CN115684812A - Flexible direct current transmission line lightning stroke interference identification method and system - Google Patents
Flexible direct current transmission line lightning stroke interference identification method and system Download PDFInfo
- Publication number
- CN115684812A CN115684812A CN202211449142.7A CN202211449142A CN115684812A CN 115684812 A CN115684812 A CN 115684812A CN 202211449142 A CN202211449142 A CN 202211449142A CN 115684812 A CN115684812 A CN 115684812A
- Authority
- CN
- China
- Prior art keywords
- line
- transmission line
- time
- lightning stroke
- current
- 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.)
- Pending
Links
Images
Landscapes
- Locating Faults (AREA)
Abstract
The invention belongs to the field of direct current transmission line protection, and particularly relates to a lightning stroke interference identification method and system for a flexible direct current transmission line. The invention is characterized in that: the method determines the judgment condition that the rise time of the current fault component in a specific time window is less than the fall time of the current fault component in the specific time window when the direct current transmission line suffers from lightning stroke interference, lightning stroke fault and common short circuit fault through the waveform characteristics of the differential mode current fault component, so that fault traveling waves caused by the lightning stroke interference and other faults can be more accurately distinguished according to the rise time and the fall time of the current fault component in the differential mode current fault component characteristics and the line differential mode current fault component in the set time window, misoperation of quick-break protection is avoided, and the protection reliability is improved. And when the line voltage abrupt change meets the condition, lightning stroke interference identification is carried out, so that frequent triggering of an identification process is avoided, and the lightning stroke interference identification calculated amount is saved.
Description
Technical Field
The invention belongs to the field of direct current transmission line protection, and particularly relates to a lightning stroke interference identification method and system for a flexible direct current transmission line.
Background
In the application of the traditional direct current engineering, the length of a main protection criterion data window is generally short, and because lightning current impact often occurs on a similar time scale, the criterion can also be influenced by lightning stroke interference while the protection discrimination speed is greatly improved; therefore, home and abroad manufacturers generally configure traveling wave protection and/or voltage mutation protection in the protection of the high-voltage direct-current transmission line aiming at lightning interference.
However, traveling wave protection and voltage mutation protection are generally configured with lightning interference diagnosis elements only rarely and only by setting a protection fixed value to avoid lightning interference, so that reliability is not high and certain risk exists. And in flexible direct current engineering, when direct current circuit takes place the thunderbolt and disturb, direct current circuit electric current rises, and voltage descends rapidly, and is similar with other interior fault characteristics in district especially, also has the risk of maloperation equally. For traveling wave protection, because lightning stroke and transient signals caused by faults are high-frequency signals, the existing traveling wave protection is difficult to distinguish fault traveling waves from lightning stroke interference, so that the accuracy of lightning stroke interference identification is low, and the protection is unreliable.
Disclosure of Invention
The invention aims to provide a lightning stroke interference identification method and a lightning stroke interference identification system for a flexible direct current transmission line, which are used for solving the problem that the accuracy of lightning stroke interference identification is low due to the fact that fault travelling waves and lightning stroke interference are difficult to distinguish in the existing travelling wave protection.
In order to achieve the purpose, the invention provides a lightning stroke interference identification method for a flexible direct current transmission line, which comprises the following steps:
1) Acquiring a voltage signal and positive and negative current signals of the flexible direct current transmission line in real time, and calculating positive and negative current fault components of the line by combining the current signals of the line at a steady state moment;
2) Obtaining a differential mode current fault component of the line according to the positive and negative current fault components of the line;
3) When the line voltage break variable meets the protection starting criterion, determining the rising time and the falling time of the line differential mode current fault component in a set time window;
4) Judging whether the power transmission line has lightning stroke interference according to the rising time and the falling time of the differential mode current fault component of the power transmission line: and if the rising time of the differential mode current fault component of the line is less than or equal to the falling time, or the degree that the rising time is greater than the falling time is within the set upper limit, judging that the lightning stroke interference occurs to the power transmission line.
