CN113884748B - Alternating current transmission line overvoltage measuring method and device based on controllable phase shifter - Google Patents
Alternating current transmission line overvoltage measuring method and device based on controllable phase shifter Download PDFInfo
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- CN113884748B CN113884748B CN202111126357.0A CN202111126357A CN113884748B CN 113884748 B CN113884748 B CN 113884748B CN 202111126357 A CN202111126357 A CN 202111126357A CN 113884748 B CN113884748 B CN 113884748B
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
- G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
- G01R19/16547—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies voltage or current in AC supplies
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Abstract
The invention discloses an alternating current transmission line overvoltage measuring method and device based on a controllable phase shifter, wherein the method comprises the following steps: combining a controllable phase shifter model, a power grid electromagnetic transient simulation model, a power grid running state and a power grid running mode, constructing an overvoltage simulation analysis model and outputting simulation results under different working conditions, wherein the simulation results under different working conditions comprise power frequency overvoltage simulation data under the conditions of no-load long line and no-fault load shedding and operation overvoltage simulation data under a closing no-load line; and carrying out data fitting according to simulation results, controllable phase shifter gears and line lengths under different working conditions to determine a fitting function, and measuring overvoltage values under different working conditions according to the fitting function. The fitting function constructed according to the invention can rapidly calculate the overvoltage of the transmission line of the controllable phase shifter under different working conditions, reduce the calculated amount and improve the measurement accuracy.
Description
Technical Field
The invention relates to the technical field of power systems, in particular to an alternating current transmission line overvoltage measuring method and device based on a controllable phase shifter.
Background
With the increasing size of the power grid, the alternating current power grid is more complex, and with the 'western electric east delivery, the south-north mutual supply and the national networking' pattern is gradually formed, and the 500kV power transmission line is gradually becoming the power grid alternating current backbone network frame. Because the system is affected by the grid structure, line parameters, operation modes and the like in the practical operation, the 500kV power transmission line may have the phenomenon of unreasonable line power flow distribution, thereby limiting the line transmission capacity or endangering the system safety. The phase-shifting transformer is used as an effective tide control means, and has obvious economic benefit in North America, europe and Japan power grids for years due to the advantages of good regulation performance, no change of grid structure, low investment cost and the like. Compared with the traditional transformer, the controllable phase-shifting transformer has a complex structure, particularly a double-core structure, and when additional devices such as a parallel capacitor, a lightning arrester and the like are arranged on a line, the influence of various voltages such as power frequency voltage, operation overvoltage and the like is considered, a certain margin is reserved, and the safe operation of the system after the controllable phase-shifting device is arranged is ensured.
In the prior art, the traditional modeling simulation is adopted to calculate the overvoltage by the calculation method based on the phase-shifting transformer, the calculation method is complex, the efficiency is low, the method cannot adapt to the overvoltage calculation of lines in different fault types and different positions, and most of the existing power system overvoltage calculation methods only consider the line model, the breaker model and the like independently, so that the lack of an electromagnetic transient overvoltage simulation calculation model for constructing the controllable phase shifter is caused, and the safe operation of the system is influenced.
Disclosure of Invention
The invention aims to provide an alternating current transmission line overvoltage measuring method based on a controllable phase shifter, which aims to solve the problems of large calculated amount and low efficiency in the prior art when overvoltage is calculated.
In order to achieve the above object, the present invention provides a method for measuring an overvoltage of an ac transmission line based on a controllable phase shifter, comprising:
constructing a controllable phase shifter model according to the circuit structure and the wiring mode of the controllable phase shifter;
constructing an electromagnetic transient simulation model of the power grid according to the power supply, the circuit and the load of the controllable phase shifter;
combining the controllable phase shifter model, the power grid electromagnetic transient simulation model, the power grid running state and the power grid running mode, constructing an overvoltage simulation analysis model and outputting simulation results under different working conditions, wherein the simulation results under the different working conditions comprise power frequency overvoltage simulation data under the conditions of no-load long line and no-fault load shedding and operation overvoltage simulation data under a closing no-load line;
and carrying out data fitting according to simulation results under different working conditions, the controllable phase shifter gear under different working conditions and the line length under different working conditions to determine a fitting function, and measuring overvoltage values under different working conditions according to the fitting function.
