CN114649795B - Input side fault protection method and control system of frequency converter system - Google Patents
Input side fault protection method and control system of frequency converter system Download PDFInfo
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- CN114649795B CN114649795B CN202011515136.8A CN202011515136A CN114649795B CN 114649795 B CN114649795 B CN 114649795B CN 202011515136 A CN202011515136 A CN 202011515136A CN 114649795 B CN114649795 B CN 114649795B
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Classifications
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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
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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 faults occur on the input side of the frequency converter system, so that the normal operation of the system is ensured; when the system has to be shut down due to the fault, the operation parameters in the fault are stored, and all frequency converters in the system are coordinated and associated to be shut down. The input side fault protection control system of the frequency converter system comprises: 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 input side fault 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 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, a frequency converter system consisting of a plurality of frequency converters is increasingly widely used in practical applications. The process requirements of complex production sites can be completed through the cooperative association control of a plurality of frequency converters. The power supply of the frequency converter system can be independent power supply or unified power supply of each frequency converter, so that when the input side of the processing system fails, the processing of the failure needs to be performed under different conditions.
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 failure in a short time of voltage or sudden drop of the power grid voltage caused by sudden input of a large load, if no measures are taken, the energy on the capacitor can be quickly consumed due to the load on the motor side and the loss of the frequency converter, so that the voltage of the frequency converter drops rapidly, 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 is uncontrolled due to power failure of different frequency converters in the frequency converter system, actions among the different frequency converters do not keep coordination relevance, so that the overall operation of the frequency converter system is affected, and further accidents are likely to 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 due to the fact that the frequency converter system is stopped and restarted caused by fluctuation of a power grid, so that unnecessary economic loss is caused, and measures are needed to be taken to avoid the occurrence of the situations.
In summary, the input side fault protection method and the control system of the overall inverter system become a practical problem that is getting more and more attention.
Disclosure of Invention
The invention aims to provide a method and a control system for protecting input side faults of a frequency converter system, which are used for solving the protection problem when the input side faults occur in the operation process of the frequency converter system formed by 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 unified power supply. When the input side fault of the frequency converter system occurs, the type of the input side fault 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, there are a frequency converter system input side fault detection unit 20 and a frequency converter system input side fault protection unit 40 connected thereto; the fault detection data of the frequency converter and the detection data of the fault detection unit of the input side of the frequency converter system are simultaneously provided for the fault protection logic control unit of the input side of the frequency converter system in the process of determining the fault type when the fault of the input side of the frequency converter system occurs in the later stage, so that the accuracy of fault detection is improved and misoperation is avoided; meanwhile, each unit of the input side fault protection system 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: when the frequency converter system is electrified, the basic resource table of each frequency conversion in the frequency converter system is recorded into the frequency converter system input side fault protection logic control unit through the communication between the frequency converter system input side fault protection communication unit and the frequency converter system, and the basic resource table is used as the basis for the frequency converter system input side fault protection logic control unit to execute protection action when faults occur; when the frequency converter system normally operates, an input side fault protection detection unit 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, an input side fault protection logic control unit of the frequency converter system analyzes the fault state and the number of the frequency converters with faults, and the frequency converters are analyzed according to a frequency converter system basic resource table stored in the prior stage to determine the protection measure to be adopted; the protection measures are executed by a fault protection executing unit at the input side of the frequency converter system, and the operation data of the current frequency converter system is saved to a fault protection logic control unit at the input side of the frequency converter system, and simultaneously, an alarm is given; after the fault is removed, the input side fault protection logic control unit of the frequency converter system restores the frequency converter system on site and continues to operate.
The input side fault detection unit of the frequency converter system can perform fault detection on an input side fault in the frequency converter system, and the fault detection comprises:
1) For a single frequency converter, input side fault detection comprises input power supply voltage amplitude detection, input three-phase power supply open-phase detection, input power supply three-phase imbalance detection, direct current bus voltage limit detection and direct current bus current detection;
2) For a frequency converter system, input side fault detection comprises incoming line power supply voltage detection and input side incoming line current detection; 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 be mutually verified, as shown in fig. 3, the accuracy of fault judgment can be improved, and misoperation is avoided.