According to the lightning interference identification method, the rising and falling time length characteristics in the differential mode current fault component characteristics are adopted, so that lightning interference and fault traveling waves caused by other faults can be more accurately distinguished, the quick-break protection misoperation is avoided, and the protection reliability is improved. And when the sudden line voltage variation meets the condition, lightning interference identification is carried out, frequent triggering of an identification process is avoided, and lightning interference identification calculated amount is saved.
Further, the protection starting criterion is specifically as follows:
in the formula: Δ u p (k) For the current time of the sudden change of the DC line voltage u p (k) For the voltage sample value at the present moment, u p And (k-1) is a voltage sampling value at the previous sampling moment of the current moment, and delta 1 is a starting criterion threshold value.
Further, in step 4), the manner of determining whether the power transmission line has the lightning interference according to the rise time and the fall time of the differential mode current fault component of the power transmission line is specifically as follows:
if r is less than or equal to delta 2 Judging that the lightning stroke interference occurs; if r > Δ 2 If so, judging that the line ground fault occurs;
wherein, t up For the rise time of the fault component of the differential-mode current of the line, t down For the duration of the fall of the fault component of the differential-mode current of the line, Δ 2 For a set lightning strike interference threshold value, and 2 ≥1。
further, the rising time and the falling time of the differential mode current fault component of the line are specifically calculated as follows:
in the formula: t is t up (k) For rising time sampling point, t down (k) Sampling points for falling time; Δ i 1 (k) For the differential-mode current fault component at the present moment, Δ i 1 (k-1) a differential mode current fault component of a sampling period prior to a current time;
the rise time and fall time are:
in the formula: t is t up For the rise time of the fault component of the differential-mode current of the line, t down The time length of the reduction of the differential mode current fault component of the line is taken as the time length; k =1 is a sampling point at the starting moment of the protection starting criterion, and n is the number of sampling points in the set time window.
The calculation method normalizes the sampling point data into the rising state and the falling state, so that the statistics of the rising time and the falling time of the differential mode current fault component of the line is more accurate.
Further, in the step 2), differential mode conversion decoupling is carried out on the positive and negative current fault components of the line, and the differential mode current fault component of the line is calculated; the specific formula for calculating the fault component of the differential mode current of the line through differential mode conversion decoupling is as follows:
in the formula: Δ i 1 (k) Is a line differential mode current fault component; delta i P (k)、Δi N (k) The line positive and negative current fault components, respectively, and subscript 1 represents the differential mode component.
Further, in step 1), the calculation method of the fault components of the positive and negative current of the line is as follows:
in the formula: Δ i P (k)、Δi N (k) Respectively representing the current fault components of the positive pole and the negative pole of the circuit; i.e. i P (k)、i N (k) Respectively positive and negative line current signals i acquired at the present moment P (0)、i N (0) Respectively, positive and negative current signals of the line at the steady state moment.
Further, the starting criterion threshold value is larger than the maximum value of the voltage gradient under the voltage fluctuation when the power transmission line normally operates.
Further, the set lightning stroke interference threshold value delta 2 Is 1.5.
In the case of normal operation, since the current fluctuates up and down around the steady-state operation value, the rise and fall times are substantially equal, and therefore Δ 2 The value of (2) is set to 1.5 according to the ratio of the rising time to the falling time of the current differential mode component under the condition of avoiding normal operation.
The invention also provides a lightning stroke interference recognition system of the flexible direct current transmission line, which comprises a collector and a processor, wherein the collector is used for collecting the positive and negative current signals and the voltage signal of the transmission line at the fault end in real time, and the processor is used for executing the program instruction so as to realize the lightning stroke interference recognition method of the flexible direct current transmission line. The system can achieve the same beneficial effects as the flexible direct current transmission line lightning stroke interference identification method.