Preferably, the overvoltage values of the different working conditions include: maximum overvoltage with no-load long line, maximum overvoltage without fault load shedding, and maximum overvoltage of no-load closing line.
Preferably, the constructing the overvoltage simulation analysis model and outputting simulation results under different working conditions includes:
measuring steady-state operation voltage along the transmission line according to the overvoltage simulation analysis model;
measuring the unloaded overvoltage value of the line end and the dump load overvoltage value of the line end under different controllable phase-shifting transformer gears according to the overvoltage simulation analysis model;
and determining the power frequency overvoltage simulation data according to the steady-state operation voltage of the power transmission line along the line, the overvoltage value of the no-load at the tail end of the line and the overvoltage value of the load shedding at the tail end of the line.
Preferably, the constructing the overvoltage simulation analysis model and outputting simulation results under different working conditions further includes:
determining a closing statistical model according to the statistics of the closing time of the circuit breaker and the three-phase different periods;
determining steady-state overvoltage before closing and transient overvoltage during closing according to the overvoltage simulation analysis model and the closing statistical model;
and determining the operation overvoltage simulation data according to the steady-state overvoltage before closing and the transient overvoltage during closing.
Preferably, the measuring the overvoltage values of different working conditions according to the fitting function includes:
and measuring the maximum overvoltage of the long line with no-load, the maximum overvoltage of the load without fault and the maximum overvoltage of the no-load closing line by combining the fitting function with a preset voltage class, a preset line parameter and a preset fault type.
The invention also provides an alternating current transmission line overvoltage measuring device based on the controllable phase shifter, which comprises:
the first construction module is used for constructing a controllable phase shifter model according to the circuit structure and the wiring mode of the controllable phase shifter;
the second construction module is used for constructing an electromagnetic transient simulation model of the power grid according to the power supply, the circuit and the load of the controllable phase shifter;
the simulation module is used for combining the controllable phase shifter model, the power grid electromagnetic transient simulation model, the power grid running state and the power grid running mode, constructing an overvoltage simulation analysis model and outputting simulation results under different working conditions, wherein the simulation results under the different working conditions comprise power frequency overvoltage simulation data with no-load long lines and no-fault load shedding and operation overvoltage simulation data under a closing no-load line;
and the acquisition module is used for carrying out data fitting according to simulation results under different working conditions, the gear of the controllable phase shifter under different working conditions and the line length under different working conditions to determine a fitting function, and measuring overvoltage values under different working conditions according to the fitting function.
Preferably, the acquiring module is further configured to: maximum overvoltage with no-load long line, maximum overvoltage without fault load shedding, and maximum overvoltage of no-load closing line.
Preferably, the simulation module is further configured to:
measuring steady-state operation voltage along the transmission line according to the overvoltage simulation analysis model;
measuring the unloaded overvoltage value of the line end and the dump load overvoltage value of the line end under different controllable phase-shifting transformer gears according to the overvoltage simulation analysis model;
and determining the power frequency overvoltage simulation data according to the steady-state operation voltage of the power transmission line along the line, the overvoltage value of the no-load at the tail end of the line and the overvoltage value of the load shedding at the tail end of the line.
Preferably, the simulation module is further configured to:
determining a closing statistical model according to the statistics of the closing time of the circuit breaker and the three-phase different periods;
determining steady-state overvoltage before closing and transient overvoltage during closing according to the overvoltage simulation analysis model and the closing statistical model;
and determining the operation overvoltage simulation data according to the steady-state overvoltage before closing and the transient overvoltage during closing.
