技术领域technical field
本发明涉及一种电力系统变压器继电保护中的故障电流鉴别方法，特别涉及一种变压器继电保护中的和应涌流与故障电流的鉴别方法，通过该方法能够准确判别出变压器保护装置的故障电流性质，达到保障变压器安全运行的目的。The invention relates to a fault current identification method in the relay protection of a power system transformer, in particular to a method for identifying a surge current and a fault current in the relay protection of a transformer, by which the fault of a transformer protection device can be accurately identified The nature of the current, to achieve the purpose of ensuring the safe operation of the transformer.
背景技术Background technique
随着高压远距离输电线路的大规模建设和投入运行，大容量变压器的应用日益增多，在满足大容量输电的同时，也对变压器保护的可靠性和速动性提出了更高的要求。差动保护是变压器内部故障的主保护方案之一，差动保护主要解决两个问题：一是鉴别励磁涌流和故障电流；二是区分内部故障和外部故障。长期的运行经验表明，变压器差动保护在一定程度上能够较好地区分内部故障和外部故障，但在励磁涌流和故障电流的鉴别上还存在一定的问题。近年来，在运行过程中，出现了多起空投变压器的现象，导致相邻并联或级联变压器差动保护误动的事故，给主设备的正常运行带来了很大的危害。目前，还没有有效地鉴别变压器故障电流与和应涌流的方法，给大容量变压器的安全运行带来了隐患。With the large-scale construction and operation of high-voltage long-distance transmission lines, the application of large-capacity transformers is increasing. While meeting the needs of large-capacity power transmission, higher requirements are placed on the reliability and quickness of transformer protection. Differential protection is one of the main protection schemes for internal faults of transformers. Differential protection mainly solves two problems: one is to identify inrush current and fault current; the other is to distinguish internal faults from external faults. Long-term operation experience shows that transformer differential protection can better distinguish internal faults and external faults to a certain extent, but there are still some problems in the identification of inrush current and fault current. In recent years, in the process of operation, there have been many air-dropped transformers, resulting in misoperation of differential protection of adjacent parallel or cascaded transformers, which has brought great harm to the normal operation of the main equipment. At present, there is no effective method to identify transformer fault current and inrush current, which brings hidden dangers to the safe operation of large-capacity transformers.
发明内容Contents of the invention
本发明提供了一种变压器保护中的和应涌流与故障电流的鉴别方法，解决了准确鉴别变压器故障电流与和应涌流的难题，避免了变压器差动保护的误动作。The invention provides a method for distinguishing the sum surge current and the fault current in transformer protection, which solves the problem of accurately identifying the transformer fault current and the sum surge current, and avoids the misoperation of the differential protection of the transformer.
本发明是通过以下技术方案解决以上技术问题的：The present invention solves the above technical problems through the following technical solutions:
一种变压器保护中的和应涌流与故障电流的鉴别方法，包括以下步骤：A method for discriminating an inrush current and a fault current in transformer protection, comprising the following steps:
第一步、获取Y-Y-Δ接线型式的变压器的高压侧二次电流采样值，获取Y-Y-Δ接线型式的变压器的中压侧二次电流采样值，获取Y-Y-Δ接线型式的变压器的低压侧二次电流采样值；The first step is to obtain the secondary current sampling value of the high-voltage side of the transformer with Y-Y-Δ connection type, obtain the sampling value of the secondary current of the medium-voltage side of the transformer with Y-Y-Δ connection type, and obtain the low-voltage side of the transformer with Y-Y-Δ connection type Secondary current sampling value;
第二步、将获取的高压侧二次电流采样值、中压侧二次电流采样值和低压侧二次电流采样值，分别进行差分滤波；The second step is to perform differential filtering on the acquired high-voltage side secondary current sampling value, medium-voltage side secondary current sampling value and low-voltage side secondary current sampling value respectively;
第三步、将差分滤波后的高压侧二次电流采样值、差分滤波后的中压侧二次电流采样值和差分滤波后的低压侧二次电流采样值，分别进行全波傅立叶数字滤波，得到变压器高压侧二次电流基波幅值和相角、变压器中压侧二次电流基波幅值和相角、变压器低压侧二次电流基波幅值和相角；The third step is to perform full-wave Fourier digital filtering on the sampled value of the secondary current on the high-voltage side after differential filtering, the sampled value of the secondary current on the medium-voltage side after differential filtering, and the sampled value of the secondary current on the low-voltage side after differential filtering. Obtain the fundamental wave amplitude and phase angle of the secondary current at the high voltage side of the transformer, the fundamental wave amplitude and phase angle of the secondary current at the medium voltage side of the transformer, and the fundamental wave amplitude and phase angle of the secondary current at the low voltage side of the transformer;
