CN109856505B - Immune time detection method for voltage sag - Google Patents
Immune time detection method for voltage sag Download PDFInfo
- Publication number
- CN109856505B CN109856505B CN201910025140.7A CN201910025140A CN109856505B CN 109856505 B CN109856505 B CN 109856505B CN 201910025140 A CN201910025140 A CN 201910025140A CN 109856505 B CN109856505 B CN 109856505B
- Authority
- CN
- China
- Prior art keywords
- time
- sensitive
- circuit
- immunization
- equipment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Measurement Of Current Or Voltage (AREA)
- Testing Electric Properties And Detecting Electric Faults (AREA)
Abstract
The application relates to an immune time detection method for voltage sag, which comprises the following steps: the analysis circuit acquires sensitive equipment in the circuit; obtaining the immunization time of each sensitive device; and acquiring the immunization time of the circuit according to the immunization time of each sensitive device. In the application, the immune time of the sensitive process of the circuit is obtained based on the immune time of the sensitive equipment, so that the power supply reliability of the circuit is effectively detected.
Description
Technical Field
The application relates to the technical field of power supply testing, in particular to an immune time detection method for voltage sag.
Background
With the overall improvement of social productivity, the basic problems of power supply reliability and the like reach higher levels, the increasing demand of a highly automated production process for ensuring efficient production on power supply quality becomes a main contradiction which power enterprises need to deal with in a new era, and voltage sag is the problem of the greatest contribution degree in various power quality problems causing economic loss of users. The first step in improving voltage quality requires knowledge of the voltage sag tolerance of a typical sensitive device or process through testing and certain evaluation means.
At present, certain research results are available in the aspect of sensitive equipment testing. The release is tested by an Ouyangen team of university of southern China, a voltage sag resistance curve (VTC) of the equipment is drawn, and the influence of sag amplitude, duration, starting waveform point and phase jump characteristics on the immunity of the equipment is analyzed. Sensitive devices such as an Adjustable Speed Drive (ASD) and an alternating current contactor are researched by a Shaoxing Xiangning and Xuyonghai team of China North China electric power university, and a certain immunity improving measure is provided. The Wu Asia basin team, university of North China, tested the voltage sag tolerance of the PLC. The millanovic group also made intensive studies on the sag tolerance of a variety of sensitive devices such as ac contactors, PCs, and the like.
Some researchers are aware that sensitive devices typically in a production process affect each other in their research, and the tolerance of the research devices alone is insufficient for the evaluation of immunity in the whole production process. An exemplary industrial process consisting of an ACC, an ASD and an induction motor simulating a load is built in an Experimental initiation on the sensitivity of an industrial process to a voltage disps [ C ].2015IEEE Eddhowen Power Tech. Eindohoven ], the tolerance of the related sensitive equipment and process is tested, respective VTCs are obtained, and the mutual influence among the equipment and the relation among the process tolerance are verified.
The VTC obtained through testing through a large number of existing researches evaluates the voltage sag tolerance of equipment, and for users, a voltage tolerance curve constructed based on network side indexes cannot intuitively and accurately reflect the influence suffered by an actual production process, so that weak link discrimination and economic loss evaluation are not utilized. The concept of Immunity is proposed in the document of Voltage dip Immunity and Immunity, which adopts Immunity Time (IT) as an index for evaluating the Voltage sag tolerance of equipment or process, and describes the application of the index by listing some typical industrial processes. The index takes industrial process parameters facing users as judgment standards, evaluates immunity laterally by time, and is more beneficial to establishing intuitive understanding of sag influence from the user side. However, the article does not suggest a specific implementation method, and further ground research is required for specific typical industrial production evaluation.
Disclosure of Invention
Based on this, it is necessary to provide an immune time detection method capable of voltage sag.
A method of immune time detection of voltage sags, the method comprising:
the analysis circuit acquires sensitive equipment in the circuit;
obtaining the immunization time of each sensitive device;
and acquiring the immunization time of the circuit according to the immunization time of each sensitive device.
In one embodiment, the step of obtaining the sensitive device in the circuit by the parsing circuit further includes:
establishing a test circuit of the sensitive equipment;
providing a disturbance power supply for the sensitive equipment, and detecting voltage waveforms at two ends of the sensitive equipment;
and obtaining the immunization time of the sensitive equipment according to the change of the voltage waveform at the two ends of the sensitive equipment.
In one embodiment, the step of obtaining the immunization time of the sensitive device according to the change of the voltage waveform at two ends of the sensitive device comprises:
acquiring the change of voltage waveforms at two ends of the sensitive equipment, and detecting the sag characteristic and the occurrence of a top wave of the voltage waveforms;
and obtaining the time difference between the sag characteristic and the flat-top wave according to the sag characteristic of the voltage waveform and the occurrence time of the flat-top wave, and taking the time difference as the immunization time of the sensitive equipment.
In one embodiment, the step of providing a disturbance power source for the sensitive device, and the step of detecting a voltage waveform across the sensitive device includes:
and providing a disturbance power supply for the sensitive equipment, and detecting voltage waveforms at two ends of the sensitive equipment through an oscilloscope.
