Current transformer error adjustment test platform

Abstract

The present invention discloses a current transformer error adjustment test platform, which includes an isolation transformer, an isolation switch and a load; the power supply is connected to the first isolation transformer and the second isolation transformer through the first isolation switch and the second isolation switch respectively, the first isolation transformer is connected to the first load through the third isolation transformer, and the second isolation transformer is connected to the second load through the fourth isolation transformer; the third isolation switch connects the input ends of the third isolation transformer and the fourth isolation transformer, and the fourth isolation switch connects the output ends of the third isolation transformer and the fourth isolation transformer; the platform also includes a plurality of CT groups, the CT groups include standard CTs and test CTs with adjustable errors; and the plurality of CT groups are distributed in the line. The present invention uses a plurality of isolation transformers and isolation switches to simulate CT multi-way incoming and outgoing lines, different operation modes, and different CT numbers on a test platform, and the platform can cover the full-featured operation of CTs in a substation.

Description

Technical Field

[0001] The invention belongs to the technical field of intelligent measurement, and in particular relates to a current transformer error adjustment test platform. Background Art

[0002] In order to develop online monitoring and status evaluation technology for transformer metering performance and accelerate the online monitoring and status evaluation of gateway transformers, the requirement of carrying out research on online monitoring technology for current transformers (CT) is proposed. At present, a variety of CT metering performance status evaluation algorithms including principal component analysis and cyber-physical correlation have been proposed. However, the evaluation of algorithm accuracy is verified on a single CT operation platform built by the algorithm developers themselves. Summary of the invention

[0003] The purpose of the present invention is to provide a channel-expandable current transformer error adjustment test platform to solve the problem that the verification of the CT metering performance status evaluation algorithm is too single.

[0004] The present invention provides a current transformer error adjustment test platform, which includes a first isolation transformer T1, a second isolation transformer T2, a third isolation transformer T3, a fourth isolation transformer T4, a first isolation switch K1, a second isolation switch K2, a third isolation switch K3, a fourth isolation switch K4, a first load and a second load;

[0005] The power supply is connected to the first isolation transformer T1 and the second isolation transformer T2 through the first isolation switch K1 and the second isolation switch K2 respectively; the first isolation transformer T1 is connected to the first load through the third isolation transformer T3; the second isolation transformer T2 is connected to the second load through the fourth isolation transformer T4; the third isolation switch K3 is connected to the input ends of the third isolation transformer T3 and the fourth isolation transformer T4; the fourth isolation switch K4 is connected to the output ends of the third isolation transformer T3 and the fourth isolation transformer T4;

[0006] The first isolation transformer T1 and the second isolation transformer T2 simulate the main transformers in the substation; when there are two main transformers running simultaneously in the simulated substation, K1 and K2 are merged; when simulating a substation with a single main transformer, one of K1 and K2 is selected to be merged and the other is disconnected; when two main transformers in the simulated substation are running in parallel, K1, K2 and K3 are all merged; when two main transformers in the simulated substation are running separately, K1 and K2 are merged and K3 is opened;

[0007] The third isolation transformer T3 and the fourth isolation transformer T4 simulate the line-side transformer; when K4 is combined, multiple groups of outgoing lines running in parallel are simulated; when K4 is opened, multiple groups of outgoing lines running independently are simulated;

[0008] The platform also includes a plurality of CT groups, wherein the CT groups include a standard CT and a test CT with adjustable error; and the plurality of CT groups are distributed in the circuit.

[0009] Furthermore, the CT group includes a 0.05-level standard CT and a 0.2-level error-adjustable test CT.

[0010] Furthermore, the output end of the third isolation transformer T3 and / or the fourth isolation transformer T4 is connected to a plurality of third loads via a plurality of fifth isolation switches.

[0011] Furthermore, the load size is adjustable.

[0012] Furthermore, the error-adjustable test CT uses low-voltage end connection and high-voltage three-stage cascade adjustment internally, and a tracker method is used at the output end to improve the platform's load-bearing capacity.