高压侧二次电流基波幅值和相角的计算方法为：The calculation method of the fundamental wave amplitude and phase angle of the secondary current on the high voltage side is:
先设定变压器高压侧二次电流每周波的采样点数为N，则变压器高压侧二次电流采样点的电流采样值为i（k），k=0，1，2，…N-1，采样间隔为Δt；First set the number of sampling points of the secondary current cycle cycle of the high voltage side of the transformer as N, then the current sampling value of the secondary current sampling point on the high voltage side of the transformer isi (k ),k = 0, 1, 2, ... N-1, sampling The interval is Δt;
根据如下傅立叶变换公式：According to the following Fourier transform formula:
其中：in:
ω—变压器高压侧二次电流周波的角频率；ω —the angular frequency of the secondary current cycle on the high voltage side of the transformer;
求出基波的正弦系数后，则基波分量的复数形式为：After calculating the sine coefficient of the fundamental wave, the complex number form of the fundamental wave component is:
高压侧二次电流基波幅值为：The amplitude of the fundamental wave of the secondary current on the high voltage side is:
高压侧二次电流基波相角为：The fundamental phase angle of the secondary current at the high voltage side is:
利用以上同样方法，计算出变压器中压侧二次电流基波幅值和相角，以及变压器低压侧二次电流基波幅值和相角；Using the same method above, calculate the amplitude and phase angle of the secondary current fundamental wave on the medium voltage side of the transformer, and the amplitude and phase angle of the secondary current fundamental wave on the low voltage side of the transformer;
第四步、利用Y-Δ变换方法，调整变压器各侧电流幅值及相角；将Y-Y-Δ接线型式的变压器的Y接法的高压侧二次电流转换为Δ接法的高压侧二次电流，将Y-Y-Δ接线型式的变压器的Y接法的中压侧二次电流转换为Δ接法的中压侧二次电流，Y-Y-Δ接线型式的变压器的Δ接法的低压侧二次电流侧不变；将变压器中压侧电流幅值按照变压器变比折算至变压器高压侧，将变压器低压侧电流幅值按照变压器变比折算至变压器高压侧；由此得到滤波及转换后的：高压侧A相二次电流、高压侧B相二次电流、高压侧C相二次电流、中压侧A相二次电流、中压侧B相二次电流、中压侧C相二次电流、低压侧A相二次电流、低压侧B相二次电流、低压侧C相二次电流；The fourth step is to use the Y-Δ transformation method to adjust the current amplitude and phase angle of each side of the transformer; convert the secondary current of the high-voltage side of the Y-connection method of the YY-Δ connection type transformer to the secondary current of the high-voltage side of the Δ connection method Current, convert the secondary current on the medium-voltage side of the Y-connection method of the YY-Δ connection type transformer to the secondary current on the medium-voltage side of the Δ connection method, and the secondary current on the low-voltage side of the Y-connection method of the transformer with the YY-Δ connection type The current side remains unchanged; the current amplitude of the medium-voltage side of the transformer is converted to the high-voltage side of the transformer according to the transformation ratio of the transformer, and the current amplitude of the low-voltage side of the transformer is converted to the high-voltage side of the transformer according to the transformation ratio of the transformer; thus obtained after filtering and conversion: high voltage Side A phase secondary current , High voltage side B-phase secondary current , Secondary current of phase C on the high voltage side , Secondary current of phase A on medium voltage side , B-phase secondary current on medium voltage side , Secondary current of phase C on medium voltage side , A-phase secondary current on the low-voltage side , B-phase secondary current on the low-voltage side , C-phase secondary current on the low-voltage side ;
第五步、获取Y-Y-Δ接线型式的变压器保护的差电流启动整定值ΔI；The fifth step is to obtain the differential current start-up setting value ΔI of the transformer protection of the Y-Y-Δ connection type;
第六步、计算A相相差电流、B相相差电流和C相相差电流，计算公式如下：Step 6. Calculate the phase difference current of phase A , Phase B phase difference current Phase difference current with phase C ,Calculated as follows:
第七步、分别获取：变压器的高压侧A相二次电流面积与变压器的中压侧A相二次电流面积差的A相二次电流面积差整定值SA；变压器的高压侧B相二次电流面积与变压器的中压侧B相二次电流面积差的B相二次电流面积差整定值SB；变压器的高压侧C相二次电流面积与变压器的中压侧C相二次电流面积差的C相二次电流面积差整定值SC；The seventh step is to obtain: the setting value SA of the secondary current area difference of phase A between the secondary current area of phase A on the high voltage side of the transformer and the secondary current area of phase A on the medium voltage side of the transformer; The setting value SB of the difference between the secondary current area of the secondary current area and the secondary current area of the phase B of the medium-voltage side of the transformer; the secondary current area of the C-phase of the high-voltage side of the transformer The setting value SC of the secondary current area difference of phase C of the area difference;
第八步、当A相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，计算变压器的高压侧A相二次电流面积Sy高压侧A与变压器的中压侧A相二次电流面积Sy中压侧A的差ΔSa，计算时要采用高压侧A相二次电流、中压侧A相二次电流、低压侧A相二次电流；The eighth step, when phase A phase difference current When the amplitude is greater than or equal to the differential current startup setting value ΔI of the transformer protection, calculate the secondary current area Sy high voltage side A of the high voltage side of the transformer and the secondary current area Sy medium voltage side A of the A phase of the transformer The difference ΔSa of the high-voltage side A-phase secondary current should be used in the calculation , Secondary current of phase A on medium voltage side , A-phase secondary current on the low-voltage side ;
高压侧二次电流面积Sy高压侧A的计算方法为：The calculation method of the high-voltage side secondary current area Sy high-voltage side A is:
先设定变压器高压侧电流每周波的采样点数为N，变压器高压侧电流采样点的电流采样值i（k），k=0，1，2，…N-1，采样间隔为Δt，利用矩形（或梯形）法，计算出两个采样点之间的间隔面积，计算公式如下：First set the number of sampling points of the transformer high-voltage side current per cycle as N, the current sampling valuei (k ) of the transformer high-voltage side current sampling point,k = 0, 1, 2, ... N-1, the sampling interval is Δt, use the rectangular (or trapezoidal) method to calculate the interval area between two sampling points, the calculation formula is as follows:
ΔS0=i(0)*Δt；ΔS0 =i (0)*Δt;
ΔS1=i(1)*Δt；ΔS1 =i (1)*Δt;
ΔS2=i(2)*Δt；ΔS2 =i (2)*Δt;
……；...;
ΔSN-1=i(N-1)*Δt；ΔSN -1 =i (N -1)*Δt;
获取相差电流大于或等于变压器保护的差电流启动整定值ΔI时刻的采样点为x；The sampling point at which the phase difference current is greater than or equal to the start-up setting value ΔI of the transformer protection difference current isx;
则y时刻变压器高压侧A相二次电流面积：Then the secondary current area of phase A on the high voltage side of the transformer at timey :
中压侧A相二次电流面积Sy中压侧A的计算方法为：The calculation method of secondary current area Sy of medium voltage side A of medium voltage side A is:
先设定变压器中压侧电流每周波的采样点数为N，变压器中压侧电流采样点的电流采样值i（k），k=0，1，2，…N-1，采样间隔为Δt，利用矩形（或梯形）法，计算出两个采样点之间的间隔面积，计算公式如下：First set the number of sampling points of the current cycle of the medium-voltage side of the transformer as N, the current sampling valuei (k ) of the current sampling points on the medium-voltage side of the transformer,k = 0, 1, 2, ... N-1, and the sampling interval is Δt, Use the rectangular (or trapezoidal) method to calculate the interval area between two sampling points, the calculation formula is as follows:
ΔS0=i(0)*Δt；ΔS0 =i (0)*Δt;
ΔS1=i(1)*Δt；ΔS1 =i (1)*Δt;
ΔS2=i(2)*Δt；ΔS2 =i (2)*Δt;
……；...;
ΔSN-1=i(N-1)*Δt；ΔSN -1 =i (N -1)*Δt;
获取相差电流大于或等于变压器保护的差电流启动整定值ΔI时刻的采样点为x；The sampling point at which the phase difference current is greater than or equal to the start-up setting value ΔI of the transformer protection difference current isx;
则y时刻变压器中压侧A相二次电流面积：Then the secondary current area of phaseA on the medium voltage side of the transformer at time y:
高压侧A相二次电流面积Sy高压侧A与中压侧A相二次电流面积Sy中压侧A的面积差为ΔSa；The area difference between the high-voltage side A-phase secondary current area Sy high-voltage side A and the medium-voltage side A-phase secondary current area Sy medium-voltage side A is ΔSa ;
第九步、当A相相差电流幅值大于或等于变压器的差电流启动整定值ΔI时，同时计算高压侧A相二次电流基波相角和中压侧A相二次电流基波相角，计算时要采用第四步调整后的高压侧A相二次电流、中压侧A相二次电流、低压侧A相二次电流；The ninth step, when the phase A phase difference current When the amplitude is greater than or equal to the differential current start-up setting value ΔI of the transformer, the fundamental phase angle of the secondary current of phase A on the high-voltage side and the fundamental phase angle of the secondary current of phase A on the medium-voltage side are calculated at the same time, and the fourth step is used to adjust the calculation After the high voltage side A phase secondary current , Secondary current of phase A on medium voltage side , A-phase secondary current on the low-voltage side ;