In one embodiment, the step of obtaining the immunization time of each of the sensitive devices comprises:
acquiring a plurality of minimal cut sets corresponding to the sensitive equipment in the circuit according to a logic connection structure of the sensitive equipment in the circuit;
obtaining the immune time of each minimal cut set;
the step of obtaining the immunization time of the circuit according to the immunization time of each sensitive device comprises the following steps:
and acquiring the immunization time of the circuit according to the immunization time of each minimum cut set.
In one embodiment, the step of obtaining the immunization time of each of the minimal cut sets comprises:
determining the sensitive equipment in each minimum cut set;
and taking the immunization time of the sensitive device as the immunization time of the minimum cut set.
In one embodiment, the step of obtaining the immunization time of the circuit according to the immunization time of each of the minimal cut sets comprises:
and taking the maximum value of the immunization time of each minimum cut set connected in series as the immunization time of the circuit.
In one embodiment, the step of obtaining the immunization time of each of the minimal cut sets comprises:
and obtaining the immune time of a plurality of links which are connected in parallel in the minimum cut set, and taking the maximum value of the immune time of each link as the immune time of the minimum cut set.
In one embodiment, a plurality of said segments within the same said minimal cut set have digital coupling characteristics.
In one embodiment, the step of obtaining a plurality of minimal cut sets of the circuit according to the logical connection structure of the sensitive device in the circuit includes:
dividing the circuit into a plurality of the minimal cut sets based on the digital coupling characteristics of the sensitive device according to the logical connection structure of the sensitive device in the circuit;
a plurality of the minimal cut sets of the circuit are obtained.
According to the voltage sag immunity time detection method, the immunity time of the circuit in the sensitive process is obtained based on the immunity time of the sensitive equipment, so that the power supply reliability of the circuit is effectively detected.
Drawings
FIG. 1 is a schematic flow chart of a method for detecting an immunity time of a voltage sag according to an embodiment;
FIG. 2 is a schematic diagram of an exemplary ACC configuration in one embodiment;
FIG. 3 is a schematic diagram of a PIT curve in one embodiment;
FIG. 4 is a schematic diagram of the circuit connections of the test circuit in one embodiment;
FIG. 5 is a schematic diagram of the circuit configuration of an experimental platform of an exemplary process in one embodiment;
FIG. 6a is a diagram illustrating a connection structure of a random network in one embodiment;
FIG. 6b is a diagram illustrating an exemplary connection structure of an equivalent network;
FIG. 7 is a schematic diagram of an industrial process in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In one embodiment, as shown in fig. 1, there is provided a method for immune time detection of voltage sag, comprising the steps of:
and step 110, analyzing the circuit to obtain the sensitive equipment in the circuit.
In particular, a sensitive device is a device that produces a withstand characteristic when a voltage sag occurs. I.e. sensitive devices will develop a tolerant behaviour when the voltage is dropped. The sensitive equipment has certain tolerance capability. Different sensitive devices differ in their tolerance capabilities.
In this step, the circuit structure is analyzed to obtain each sensitive device in the circuit, and the sensitive device is an element in the circuit. By analyzing the circuit, the sensitive equipment can be determined from the circuit. And determining the position of the sensitive device in the circuit and the logical connection relation of the sensitive device. In this embodiment, a plurality of sensitive devices in a circuit are acquired, and a device type of the sensitive device is acquired. In one embodiment, the sensitive device includes a switching element. In this embodiment, the sensitive devices include an ACC (contactor) and an ASD (adjustable speed drive), that is, the types of the sensitive devices include an ACC and an ASD.
In this embodiment, according to the acquired sensitive device, the immunization time of the sensitive device is acquired. According to the acquired device type of the sensitive device, the immunization time corresponding to the device type of the sensitive device is acquired.
In particular, Immunity Time (IT) is an index used to evaluate the device or process voltage sag tolerance. In one embodiment, the immunization time is the length of time that the sensitive device is ready to disconnect to complete disconnection.
It should be understood that the immunization time is a pre-stored time corresponding to the sensitive device, or the immunization time is a pre-stored time corresponding to the sensitive device type. Each device type corresponds to an immunization time, namely the immunization time is prestored, and a plurality of prestored immunization times correspond to the prestored device types one by one. It is worth mentioning that the pre-stored immunization schedule may be obtained by testing and stored.
And 150, acquiring the immunization time of the circuit according to the immunization time of each sensitive device.
In this embodiment, after the immunization time of each sensitive device is obtained, the immunization time of the circuit is obtained through the immunization time of each sensitive device, and in one embodiment, the maximum value of the immunization times of each sensitive device is used as the immunization time of the circuit.
In the embodiment, the immune time of the sensitive process of the circuit is obtained based on the immune time of the sensitive equipment, so that the power supply reliability of the circuit is effectively detected.
