Capacitive voltage transformer dynamic model platform with adjustable metering state

Abstract

The application discloses a kind of movable mode platforms of capacitive voltage transformer with adjustable metering state, including first transformer and second transformer, and the first transformer is used for the access of platform power supply;The input end of the second transformer is connected in parallel with two groups of three-phase 0.2-level CVT and a group of three-phase 0.01-level PT;The output end of the second transformer is connected in parallel with two groups of three-phase 0.2-level CVT and a group of three-phase 0.01-level PT, and the second transformer is used to simulate 220kV to 110kV transformer in substation, and the primary voltage of CVT connected in parallel at the input end is twice the primary voltage of CVT connected in parallel at the output end.The application designs error-adjustable micro CVT using movable mode idea, and according to the current application scene of the technology, designs error test platform of double-voltage-grade 4 groups of error-adjustable CVT, to verify the accuracy, reliability and universality of voltage transformer metering performance state evaluation algorithm.

Description

Technical Field

[0001] This invention relates to the field of power grid operation and maintenance technology, specifically to a dynamic model platform for a capacitive voltage transformer with adjustable metering status. Background Technology

[0002] Currently, the power industry is striving to achieve full coverage of online monitoring technology for capacitive voltage transformers (CVTs) used in spot transactions within the system. At present, many universities and research institutions both domestically and internationally have proposed various voltage transformer metering performance status assessment algorithms, including principal component analysis and cyber-physical correlation. However, the accuracy, reliability, and universality verification of these algorithms are still in the initial research stage and require further investigation. Summary of the Invention

[0003] In view of the current status of verification of voltage transformer metering performance status evaluation algorithms, the purpose of this invention is to provide a dynamic model platform for capacitive voltage transformers with adjustable metering status.

[0004] To achieve the objectives of this invention, the technical solution provided by this invention is as follows:

[0005] A dynamic simulation platform for capacitive voltage transformers with adjustable metering status includes a first transformer with a transformation ratio of 1:1 and a second transformer with a transformation ratio of 2:1. The first transformer is used for power supply to the platform. Two sets of three-phase 0.2-class capacitive voltage transformers (CVTs) and one set of three-phase 0.01-class voltage transformers (PTs) are connected in parallel at the input end of the second transformer. Two sets of three-phase 0.2-class CVTs and one set of three-phase 0.01-class PTs are connected in parallel at the output end of the second transformer. The second transformer is used to simulate a 220kV to 110kV transformer in a substation. The primary rated voltage of the CVTs connected in parallel at its input end is twice the primary rated voltage of the CVTs connected in parallel at its output end.

[0006] The platform is powered by either mains power or a standard power source.

[0007] The capacitive voltage transformer (CVT) includes a capacitor unit and an electromagnetic unit.

[0008] The capacitor unit includes a high-voltage capacitor unit C1 and an adjustable low-voltage capacitor unit C2 connected in parallel. By controlling the size of the adjustable low-voltage capacitor unit C2, the output voltage of the entire capacitor unit is adjusted. The output voltage is the input voltage of the electromagnetic unit connected in parallel at the rear end.

[0009] The electromagnetic unit includes a three-stage adjustment structure. The first stage consists of an iron core T and winding W1, the second stage consists of winding W1 and winding W2, and the third stage consists of winding W1 and winding W3. The number of taps on windings W1, W2, and W3 can be adjusted as needed. By changing the number of turns in windings W1, W2, and W3 in a stepped manner, the actual secondary winding value of the iron core T is changed, thereby changing the output of the capacitive voltage transformer (CVT). Adjustable resistors R1 and R2 are used to adjust the phase difference of the CVT. Adjustable resistor R1 is for coarse adjustment, and adjustable resistor R2 is for fine adjustment.

[0010] The adjustable low-voltage capacitor unit C2 includes adjustable low-voltage capacitor units C connected in series and parallel. 21 To the adjustable low-voltage capacitor unit C 28 The adjustable low-voltage capacitor unit C 21 To the adjustable low-voltage capacitor unit C 27 By controlling the corresponding switch, it is brought into contact with the adjustable low-voltage capacitor unit C. 28 Series connection with adjustable low-voltage capacitor unit C 28 The adjustable low-voltage capacitor unit C has three states: parallel connection, no connection to the circuit, and so on. 28 Not adjustable, 3 exist in total 7 =2187 different permutations and combinations. When using 8 capacitors, the adjustable low-voltage capacitor unit C2 can be freely adjusted among 2187 different values.