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

[0014] The present invention uses multiple transformers and disconnectors to simulate CT multi-way incoming and outgoing lines, different operating modes, and different numbers of CTs on a test platform. The platform can cover the full-featured operation of CTs in the substation. The branch output adopts a modular design and can be expanded according to the user's requirements for the number of simulated CTs, greatly improving the test efficiency and test flexibility, and providing output values ​​and label values ​​for verifying the accuracy of the CT metering performance status evaluation algorithm.

[0015] The present invention improves the platform's load-carrying capacity for the back-end data acquisition device by adding a tracker at the end of the three-stage cascade adjustment, thereby overcoming the problem that the cascade error adjustment technology cannot carry loads. While achieving a 0.01% error adjustment step, the present invention can provide a current power signal to the outside, thereby meeting the power consumption requirements of the signal terminals of the current CT metering performance status evaluation device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the schematic diagram of the current transformer error adjustment test platform;

[0017] Figure 2 This is the schematic diagram of the error adjustable CT. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] In view of the current situation that the verification of CT metering performance status evaluation algorithm is too single, the present invention proposes a channel-expandable CT error adjustment test platform. The platform can simulate the typical operation mode of CT on multiple incoming and outgoing lines in the substation, and the error of each CT can be adjusted independently. The platform is modularly designed, and the number of outgoing lines can be increased according to user needs, and the number of CTs on each outgoing line can also be expanded. The platform meets the operation mode and number of all CTs in the existing substation, and can be used as a verification platform for CT metering performance status evaluation algorithm, providing verification data to companies, universities and research institutions that develop various algorithms, with great market benefits.

[0020] The objectives of the present invention include: 1. simulating the operation mode of a KCL node composed of multiple CTs in different substations under low voltage; 2. simulating the CT error operation in multiple incoming and outgoing lines in a substation; 3. The number of CTs involved in the operation can be arbitrarily selected, and the error value of each CT can be controlled; 4. Providing training data for the verification of the CT metering performance status evaluation algorithm.

[0021] A design scheme of a current transformer error adjustment test platform with expandable channels of the present invention:

[0022] 1) Principle Figure 1 As shown in the figure, the platform includes 0.05-level standard CT, 0.2-level error adjustable test CT, isolation transformer Tx, isolation switch Kx and load composition design. Through the opening and closing of the isolation switch and the change of load, the operation status and quantity of CT in the platform are switched, and the simulation of different operation modes of incoming and outgoing CT in the substation is realized;

[0023] 2) According to Figure 1 It can be seen that the power supply is connected to transformer T1 and transformer T2 through disconnectors K1 and K2. T1 and T2 simulate the main transformer 1 and main transformer 2 in the substation. When there are two main transformers in the simulated substation running at the same time, K1 and K2 are merged. When simulating a substation with a single main transformer, one of K1 and K2 is selected to be merged and the other is disconnected; when two main transformers in the simulated substation are running in parallel, K1, K2 and K3 are all merged; when two main transformers in the simulated substation are running separately, the disconnector K3 is opened; the above part is the design of the operation mode of the incoming line CT in the substation;

[0024] 3) Figure 1After K4~K6, the operation mode of the outgoing line in the substation is simulated. The number of outgoing lines can be expanded according to user requirements, that is, the number of disconnectors in series is increased; when the disconnector K4 is merged, multiple groups of outgoing lines running in parallel are simulated; when the disconnector K4 is opened, multiple groups of outgoing lines running independently are simulated; transformers T3 and T4 simulate the line-side transformers to achieve voltage isolation; each outgoing line is equipped with a total CT, and the branch outgoing lines are designed according to user requirements on each line. CTs are installed on each branch, and the load at the rear end of each branch simulates the real load at the rear end of the substation outgoing line. The load can be adjusted to control the size of the primary current in the outgoing line;