Faults aimed at by fault protection of the input side of the frequency converter system can be classified into short-time voltage drop faults and power failure faults. The protection measures adopted for short-time voltage drop faults mainly ensure that the frequency converter can normally operate unaffected; for the power failure, the protection measures adopted mainly ensure that the frequency converters in the frequency converter system can be mutually coordinated and associated to orderly shutdown or synchronously shutdown, so that adverse effects on the system due to uncontrolled shutdown of the frequency converters in the system are avoided.
Under the condition that the frequency converter system is required to be stopped, the operation data of the frequency converter system during failure should be saved, and a reference is provided for the recovery operation after the later system failure is removed. The common direct current bus system is adopted in the frequency converter system so as to ensure that the frequency converter system is in coordination with the shutdown, and the method 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 operation system according to actual conditions by a direct current bus capacitor contactor of each frequency converter through a frequency converter system input side fault protection execution unit; secondly, considering reasonable avoidance of unnecessary energy loss, breaking all unnecessary loss circuits at the front and rear ends 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 to form a common direct current bus system, and other energy loss is reduced; further, after the total energy storage of the direct current bus of the frequency converter system is determined, the time that the frequency converter system can normally operate when the power failure occurs can be determined; and finally, after reserving a corresponding allowance for the upper limit according to the running time, setting shutdown parameters of all the frequency converters in the system, and ensuring that all the frequency converters in the frequency converter system are shut down or enter a protection state according to the system instruction requirement. And simultaneously, the alarm is given to the outside, the field operation data of the frequency converter system is saved, and the data support is provided for the recovery operation of the frequency converter system.
The invention also provides a fault protection control system of the input side of the frequency converter system, which comprises the following units: the frequency converter system input side protection system communication unit, the frequency converter system input side fault detection unit, the frequency converter system input side fault protection logic control unit and the frequency converter system input side fault protection execution unit; the input side fault detection unit of the frequency converter system comprises fault detection of an internal input side of the frequency converter and fault detection of an external input side of 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; the input side fault protection communication unit of the frequency converter system is responsible for the communication between the input side fault protection system of the frequency converter system and the frequency converter system.
The beneficial effects are that: the invention has the protection function of 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 of the input side of the frequency converter system, ensures that the frequency converter system can safely and efficiently operate, and also provides data support for the recovery of the system after the fault occurs.
Drawings
The invention will be further described with reference to the accompanying drawings, in which embodiments do not constitute any limitation of the invention, and other drawings can be obtained by one of ordinary skill in the art without inventive effort from the following drawings.
FIG. 1 is a schematic diagram of an input side failsafe control system of a frequency converter system of the present invention;
FIG. 2 is a schematic diagram of a working logic control flow of a method for protecting an input side fault of a frequency converter system according to the present invention;
FIG. 3 is a schematic diagram of a failure judgment principle of a failure protection method for an input side of a frequency converter system according to the present invention;
FIG. 4 is a schematic diagram of a fault determination flow of a fault protection method for an input side of a frequency converter system according to the present invention;
FIG. 5 is a flow chart of a fault analysis and processing method for protecting the input side fault of the frequency converter system according to the present invention;
FIG. 6 is a schematic diagram of a system for protecting an input side fault of a frequency converter system according to the present invention when a single frequency converter is used to form the frequency converter system;
Fig. 7 is a schematic structural diagram of an input side fault protection control system of a frequency converter system for protecting input side faults of a plurality of frequency converter systems.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the 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, wherein the specific implementation steps comprise:
Step S201: after the frequency converter system is electrified and started, each frequency converter carries out self-checking, the fault protection communication unit at the input side of the frequency converter system establishes communication connection with each frequency converter in the frequency converter system, and the communication mode is selectable: 485 communication and Modbus communication, which is based on a communication mode used by an actual frequency converter system;
Step S202: the frequency converter system establishes communication with the frequency converter system input side fault protection logic control unit through the frequency converter system input side fault protection communication unit, stores basic operation parameters of the frequency converter into the frequency converter system input side fault protection logic control unit, wherein 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 current limit value of the input side of each frequency converter; all relevant data are recorded into a resource table corresponding to each frequency converter, and are stored in a designated storage unit in a fault protection logic control unit at the input side of the frequency converter system, so that a basic resource table of the frequency converter system is established;