[0011] Both the high-voltage capacitor unit C1 and the adjustable low-voltage capacitor unit C2 are ceramic capacitors.

[0012] The platform also includes a multi-channel high-precision transformer calibrator connected to capacitive voltage transformers (CVTs) and voltage transformers (PTs). It is used to compare the difference between the secondary voltage signals of each CVT and PT using the difference method, and then divide it by the PT value to obtain the true error of each CVT after error adjustment.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] This invention proposes a dynamic model platform for capacitive voltage transformers (CVTs) with adjustable metering status. Under low-voltage conditions, the platform designs CVTs using a dynamic model approach and, based on typical application scenarios of this technology, designs an error testing platform for four sets of CVTs with dual voltage levels. This platform verifies the accuracy, reliability, and universality of the voltage transformer metering performance status assessment algorithm. This platform can serve as a verification platform for voltage transformer metering performance status assessment algorithms, providing verification data to companies, universities, and research institutions developing these algorithms, thus possessing significant market benefits. Attached Figure Description

[0015] Figure 1 A schematic diagram of the principle of a dynamic model platform for a capacitive voltage transformer with adjustable metering status provided in this application;

[0016] Figure 2 A schematic diagram of the principle of the capacitive voltage transformer (CVT) provided in this application;

[0017] Figure 3 This is a schematic diagram of the adjustable low-voltage capacitor unit C2 provided in this application.

[0018] In the diagram, 1 represents the first transformer, and 2 represents the second transformer. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Figures 1 to 3 This is a schematic diagram of the structure of an embodiment of the present invention.

[0021] like Figure 1 As shown in the figure, this embodiment provides a dynamic model platform for a capacitive voltage transformer with adjustable metering status, including a first transformer 1 with a transformation ratio of 1:1 and a second transformer 2 with a transformation ratio of 2:1. The first transformer 1 is used for the platform power supply, which can be obtained from the mains power or from a standard power source. Since the device under test needs to absorb a certain amount of power, the power supply must have load-carrying capacity. The input terminal of the second transformer 2 is connected in parallel with two sets of three-phase 0.2-class capacitive voltage transformers (CVTs) and one set of three-phase 0.01-class voltage transformers. PT; The output terminal of the second transformer 2 is connected in parallel with two sets of three-phase 0.2-class capacitive voltage transformers (CVTs) and one set of three-phase 0.01-class voltage transformers (PTs). The second transformer 2 is used to simulate a 220kV to 110kV transformer in a substation. The primary rated voltage of the capacitive voltage transformer (CVT) connected in parallel at its input terminal is twice the primary rated voltage of the capacitive voltage transformer (CVT) connected in parallel at its output terminal, ensuring that the secondary rated output voltage values ​​of the capacitive voltage transformers (CVTs) at the input and output terminals of the second transformer 2 are theoretically equal.

[0022] like Figure 2The diagram shown is a schematic of the internal principle of the capacitive voltage transformer (CVT) in this embodiment. U1 is the input voltage value, U2 is the output voltage value, C1 is the high-voltage capacitor unit, and C2 is the adjustable low-voltage capacitor unit. Both the high-voltage capacitor unit C1 and the adjustable low-voltage capacitor unit C2 use ceramic capacitors with good stability. The adjustable low-voltage capacitor unit C2 is adjustable to control the resonance point between the capacitor unit and the downstream electromagnetic unit, and to adjust the error of the capacitive voltage transformer (CVT) as a whole with the downstream electromagnetic unit. The circuit after the iron core T is the electromagnetic unit. The electromagnetic unit has three levels of adjustment. The first level consists of the iron core T and winding W1; the second level consists of windings W1 and W2; and the third level consists of windings W1 and W3. The adjustment step of the output voltage value of U1 is determined by the number of turns tapped in windings W1, W2, and W3 as needed. When the tap of winding W1 is designed to have 100 turns, the adjustment step of the output voltage value of U1 is 1% when winding W2 moves up and down once. Similarly, when the tap of winding W2 is designed to have 100 turns, the adjustment step of the output voltage value of U1 is 0.01% when winding W3 moves up and down once. The cascaded coil method is used to adjust the ratio difference of the capacitive voltage transformer (CVT); resistors R1 and R2 are used to adjust the phase difference of the CVT. The magnitude of phase adjustment is consistent with the magnitude of coil position control where the ratio difference is located. That is, resistor R1 is for coarse adjustment and resistor R2 is for fine adjustment. The platform can add adjustable resistors in subsequent windings according to the user's fineness of phase difference adjustment, and complete the phase difference adjustment through R, C, L parameter matching. In actual operation, the phase difference should be adjusted first, because the adjustment of the phase difference will affect the ratio difference; however, the adjustment of the ratio difference will not affect the phase difference.