[0025] 4) The internal principle of error adjustable CT is as follows Figure 2 As shown, the internal low-voltage end is connected, the high-voltage three-stage cascade is adjusted, and the output end adopts a tracker method to improve the platform's load capacity; T represents a bipolar core, W 1 Represents the primary winding, W 2 Represents the secondary winding, and the third winding W with the number of turns adjusted is cascaded at the rear end of the secondary winding 3 , W 2 The error ratio can be adjusted, R 1 and C 1 The phase difference in the error can be adjusted. 3 and W 4 Become the second and third level of error joint adjustment, R 2 and C 2 , R 3 and C 3 The phase difference adjustment of the second and third stages is realized respectively; the number of winding turns of W, the values ​​of R and C determine the range and step of error adjustment.

[0026] This platform can simulate multiple incoming and outgoing lines, separate operation, parallel operation and other modes. The simulated operation modes cover the full-featured operation of CT in 110kV-500kV substations. The error of each CT can be adjusted independently, and the adjustment accuracy reaches ±0.01% and ±1′. This platform has powerful expansion functions and can add incoming and outgoing CT lines according to user needs. The current change on each branch outgoing line depends on the RLC load, which is completely consistent with the primary current fluctuation with load in the substation. This platform has built-in standard CT and transformer calibrator, which can not only provide the operating output of multiple CTs to the outside, but also provide the standard error value of each CT as a label quantity to verify the accuracy of the CT metering performance evaluation algorithm.

[0027] An example of a design scheme of a current transformer error adjustment test platform with expandable channels of the present invention:

[0028] 1) Simulate the operation mode of a substation with 1 incoming line, 2 outgoing lines, and 4 groups of outgoing line CTs. The error-adjustable CT meets the 0.01 level error adjustment.

[0029] Combine K1, open K2, connect transformer T1, and realize 1 incoming line simulation. Combine K3, connect transformers T3 and T4, and realize 2 outgoing line simulation. Disconnect K4, K5, and K6 to realize 4 outgoing line CT operation mode. Error adjustable CT, W 2 Designed for 100 turns, W 3 1% adjustment can be achieved with each sliding turn; W 3 Designed for 10 turns, W 4 0.1% adjustment can be achieved with each sliding turn; W 4 Designed with 10 turns, the tracker front end can achieve 0.01% adjustment each time it slides one turn, meeting the 0.01 level error adjustment.

[0030] 2) Simulate the substation with two incoming lines running in parallel and two outgoing lines running separately, realize the operation mode of 10 groups of CTs, and the error-adjustable CT meets the 0.01 level error adjustment.

[0031] Combine K1 and K2, connect transformers T1 and T2, and realize 2 incoming line simulation. Disconnect K3 to realize 2 incoming lines running in parallel, open K4 to realize 2 outgoing lines running in parallel, combine K5 and K6 to realize 10 groups of CT operation mode, and the error adjustment is the same as above.

[0032] This platform simulates different incoming and outgoing lines, different operating modes, and different numbers of CTs through the switching on and off of disconnectors. The platform can also add CTs in series with disconnectors to increase the number of simulated CTs and verify the accuracy of various existing CT metering performance status evaluation algorithms.

[0033] In summary, the present invention realizes the design of a test simulation platform with multiple incoming lines, multiple outgoing lines, multiple operating modes, and adjustable errors of multiple groups of CTs by connecting four transformers and six disconnectors in parallel. The innovative outgoing line segmentation design can flexibly connect multiple outgoing line CTs on the segments, greatly improving the flexibility of the test bench.

[0034] The error-adjustable CT designed by the present invention adopts low-voltage end connection internally, and adopts a tracker mode at the output end to improve the platform load capacity. The three-level cascade achieves 0.01% error adjustment accuracy, achieving a breakthrough in high-precision error adjustment technology with load capacity.