Drawings
FIG. 1 is a flow chart of a lightning stroke interference identification method in an embodiment of the flexible direct current transmission line lightning stroke interference identification method of the invention;
FIG. 2 is a differential mode current fault component waveform of a DC transmission line in the case of suffering from lightning interference in the embodiment of the flexible DC transmission line lightning interference identification method of the present invention;
FIG. 3 is a differential mode current fault component waveform of a DC transmission line in the case of a fault caused by counterattack in the embodiment of the flexible DC transmission line lightning stroke interference identification method of the present invention;
FIG. 4 is a differential mode current fault component waveform of a direct current transmission line in the case of a fault caused by shielding failure in the embodiment of the flexible direct current transmission line lightning stroke interference identification method of the invention;
FIG. 5 is a differential mode current fault component waveform of a direct current transmission line under a condition of a common short circuit fault in the embodiment of the flexible direct current transmission line lightning stroke interference identification method.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.
Embodiment of method for identifying lightning stroke interference of flexible direct current transmission line
The embodiment provides a technical scheme of a flexible direct current transmission line lightning stroke interference identification method, and with reference to fig. 1, the method specifically comprises the following steps:
1) Acquiring a voltage signal and positive and negative current signals of the flexible direct current transmission line in real time, and calculating positive and negative current fault components of the line by combining the current signals of the line at a steady state moment; in the embodiment, in order to reduce the difficulty in acquiring the voltage and current signals required by lightning interference identification, the current signal, the current voltage signal, the positive and negative current signals of the line at the steady state time of the power transmission line at the local terminal (i.e., the line terminal executing the lightning interference identification method process) are directly acquired for identifying the lightning interference, and the relevant circuit data can be directly acquired from the local terminal and then directly used for judgment, so that the cost for acquiring the data can be reduced.
The calculation method of the fault components of the positive and negative current of the line comprises the following steps:
in the formula: Δ i P (k)、Δi N (k) Respectively representing the current fault components of the positive pole and the negative pole of the circuit; i.e. i P (k)、i N (k) Respectively for the current time acquisitionPositive and negative line current signals i P (0)、i N (0) Respectively, positive and negative current signals of the line at the steady state moment.
2) And obtaining a differential mode current fault component of the line according to the positive and negative current fault components of the line.
For the flexible direct current bipolar system, a transformation matrix Q can be constructed by using a differential mode transformation method to decouple the bipolar line into a common mode system and a differential mode system. The differential mode current fault component adopted in the embodiment is obtained by the positive and negative current fault components through a differential mode transformation matrix Q as follows:
therefore, in this embodiment, differential-mode transformation decoupling is performed on the line positive and negative current fault components, and a specific formula for calculating the line differential-mode current fault component is as follows:
in the formula: Δ i 1 (k) Is a line differential mode current fault component; delta i P (k)、Δi N (k) The line positive and negative current fault components, respectively, and subscript 1 represents the differential mode component.
3) And when the line voltage abrupt change meets the protection starting criterion, determining the rising time and the falling time of the line differential mode current fault component in a set time window.
The protection starting criterion that the sudden change of the line voltage needs to meet is as follows:
in the formula: Δ u p (k) For the current time DC line voltage sudden change u p (k) For the voltage sample value at the present moment, u p (k-1) is a voltage sampling value at a time immediately before the current time, and Δ 1 is a start judgmentAccording to a threshold value, and Δ 2 Not less than 1; the time instants mentioned in this embodiment are all referred to as sampling time instants. Under normal conditions, the selection of a starting criterion threshold value is larger than the maximum value of a voltage gradient under normal operation voltage fluctuation, and meanwhile, accurate and quick starting of internal faults of a direct-current power grid is guaranteed; in this embodiment, the start criterion threshold value Δ 1 is 0.02. When the line voltage break variable meets the protection starting criterion, the step of identifying the lightning stroke interference is continued, so that the frequent triggering of the identification process is avoided, and the cost of identifying the lightning stroke interference is saved.
The calculation of the rising time and the falling time of the differential mode current fault component of the line is specifically as follows:
in the formula: t is t up (k) For rising time sampling point, t down (k) Sampling points for falling time; Δ i 1 (k) For the differential-mode current fault component at the present moment, Δ i 1 (k-1) a differential mode current fault component of a sampling period prior to a current time;
the rise time and fall time are:
in the formula: t is t up For the rise time of the fault component of the differential-mode current of the line, t down The time length of the reduction of the differential mode current fault component of the line; k =1 is a sampling point at the starting moment of the protection starting criterion, and n is the number of sampling points in the set time window. In the protection of a flexible direct current line, the requirement on the quick action of the line protection is usually high, if a certain project requires protection action export within 3ms, a 1ms time window is generally adopted, and if the sampling rate is 20KHz, n is 20. The calculation method normalizes the sampling point data into the rising state and the falling state, so that the statistics of the rising time and the falling time of the differential mode current fault component of the line is more accurate.