further, the base resource table of the frequency converter system in the fault protection logic control unit of the input side of the frequency converter system further comprises: the number of frequency converters forming a frequency converter system, and the linkage relation of all the frequency converters 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 designated storage unit;
Step S203: the basic operation parameters of the input side fault detection unit of the frequency converter system corresponding to each frequency converter in the frequency converter system are stored in the input side fault protection logic control unit of the frequency converter system, and the basic operation parameters of the input side fault detection unit of the frequency converter system comprise: the number of fault detection units at the input side of each frequency converter, the number of fault detection units at the input side of the frequency converter and the number of fault detection units at the external input side of the frequency converter; the number of the fault detection unit at the input side of the frequency converter system among all frequency converters in the frequency converter system; 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 designated storage unit to provide basic data for protection actions in the later fault;
Step S204: the basic parameters of the input side fault protection execution unit of the frequency converter system corresponding to each frequency converter in the frequency converter system are stored in the input side fault protection logic control unit of the frequency converter system, and the basic parameters of the input side fault protection execution unit of the frequency converter system comprise: the number of fault protection execution units at the input side of each frequency converter, the number of fault protection execution units at the input side of each frequency converter and the number of fault protection execution units at the external input side of each frequency converter; the method comprises the steps that input side fault protection execution unit information of a frequency converter system is stored in a designated storage unit, and basic data is provided for protection actions when faults occur in the later period;
Step S205: receiving running state information of the frequency converter system in real time through a communication unit of the frequency converter system input side fault protection system, receiving detection data of the frequency converter system input side fault detection unit, and sending real-time voltage and current parameters of a frequency converter system input side power supply and voltage and current data of a direct current bus inside the frequency converter to a frequency converter system input side fault protection logic control unit to comprehensively judge whether the frequency converter system input side has faults and fault information;
Step S206: if the input side of the frequency converter system fails, the input side fault protection executing unit of the frequency converter system acts according to the fault information through the instruction of the input side fault protection logic control unit of the frequency converter system, meanwhile, the running state information of the frequency converter system is stored, the running state of each frequency converter in the frequency converter system when the fault occurs is recorded, and necessary information is provided for the running after the fault is removed;
step S207: when the input side fault of the frequency converter system occurs, the input side fault protection of the frequency converter system can protect a single frequency converter, and also can protect the whole frequency converter system, and the adopted measures are executed according to the instructions of the logic control unit at the input side of the frequency converter system;
step S208: after the fault of the input side of the frequency converter system occurs, alarming and waiting for fault removal after the fault protection action of the input side of the frequency converter system is executed; and after the fault is removed, the operation of the frequency converter system is restored according to the operation state recorded during the fault.
The input side of the frequency converter system refers to a bridge type three-phase rectifying circuit at the front end and a direct current bus capacitor circuit in the middle in the main circuit structure of the frequency converter. For protection of the input side, the frequency converter generally comprises an input open-phase, an input overvoltage and a direct current bus voltage alarm.
The protection of the voltage of the direct current bus is to prevent the damage of devices such as a capacitor or an IGBT (insulated gate bipolar transistor) caused by the overhigh voltage of the direct current bus when overvoltage occurs, and the frequency converter judges that the overvoltage detection point is on the direct current bus, and the normal direct current bus voltage is calculated by taking the alternating current inlet voltage of which the voltage is about 1.35 times as high as the alternating current voltage of 3AC380-480V as an example, and is usually between DC 520V and DC 540V.
When the load inertia driven by the frequency converter is relatively large and the speed is reduced rapidly, or when the potential energy load dragged by the frequency converter is lowered, the actual rotating speed of the motor rotor is higher than the rotating speed output by the frequency converter to the motor, so that the load is reversely dragged to the motor, 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 anti-parallel 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 the fed back energy, and the damage of devices possibly is caused by reaching a certain limit value, so that the overvoltage trend must be restrained at the moment.
The under-voltage protection detects that the voltage of the DC bus of the frequency converter is lower than a certain value, such as the normal alternating voltage which is 1.35 times, if the voltage is lower than 10 percent, under-voltage alarm or fault can occur to the frequency converter at the moment, the input side of the frequency converter system indirectly reflected by the under-voltage fault can have problems, the under-voltage protection has the function of preventing the output power from being limited when the voltage of the DC bus of the frequency converter is too low, the working characteristics of a power device from changing, controlling the voltage to be abnormal and preventing the hardware of the frequency converter from being damaged.