Preferably, the acquiring module is further configured to:
and measuring the maximum overvoltage of the long line with no-load, the maximum overvoltage of the load without fault and the maximum overvoltage of the no-load closing line by combining the fitting function with a preset voltage class, a preset line parameter and a preset fault type.
Compared with the prior art, the invention has the beneficial effects that:
by combining the controllable phase shifter model, the power grid electromagnetic transient simulation model, the power grid running state and the power grid running mode, an overvoltage simulation analysis model is constructed, simulation results under different working conditions are output, a fitting function is determined by fitting data according to the simulation results under different working conditions, the controllable phase shifter gear under different working conditions and the line length under different working conditions, the overvoltage under different working conditions is measured according to the fitting function, and the calculated amount of the calculated overvoltage value and the accuracy of the measured overvoltage value are reduced.
The statistics of the closing time of the circuit breaker and the three-phase different period are further considered, the established closing statistical model is more practical, and the accuracy of the calculation result is further ensured.
Drawings
In order to more clearly illustrate the technical solutions of the present invention, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic flow chart of an ac transmission line overvoltage measurement method based on a controllable phase shifter according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a thyristor voltage regulation circuit according to another embodiment of the invention;
FIG. 3 is a schematic diagram of equivalent wiring of a controllable phase shifter according to yet another embodiment of the present invention;
fig. 4 is a schematic diagram of an established simulation analysis model of overvoltage of an ac transmission line with a controllable phase shifter according to an embodiment of the present invention;
fig. 5 is a diagram of a closing statistical model according to another embodiment of the present invention;
fig. 6 is a schematic structural diagram of an ac transmission line overvoltage measurement device based on a controllable phase shifter according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be understood that the step numbers used herein are for convenience of description only and are not limiting as to the order in which the steps are performed.
It is to be understood that the terminology used in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The terms "comprises" and "comprising" indicate the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The term "and/or" refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
Referring to fig. 1, an embodiment of the present invention provides a method for measuring an overvoltage of an ac transmission line based on a controllable phase shifter, which includes the following steps:
s101: and constructing a controllable phase shifter model according to the circuit structure and the wiring mode of the controllable phase shifter.
Specifically, an alternating current power grid overvoltage simulation analysis model containing a controllable phase shifter is built based on electromagnetic transient simulation software, and the simulation analysis model mainly comprises a controllable phase shifter model built according to a controllable phase shifter circuit structure and a wiring mode, a power transmission line tower model taking the coupling effect between different phases of lines and the coupling effect between different lines into consideration, and a power supply model of other equivalent branches.
S102: and constructing an electromagnetic transient simulation model of the power grid according to the power supply, the circuit and the load of the controllable phase shifter.
Specifically, an alternating current power grid overvoltage simulation analysis model containing a controllable phase shifter is built based on power grid electromagnetic transient simulation software, and the simulation analysis model mainly comprises a detailed controllable phase shifter model, a power transmission line model and a power supply model of other equivalent branches.
Further, the established controllable phase shifter model is composed of a series transformer, an exciting transformer and a power electronic switch, wherein the series transformer is represented by three single-phase three-winding transformers, the exciting transformer is represented by three single-phase four-winding transformers, and the controllable phase shifter series transformer and the exciting transformer are connected through a thyristor voltage regulating circuit. Each phase of the thyristor voltage regulating circuit is composed of 12 groups of thyristor groups, and different configurations are obtained by controlling the series connection of secondary windings with different polarities by using the on-off of a thyristor switch, so that the shift of the controllable phase shifter is realized.
Referring to fig. 2, fig. 2 is a thyristor voltage regulating circuit, and the control of the trigger signal causes the thyristor groups 1 and 4, 5 and 8, 9 and 12 to be turned on, which respectively indicates that the secondary windings 2, 3 and 4 of the parallel transformer are connected in series to the circuit, whereas the trigger of the thyristor groups 1 and 2, 5 and 6, 9 and 10 to be turned on indicates that the corresponding secondary windings are not connected.