In order to obtain the immunization time of the sensitive device, the sensitive device needs to be detected, and in one embodiment, the step of analyzing the circuit to obtain the sensitive device in the circuit further includes: establishing a test circuit of the sensitive equipment; providing a disturbance power supply for the sensitive equipment, and detecting voltage waveforms at two ends of the sensitive equipment; and obtaining the immunization time of the sensitive equipment according to the change of the voltage waveform at the two ends of the sensitive equipment.
In the embodiment, a test circuit of the sensitive equipment is established; providing a disturbance power supply for the sensitive equipment, and detecting the change condition of key parameters of the sensitive equipment; and obtaining the immunization time of the sensitive equipment according to the change condition of the parameters of the sensitive equipment and the occurrence time of the sag.
One embodiment is that the immunization time of the sensitive device is detected according to the change of the voltage waveform at two ends of the sensitive device.
In this embodiment, a test circuit is set up, the test circuit includes a sensitive device, and the test circuit further includes a power supply, the power supply is configured to provide a disturbance power supply, that is, the power supply is configured to provide a disturbance voltage, the disturbance voltage is a fluctuating voltage, the voltage of the disturbance power supply continuously fluctuates within a preset time, and the sensitive device is turned off or turned on under the influence of the disturbance voltage.
In this embodiment, voltages at two ends of the sensitive device are detected to obtain voltage waveforms at two ends of the sensitive device, and when the disturbance voltage fluctuates, the off or on state of the sensitive device is affected, so that the voltages at two ends of the sensitive device also change, and further a voltage waveform is generated. The variation of the voltage transformation waveform is based on the variation of a time axis, and the immunization time of the sensitive equipment can be detected according to the variation of the voltage waveform.
In order to detect the immunity time of the sensitive device, in one embodiment, the step of obtaining the immunity time of the sensitive device according to the change of the voltage waveform of the two ends of the sensitive device includes: acquiring the change of voltage waveforms at two ends of the sensitive equipment, and detecting the sag characteristic and the occurrence of a top wave of the voltage waveforms; and obtaining the time difference between the sag characteristic and the flat-top wave according to the sag characteristic of the voltage waveform and the occurrence time of the flat-top wave, and taking the time difference as the immunization time of the sensitive equipment.
In one embodiment, the step of providing a disturbance power supply for the sensitive device, and detecting a change of a key parameter of the sensitive device includes: acquiring the change condition of key performance parameters of the sensitive equipment, detecting the change condition of the voltage of a contact end when a direct-current power supply is applied to two ends of a main contact of the contactor, and detecting the change condition of the direct-current bus voltage of the frequency converter; and obtaining the time difference between the key performance parameters of the observed equipment and the voltage sag of the power supply side according to the time when the key performance parameters of the observed equipment are subjected to mutation or out-of-limit and the time when the voltage sag of the power supply side is generated, and taking the time difference as the immunization time of the sensitive equipment.
In this embodiment, the change condition of the key performance parameter of the sensitive device is obtained, for a contactor, the terminal voltage condition of a contact when a direct current power supply is applied to two ends of a main contact of the contactor needs to be monitored, and for a frequency converter, the direct current bus voltage of the frequency converter needs to be monitored; and obtaining the time difference between the key performance parameters of the observed equipment and the voltage sag of the power supply side according to the time when the key performance parameters of the observed equipment are subjected to mutation or out-of-limit and the time when the voltage sag of the power supply side is generated, and taking the time difference as the immunization time of the sensitive equipment.
In one embodiment, the presence of flat-top and dip features of the voltage waveform is detected; and obtaining the time difference of the flat-top wave and the sag characteristic according to the occurrence time of the flat-top wave and the sag characteristic of the voltage waveform, and taking the time difference as the immunization time of the sensitive equipment.
In this embodiment, the sensitive device may be regarded as a switch, and the disturbance power supply provides a disturbance voltage for the sensitive device. The test circuit also includes a circuit power supply and a load, the circuit power supply being connected in series with the load and the sensitive device.
When the sensitive equipment is switched on, the voltage at two ends of the sensitive equipment is zero, when the sensitive equipment is switched off due to the change of disturbance voltage, the circuit is equivalent to the circuit open circuit, the oscilloscope detects the voltage at two ends of the sensitive equipment in the open circuit state, and the resistance at two ends of the sensitive equipment is infinite at the moment, so that the voltage at two ends of the sensitive equipment is the voltage of a circuit power supply in a test circuit, and at the moment, the voltage waveform at two ends of the sensitive equipment generates a flat-top wave.
In order to detect the voltage waveform across the sensitive device, in one embodiment, the step of providing a disturbance power to the sensitive device includes: and providing a disturbance power supply for the sensitive equipment, and detecting voltage waveforms at two ends of the sensitive equipment through an oscilloscope.
In this embodiment, the test circuit further includes an oscilloscope, two input ends of the oscilloscope are connected to two ends of the sensitive device, and the oscilloscope is connected in parallel with the sensitive device, so that the oscilloscope can detect voltages at two ends of the sensitive device, and further can detect a voltage waveform of the sensitive device.