[0035] Each set of error-adjustable CT in the present invention is equipped with a 0.05-level standard CT, which is practical as a standard quantity for error monitoring. A transformer calibrator is installed inside, and the true error value of each error-adjustable CT can be accurately obtained during the operation of the platform. As a dual error monitoring guarantee, it can provide accurate and reliable output signals and label quantities to the online monitoring device, thereby verifying the accuracy of the CT metrological performance status evaluation algorithm.

[0036] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A current transformer error adjustment test platform, characterized in that: The platform includes a first isolation transformer T1, a second isolation transformer T2, a third isolation transformer T3, a fourth isolation transformer T4, a first isolation switch K1, a second isolation switch K2, a third isolation switch K3, a fourth isolation switch K4, a first load and a second load; The load size is adjustable; The power supply is connected to the first isolation transformer T1 and the second isolation transformer T2 through the first isolation switch K1 and the second isolation switch K2 respectively; the first isolation transformer T1 is connected to the first load through the third isolation transformer T3; the second isolation transformer T2 is connected to the second load through the fourth isolation transformer T4; the third isolation switch K3 is connected to the input ends of the third isolation transformer T3 and the fourth isolation transformer T4; the fourth isolation switch K4 is connected to the output ends of the third isolation transformer T3 and the fourth isolation transformer T4; The first isolation transformer T1 and the second isolation transformer T2 simulate the main transformers in the substation; when there are two main transformers running simultaneously in the simulated substation, K1 and K2 are merged; when simulating a substation with a single main transformer, one of K1 and K2 is selected to be merged and the other is disconnected; when two main transformers in the simulated substation are running in parallel, K1, K2 and K3 are all merged; when two main transformers in the simulated substation are running separately, K1 and K2 are merged and K3 is opened; The third isolation transformer T3 and the fourth isolation transformer T4 simulate the line-side transformer; when K4 is combined, multiple groups of outgoing lines running in parallel are simulated; when K4 is opened, multiple groups of outgoing lines running independently are simulated; The platform also includes several CT groups, including 0.05-level standard CTs and 0.2-level error-adjustable test CTs; several CT groups are distributed in the line; Among them, the error-adjustable tested CT uses low-voltage connection inside, high-voltage three-stage cascade adjustment, and the output end uses a tracker to improve the platform's load capacity; The error-adjustable tested CT includes a bipolar iron core T, on which a primary winding W1 and a secondary winding W2 are provided, and the primary winding W1 serves as an input terminal; a third winding W3 is slidably connected to the secondary winding W2, and a first adjustable resistor R1 and a first adjustable capacitor C1 are provided in parallel between the secondary winding W2 and the third winding W3, and the first-stage phase difference adjustment is realized by the first adjustable resistor R1 and the first adjustable capacitor C1; a fourth winding W4 is slidably connected to the third winding W3, and a second adjustable resistor R2 and a second adjustable capacitor C2 are provided in parallel between the third winding W3 and the fourth winding W4, and the first-stage phase difference adjustment is realized by the second adjustable resistor R1 and the first adjustable capacitor C1; The resistor R2 and the second adjustable capacitor C2 realize the second-stage phase difference adjustment; the fourth winding W4 is slidingly connected with the third adjustable resistor R3 and the third adjustable capacitor C3 in parallel, and the third-stage phase difference adjustment is realized by the third adjustable resistor R3 and the third adjustable capacitor C3. The other ends of the third adjustable resistor R3 and the third adjustable capacitor C3 in parallel are connected to an input end of the operational amplifier through a resistor, and the input end of the operational amplifier is also connected to the output end of the operational amplifier through a resistor. The other input end of the operational amplifier is grounded through a resistor, and the output end of the operational amplifier and the secondary winding W2 constitute an output end.

2. The current transformer error adjustment test platform according to claim 1, characterized in that: The output end of the third isolation transformer T3 and / or the fourth isolation transformer T4 is connected to a plurality of third loads via a plurality of fifth isolation switches.

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