantages that: the invention has the protection function on the input side of the frequency converter system, is easy to expand according to the requirements of the frequency converter system, provides a reasonable protection scheme for the fault protection on the input side of the frequency converter system, ensures that the frequency converter system can safely and efficiently operate, and provides data support for the system recovery after the fault occurs.
Drawings
The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, other drawings can be derived on the basis of the following drawings without inventive effort.
FIG. 1 is a schematic diagram of the input side fault protection control system of the frequency converter system of the present invention;
FIG. 2 is a schematic diagram of the working logic control flow of the input side fault protection method of the frequency converter system according to the present invention;
FIG. 3 is a schematic diagram of the fault judgment principle of the fault protection method for the input side of the frequency converter system according to the present invention;
FIG. 4 is a schematic diagram of a fault judgment process of the fault protection method for the input side of the frequency converter system according to the present invention;
FIG. 5 is a flow chart of fault analysis and processing of the input side fault protection method of the frequency converter system according to the present invention;
FIG. 6 is a schematic structural diagram of an input-side fault protection control system of a frequency converter system according to the present invention, wherein a single frequency converter constitutes a frequency converter system and the input-side fault protection control system protects the single frequency converter from occurring;
fig. 7 is a schematic structural diagram of the input side fault protection control system of the frequency converter system for protecting the frequency converter system composed of a plurality of frequency converter systems from the input side fault.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The fault protection method for the input side of the frequency converter system comprises the following steps as shown in fig. 2, and the specific implementation steps comprise:
step S201: after the frequency converter system is powered on and started, each frequency converter carries out self-checking, a fault protection communication unit at the input side of the frequency converter system establishes communication contact with each frequency converter in the frequency converter system, and the communication mode can be selected: 485 communication and Modbus communication, which are based on the communication mode used by the actual frequency converter system;
step S202: the frequency converter system and the frequency converter system input side fault protection logic control unit establish communication through the frequency converter system input side fault protection communication unit, and the basic operation parameters of the frequency converter are stored in the frequency converter system input side fault protection logic control unit, and the basic operation parameters of a single frequency converter comprise: rated power of each frequency converter, capacity of a direct current bus capacitor of each frequency converter, direct current bus voltage limit of each frequency converter and input side current limit of each frequency converter; recording all related data into a resource table corresponding to each frequency converter, storing the resource table in a designated storage unit in a fault protection logic control unit at the input side of the frequency converter system, and establishing a frequency converter system basic resource table;
further, the frequency converter system basic resource table in the frequency converter system input side fault protection logic control unit further includes: the number of frequency converters forming the frequency converter system and the linkage relation of each frequency converter in the system; the information is used as a basic resource table of the frequency converter system and a basic resource table of a single frequency converter to be respectively stored in a specified storage unit;
step S203: the basic operation parameters of the fault detection unit at the input side of the frequency converter system corresponding to each frequency converter in the frequency converter system are stored in the fault protection logic control unit at the input side of the frequency converter system, and the basic operation parameters of the fault detection unit at the input side of the frequency converter system comprise: the number of fault detection units on the input side of each frequency converter, the number of fault detection units on the input side inside the frequency converter and the number of fault detection units on the input side outside the frequency converter are respectively the same; the fault detection units on the input side of the frequency converter system among the frequency converters in the frequency converter system are numbered; all the information forms a basic resource table of a fault protection detection unit at the input side of the frequency converter, and the basic resource table is stored in a specified storage unit and provides basic data for protection actions when faults occur at the later stage;