In order to accurately obtain the immunization time of the circuit when a plurality of sensitive devices exist in the circuit, in one embodiment, the step of obtaining the immunization time of each of the sensitive devices includes: acquiring a plurality of minimal cut sets corresponding to the sensitive equipment in the circuit according to a logic connection structure of the sensitive equipment in the circuit; obtaining the immune time of each minimal cut set; the step of obtaining the immunization time of the circuit according to the immunization time of each sensitive device comprises the following steps: and acquiring the immunization time of the circuit according to the immunization time of each minimum cut set.
In this embodiment, according to a logical connection structure of the sensitive device in the circuit, a direct connection relationship between the circuit and the sensitive device is obtained, and a minimum cut set method is further adopted to perform a topology standardization-multiple minimum cut set series topology form; combining immunity time by utilizing parallel modules to obtain the relationship to obtain the immunity time of each minimal cut set; the step of obtaining the immunization time of the circuit according to the immunization time of each minimal cut set comprises the following steps: and acquiring the immune time of the circuit according to the immune time acquisition mode of the combination of the immune time of each minimum cut set and the serial module.
In particular, the minimal cut set comprises a plurality of elements, or a plurality of elements form the minimal cut set, and the minimal cut set is switched on and off so that the circuit is switched on and off with the minimum unit. It should be understood that for a process consisting of random elements independent of each other, a cut-set refers to a combination of elements whose shutdown would result in a power interruption, and if any element is removed from the cut-set, the cut-set is no longer a cut-set, and the cut-set is the minimum-cut-set (MCS). According to the description, the MCS internal elements are in parallel relation, and the MCS internal elements are in series relation. It is worth mentioning that the minimal cut set comprises at least one sensitive device.
In this embodiment, since the on/off of the minimum cut sets can affect the on/off of the entire circuit, a plurality of minimum cut sets exist in the circuit, and thus, the plurality of minimum cut sets correspond to a plurality of immunization times, and the overall immunization of the circuit can be obtained by calculation according to the immunization times of the minimum cut sets.
In order to accurately obtain the immune time of the circuit, in one embodiment, the step of obtaining the immune time of each of the minimal cut sets is: determining the sensitive equipment in each minimum cut set; and taking the immunization time of the sensitive device as the immunization time of the minimum cut set.
In one embodiment, the step of obtaining the immunization time of each of the minimal cut sets by using the parallel modules to combine immunization time calculation relationship includes: determining the sensitive equipment in each minimum cut set; and taking the maximum immunization time of the sensitive device as the immunization time of the minimum cut set.
In this embodiment, the largest one of the immunization times of the sensitive device is taken as the immunization time of the minimum cut set.
In one embodiment, the sensitive devices in each of the minimal cut sets are obtained, the device types of the sensitive devices in each of the minimal cut sets are determined, and the immunization time corresponding to the device types of the sensitive devices is taken as the immunization time of the minimal cut set.
In this embodiment, the immunization time of the minimum cut set is obtained according to the immunization time of the sensitive device in the minimum cut set, and then the immunization time of the circuit is determined, so that the acquisition of the immunization time of the circuit is more accurate.
In order to accurately obtain the immunization time of the circuit, in one embodiment, the step of obtaining the immunization time of the circuit according to the immunization time of each of the minimal cut sets comprises: and taking the minimum value of the immunization time of each minimum cut set connected in series as the immunization time of the circuit.
In this embodiment, the step of obtaining the immunization time of the circuit according to the immunization time obtaining manner of the combination of the immunization time of each of the minimum cut sets and the serial module includes: and taking the minimum value of the immunization time of each minimum cut set connected in series as the immunization time of the circuit.
In this embodiment, the step of obtaining the immunization time of the circuit according to the immunization time of each of the minimum cut sets includes: detecting whether the minimal cut sets are mutually connected in series; and when the minimum cut sets are connected in series, taking the minimum value of the immunization time of the minimum cut sets as the immunization time of the circuit.
In this embodiment, when a plurality of minimum cut sets exist in a circuit, the minimum cut sets are connected in series, and the minimum value of the immunization time of each minimum cut set is used as the immunization time of the circuit, so that the immunization time of the circuit can be accurately obtained.
In order to obtain the immunization times of the minimum cut sets, in one embodiment, the step of obtaining the immunization time of each of the minimum cut sets comprises: and obtaining the immune time of a plurality of links which are connected in parallel in the minimum cut set, and taking the maximum value of the immune time of each link as the immune time of the minimum cut set. In this embodiment, the step of obtaining the immunization time of each of the minimum cut sets includes: detecting whether the minimum cut set comprises a plurality of links which are connected in parallel; and when the minimum cut set comprises a plurality of links which are connected in parallel, acquiring the immune time of each link, and taking the maximum value of the immune time of each link as the immune time of the minimum cut set.
In this embodiment, the minimal cut set includes a plurality of links, and each link may be regarded as an independent element or a plurality of elements. Multiple links in the same minimal cut set are connected in parallel. Therefore, the immunization time of the minimal cut set is equal to the maximum value among the immunization times of a plurality of links in the minimal cut set. Therefore, by taking the maximum value of the immunization time of each link as the immunization time of the minimum cut set, the immunization time of the minimum cut set can be earned.