Referring to fig. 3, the connection modes of the controllable phase shifters include a connection mode of a series-to-internal winding of the controllable phase shifters, a connection mode of an excitation-to-internal winding of the controllable phase shifters, and a connection mode of series-to-excitation-to-inter windings of the controllable phase shifters. The primary winding and the secondary winding of the exciting transformer are connected in star mode, the primary winding of the series transformer is divided into two sections, each section is connected in series in the transmission line, the middle tap is connected with the primary side high-voltage end of the parallel transformer, and the secondary side of the series transformer is connected in triangle. Finally, parameters and operation modes of the controllable phase shifter are obtained, and an electromagnetic transient simulation model of the controllable phase shifter is established by combining the circuit principle and the wiring mode of the controllable phase shifter.
S103: and combining the controllable phase shifter model, the power grid electromagnetic transient simulation model, the power grid running state and the power grid running mode, constructing an overvoltage simulation analysis model and outputting simulation results under different working conditions, wherein the simulation results under the different working conditions comprise power frequency overvoltage simulation data under the conditions of no-load long line and no-fault load shedding and operation overvoltage simulation data under the condition of closing a no-load line.
Based on step S101 and step S102, further, a small-loss berlong parameter model of the power transmission line is established, and a power transmission line model containing positive and negative zero three-sequence parameters is established in consideration of coupling effects between different phases of the lines and coupling effects between different lines.
Furthermore, the power supply models of other equivalent branches only keep nodes on two sides of the overvoltage line, the influence of other branches on the alternating current power transmission line is equivalent to the power supply, and the power supply parameters can effectively reflect the running state and the running mode of the actual power grid. Simplifying the grid, the following equivalence principle should be followed: the voltage and the power angle of the reserved node are consistent with the load flow calculation result, and the short circuit currents of the nodes before and after the equivalent value are consistent.
Referring to fig. 4, the controllable phase shifter model and the electromagnetic transient simulation model of the power grid including the power supply, the line, the load and the like are combined, and the overvoltage simulation analysis model of the alternating current transmission line of the controllable phase shifter is obtained by combining the actual power grid state and the operation mode.
Specifically, steady-state operation voltage of the power transmission line along the line is calculated according to an overvoltage simulation analysis model, the unloaded overvoltage value at the tail end of the line and the load shedding overvoltage value at the tail end of the line under different controllable phase-shifting transformers are calculated according to the overvoltage simulation analysis model, and power frequency overvoltage simulation data are determined according to the steady-state operation voltage of the power transmission line along the line, the unloaded overvoltage value at the tail end of the line and the load shedding overvoltage value at the tail end of the line. And determining a switching-on statistical model according to the switching-on time statistics and the three-phase different phases of the circuit breaker, determining steady-state overvoltage before switching on and transient overvoltage during switching on according to the overvoltage simulation analysis model and the switching-on statistical model, and determining operation overvoltage simulation data according to the steady-state overvoltage before switching on and the transient overvoltage during switching on.
Based on the overvoltage simulation analysis model, simulation calculation is carried out under different working conditions, and the power frequency overvoltage simulation data of the alternating current transmission line based on the controllable phase shifter is obtained. Comprising the following steps: calculating steady-state operation voltage of the power transmission line based on the controllable phase shifter according to an overvoltage simulation analysis model, calculating no-load overvoltage at the tail end of the line and load shedding overvoltage at the tail end of the line according to the overvoltage simulation analysis model, and determining power frequency overvoltage simulation data according to the steady-state operation voltage of the power transmission line, the no-load overvoltage value at the tail end of the line and the load shedding overvoltage value at the tail end of the line.
Based on an overvoltage simulation analysis model, taking statistics of the closing time of the circuit breaker and three-phase different period into consideration, establishing a closing statistical model, and calculating the operation overvoltage of the closing idle line. Comprising the following steps: and calculating the steady-state voltage before switching on based on the controllable phase shifter power transmission line according to the overvoltage simulation analysis model, calculating the transient overvoltage when switching on based on the controllable phase shifter power transmission line according to the overvoltage simulation analysis model, and determining the operation overvoltage simulation data according to the steady-state overvoltage before switching on and the transient overvoltage when switching on.