step S204: the basic parameters of the fault protection execution unit at the input side of the frequency converter system corresponding to each frequency converter in the frequency converter system are stored in the fault protection logic control unit at the input side of the frequency converter system, and the basic parameters of the fault protection execution unit at the input side of the frequency converter system comprise: the number of fault protection execution units on the input side of each frequency converter, the number of fault protection execution units on the input side inside each frequency converter, and the number of fault protection execution units on the input side outside each frequency converter; the fault protection execution unit information of the input side of the frequency converter system and the fault protection execution unit information of the input side of the frequency converter system between two frequency converters in the frequency converter system form a fault protection execution unit basic resource table of the input side of the frequency converter system, and the fault protection execution unit basic resource table is stored in a specified storage unit to provide basic data for protection action when a fault occurs in the later period;
step S205: the method comprises the steps that running state information of a frequency converter system is received in real time through a communication unit of a fault protection system at the input side of the frequency converter system, detection data of a fault detection unit at the input side of the frequency converter system are received, real-time voltage and current parameters of a power supply at the input side of the frequency converter system and voltage and current data of a direct-current bus inside the frequency converter are sent to a fault protection logic control unit at the input side of the frequency converter system, and whether fault occurs at the input side of the frequency converter system and fault information are comprehensively judged;
step S206: if the input side of the frequency converter system has faults, the fault protection execution unit at the input side of the frequency converter system acts according to the fault information through the instruction of the fault protection logic control unit at the input side of the frequency converter system, the running state information of the frequency converter system is stored, the running state of each frequency converter in the frequency converter system is recorded when the faults occur, and necessary information is provided for the running after the faults are eliminated;
step S207: when the fault of the input side of the frequency converter system occurs, the fault protection of the input side of the frequency converter system can protect a single frequency converter and can also protect the whole frequency converter system, and the adopted measures are executed according to the instruction of a logic control unit of the input side of the frequency converter system;
step S208: after the fault of the input side of the frequency converter system occurs and the fault protection action of the input side of the frequency converter system is finished, alarming and waiting for fault removal; and after the fault is eliminated, the operation of the frequency converter system is recovered according to the operation state recorded during the fault.
The input side of the frequency converter system refers to a bridge type three-phase rectification circuit at the front end and a middle direct current bus capacitor circuit in the main circuit structure of the frequency converter. Aiming at the protection of an input side, the frequency converter generally comprises input open phase, input overvoltage and direct current bus voltage alarm.
In the direct current bus voltage protection, when overvoltage occurs, in order to prevent the direct current bus voltage from being too high, and causing damage to devices such as a capacitor or an IGBT, a frequency converter judges that a detection point of the overvoltage is on the direct current bus, and by taking the 3AC380-480V alternating current voltage level as an example, the alternating current incoming line voltage of which the normal direct current bus voltage is about 1.35 times is calculated, and is usually between DC 520V and DC 540V.
When the load inertia driven by the frequency converter is large and the speed is rapidly reduced or the frequency converter drags the potential energy load to be transferred, the actual rotating speed of a rotor of the motor is higher than the rotating speed output by the frequency converter to the motor, so that the motor is reversely dragged by the load, the motor is in a power generation running state, mechanical energy is converted into electric energy, the electric energy is fed back to a direct current bus of the frequency converter through an inverse bridge IGBT (insulated gate bipolar transistor) antiparallel diode of the frequency converter, and as the capacitance capacity of the direct current bus is fixed, the voltage of the direct current bus is increased along with the increase of feedback energy, and the device is possibly damaged when a certain limit value is reached, so that the overvoltage trend must be restrained at the moment.
The undervoltage protection detects that the voltage of a direct-current bus of the frequency converter is lower than a certain value, for example, the normal alternating-current voltage is 1.35 times, if the voltage is lower than 10%, the frequency converter can possibly generate undervoltage alarm or fault at the moment, the input side of the frequency converter system indirectly reflected by the undervoltage fault can possibly generate problems, and the undervoltage protection has the function of preventing the output power from being limited when the voltage of the direct-current bus of the frequency converter is too low, the working characteristic of a power device is changed, the control voltage is abnormal, and the hardware of the frequency converter is prevented from being damaged.
The input side overcurrent protection usually exceeds a certain limit value of rated output current of the frequency converter, is usually related to the model selection design of an IGBT power device, and sets different protection limit values according to different power sections of the frequency converter.