In one embodiment, a plurality of said segments within the same said minimal cut set have digital coupling characteristics.
Specifically, the digital coupling characteristic of a link means that when the key parameter of the link is out of limit, other links are affected due to the output change of the links, so that mutual independence among the links is ensured to a certain extent. And for two parameters with continuously changing functional relation, classifying the two parameters into the same link.
In order to divide the minimal cut sets in the circuit, in one embodiment, the step of obtaining a plurality of minimal cut sets of the circuit according to the logical connection structure of the sensitive device in the circuit includes: dividing the circuit into a plurality of the minimal cut sets based on the digital coupling characteristics of the sensitive device according to the logical connection structure of the sensitive device in the circuit; a plurality of the minimal cut sets of the circuit are obtained.
In this embodiment, the minimal cut sets of the circuit are divided based on the digital coupling characteristics of the links, so that the links in each minimal cut set can have the digital coupling characteristics.
In various embodiments, the method for detecting the immunity time of the voltage sag is also referred to as a method for testing the immunity time of a typical voltage sag sensitive object or a method for testing the immunity time of a typical voltage sag sensitive device.
The following are specific examples:
in order to obtain the immunization time of the sensitive device, the sensitive device needs to be tested.
(1) Typical sensitive device IT testing
The determination of a typical sensitive device IT comprises several steps of determining key parameters, determining parameter thresholds, and performing a test, wherein the parameter thresholds are generally obtainable by a relevant technical parameter or standard. In order to show the practicability of the test method, the technical scheme is developed by taking the research of typical sensitive equipment ACC in the industrial process as an example.
A commonly used double E-type direct-acting ACC structure in industrial processes is shown in fig. 2. When the main coil is electrified, magnetic flux is generated in the iron core, and electromagnetic force is generated on the end face of the pole of the iron core. Under the condition of overcoming the restoring force of the spring, the movable iron core linkage contact moves downwards to cause the movable contact and the static contact to be contacted with each other. After the main loop is closed, the movable iron core continues to move downwards under the condition of overcoming the acting force of all the spring groups, and the reliable attraction of the iron core is ensured. This displacement of the segment of the plunger is referred to as a Reliable Distance (RD).
According to CIGRE/CIRED/UIE Joint Working Group C4.110, volume di immunity of equations and equations [ R ]. Paris, France: CIGRE, 2010 judges that the condition of the sensitive object fault is a certain key physical parameter, and the selection of the key parameter will have a larger influence on the evaluation result of the object. Since the purpose of evaluating the immunity of the device is to infer the immunity of the process, it is appropriate to determine the key parameters based on whether the device affects the subsequent links or the function of the device. The main function of the ACC in the circuit is to control the power supply circuit of the device to be opened or closed, so whether the contact of the ACC is contacted or not can be used as the criterion for triggering failure of the ACC. Therefore, the displacement x describing the relative position of the movable iron core can be used as a key parameter, and the position in the attraction state is 0, and the limit value is RD.
PIT (Process IT, PIT, Process immunization time) is defined as a key parameter PnomFrom the moment of interruption occurrence up to its arrival limit PlimitAs shown in fig. 3, Δ t is the "dead time" of the subject after a dip. Similarly, for ACC, the time from when the sag occurs until the displacement x exceeds RD can be defined as the immune time (EIT) of the device, while its corresponding dead time is the time when the transient electromagnetic force decreases to a counter force (the difference between the spring force and the weight of the plunger), resulting in the release of the plunger.
The test is carried out according to the scheme described in the standard IEEE Std 1668-2017, IEEE Recommended Practice for Voltage Sag and Short interpretation Ring-Through Testing for End-Use electric Equipment speed loss 1000V, and the test environment is shown in FIG. 4: the disturbance power supply adopts an MX45 type program-controlled power supply of AMETEK company, the voltage output range is 0-400V, and the maximum output power is 45 kVA. The oscilloscope was a YOKOGAWA DL850 program controlled type oscilloscope for monitoring the voltage waveform across the contactor. The main loop of ACC control is simulated by a lamp powered by an external power supply, so that the influence of sag on the ACC is better reflected. When the contactor is electrified and attracted, the main loop is closed, the lamp emits light, and the voltage at the two ends of the contactor is zero. When the contactor suffers from sag and the contacts are effectively separated, the lamp has obvious brightness change, and a flat-top wave with a certain width and amplitude as the power supply voltage of the indicator lamp appears in the monitoring window of the oscilloscope. The EIT, which is the time difference between the occurrence of the sag and the occurrence of the flat-top wave under the current sag characteristic, can be obtained through an oscilloscope. In Voltage dip immunity of equipment and environments [ R ], only PIT is defined under interruption condition, which is obviously far from enough for practical research because the probability of temporary drop is far higher than the interruption probability in practical situation, and contactor type equipment has higher immunity in interruption, and the discussion of the situation in interruption is not typical. The premises of this concept are thus broadened to a sag for a more comprehensive assessment of the immunity of the device. Therefore, the EIT can be used as a new characteristic of the voltage sag to be combined with the original characteristic to evaluate the immunity of the ACC, for example, a two-dimensional graph formed by the EIT and the amplitude characteristic is a VTC formed by taking parameters facing a user side as judgment conditions. The results obtained from the test of the single-phase circuit condition in this experiment can be regarded as the most severe case when the faulty phase occurs in the ACC supply phase in the case of multiple phases, and the EIT in this case is representative.