Further, the closing time adopts a normal distribution model N (T0, +/-0.5t0), wherein T0 and T0 are a closing time setting value and a power frequency period respectively. And on the basis of the closing time, different time offsets are added to each phase to simulate the different phases of the closing three phases, and the time offsets adopt an even distribution model and are randomly valued within +/-0.0015 s. Based on the established closing statistical model, 2% of operation overvoltage is calculated under the condition that three-phase different-period closing of the circuit breaker and the time sequence is 120, and the calculated value is larger than 98%.
Referring to fig. 5, a closing statistical model is disclosed, on the basis of three-phase synchronous closing time BTD, a time offset BAT, BBT, BCT is added to adjust the closing time of the three phases of the circuit breaker, so that the three phases of the circuit breaker are not closed at the same time, different phases of the three phases of the circuit breaker are simulated, the closing time BTD accords with normal distribution, the time offset BAT, BBT, BCT adopts a uniform distribution model, and values are randomly taken within +/-0.0015 s.
S104: and carrying out data fitting according to simulation results under different working conditions, the controllable phase shifter gear under different working conditions and the line length under different working conditions to determine a fitting function, and measuring overvoltage values under different working conditions according to the fitting function.
Specifically, the fitting function is combined with a preset voltage class, a preset line parameter and a preset fault type to obtain the maximum overvoltage of the long line with no-load, the maximum overvoltage of the load without fault and the maximum overvoltage of the no-load line. The overvoltage values of different working conditions comprise the maximum overvoltage of the long line with no-load, the maximum overvoltage of the load without fault and the maximum overvoltage of the no-load line for closing.
And determining a fitting function, firstly marking simulation data on a coordinate system, respectively observing the approximate trend of the gear and the overvoltage value of the controllable phase shifter and the approximate trend of the line length and the overvoltage value, and selecting a proper function to fit the simulation data. Through a plurality of test results, the relationship between the controllable phase shifter gear and the line length and the overvoltage can be expressed by polynomials respectively, namely, the controllable phase shifter gear and the line length are independent variables, and when the overvoltage value is dependent variable, binary polynomials can be used for fitting data.
When the expression of the function polynomial is f (x, y) =p00+p10 x+p01 x+p20 x 2+p11 x y+p02 x y 2, the highest order of the controllable phase shifter gear and the line length is 2 order, the fitting determination coefficients under the three working conditions are all larger than 0.994, when the sum of squares of absolute deviations under three working conditions of the no-load long line, the fault-free load shedding line and the switching-on no-load line is 2.518, 0.3417 and 94.68 respectively and the highest order of the gear y of the increasing controllable phase shifter is 3, the expression of the function polynomial is f (x, y) =p00+p10 x+p01+p20+p20 x 2+p11 x y+p02 y+p21 x 2 y+p12 x y+p03 y 3, the fitting determination coefficient under the three working conditions is greater than 0.997, the square sum distribution of absolute deviation is 0.888, 0.03671 and 35.69, when the highest order of the line length x is increased to be 3, f (x, y) =p00+p10+x+p01+p20+x2+p11 x+p02 x 2+p30 x 3+p21 x 2 x 2+p12 x 2, the square sum distribution of absolute deviation is greater than 0.997, but the observation graph can find that the fitting function graph does not accord with the actual overvoltage trend under the conditions of no-load long line and load shedding. The determination coefficients of the three fitting functions are only 0.003 difference, under the condition of ensuring the fitting precision, the calculation amount is greatly increased by considering the increase of the highest order of the polynomial of the fitting functions, thus, the fitting function takes the form f (x, y) =p00+p10×x+p01×y+p20×x≡2+p11×y+p02×y≡2.