Inputting a default phase by a frequency converter: the input phase loss detection of the frequency converter is generally not directly measured, the judgment is carried out through the ripple of the voltage of the direct-current bus, when the load of the frequency converter runs, if the input phase loss of the frequency converter occurs, the ripple of the direct-current bus is increased, the load of a rectifier diode on the input side of the frequency converter is increased, and the condition that a rectifier bridge is damaged can be caused.
As shown in fig. 3, when a failure occurs in the inverter system itself and the input side fault protection system pair of the inverter system, mutual data confirmation is possible. The specific implementation steps are shown in FIG. 4, and the flow is as follows:
step S401: the frequency converter system and the fault protection system on the input side of the frequency converter system operate normally, communication is established between the frequency converter system and the fault protection system, and frequency converter operation data and real-time detection data are interacted.
Step S402: and detecting the voltage and the current of the direct-current bus of the frequency converter, judging whether the direct-current bus is abnormal or not, keeping a detection state if the direct-current bus is not abnormal, and further judging the fault position and the fault type when the direct-current bus is abnormal.
Step S403: judging whether the direct current bus of the frequency converter is abnormal or not, if so, entering a step S404, and protecting the power failure; if not, the flow proceeds to step S405 to further determine the point and type of failure.
Step S404: when the incoming line power supply occurs, corresponding protective measures should be taken when the power supply of the frequency converter is abnormal, and the fault power supply is disconnected and the subsequent operation is carried out.
Step S405: at the moment, whether the internal components of the frequency converter break down or not is determined through the detection unit of the frequency converter.
Step S406: when the device at the input side of the frequency converter system fails, the power supply of the frequency converter is abnormal, manual intervention is needed for recovery, and an external alarm is given.
Step S407: and when the short-time fault occurs, the voltage and the current of the bus can be continuously detected, and a short-time common direct-current bus system is formed, so that the normal work of the frequency converter system is ensured, and the normal work is realized after the fault is recovered.
The steps shown in fig. 5 can be performed when the common dc bus system is established, and the specific steps are as follows:
step S501: determining the total capacity of a direct current bus of the frequency converter system according to the data of the basic resource table of the frequency converter system; the direct current bus system is used as an energy storage link in the frequency converter, and the energy storage can be calculated according to a formula 1:
Pc ＝ UdcIc （1）
where Pc is the power injected into the bus capacitor, Ic is the current flowing through the bus capacitor, and Udc is the bus voltage. When the system normally operates, the direct current bus energy storage link of the frequency converter is fully charged, and energy is stored.
Step S502: in the event of a fault, the frequency converter system base resource table determines the system run time that the system energy storage can maintain, and thus determines the system down time.
Step S503: the converter system input side fault protection logic control unit confirms the converter information that breaks down in the converter system according to real time monitoring data and converter self-checking system of converter system input side fault detection unit, includes: determining the total power of the frequency converter with faults according to the fault type and the number of the frequency converters with faults; it is determined whether the system can maintain normal operation.
Step S504: the fault protection logic control unit at the input side of the frequency converter system determines the protection action to be taken, and the fault protection logic control unit at the input side of the frequency converter system protects the system to form a common direct-current bus system and gives an alarm to the outside; and the protection unit acts to break the unnecessary energy consumption unit, so that the normal implementation of the protection action of the system is ensured.
Step S505: and after the fault is eliminated, the normal operation of the frequency converter system is recovered, and the normal operation of the fault protection system at the input side of the frequency converter system is recovered.
The fault protection method for the input side of the frequency converter system is described below with reference to specific embodiments.
The first embodiment is as follows: the method for fault protection at the input side of the frequency converter system is described with reference to fig. 6 for a frequency converter system composed of a single frequency converter.
When the input side of a frequency converter system consisting of a single frequency converter fails, the contactors KM1, KM2, KM3 and KM4 can be controlled to act according to different positions of the failure, so that the frequency converter is protected.