[0023] It should be noted that the high-voltage capacitor unit C1 and the adjustable low-voltage capacitor unit C2 are analog capacitor units of a capacitive voltage transformer (CVT), and are connected in parallel. Controlling the size of the adjustable low-voltage capacitor unit C2 adjusts the output voltage of the entire capacitor unit. This output voltage is the input voltage of the electromagnetic unit connected in parallel at the back end. The iron core T is the isolation transformer of the electromagnetic unit. The iron core T has two windings: the primary winding is closer to the capacitor unit, and the secondary winding is on the other side. The iron core T is a voltage transformer used to transform a large primary voltage to a small secondary voltage according to a specified number of turns in the primary and secondary windings. Therefore, the number of turns in the rear windings W1, W2, and W3 directly affects the magnitude of the voltage change and the phase angle of the iron core T. By changing the number of turns in windings W1, W2, and W3 in a stepped manner, the actual secondary winding value of the iron core T can be continuously changed, thus changing the output of the capacitive voltage transformer (CVT) and essentially correcting the error. Therefore, windings W1, W2, and W3 are cascaded, essentially a series structure. The final resistor R1 simulates the load. By adjusting the value of R, the phase can be changed. C, L, and R work together to adjust parameters in simulation software. In actual equipment manufacturing, adjustable margins are provided in the simulation parameters to compensate for simulation deficiencies. Here, R refers to the adjustable resistors R1 and R2, used to adjust the phase of the capacitive voltage transformer (CVT); C refers to the high-voltage capacitor unit C1 and the adjustable low-voltage capacitor unit C2; and L refers to the entire electromagnetic unit, including the core T, windings W1, W2, and W3.

[0024] like Figure 3 As shown, in this embodiment, the adjustable low-voltage capacitor unit C2 includes adjustable low-voltage capacitor units C connected in series and parallel. 21 To the adjustable low-voltage capacitor unit C 28 Adjustable low-voltage capacitor unit C 21 To the adjustable low-voltage capacitor unit C 28 It belongs to a series-parallel structure and has an adjustable low-voltage capacitor unit C. 21 To the adjustable low-voltage capacitor unit C 28 These capacitors are part of the adjustable low-voltage capacitor unit C2 and constitute its internal structure. They together form the adjustable low-voltage capacitor unit C2. The adjustable low-voltage capacitor unit C... 21 To the adjustable low-voltage capacitor unit C 27 The adjustable low-voltage capacitor unit C can be switched on by controlling the corresponding switch. 28 Series connection with adjustable low-voltage capacitor unit C 28 The adjustable low-voltage capacitor unit C has three states: parallel connection and no connection to the circuit. 28 Not adjustable, 3 exist in total 7=2187 different permutations and combinations, meaning that the adjustable low-voltage capacitor unit C2 can be freely adjusted among 2187 different values ​​using only 8 capacitors.

[0025] It should be noted that the adjustable low-voltage capacitor unit C 21 - Adjustable low-voltage capacitor unit C 28 Each small module can be switched as needed.

[0026] In one application scenario, after current enters from the positive terminal, the adjustable low-voltage capacitor unit C... 23 and adjustable low-voltage capacitor unit C 26 The adjustable low-voltage capacitor unit C is connected in series. 22 and adjustable low-voltage capacitor unit C 25 The adjustable low-voltage capacitor unit C is connected in series. 21 Adjustable low-voltage capacitor unit C 24 and adjustable low-voltage capacitor unit C 27 It is a series connection, adjustable low-voltage capacitor unit C 23 and adjustable low-voltage capacitor unit C 26 Common with adjustable low-voltage capacitor unit C 21 Adjustable low-voltage capacitor unit C 24 and adjustable low-voltage capacitor unit C 27 And adjustable low-voltage capacitor unit C 22 and adjustable low-voltage capacitor unit C 25 It is connected in parallel, and the capacitance they together form is then combined with the adjustable low-voltage capacitor unit C. 28 It is a parallel connection. According to the capacitance formula, parallel connection is the sum of capacitances, while series connection is the sum of partial capacitances, which is the opposite of resistance. Therefore, by connecting eight small capacitors in series and parallel, the value of the adjustable low-voltage capacitor unit C2 can be adjusted.