Input-side overcurrent protection normally has an output current of the frequency converter exceeding a certain limit value of the rated output current of the frequency converter, and is normally related to the design of IGBT power device selection, and different protection limit values are set according to different power sections of the frequency converter.
Input phase failure of the frequency converter: the input open-phase detection of the frequency converter is not generally directly measured, the ripple wave of the voltage of the direct current bus is used for judging, when the load of the frequency converter operates, if the input open-phase of the frequency converter occurs, the ripple wave of the direct current bus is increased, so that the load of the rectifying diode at the input side of the frequency converter is increased, and the damage condition of the rectifying bridge is possibly caused.
As shown in fig. 3, when the fault occurs in the inverter system itself and the input side fault protection system pair of the inverter system, mutual data confirmation can be performed. 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 at the input side of the frequency converter system are operated normally, communication connection is established between the frequency converter system and the fault protection system, and operation data and real-time detection data of the frequency converter are interacted.
Step S402: detecting the voltage and the current of the direct current bus of the frequency converter, judging whether the frequency converter is abnormal, keeping the detection state without abnormality, and further judging the fault position and the fault type when abnormality occurs.
Step S403: aiming at the abnormality of the direct current bus of the frequency converter, judging whether the direct current bus is a line incoming power failure, if so, entering step S404, and protecting the line incoming power failure; if not, the process proceeds to step S405 to further determine the fault point and type.
Step S404: when the incoming line power supply happens, the power supply of the frequency converter is abnormal, corresponding protection measures are adopted, the fault power supply is disconnected, and subsequent operation is carried out.
Step S405: at this time, through the detection unit of the frequency converter, whether the internal components of the frequency converter have faults or not is determined.
Step S406: if the device at the input side of the frequency converter system fails, the power supply of the frequency converter is abnormal, and the recovery needs manual intervention to alarm outwards.
Step S407: short-time faults can be continuously detected, a short-time common direct current bus system is formed, normal operation of the frequency converter system is guaranteed, and normal operation is achieved after faults are 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 the formula 1:
Pc ＝ UdcIc （1）
Where Pc is the power injected into the bus capacitor, ic is the current flowing through the bus capacitor, udc is the bus voltage. When the system operates normally, 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 failure, the base resource table of the frequency converter system may determine the system run time during which the energy storage of the system is sustainable, and thus the downtime of the system.
Step S503: the input side fault protection logic control unit of the frequency converter system determines the frequency converter information of faults in the frequency converter system according to the real-time monitoring data of the input side fault detection unit of the frequency converter system and the frequency converter self-checking system, and comprises the following components: the fault type and the number of the fault frequency converters determine the total power of the frequency converters with faults; it is determined whether the system can maintain normal operation.
Step S504: the input side fault protection logic control unit of the frequency converter system determines the protection action to be taken, protects the system through the input side fault protection unit of the frequency converter system, forms a common direct current bus system and gives an alarm to the outside; the protection unit acts to break unnecessary energy consumption units, so that the normal implementation of the protection action of the system is ensured.
Step S505: and after the fault is removed, 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 following describes a method for protecting an input side fault of a frequency converter system in connection with a specific embodiment.
Embodiment one: the input side fault protection method of the frequency converter system is described with reference to a frequency converter system formed by a single frequency converter in fig. 6.
When a fault occurs on the input side of a frequency converter system formed by a single frequency converter, the action of the contactors KM1, KM2, KM3 and KM4 can be controlled according to different fault positions, so that the frequency converter is protected.
When the power supply fault of the frequency converter is determined, the KM1 can be controlled to act to break the link between the frequency converter and the power supply, so that the power supply safety of a rectifying circuit and other systems of the frequency converter is ensured, and the frequency converter is not damaged due to power supply accidents; meanwhile, the contactor KM4 can be operated, so that energy storage of the frequency converter during shutdown is ensured, and the frequency converter is only required to be shut down at the moment, and meanwhile, the running state during faults is saved and used as 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, so that the power supply fault caused by the fault of the frequency converter system can not be caused, and the fault range is enlarged. The contactor KM3 is controlled to act, so that the safety of a subsequent circuit is protected, and an alarm is required to be given to the outside at the moment, so that a fault element is protected.