When the power supply failure of the frequency converter is determined, KM1 action can be controlled to break the link between the frequency converter and the power supply, so that the power supply safety of the rectifying circuit and other systems of the frequency converter is ensured, and the frequency converter is not damaged due to power supply accidents; and meanwhile, the contactor KM4 can be actuated to ensure the energy storage of the frequency converter during shutdown, because only the frequency converter needs to be shut down at the moment, and the running state during fault is stored and serves as the field data storage for later recovery running.
When the fault of the rectifying circuit device is determined, the breaking contactor KM2 provides protection for a system power supply, the power supply fault caused by the fault of a frequency converter system can not be caused, and the fault range is enlarged. The contactor KM3 is controlled to act to protect the safety of a subsequent circuit, and at the moment, an external alarm is needed to protect a fault element.
When a direct current bus link fails, the contactor KM4 is controlled to act, normal operation of the sorting and pre-charging circuit is guaranteed, and meanwhile, an external alarm is given. And storing the operation parameters during the failure, and providing basic data for later system recovery operation.
Example two: referring to fig. 7, a method for protecting a converter system from a power failure at an input side of the converter system will be described.
As shown in fig. 7, in the frequency converter system composed of a plurality of frequency converters, the fault protection execution unit at the input side of the frequency converter system includes fault protection execution units between frequency converters, such as contactors KMO1-1 to KMO1-n in fig. 7, and the specific number can be adjusted according to the actual needs of the system.
According to the fault type judgment of the input side of the frequency converter system, when a power-shaking fault or a short-time power-down fault occurs, the number of the frequency converters with the fault can be firstly determined according to the steps shown in fig. 5. The number of the fault frequency converters and the number of the frequency converters in normal operation can be respectively determined at the moment.
The total direct-current energy storage of the frequency converter system can be calculated according to a formula 2:
total stored energy of P = P1+ P2+ … … + Pn (2)
Wherein the P total stored energy is the total stored energy of the frequency converter system; p1, P2 and P … … Pn are energy storage of each frequency converter in the frequency converter system; n is the total number of frequency converters in the frequency converter system.
The frequency converter in normal operation can provide normal energy for the system, and the total energy provided by the normal frequency converter can be calculated according to formula 3:
p energy = pwormal 1+ pwormal 2+ … … + pwormal m (3)
Wherein the P energy supply is the total energy storage of the frequency converter system; the power supply comprises a power supply system, a frequency converter system and a power supply system, wherein the frequency converter system comprises a frequency converter system and a frequency converter system, wherein Pnormal 1, Pnormal 2 and … … Pnormal m are energy storage of each frequency converter in the frequency converter system; and m is the number of the frequency converters which normally run in the frequency converter system.
At this time, the fault frequency converter in the frequency converter system is broken by the method in embodiment 1, and each unit in the frequency converter system can be ensured to normally operate.
According to the calculation of the formula 2 and the formula 3, the energy which can be maintained by the system is determined, a common direct current bus system meeting the requirement is established through a contactor of the KMO1-n, and the buffer circuit, the bleeder circuit and the filter circuit can be selected according to a conventional method and are not described herein.
And meanwhile, an external alarm is given, so that the fault is eliminated and the system is recovered to normally operate under the condition that the system is kept to operate. And at the moment, the direct-current bus link of the frequency converter system is powered through the frequency converter rectification link which normally works, so that the overall normal operation of the frequency converter system is maintained.
Example three: the method for protecting the input side of the frequency converter system from power failure is described with reference to fig. 7 for a frequency converter system composed of a plurality of frequency converters.
When the frequency converter system has power failure, all frequency converters in the frequency converter system need to ensure coordinated and associated shutdown. Determining the shutdown time of a frequency converter system, and according to the number of the frequency converters with faults, combining a basic resource table of the frequency converter system and the system maintenance energy determined by the formulas 2 and 3, calculating the energy required by the shutdown of a single frequency converter according to the formula 4:
wting = pding ═ ttting ═ U-ttng ═ ttg & (4)
Wherein W stop is energy required by the shutdown, P stop is power required by the shutdown, T stop is time required by the shutdown, U stop is the frequency converter supply voltage of the shutdown, and I stop is the supply current of the shutdown.