The test of the ASD can be similar to the scheme, and for the ASD, the key parameter can be selected as the low-voltage limit value U of the direct-current bus voltagedc-minAnd an overcurrent protection limit Δ imaxWhen the voltage of the direct current bus capacitor terminal is lower than a threshold value or the current in the recovery stage is higher than the threshold value, the ASD trips, and therefore sudden change of influence is caused on the subsequent links.
For the motor itself, when the supply voltage condition changes, the change also appears in the aspect of rotational speed, torque, therefore also is important to the monitoring of motor state itself. For example, the rotating speed of the motor is a key parameter for the industrial process, and the motor cannot work normally when the rotating speed is lower than 80% of a rated value, so that the parameter is convenient to monitor and can be acquired by a special motor laser velocimeter, a data acquisition system and other equipment.
During the test, the ACC, ASD and the motor module are also often considered as a typical combination to be tested, and the variation of the motor parameters can be focused to define the operation state of the combination. Where ACC and ASD are present for the motor to have a voltage sagThe original response has the additional effect that failure of both types of equipment can cause the power supply to be interrupted, which is the primary cause of failure in the case of motors approaching rated load (l.e. weldemam, h.j).
V.Cuk，J.F.G.Cobben and W.L.Kling《Experimental investigation on the sensitivity of an industrial process to voltage dips》[C]2015IEEE Eindhoven powertech. IEEE Press, 2015.1-6). The change rule of the rotating speed of the motor after the power supply is interrupted in the initial state of a certain state can be obtained by various methods, so that the IT of the typical combination can be divided into two parts, namely the time required by the fault of the front-end equipment and the additional time of the fault of the rear-end equipment. Thus, the immune characteristics of the process can be estimated by measuring local links in the process, and a test scheme based on the idea will be described in detail below.
(3) Test scheme for equipment PIT
The device PIT is the IT of the process under study when a certain device fails. The index can be used for judging the key degree of equipment so as to provide guidance for treatment and prevention of sag, and is applied to a plurality of examples in Voltage dip immunity of effectiveness and effectiveness [ R ].
The device PIT is not easily obtained by direct testing because all sensitive devices are affected when subjected to a dip, and a device cannot be discussed alone. In the method, the parameter change condition of the subsequent process link under the condition of certain equipment failure can be analyzed independently to obtain the parameter out-of-limit time, the failure time EIT of the equipment subjected to sag and the rotating speed change curve of the motor under the working condition state subjected to the sag event can be obtained independently, and the two are summed to obtain the approximate value of the equipment PIT.
The industrial process only comprises two levels, and the multi-level industrial process can be deduced step by step according to the method. For some simple industrial processes, the influence of relevant sensitive equipment on process parameters can be independently researched in a mode of reproducing the industrial process, so that the equipment PIT can be directly tested.
(4) Determination scheme of typical procedure PIT:
a) combing all sensitive equipment or links in the study process.
In this section, the conditions of the links to be divided need to be noticed, and the links to be divided should have certain digital coupling characteristics. Specifically, under an ideal condition, when the key parameters of the links are out of limit, other links are influenced due to the output change of the links, so that mutual independence among the links is ensured to a certain extent. And for two parameters with continuously changing functional relation, classifying the two parameters into the same link. In order to facilitate understanding and research of the divided links, the divided links can be divided from the functional perspective, and the division results can be appropriately adjusted. Specific equipment has definite functions and often has better digital coupling characteristics with other equipment, so that the equipment can be directly used as a link. If the operation state of some links depends on other links, the link is an upper link formed by related sub-links.
An experimental platform of a typical process studied in this document is shown in fig. 5, and an industrial structure shown in fig. 5 widely exists in various industrial processes, sensitive devices involved in the typical process are ASD and ACC, and a load link is an upper link determined by the ASD and ACC.
b) Analyzing the logic connection mode between the devices or links.
The logic connection mode among the ring nodes at the same level is crucial to the determination of the PIT, and the influence of the failure of equipment on different logic nodes on the process is greatly different. The logical structure of each link in the industrial process may be more complex, but it can be normalized according to the minimal cut-set method. For a process consisting of random elements that are independent of each other, a cutset refers to a combination of elements whose shutdown would cause a Power interruption, and if any one element is removed from the cutset, the cutset is no longer a cutset, and this is the minimum-cut-set (MCS), Bollen M H J. IEEE press, 2000. From this description, it can be known that MCS internal elements are in parallel relation and MCS are in series relation, and the equivalent structure of the network shown in fig. 6(a) is shown in fig. 6 (b):
the theory shows that the same-level links with digital coupling characteristics can be represented by an equivalent network formed by series and parallel elements.