4) Judging whether the power transmission line has lightning stroke interference according to the rising time and the falling time of the differential mode current fault component of the power transmission line: and if the rising time of the differential mode current fault component of the line is less than or equal to the falling time, or the degree that the rising time is greater than the falling time is within the set upper limit (namely the degree that the rising time is greater than the falling time is smaller), judging that the lightning stroke interference occurs to the power transmission line.
Fig. 2, fig. 3, fig. 4 and fig. 5 show waveforms of differential mode current fault components collected in four cases of a direct current transmission line suffering from lightning interference, a fault caused by counterattack, a fault caused by shielding failure and a common short circuit fault, respectively; the faults caused by counterattack and shielding failure belong to lightning stroke faults, the lightning stroke faults also belong to line ground faults, and the common short circuit faults also belong to line ground faults. According to the waveform image, it can be determined that when a lightning stroke fault and a common short circuit fault occur on a line, the rising time of a differential mode current fault component is longer than the falling time of the differential mode current fault component in a specific time window after protection starting; when the line is interfered by lightning, the rise time of the differential mode current fault component is shorter than the fall time of the differential mode current fault component in a specific time window after the protection is started. Based on the characteristics, the system error and the normal fluctuation are considered, and the conditions for judging whether the power transmission line has lightning stroke interference are summarized as follows: in a specific time window after the protection is started, the rising time of the differential mode current fault component is less than or equal to the falling time of the differential mode current fault component, or the degree that the rising time is greater than the falling time is in a set upper limit range.
In this embodiment, the determination condition is specifically expressed as follows:
if r is less than or equal to Δ 2 Judging that lightning stroke interference occurs; if r > Δ 2 If so, judging that the line ground fault occurs;
wherein, t up Is the rise time, t, of the differential-mode current fault component of the line down For the duration of the fall of the fault component of the differential-mode current of the line, Δ 2 Is a set lightning stroke interference threshold value. To meet the reliability and selectivity of protection, minesAttack interference threshold value delta 2 Setting the value to be slightly larger than 1, and setting the specific value according to the ratio of the rising time and the falling time of the current-mode component under the condition of avoiding normal operation, namely setting the degree that the rising time length of the differential-mode current fault component is larger than the falling time length in a set upper limit range. Under the condition of normal operation, because the current fluctuates up and down around the steady-state operation value, the rising time and the falling time are approximately equal, in the embodiment, a certain reliability coefficient is considered, and delta is calculated 2 Set to 1.5.
In other embodiments, the above-mentioned determination condition may also be expressed in other ways, such as using the difference between the falling time length and the rising time length of the differential mode current fault component of the line as the determination index, and if the difference is Δ t = t down -t up And if the difference value is larger than or equal to the set difference value threshold value, or the degree that the difference value is smaller than the set difference value threshold value is within a certain upper limit range, judging that the lightning interference occurs, and otherwise, judging that the line ground fault occurs.
Flexible direct current transmission line lightning stroke interference recognition system embodiment
The embodiment provides a lightning stroke interference recognition system for a flexible direct current transmission line, which comprises a collector and a processor; the collector is used for collecting positive and negative current signals and voltage signals of the power transmission line at the fault end in real time, and the processor is used for executing program instructions so as to realize the lightning stroke interference identification method in the embodiment of the lightning stroke interference identification method of the flexible direct current power transmission line. Because the processing principle and content of the system processor and the corresponding beneficial effects are explained in detail in the embodiment of the flexible direct current transmission line lightning stroke interference identification method, the details are not repeated here.