When the direct current bus link fails, the contactor KM4 is controlled to act, so that the normal operation of the arrangement and pre-charging circuit is ensured, and meanwhile, an alarm is given to the outside. And storing the operation parameters in the fault state, and providing basic data for the recovery operation of the later-stage system.
Embodiment two: the method for protecting the input side interference electricity fault of the frequency converter system is described with reference to a frequency converter system formed by a plurality of frequency converters in fig. 7.
As shown in fig. 7, in a frequency converter system formed by a plurality of frequency converters, the fault protection execution unit on the input side of the frequency converter system comprises fault protection execution units among the 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.
When an electric interference fault, or a short-time power failure fault, occurs according to the fault type judgment of the input side of the frequency converter system, the number of frequency converters with faults can be firstly determined according to the steps shown in fig. 5. The number of faulty frequency converters and the number of frequency converters operating normally can be determined at this time, respectively.
The total dc energy storage of the frequency converter system can be calculated according to formula 2:
ptotal energy storage=p1+p2+ … … +pn (2)
Wherein the P total energy storage is the total energy storage of the frequency converter system; p1, P2 and … … 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 normal operating frequency converter can provide normal energy for the system, and the total energy provided by the normal frequency converter can be calculated according to the formula 3:
Penergy=pnormal 1+P normal 2+ … … +pnormal m (3)
Wherein P energy is the total energy storage of the frequency converter system; pnormal 1, pnormal 2 and … … Pnormal m are energy storage of each frequency converter in the frequency converter system; m is the number of normally operating frequency converters in the frequency converter system.
At this time, the fault frequency converter in the frequency converter system is disconnected according to the method in the embodiment 1, so that each unit in the frequency converter system can be ensured to normally operate.
According to the calculations of formulas 2 and 3, it is determined that the system can maintain operating energy, and a common dc bus system meeting the requirements is established through the contactors of KMOs 1-n, and the buffer circuit, the bleeder circuit and the filter circuit at this time can be selected according to conventional methods, which are not described herein.
And simultaneously, the alarm is given to the outside, so that the fault is removed and the system is recovered to normal operation under the condition that the system keeps running. At the moment, the direct current bus link of the frequency converter system is powered through the frequency converter rectifying link which works normally, so that the whole normal operation of the frequency converter system is maintained.
Embodiment III: the method for protecting the power failure of the input side of the frequency converter system is described with reference to the frequency converter system formed by a plurality of frequency converters in fig. 7.
When the frequency converter system has a power failure fault, each frequency converter in the frequency converter system needs to ensure coordinated and associated shutdown. Determining the downtime of a frequency converter system, combining a frequency converter system basic resource table and the system maintenance energy determined by the formulas 2 and 3 according to the number of frequency converters with faults, and calculating the energy required by a single frequency converter when the frequency converter is stopped according to the formula 4:
Wtop=pstone=u-tone-pstone (4)
Wherein, W is the energy required by the shutdown, P is the power required by the shutdown, T is the time required by the shutdown, U is the power supply voltage of the frequency converter which is the shutdown, and I is the power supply current when the shutdown.
And determining the total energy required for shutdown according to the formula 5:
wtop = wtop 1+W to stop 2+ … … + wtop n (5)
W stands for the total energy that the shut down needs, W stands for the energy that each converter shut down, n is the total number of converters in the converter system.
At this time, according to the data in the resource table of the frequency converter system stored in the fault protection logic control unit at the input side of the frequency converter system, the shutdown time of each frequency converter is set respectively, provided that the requirement of formula 5 is satisfied, that is, the total energy of the frequency converter system satisfies the shutdown requirement.
Other operation steps are the same as the previous embodiment, a common direct current bus system is established, a fault unit is broken, operation parameters of the system during fault are saved, an alarm is given to the outside, and after the operation of the frequency converter system is restored, operation data support is provided.
It should be noted that, each embodiment in the present specification is described in a progressive manner, and each specific implementation focuses on differences from other embodiments, and identical and similar parts between each embodiment are all enough to refer to each other.