The normal value range of the determined coefficient is [0,1], the closer to 1, the stronger the interpretation capability of the variable of the equation to z is, the better the function is fit to the data, the square sum of absolute deviation refers to the square sum of errors of corresponding points of the fit data and the original data, and the closer to 0, the better the value is fit.
The square sum of absolute deviation is considered, coefficients are determined, the function calculation amount and the generality of the function under different working conditions are considered when a fitting function is constructed, and finally z=a+b+b+c+d+x+y+e+x 2+f y 2 are adopted to fit data, x is the length of a line, y is the gear of the controllable phase shifter, z is the overvoltage value at the tail end of the line, and the voltage level, the line parameters, the fault types and the like are related.
According to the overvoltage calculation method for the alternating current transmission line based on the controllable phase shifter, the actual large power grid is simplified and equivalent through the overvoltage simulation analysis model formed by detailed modeling of the controllable phase shifter, the transmission line and the equivalent power supply, network calculation speed and simulation precision are improved, overvoltage on different controllable phase shifter gears and different positions is calculated through the simulation analysis model under different fault types, the overvoltage added into the controllable phase shifter is guaranteed to accord with actual working conditions, accurate calculation of system overvoltage after the controllable phase shifter is installed is achieved, fitting functions of the controllable phase shifter gears, line lengths and overvoltage are obtained through MATLAB (matrix laboratory) data fitting based on overvoltage data obtained through the simulation analysis model, the maximum overvoltage value under different fault conditions can be obtained quickly, calculation results are accurate and reliable, the overvoltage level of the transmission line can be analyzed well by using the results of the method, and accurate basis is provided for configuration of a follow-up lightning arrester.
In one embodiment, a 500 kV-level overvoltage simulation analysis model is established in a PSCAD environment, and the simulation analysis model consists of a controllable phase shifter, a transformer, a power transmission line, an equivalent power supply and the like, and the following parameters are obtained.
Table 1 controllable phase shifter parameters
Table 2 500kv double-circuit power transmission line parameters
| Positive sequence of | Negative sequence | Zero sequence | |
| R/(Ω/km) | 0.0184 | 0.0184 | 0.1831 |
| X/(Ω/km) | 0.2721 | 0.2721 | 0.86014 |
| C/(μF/km) | 0.0137 | 0.0137 | 0.00102 |
Referring to fig. 4, the controllable phase shifter is installed at the head end of the line, the effective value of the line voltage of the generator at one side of the bus is 230kV, the initial phase angle is 15 °, the effective value of the line voltage of the generator at both sides of the bus is 230kV, and the initial phase angle is 0 °. The generator step-up transformer adopts a double-winding transformer model, the connection group is marked as Y0/d11, and the capacity is 1000MVA.
And combining the controllable phase shifter model with a power grid electromagnetic transient simulation model containing a power supply, a circuit, a load and the like, and combining the actual power grid state and an operation mode to obtain an alternating current power grid simulation analysis model with the controllable phase shifter. The simulation model calculates overvoltage in different lengths and different controllable phase shifters under three different working conditions of dead load, load shedding and dead load shedding lines at the tail end.
TABLE 3 Power frequency overvoltage simulation data
TABLE 4 operation overvoltage U 2％ Simulation data
Fitting the simulation data through MATLAB software to obtain a fitting function of line overvoltage, line length and controllable phase shifter gear: z=a+b x+c x+d x y+e x 2+f y 2.z is the overvoltage value (unit kV), x represents the line length (unit km), and y represents the controllable phase shifter gear. a, b, c, d, e, f are related to fault type, voltage class, line parameters, etc.
Band no-load long line fitting parameters: a=595.5, b=0.1453, c= -0.02132, d= 9.091e-06, e= -0.000383, f= 0.01731.
Load shedding fitting parameters: a=600.9, b=0.1523, c=1.237, d=0.001238, e= -0.0004025, f= -0.004182.
Fitting parameters of a closing no-load line: a=609, b=0.5041, c= -3.182, d=0.003842, e= -0.001032, f= -0.007703.