The total energy required for shutdown is then determined according to equation 5:
wtimel = wtimel 1+ wtimel 2+ … … + wtimel n (5)
W stop is total energy required by stopping, W stop n is energy required by stopping each frequency converter, and n is total number of the frequency converters in the frequency converter system.
At this time, the shutdown time of each frequency converter is respectively set according to the data in the frequency converter system resource table stored in the fault protection logic control unit at the input side of the frequency converter system, on the premise that the requirement of a formula 5 is met, namely the total energy of the frequency converter system meets the shutdown requirement.
The other operation steps are the same as the previous embodiment, a common direct current bus system is established, a fault unit is disconnected, the operation parameters of the system during fault are stored, an external alarm is given, and the frequency converter system provides operation data support after operation is recovered.
It should be noted that, in the present specification, each embodiment is described in a progressive manner, each specific embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other.
The fault protection method and the control system for the input side of the frequency converter system provided by the invention are described in detail, a specific example is applied in the text to explain the principle and the implementation mode of the invention, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. The fault protection method for the input side of the frequency converter system is characterized in that the frequency converter system consists of one or more frequency converters, and the number of the frequency converters in the frequency converter system is increased or reduced according to actual needs to form the frequency converter system meeting the needs; the fault protection method for the input side of the frequency converter system protects the fault of the input side of the frequency converter system aiming at the actual situation of the frequency converter system, and comprises the following steps:
after the frequency converter system is powered on and started, each frequency converter carries out self-checking, a fault protection communication unit at the input side of the frequency converter system establishes communication contact with each frequency converter in the frequency converter system, and the communication mode can be selected: 485 communication and Modbus communication, which are based on the communication mode used by the actual frequency converter system;
the frequency converter system and the frequency converter system input side fault protection logic control unit establish communication connection through the frequency converter system input side fault protection communication unit, and the basic operation parameters of the frequency converter are stored in the frequency converter system input side fault protection logic control unit, and the basic operation parameters of a single frequency converter comprise: rated power of each frequency converter, capacity of a direct current bus capacitor of each frequency converter, direct current bus voltage limit of each frequency converter and input side current limit of each frequency converter; recording all related data into a resource table corresponding to each frequency converter, storing the resource table in a designated storage unit in a fault protection logic control unit at the input side of the frequency converter system, and establishing a frequency converter system basic resource table;
the frequency converter system basic resource table in the frequency converter system input side fault protection logic control unit further comprises: the number of frequency converters forming the frequency converter system and the linkage relation of each frequency converter in the system; the information is used as basic data of a frequency converter system and a basic resource table of a single frequency converter to be respectively stored in a specified storage unit;
the basic operation parameters of the fault detection unit at the input side of the frequency converter system corresponding to each frequency converter in the frequency converter system are stored in the fault protection logic control unit at the input side of the frequency converter system, and the basic operation parameters of the fault detection unit at the input side of the frequency converter system comprise: the number of fault detection units on the input side of each frequency converter, the number of fault detection units on the input side inside the frequency converter and the number of fault detection units on the input side outside the frequency converter are respectively the same; the fault detection units on the input side of the frequency converter system among the frequency converters in the frequency converter system are numbered; all the information forms a basic resource table of a fault protection detection unit at the input side of the frequency converter, and the basic resource table is stored in a specified storage unit and provides basic data for protection actions when faults occur at the later stage;