The input side fault protection method and control system of the frequency converter system provided by the invention are described in detail, and specific examples are applied to illustrate the principle and implementation of the invention, and the description of the above examples is only used for helping to understand the method and core ideas of the invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
Claims (6)
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 requirements to form the frequency converter system meeting the requirements; the protection method for the input side of the frequency converter system comprises the following steps:
after the frequency converter system is electrified and started, each frequency converter carries out self-checking, and a fault protection communication unit at the input side of the frequency converter system establishes communication connection with each frequency converter in the frequency converter system, wherein the communication mode is based on the communication mode used by the actual frequency converter system;
The frequency converter system establishes communication connection with the frequency converter system input side fault protection logic control unit through the frequency converter system input side fault protection communication unit, and stores basic operation parameters of the frequency converter into the frequency converter system input side fault protection logic control unit, wherein 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 current limit value of the input side of each frequency converter; all data are recorded into a resource table corresponding to each frequency converter, and are stored in a designated storage unit in a fault protection logic control unit at the input side of the frequency converter system, so that a basic resource table of the frequency converter system is established;
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 a frequency converter system, and the linkage relation of all the frequency converters in the system; the information is used as basic data of the frequency converter system and a single frequency converter basic resource table to be respectively stored in a designated storage unit;
The basic operation parameters of the input side fault detection unit of the frequency converter system corresponding to each frequency converter in the frequency converter system are stored in the input side fault protection logic control unit of the frequency converter system, and the basic operation parameters of the input side fault detection unit of the frequency converter system comprise: the number of fault detection units at the input side of each frequency converter, the number of fault detection units at the input side of the frequency converter and the number of fault detection units at the external input side of the frequency converter; the number of the fault detection unit at the input side of the frequency converter system among all frequency converters in the frequency converter system; 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 designated storage unit to provide basic data for protection actions in the later fault;
The basic parameters of the input side fault protection execution unit of the frequency converter system corresponding to each frequency converter in the frequency converter system are stored in the input side fault protection logic control unit of the frequency converter system, and the basic parameters of the input side fault protection execution unit of the frequency converter system comprise: the number of fault protection execution units at the input side of each frequency converter, the number of fault protection execution units at the input side of each frequency converter and the number of fault protection execution units at the external input side of each frequency converter; the method comprises the steps that input side fault protection execution unit information of a frequency converter system is stored in a designated storage unit, and basic data is provided for protection actions when faults occur in the later period;
Receiving running state information of the frequency converter system in real time through a communication unit of the frequency converter system input side fault protection system, receiving detection data of the frequency converter system input side fault detection unit, and sending real-time voltage and current parameters of a frequency converter system input side power supply and voltage and current data of a direct current bus inside the frequency converter to a frequency converter system input side fault protection logic control unit to comprehensively judge whether the frequency converter system input side has faults and fault information;
If the input side of the frequency converter system fails, the input side fault protection executing unit of the frequency converter system acts according to the fault information through the instruction of the input side fault protection logic control unit of the frequency converter system, meanwhile, the running state information of the frequency converter system is stored, the running state of each frequency converter in the frequency converter system when the fault occurs is recorded, and necessary information is provided for the running after the fault is removed;
When the input side fault of the frequency converter system occurs, the input side fault protection executing unit of the frequency converter system can protect a single frequency converter, and also can protect the whole frequency converter system, and the adopted measures are executed according to the instructions of the 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, alarming and waiting for fault removal after the fault protection action of the input side of the frequency converter system is executed; and after the fault is removed, the operation of the frequency converter system is restored according to the operation state recorded during the fault.
2. The method for protecting input side faults of a frequency converter system according to claim 1, wherein the input side fault protection of 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 working flow and the coordination relation among the frequency converters; basic resource tables of the frequency converters; a communication unit basic resource table of a fault protection 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 for 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 all frequency converters in the frequency converter system; all the resource tables are stored in the appointed storage position in the fault protection logic control unit of the input side of the frequency converter system and are called in real time.