And calculating an overvoltage value under the required working condition through a fitting function. To verify the effectiveness of the method, the effectiveness of the method is verified for a specific example by comparing the overvoltage value calculated by the conventional method employing the PSCAD model simulation with the method employing the overvoltage fitting presented herein. And comparing with an overvoltage standard to check whether the overvoltage meets the requirement. The results are compared in Table 5 below.
Table 5 results alignment
As can be seen from table 5, the overvoltage value calculated by the present invention is not greatly different from the overvoltage value calculated by the PSCAD simulation, and the result shows that the value calculated by the fitting function is feasible as an overvoltage judgment basis. By analyzing the fitting function, all overvoltage values under the simulation conditions of the example are within the allowable range. The maximum overvoltage of the long line with no load is 1.11pu, the maximum overvoltage of the load without fault is 1.15pu, the maximum overvoltage of the idle line with closing is 1.22pu, the overvoltage of the power frequency is not more than 1.3pu, the overvoltage of the operation is not more than 2.0pu, and the standard is met.
Referring to fig. 6, another embodiment of the present invention provides an ac transmission line overvoltage measurement device based on a controllable phase shifter, including:
the first construction module 11 is configured to construct a controllable phase shifter model according to a circuit structure and a wiring mode of the controllable phase shifter.
The second construction module 12 is configured to construct an electromagnetic transient simulation model of the power grid according to the power supply, the line and the load of the controllable phase shifter.
The simulation module 13 is configured to combine the controllable phase shifter model, the power grid electromagnetic transient simulation model, the power grid running state and the power grid running mode to construct an overvoltage simulation analysis model and output simulation results under different working conditions, wherein the simulation results under different working conditions comprise power frequency overvoltage simulation data under the conditions of no-load long line and no-fault load shedding and operation overvoltage simulation data under the condition of no-load closing.
And the obtaining module 14 is used for carrying out data fitting according to the simulation results under different working conditions, the controllable phase shifter gear under different working conditions and the line length under different working conditions to determine a fitting function, and measuring the overvoltage values under different working conditions according to the fitting function.
The specific limitation of the ac transmission line overvoltage measuring device based on the controllable phase shifter can be referred to as the limitation of the ac transmission line overvoltage measuring method based on the controllable phase shifter, and the description thereof is omitted herein. The modules in the alternating current transmission line overvoltage measuring device based on the controllable phase shifter can be fully or partially realized by software, hardware and a combination thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.
Claims (10)
1. An alternating current transmission line overvoltage measurement method based on a controllable phase shifter is characterized by comprising the following steps of:
constructing a controllable phase shifter model according to the circuit structure and the wiring mode of the controllable phase shifter;
constructing an electromagnetic transient simulation model of the power grid according to the power supply, the circuit and the load of the controllable phase shifter;
combining the controllable phase shifter model, the power grid electromagnetic transient simulation model, the power grid running state and the power grid running mode, constructing an overvoltage simulation analysis model and outputting simulation results under different working conditions, wherein the simulation results under the different working conditions comprise power frequency overvoltage simulation data under the conditions of no-load long line and no-fault load shedding and operation overvoltage simulation data under a closing no-load line;
and carrying out data fitting according to simulation results under different working conditions, the controllable phase shifter gear under different working conditions and the line length under different working conditions to determine a fitting function, and measuring overvoltage values under different working conditions according to the fitting function.
2. The method for measuring the overvoltage of the alternating current transmission line based on the controllable phase shifter according to claim 1, wherein the overvoltage values of different working conditions comprise: maximum overvoltage with no-load long line, maximum overvoltage without fault load shedding, and maximum overvoltage of no-load closing line.