the basic parameters of the fault protection execution unit at the input side of the frequency converter system corresponding to each frequency converter in the frequency converter system are stored in the fault protection logic control unit at the input side of the frequency converter system, and the basic parameters of the fault protection execution unit at the input side of the frequency converter system comprise: the number of fault protection execution units on the input side of each frequency converter, the number of fault protection execution units on the input side inside each frequency converter, and the number of fault protection execution units on the input side outside each frequency converter; the fault protection execution unit information of the input side of the frequency converter system, the fault protection execution unit information of the input side of the frequency converter system between two frequency converters in the frequency converter system, all data form a fault protection execution unit basic resource table of the input side of the frequency converter system, and the fault protection execution unit basic resource table is stored in a specified storage unit, so that basic data are provided for protection actions when faults occur in the later period;
the method comprises the steps that running state information of a frequency converter system is received in real time through a communication unit of a fault protection system at the input side of the frequency converter system, detection data of a fault detection unit at the input side of the frequency converter system are received, real-time voltage and current parameters of a power supply at the input side of the frequency converter system and voltage and current data of a direct-current bus inside the frequency converter are sent to a fault protection logic control unit at the input side of the frequency converter system, and whether fault occurs at the input side of the frequency converter system and fault information are comprehensively judged;
if the input side of the frequency converter system has faults, the fault protection execution unit at the input side of the frequency converter system acts according to the fault information through the instruction of the fault protection logic control unit at the input side of the frequency converter system, the running state information of the frequency converter system is stored, the running state of each frequency converter in the frequency converter system is recorded when the faults occur, and necessary information is provided for the running after the faults are eliminated;
when the fault of the input side of the frequency converter system occurs, the fault protection of the input side of the frequency converter system can protect a single frequency converter and can also protect the whole frequency converter system, and the adopted measures are executed according to the instruction of a logic control unit of the input side of the frequency converter system;
after the fault of the input side of the frequency converter system occurs and the fault protection action of the input side of the frequency converter system is finished, alarming and waiting for fault removal; and after the fault is eliminated, the operation of the frequency converter system is recovered according to the operation state recorded during the fault.
2. The input-side fault protection control method of the frequency converter system according to claim 1, wherein the input-side fault protection for the frequency converter system is based on a corresponding data resource table, and specifically comprises: the frequency converter system data resource table comprises the number of frequency converters forming the frequency converter system, and the work flow and the coordination relation among the frequency converters; the basic resource table of each frequency converter; a basic resource table of a fault protection unit communication unit at the input side of the frequency converter system; the basic resource table of the fault detection unit at the input side of the frequency converter system comprises basic information of the detection unit of each frequency converter and basic information of the fault detection unit among different frequency converters in the frequency converter system; the basic resource table of the fault protection execution unit at the input side of the frequency converter system comprises fault protection unit information of each frequency converter and fault protection unit information among the frequency converters in the frequency converter system; all resource tables are stored in a designated storage position in a fault protection logic control unit at the input side of the frequency converter system and are called in real time.
3. An input-side fault protection control method for a frequency converter system according to claim 1, characterized in that the following measures are taken for the input-side fault of the frequency converter system: when a fault occurs, determining the fault type of the input side of the frequency converter system and the protection measures to be taken according to the data of a fault detection system of the frequency converter system and a fault detection unit of the input side of the frequency converter system; when the system needs to be shut down, the normal operation time of the frequency converter system can be determined when the system has power failure according to an initial resource table of the frequency converter system and the capacity of a direct current bus capacitor of the frequency converter system; furthermore, when part of the frequency converters have faults and normally run, the system can be ensured to run stably or the coordinated and associated shutdown is ensured by reasonably distributing the direct-current bus voltage.