3. The method for protecting an input side fault of a frequency converter system according to claim 1, wherein the following measures can be taken for the input side fault of the frequency converter system: when faults occur, determining the type of faults at the input side of the frequency converter system through the fault detection system of the frequency converter system and the data of the fault detection unit at the input side of the frequency converter system, and determining the protection measure to be adopted; when the system is required to be stopped, the normal operation time of the frequency converter system can be determined according to the initial resource table of the frequency converter system and the capacity of the direct current bus capacitor of the frequency converter system; when part of the frequency converters are in fault and the part of the frequency converters are in normal operation, the stable operation or the coordinated associated shutdown of the system is ensured by reasonably distributing the direct current bus voltage.
4. The method for protecting an input side fault of a frequency converter system according to claim 1, wherein the frequency converter system input side fault protection performing unit is capable of protecting a plurality of positions on the input side of the frequency converter system, the protecting method comprising:
The corresponding single frequency converter can divide the circuit between the direct current bus capacitor and the rectifying circuit, so that the rectifying circuit and the follow-up direct current bus capacitor circuit are divided when the input side fails;
Breaking operation is carried out at the connection part of the rectifying circuit and the power supply, so that the frequency converter is not influenced by the fault of the external power supply;
for more than two frequency converter systems, when one input side of the frequency converter fails, the on-off of a contactor between each frequency converter bus capacitor in the frequency converter system can be controlled, so that the failed frequency converter bus capacitor can obtain working voltage through other frequency converters, and the continuous normal work of the failed frequency converter is ensured;
When the input sides of the frequency converters in the system are in failure, the connection of all the frequency converters and the power supply thereof can be disconnected, and a common direct current bus structure is formed in the frequency converter system, so that the frequency converter system can synchronously or coordinately and associatively start and stop according to the requirement, the association of actions among the frequency converters in the system is ensured, and the guarantee is provided for continuous operation after the subsequent failure recovery;
when a fault occurs, the current operation data of the frequency converter system is stored, and meanwhile, an alarm is given to the outside.
5. The method of claim 1, wherein the frequency converter system input side fault protection provides effective base operational data upon restarting the frequency converter system after the frequency converter system input side fault has been cleared, the method comprising: after the fault is thoroughly removed, the fault protection execution unit at the input side of the frequency converter system can be restored to the operation state before the fault, so that the normal continuous operation of the frequency converter system is ensured; the frequency converter system restores the running state before the system according to the running information before the fault stored by the fault protection logic control unit at the input side of the frequency converter system; the action of the corresponding protection unit at the input side of the frequency converter is recovered to an unprotected state after the fault is removed, and the operation of the frequency converter system is not affected; the fault detection unit at the input side of the frequency converter system continues to perform fault detection on 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 components: the input side fault protection communication unit of the frequency converter system, the input side fault detection unit of the frequency converter system, the input side fault protection logic control unit of the frequency converter system and the input side fault protection execution unit of the frequency converter system; the system can be expanded according to the requirements of the actual site; the input side fault protection control system of the frequency converter system comprises the following units:
The functions of the input side fault protection logic control unit of the frequency converter system comprise: logic control, communication control, instruction input and output, alarm control, data acquisition and data storage; the logic control part carries out comprehensive research and judgment on the data of each detection unit to determine the fault type and determine the protection action of the fault protection execution unit at the input side of the frequency converter system; each component can be expanded according to the requirement so as to adapt to the actual requirement of the frequency converter system;
The functions of the frequency converter system input side fault protection communication unit include: the communication connection between the frequency converter system and the fault protection system at the input side of the frequency converter system is ensured, the timely intercommunication of data is ensured, and the communication mode is selected according to the communication mode of the actual frequency converter system;
The functions of the input side fault detection unit of the frequency converter system comprise: detecting the amplitude phase of alternating current, detecting direct current, detecting the amplitude 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 the detection units can be reasonably increased or decreased according to the requirements of the frequency converter system, so that the normal operation of the frequency converter system is ensured;
The functions of the fault protection execution unit at the input side of the frequency converter system comprise: after communication is established with an output control part of a fault protection logic control unit at the input side of the frequency converter system, breaking and closing operations can be executed, a main execution part is a contactor, an intermediate relay can be controlled to complete corresponding functions for a low-voltage part, and the execution unit comprises a buffer circuit, a bleeder circuit and a filter circuit.
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| JP2006094685A (en) * | 2004-09-27 | 2006-04-06 | Toshiba Mitsubishi-Electric Industrial System Corp | Controller of frequency converter |
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