The invention is characterized in that: the method determines the judgment condition that the rising time length of the current fault component in a specific time window is less than the falling time length of the current fault component in the specific time window when the direct current transmission line suffers from lightning stroke interference, lightning stroke faults and common short circuit faults through the waveform characteristics of the differential mode current fault component under the conditions that the direct current transmission line suffers from the lightning stroke interference, the lightning stroke faults and fault traveling waves caused by other faults can be more accurately distinguished through the rising time length characteristic and the falling time length characteristic in the differential mode current fault component characteristic according to the circuit differential mode current fault component in the set time window, misoperation of quick-break protection is avoided, and the protection reliability is improved. And when the line voltage abrupt change meets the condition, lightning stroke interference identification is carried out, so that frequent triggering of an identification process is avoided, and the lightning stroke interference identification calculated amount is saved.
Claims (9)
1. A lightning stroke interference identification method for a flexible direct current transmission line is characterized by comprising the following steps:
1) Acquiring a voltage signal and positive and negative current signals of the flexible direct current transmission line in real time, and calculating positive and negative current fault components of the line by combining the current signals of the line at a steady state moment;
2) Obtaining a differential mode current fault component of the line according to the positive and negative current fault components of the line;
3) When the line voltage break variable meets the protection starting criterion, determining the rising time and the falling time of the line differential mode current fault component in a set time window;
4) Judging whether the power transmission line has lightning stroke interference according to the rising time and the falling time of the differential mode current fault component of the power transmission line: and if the rising time of the differential mode current fault component of the line is less than or equal to the falling time, or the degree that the rising time is greater than the falling time is within the set upper limit, judging that the lightning stroke interference occurs to the power transmission line.
2. The method for identifying the lightning stroke interference of the flexible direct current transmission line according to claim 1, wherein the protection starting criterion is as follows:
in the formula: Δ u p (k) For the current time of the sudden change of the DC line voltage u p (k) For the voltage sample value at the present moment, u p And (k-1) is a voltage sampling value at the previous moment of the current moment, and delta 1 is a starting criterion threshold value.
3. The method for identifying the lightning stroke interference of the flexible direct current transmission line according to claim 1, wherein in the step 4), the conditions for judging the lightning stroke interference of the transmission line are as follows:
if r is less than or equal to delta 2 Judging that lightning stroke interference occurs; if r > Δ 2 If so, judging that the line ground fault occurs;
wherein, t up For the rise time of the fault component of the differential-mode current of the line, t down For the duration of the fall of the fault component of the differential-mode current of the line, Δ 2 For a set lightning strike interference threshold value, and 2 ≥1。
4. the method for identifying the lightning interference of the flexible direct current transmission line according to any one of claims 1 to 3, wherein the calculation of the rise time and the fall time of the differential mode current fault component of the line is as follows:
in the formula: t is t up (k) For rising time sampling point, t down (k) Sampling points for falling time; Δ i 1 (k) For the current time differential mode current fault component, Δ i 1 (k-1) a differential mode current fault component of a previous sampling period at a present time;
the rise time and fall time are:
in the formula: t is t up For the rise time of the fault component of the differential-mode current of the line, t down The time length of the reduction of the differential mode current fault component of the line; k =1 at the moment of initiation of the protection initiation criterionAnd n is the number of sampling points in a set time window.
5. The flexible direct current transmission line lightning stroke interference identification method according to any one of claims 1-3, characterized in that in step 2), the differential mode current fault components of the line are calculated by performing differential mode transformation decoupling on the positive and negative current fault components of the line; the specific formula for calculating the fault component of the differential mode current of the line through differential mode conversion decoupling is as follows:
in the formula: Δ i 1 (k) Is the line differential mode current fault component; delta i P (k)、Δi N (k) The line positive and negative current fault components, respectively, and subscript 1 represents the differential mode component.
6. The flexible direct current transmission line lightning stroke interference identification method according to any one of claims 1-3, characterized in that in the step 1), the calculation mode of the line positive and negative current fault components is as follows:
in the formula: delta i P (k)、Δi N (k) Respectively representing the current fault components of the positive pole and the negative pole of the circuit; i.e. i P (k)、i N (k) Respectively positive and negative line current signals i acquired at the present moment P (0)、i N (0) Respectively, positive and negative current signals of the line at the steady state moment.