4. The input-side fault protection control method of the frequency converter system according to claim 1, wherein the input-side fault protection execution unit of the frequency converter system can protect a plurality of positions of the input side of the frequency converter system, and the protection method comprises the following steps:
the corresponding single frequency converter can break the circuit between the direct-current bus capacitor and the rectifying circuit, so that the breaking of the rectifying circuit and a subsequent direct-current bus capacitor circuit is ensured when the input side fails;
the connection part of the rectifying circuit and the power supply is subjected to breaking operation, so that the frequency converter is not influenced by external power supply faults;
for more than two frequency converter systems, when the input side of one frequency converter fails, the on-off of a contactor among the bus capacitors of the frequency converters in the frequency converter system can be controlled, so that the bus capacitors of the frequency converters with the failure can obtain working voltage through other frequency converters, and the frequency converters with the failure can continuously and normally work;
when the input sides of the frequency converters in the system have faults, the connection of all the frequency converters and the power supply of the frequency converters can be disconnected, and a common direct-current bus structure is formed in the frequency converter system, so that the frequency converter system can be synchronously or coordinately and correlatively started and stopped as required, the correlation of actions among the frequency converters in the system is ensured, and the continuous operation is ensured after the subsequent fault is recovered;
when a fault occurs, the current operation data of the frequency converter system is stored, and an external alarm is given.
5. The input-side fault protection control method of the frequency converter system according to claim 1, wherein effective basic operation data can be provided when the frequency converter system is restarted after the input-side fault of the frequency converter system is removed, and the method comprises the following steps: after the fault is completely eliminated, the fault protection execution unit at the input side of the frequency converter system can be recovered to a pre-fault operation state, and the normal continuous operation of the frequency converter system is ensured; the frequency converter system restores the previous operation state of the system according to the operation information before the fault, which is stored by the fault protection logic control unit at the input side of the frequency converter system; after the fault is eliminated, the corresponding protection unit on the input side of the frequency converter acts to recover to an unprotected state, and the operation of the frequency converter system is not influenced; and the fault detection unit at the input side of the frequency converter system continuously detects the fault at the input side of the frequency converter system.
6. The input side fault protection control system of the frequency converter system is characterized by comprising the following constituent units: the fault protection system comprises a fault protection communication unit at the input side of the frequency converter system, a fault detection unit at the input side of the frequency converter system, a fault protection logic control unit at the input side of the frequency converter system and a fault protection execution unit at the input side of the frequency converter system; the formed system can be expanded according to the requirements of actual sites.
7. The input-side fault protection control system of the frequency converter system according to claim 6, wherein the input-side fault protection logic control unit of the frequency converter system comprises: logic control, communication control, instruction input and output, alarm control, data acquisition and data storage; the logic control part comprehensively studies and judges the data of each detection unit to determine the fault type and the protection action of the fault protection execution unit at the input side of the frequency converter system; furthermore, each component part can be expanded as required to adapt to the actual requirement of the frequency converter system.
8. The input-side fault protection control system of a frequency converter system according to claim 6, wherein the functions of the input-side fault protection communication unit of the frequency converter system include: and the system is responsible for the communication connection between the frequency converter system and the fault protection system at the input side of the frequency converter system, so that the timely intercommunication of data is ensured, and the communication mode is selected according to the communication mode of the actual frequency converter system.
9. The input-side fault protection control system of the frequency converter system according to claim 6, wherein the input-side fault detection unit of the frequency converter system comprises the following functions: detecting the amplitude and phase of alternating current voltage, detecting direct current voltage, detecting the amplitude and phase of alternating current, detecting direct current and detecting unbalance of a three-phase power supply; the detection data of each detection unit is analyzed in a fault protection logic control unit at the input side of the frequency converter system, and the fault type is comprehensively judged; all detection units can be reasonably increased and decreased according to the requirements of the frequency converter system, and the normal operation of the frequency converter system is ensured.
10. The input-side fault protection control system of the frequency converter system according to claim 6, wherein the input-side fault protection execution unit of the frequency converter system comprises: after the communication is established with the output control part of the input side fault protection logic control unit of the frequency converter system, the breaking and closing operation can be executed, the main execution part is a contactor, the low-voltage part can also control an intermediate relay to complete the corresponding function, and the execution unit comprises a buffer circuit, a bleeder circuit and a filter circuit.
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| CN202011515136.8A CN114649795B (en) | 2020-12-21 | Input side fault protection method and control system of frequency converter system |
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| CN202011515136.8A CN114649795B (en) | 2020-12-21 | Input side fault protection method and control system of frequency converter system |
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