For an upper link, which is determined by several lower-level links, it is studied in a similar way to a single link or device, and it is linked to a lower link in that the moment it is affected is approximately the moment the lower link fails.
By adopting the analysis means, the power supply module analyzed above can be equivalent to a series network of an ACC and an ASD. When the power supply module fails, the key parameters of the load module are obviously deviated, so that the load module can be regarded as an upper link.
c) Determining sub-processes or IT of a process in accordance with logical connections
For a links connected in parallel, the IT of MCS is:
ITMCS＝max(IT1,…,ITa) (1)
for b MCSs connected in series, the IT of all links at a certain level is:
IT＝min(ITMCS1,…,ITMCSb) (2)
in fig. 7, the IT of the power supply link depends on the minimum of the EITs of the ACC and the ASD, and the IT of the load module is the sum of the IT of the power supply link and the IT of the load module when the load module alone suffers from an interruption. In this context, the IT of the load module is also PIT.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. An immune time detection method for voltage sag, the method comprising:
the analysis circuit acquires sensitive equipment in the circuit; determining the position of the sensitive equipment in the circuit and the logical connection relation of the sensitive equipment; the sensitive device is a device which generates a tolerance characteristic when the voltage is temporarily dropped, and comprises a switching element;
obtaining the immunization time of each sensitive device;
dividing the circuit into a plurality of minimal cut sets according to a logic connection structure of a sensitive device in the circuit and the digital coupling characteristic of the sensitive device, so that a plurality of links in the same minimal cut set have the digital coupling characteristic; the digital coupling characteristic refers to the characteristic that when the key parameter of a link exceeds the limit, the output change of the link influences other links, and the key parameter is determined according to whether the parameter influences subsequent links;
acquiring a plurality of minimal cut sets corresponding to the sensitive equipment in the circuit;
obtaining the immune time of each minimal cut set; the step of obtaining the immunization time of each of the minimal cut sets comprises: obtaining the immune time of a plurality of links which are connected in parallel in the minimum cut set, and taking the maximum value of the immune time of each link as the immune time of the minimum cut set;
obtaining the immune time of the circuit according to the immune time of each minimum cut set; the step of obtaining the immunization time of the circuit according to the immunization time of each minimal cut set comprises the following steps: and taking the minimum value of the immunization time of each minimum cut set connected in series as the immunization time of the circuit.
2. The method of claim 1, wherein the step of parsing the circuit to obtain the sensitive device in the circuit is preceded by the step of:
establishing a test circuit of the sensitive equipment;
providing a disturbance power supply for the sensitive equipment, and detecting voltage waveforms at two ends of the sensitive equipment;
and obtaining the immunization time of the sensitive equipment according to the change of the voltage waveform at the two ends of the sensitive equipment.
3. The method of claim 2, wherein the step of obtaining the immunization time of the sensitive device from the change in the voltage waveform across the sensitive device comprises:
acquiring the change of voltage waveforms at two ends of the sensitive equipment, and detecting the sag characteristic and the occurrence of a top wave of the voltage waveforms;
and obtaining the time difference between the sag characteristic and the flat-top wave according to the sag characteristic of the voltage waveform and the occurrence time of the flat-top wave, and taking the time difference as the immunization time of the sensitive equipment.
4. The method of claim 2, wherein the step of providing a perturbation power supply to the sensitive device, the step of detecting the voltage waveform across the sensitive device comprises:
and providing a disturbance power supply for the sensitive equipment, and detecting voltage waveforms at two ends of the sensitive equipment through an oscilloscope.
5. The method of claim 1, wherein the sensitive apparatus further comprises: ACC (contactor) and ASD (debug drive).
6. The method of claim 1, wherein the step of obtaining the immunization time for each of the minimal cut sets comprises:
determining the sensitive equipment in each minimum cut set;
and taking the immunization time of the sensitive device as the immunization time of the minimum cut set.
7. The method of claim 1, wherein the sensitive equipment comprises a motor, and the key parameter of the link comprises a rotational speed of the motor.