7. The method for identifying the lightning stroke interference of the flexible direct current transmission line according to claim 2, wherein a starting criterion threshold value is larger than the maximum value of the voltage gradient under the voltage fluctuation when the transmission line normally operates.
8. According to claim3, the lightning interference identification method of the flexible direct current transmission line is characterized in that the set lightning interference threshold value delta is 2 Is 1.5.
9. A flexible direct current transmission line lightning stroke interference recognition system comprises a collector and a processor, and is characterized in that the collector is used for collecting a positive electrode current signal and a negative electrode current signal and a voltage signal of a fault end transmission line in real time, and the processor is used for executing a program instruction so as to realize the flexible direct current transmission line lightning stroke interference recognition method according to any one of claims 1 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211449142.7A CN115684812A (en) | 2022-11-18 | 2022-11-18 | Flexible direct current transmission line lightning stroke interference identification method and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211449142.7A CN115684812A (en) | 2022-11-18 | 2022-11-18 | Flexible direct current transmission line lightning stroke interference identification method and system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115684812A true CN115684812A (en) | 2023-02-03 |
Family
ID=85053222
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211449142.7A Pending CN115684812A (en) | 2022-11-18 | 2022-11-18 | Flexible direct current transmission line lightning stroke interference identification method and system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115684812A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118244041A (en) * | 2024-05-20 | 2024-06-25 | 昆明理工大学 | Identification method and system for lightning shielding failure and counterattack of high-voltage direct-current transmission line |
-
2022
- 2022-11-18 CN CN202211449142.7A patent/CN115684812A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118244041A (en) * | 2024-05-20 | 2024-06-25 | 昆明理工大学 | Identification method and system for lightning shielding failure and counterattack of high-voltage direct-current transmission line |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110361686B (en) | Multi-parameter-based fault detection method for capacitive voltage transformer | |
| CN110579682A (en) | Fault recording data transient homologous comparison method and device | |
| CN112202151B (en) | Pilot protection method and pilot protection system for high-voltage direct-current transmission line | |
| CN109991556B (en) | Diagnosis method for short-term failure fault of lithium iron phosphate power battery | |
| US11368011B2 (en) | Intermediate relay maloperation preventing device and method based on improved recursive wavelet algorithm | |
| CN115684812A (en) | Flexible direct current transmission line lightning stroke interference identification method and system | |
| CN111641196A (en) | High-voltage direct-current line pilot protection method based on branch current characteristics | |
| CN112014701A (en) | Direct current arc detection method of direct current system | |
| CN108181579B (en) | Converter transformer tap switch vibration-electromagnetic wave combined on-line monitoring method | |
| CN108199356B (en) | Wave-front information-based DC transmission line ultra-high speed protection method | |
| CN109557417B (en) | Distributed traveling wave diagnosis starting method and system for power transmission line | |
| CN110850333A (en) | Phase identification method for single-phase earth fault of low-voltage distribution system | |
| CN112345885A (en) | Fault detection method for high-voltage direct-current transmission line | |
| CN112067944A (en) | Single-phase grounding fault detection control method for power transmission and distribution line | |
| CN109241874B (en) | Power signal filtering method in energy decomposition | |
| CN108918929B (en) | Power signal self-adaptive filtering method in load decomposition | |
| CN115577272B (en) | Multiple lightning stroke discrimination method based on fault recording data | |
| CN115859088A (en) | High-voltage circuit breaker vibration signal feature extraction method | |
| CN115575726B (en) | Method and system for judging multiple lightning stroke properties of power transmission line | |
| CN110161363B (en) | Transformer running state vibration and sound detection method and system based on main frequency characteristic quantity | |
| CN109995005B (en) | Direct-current transmission line pilot protection method based on trigger angle change rate mean value | |
| CN113946959B (en) | Voltage sag data segment extraction method | |
| CN116482453A (en) | Flexible direct-current transmission line overvoltage interference identification method, system and device | |
| CN112186715B (en) | Differential protection method for transformer | |
| CN118501620B (en) | Power distribution network high-resistance fault identification method based on continuous filtering and kurtosis change rate |
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 |