3. The method for measuring the overvoltage of the alternating current transmission line based on the controllable phase shifter according to claim 1, wherein the steps of constructing an overvoltage simulation analysis model and outputting simulation results under different working conditions include:
measuring steady-state operation voltage along the transmission line according to the overvoltage simulation analysis model;
measuring the unloaded overvoltage value of the line end and the dump load overvoltage value of the line end under different controllable phase-shifting transformer gears according to the overvoltage simulation analysis model;
and determining the power frequency overvoltage simulation data according to the steady-state operation voltage of the power transmission line along the line, the overvoltage value of the no-load at the tail end of the line and the overvoltage value of the load shedding at the tail end of the line.
4. The method for measuring overvoltage of an ac transmission line based on a controllable phase shifter according to claim 3, wherein the constructing an overvoltage simulation analysis model and outputting simulation results under different working conditions further comprises:
determining a closing statistical model according to the statistics of the closing time of the circuit breaker and the three-phase different periods;
determining steady-state overvoltage before closing and transient overvoltage during closing according to the overvoltage simulation analysis model and the closing statistical model;
and determining the operation overvoltage simulation data according to the steady-state overvoltage before closing and the transient overvoltage during closing.
5. The method for measuring overvoltage of an ac transmission line based on a controllable phase shifter according to claim 2, wherein the measuring the overvoltage values of different working conditions according to the fitting function includes:
and measuring the maximum overvoltage of the long line with no-load, the maximum overvoltage of the load without fault and the maximum overvoltage of the no-load closing line by combining the fitting function with a preset voltage class, a preset line parameter and a preset fault type.
6. An ac transmission line overvoltage measurement device based on a controllable phase shifter, comprising:
the first construction module is used for constructing a controllable phase shifter model according to the circuit structure and the wiring mode of the controllable phase shifter;
the second construction module is used for constructing an electromagnetic transient simulation model of the power grid according to the power supply, the circuit and the load of the controllable phase shifter;
the simulation module is used for combining the controllable phase shifter model, the power grid electromagnetic transient simulation model, the power grid running state and the power grid running mode, constructing an overvoltage simulation analysis model and outputting simulation results under different working conditions, wherein the simulation results under the different working conditions comprise power frequency overvoltage simulation data with no-load long lines and no-fault load shedding and operation overvoltage simulation data under a closing no-load line;
and the acquisition module is used for carrying out data fitting according to simulation results under different working conditions, the gear of the controllable phase shifter under different working conditions and the line length under different working conditions to determine a fitting function, and measuring overvoltage values under different working conditions according to the fitting function.
7. The controllable phase shifter-based ac transmission line overvoltage measurement device according to claim 6, wherein the acquisition module is further configured to: maximum overvoltage with no-load long line, maximum overvoltage without fault load shedding, and maximum overvoltage of no-load closing line.
8. The controllable phase shifter-based ac transmission line overvoltage measurement device according to claim 6, wherein the simulation module is further configured to:
measuring steady-state operation voltage along the transmission line according to the overvoltage simulation analysis model;
measuring the unloaded overvoltage value of the line end and the dump load overvoltage value of the line end under different controllable phase-shifting transformer gears according to the overvoltage simulation analysis model;
and determining the power frequency overvoltage simulation data according to the steady-state operation voltage of the power transmission line along the line, the overvoltage value of the no-load at the tail end of the line and the overvoltage value of the load shedding at the tail end of the line.
9. The controllable phase shifter-based ac transmission line overvoltage measurement device according to claim 8, wherein the simulation module is further configured to:
determining a closing statistical model according to the statistics of the closing time of the circuit breaker and the three-phase different periods;
determining steady-state overvoltage before closing and transient overvoltage during closing according to the overvoltage simulation analysis model and the closing statistical model;
and determining the operation overvoltage simulation data according to the steady-state overvoltage before closing and the transient overvoltage during closing.
10. The controllable phase shifter-based ac transmission line overvoltage measurement device according to claim 7, wherein the acquisition module is further configured to:
and measuring the maximum overvoltage of the long line with no-load, the maximum overvoltage of the load without fault and the maximum overvoltage of the no-load closing line by combining the fitting function with a preset voltage class, a preset line parameter and a preset fault type.
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