8. The method of claim 2, wherein said step of obtaining an immunization schedule for each of said sensitive devices comprises:
and acquiring the immunization time corresponding to the equipment type of the sensitive equipment according to the equipment type of the sensitive equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910025140.7A CN109856505B (en) | 2019-01-11 | 2019-01-11 | Immune time detection method for voltage sag |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910025140.7A CN109856505B (en) | 2019-01-11 | 2019-01-11 | Immune time detection method for voltage sag |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109856505A CN109856505A (en) | 2019-06-07 |
| CN109856505B true CN109856505B (en) | 2022-04-01 |
Family
ID=66894494
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910025140.7A Active CN109856505B (en) | 2019-01-11 | 2019-01-11 | Immune time detection method for voltage sag |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109856505B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111190064B (en) * | 2020-01-02 | 2022-06-03 | 深圳供电局有限公司 | Test method and test system for voltage sag immunization time and storage medium |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103399239A (en) * | 2013-08-12 | 2013-11-20 | 四川大学 | Voltage sag immunity detection method for industrial equipment |
| CN106291244A (en) * | 2016-08-24 | 2017-01-04 | 浙江群力电气有限公司 | One repeatedly voltage dip severity appraisal procedure and system |
| US20170102416A1 (en) * | 2013-03-05 | 2017-04-13 | Texas Instruments Incorporated | Detecting power supply sag in an integrated circuit |
| CN107561347A (en) * | 2017-08-16 | 2018-01-09 | 广州供电局有限公司 | Voltage dip order of severity evaluation method and system |
| CN208092174U (en) * | 2018-05-08 | 2018-11-13 | 深圳供电局有限公司 | Automatic test platform of voltage sag |
| CN109064026A (en) * | 2018-08-03 | 2018-12-21 | 福州大学 | A kind of industrial process procedure parameter immunization time appraisal procedure considering the power supply system method of operation |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104239057B (en) * | 2014-09-18 | 2017-08-11 | 清华大学 | A kind of method for the raising emphasis user power utilization reliability actively found based on power supply |
| CN104835018B (en) * | 2015-06-01 | 2018-06-01 | 国家电网公司 | The reliability estimation method and device of medium voltage distribution network rack |
-
2019
- 2019-01-11 CN CN201910025140.7A patent/CN109856505B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20170102416A1 (en) * | 2013-03-05 | 2017-04-13 | Texas Instruments Incorporated | Detecting power supply sag in an integrated circuit |
| CN103399239A (en) * | 2013-08-12 | 2013-11-20 | 四川大学 | Voltage sag immunity detection method for industrial equipment |
| CN106291244A (en) * | 2016-08-24 | 2017-01-04 | 浙江群力电气有限公司 | One repeatedly voltage dip severity appraisal procedure and system |
| CN107561347A (en) * | 2017-08-16 | 2018-01-09 | 广州供电局有限公司 | Voltage dip order of severity evaluation method and system |
| CN208092174U (en) * | 2018-05-08 | 2018-11-13 | 深圳供电局有限公司 | Automatic test platform of voltage sag |
| CN109064026A (en) * | 2018-08-03 | 2018-12-21 | 福州大学 | A kind of industrial process procedure parameter immunization time appraisal procedure considering the power supply system method of operation |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109856505A (en) | 2019-06-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Arghandeh et al. | Topology detection in microgrids with micro-synchrophasors | |
| US8200372B2 (en) | Methods and processes for managing distributed resources in electricity power generation and distribution networks | |
| US9742181B2 (en) | Method and control system for handling a reclosing operation in a power system | |
| US11101641B2 (en) | Fault protection devices and related reclosing methods | |
| AU2020348655A1 (en) | Fast close open | |
| CN101889323A (en) | Switching arrangement and method for controlling an electromagnetic relay | |
| CN103795022A (en) | Fault current detecting circuit | |
| CN109856505B (en) | Immune time detection method for voltage sag | |
| CN110119696A (en) | Current transformer tail currents recognizer based on wave character difference | |
| Musa et al. | Linear regression index‐based method for fault detection and classification in power transmission line | |
| CN109383300A (en) | Fault detection | |
| CN106849007A (en) | Method and protection device for monitoring the power switch in electrical power net | |
| Das et al. | Real-time secured third zone relay operation under dynamic stressed conditions | |
| US9164148B2 (en) | Systems and methods for detecting over/under excitation faults | |
| CN115280625A (en) | Detecting electrical faults within a monitored area of an electrical transmission line | |
| JP2022529872A (en) | How to protect your distribution and / or transmission network from short circuits | |
| CN205945024U (en) | Ferroresonance harmonic elimination device | |
| Barzegaran et al. | Detecting the position of winding short circuit faults in transformer using high frequency analysis | |
| Shah et al. | Detection and classification of high impedance faults in transmission line using alienation-based analysis on voltage signals | |
| CN106229960B (en) | Detect the ferromagnetic resonance harmonic elimination method of zero-sequence current pulse amplitude uniformity | |
| Dai et al. | Line outage identification based on AC power flow and synchronized measurements | |
| Jagadeesh et al. | An Intuitive Alert System for Fault Detection and Fuse Burn out Recognition at the Distribution Transf ormer | |
| Bhatta et al. | Detecting High-Impedance Fault with Z-Source Circuit Breakers in Smart Grids | |
| Esmaeilian et al. | Evaluation of fault analysis tool under power swing and out-of-step conditions | |
| Bajanek et al. | Instantaneous and Definite Time Overcurrent Protection Algorithms |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| TA01 | Transfer of patent application right | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20200921 Address after: 510620 Tianhe District, Guangzhou, Tianhe South Road, No. two, No. 2, No. Applicant after: Guangzhou Power Supply Bureau of Guangdong Power Grid Co.,Ltd. Address before: 510620 Tianhe District, Guangzhou, Tianhe South Road, No. two, No. 2, No. Applicant before: GUANGZHOU POWER SUPPLY Co.,Ltd. |
|
| GR01 | Patent grant | ||
| GR01 | Patent grant |