[0027] In addition, the platform is equipped with a multi-channel high-precision transformer calibrator connected to each capacitive voltage transformer (CVT) and voltage transformer present (PT). Using the difference method, the difference between the secondary voltage signals of each CVT and PT is first obtained. Then, the difference is divided by the value of the PT to obtain the true error of each CVT after error adjustment. The configuration of the multi-channel high-precision transformer calibrator improves the reliability of the CVT error data.

[0028] The platform provided in this embodiment can simulate the operation of 220kV and 110kV junction capacitive voltage transformers (CVTs) in a typical 220kV substation. The CVTs designed within the platform have the same principle and structure as real CVTs. Each CVT internally adjusts the ratio difference and phase difference by regulating the R, C, and L parameters. Furthermore, this platform provides tag data and test data to verify the accuracy, reliability, and universality of the voltage transformer metering performance status assessment algorithm.

[0029] Finally, it should be noted that the above embodiments are merely illustrative and explanatory of the present invention, and are not intended to limit the present invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention.

Claims

1. A dynamic model platform for a capacitive voltage transformer with adjustable metering status, characterized in that, The system includes a first transformer with a turns ratio of 1:1 and a second transformer with a turns ratio of 2:

1. The first transformer is used for power supply connection to the platform. The input terminal of the second transformer has two sets of three-phase 0.2-class capacitive voltage transformers (CVTs) and one set of three-phase 0.01-class voltage transformers (PTs) connected in parallel. The output terminal of the second transformer has two sets of three-phase 0.2-class capacitive voltage transformers (CVTs) and one set of three-phase 0.01-class voltage transformers (PTs) connected in parallel. The second transformer is used to simulate a 220kV to 110kV transformer in a substation. The primary rated voltage of the CVTs connected in parallel at its input terminal is twice the primary rated voltage of the CVTs connected in parallel at its output terminal. The platform is powered either from mains power or from a standard power source. The capacitive voltage transformer (CVT) includes a capacitor unit and an electromagnetic unit. The capacitor unit includes a high-voltage capacitor unit C1 and an adjustable low-voltage capacitor unit C2 connected in parallel. By controlling the size of the adjustable low-voltage capacitor unit C2, the output voltage of the entire capacitor unit is adjusted. The output voltage is the input voltage of the electromagnetic unit connected in parallel with the two ends of the adjustable low-voltage capacitor unit C2. The electromagnetic unit includes a three-stage adjustment structure. The first stage consists of an iron core T and winding W1, the second stage consists of winding W1 and winding W2, and the third stage consists of winding W2 and winding W3. Windings W1, W2, and W3 are connected in series. The number of taps on windings W1, W2, and W3 is adjusted as needed. By changing the number of turns in windings W1, W2, and W3 in a stepped manner, the actual secondary winding value of the iron core T is changed, thereby changing the output of the capacitive voltage transformer (CVT). Adjustable resistors R1 and R2 are used to adjust the phase difference of the CVT. Adjustable resistor R1 is used for coarse adjustment, and adjustable resistor R2 is used for fine adjustment. Adjustable resistor R1 is connected in parallel at the output terminal of the electromagnetic unit, and adjustable resistor R2 is connected in parallel across winding W1.

2. The adjustable metering state capacitive voltage transformer dynamic model platform according to claim 1, characterized in that, Both the high-voltage capacitor unit C1 and the adjustable low-voltage capacitor unit C2 are ceramic capacitors.

3. The adjustable metering state capacitive voltage transformer dynamic model platform according to claim 1, characterized in that, The platform also includes a multi-channel high-precision transformer calibrator connected to capacitive voltage transformers (CVTs) and voltage transformers (PTs). It is used to compare the difference between the secondary voltage signals of each CVT and PT using the difference method, and then divide it by the PT value to obtain the true error of each CVT after error adjustment.

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