第十步、当高压侧A相二次电流面积Sy高压侧A与中压侧A相二次电流面积Sy中压侧A的面积差ΔSa大于等于A相二次电流面积差整定值SA，并且，高压侧A相二次电流基波相角与中压侧A相二次电流基波相角差大于90度时,为变压器区内故障电流；当高压侧A相二次电流面积Sy高压侧A与中压侧A相二次电流面积Sy中压侧A的面积差ΔSa大于等于A相二次电流面积差整定值SA，并且，高压侧A相二次电流基波相角与中压侧A相二次电流基波相角差小于等于90度时，为变压器区外故障电流或和应涌流；Step 10. When the area difference ΔS a of the secondary current area Sy of the secondary current area of phase A on the high voltage side and the secondary current area Sy of phase A on the medium voltage side is greater thanor equal to the setting value of the secondary current area difference of phase A SA , and, when the difference between the fundamental phase angle of the secondary current of phase A on the high voltage side and the fundamental phase angle of the secondary current of phase A on the medium voltage side is greater than 90 degrees, it is the fault current in the transformer area; when the secondary current of phase A on the high voltage side Area Sy The area difference ΔS a between the secondary current area Sy of the high-voltage side A and the medium-voltage side A phase of the medium-voltage sideA is greater than or equal to the setting value SA of the secondary current area difference of the A-phase, and the secondary current of the A-phase on the high-voltage side When the difference between the fundamental wave phase angle and the fundamental wave phase angle of the A-phase secondary current on the medium voltage side is less than or equal to 90 degrees, it is the fault current outside the transformer area or the inrush current;
第十一步、当B相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，计算变压器的高压侧B相二次电流面积Sy高压侧B与变压器的中压侧B相二次电流面积Sy中压侧B的差ΔSb，计算时要采用高压侧B相二次电流、中压侧B相二次电流、低压侧B相二次电流；The eleventh step, when the phase B phase difference current When the amplitude is greater than or equal to the differential current starting setting value ΔI of the transformer protection, calculate the secondary current area Sy high voltage side B of the high voltage side B of the transformer and the B phase secondary current area Sy medium voltage side B of the transformer The difference ΔSb of the high-voltage side B-phase secondary current should be used in the calculation , B-phase secondary current on medium voltage side , B-phase secondary current on the low-voltage side ;
高压侧B相二次电流面积Sy高压侧B和变压器的中压侧B相二次电流面积Sy中压侧B的计算方法与第八步高压侧A相二次电流面积Sy高压侧A和中压侧A相二次电流面积Sy中压侧A的计算方法相同，高压侧B相二次电流面积Sy高压侧B与中压侧B相二次电流面积Sy中压侧B的面积差为ΔSb；The calculation method of the secondary current area Sy of phase B on the high voltage side, the secondary current area S y of phase B on the high voltage side and the secondary current area Sy of phase B on the medium voltage side of the transformer, and the eighth step: the secondary current area Sy of phase A on the high voltage side A and medium voltage side A phase secondary current area Sy medium voltage side A is calculated in the same way, high voltage side B phase secondary current area Sy high voltage side B and medium voltage side B phase secondary current area Sy medium voltage side The area difference ofB is ΔSb ;
第十二步、当B相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，同时计算高压侧B相二次电流基波相角和中压侧B相二次电流基波相角，计算时要采用第四步调整后的高压侧B相二次电流、中压侧B相二次电流、低压侧A相二次电流；The twelfth step, when the phase B phase difference current When the amplitude is greater than or equal to the differential current start-up setting value ΔI of the transformer protection, the fundamental phase angle of the secondary current of the B-phase on the high-voltage side and the fundamental phase angle of the secondary current of the B-phase on the medium-voltage side are calculated at the same time, and the fourth step is used in the calculation Adjusted high-voltage side B-phase secondary current , B-phase secondary current on medium voltage side , A-phase secondary current on the low-voltage side ;
第十三步、当高压侧B相二次电流面积Sy高压侧B与中压侧B相二次电流面积Sy中压侧B的面积差ΔSb大于等于B相二次电流面积差整定值SB，并且，高压侧B相二次电流基波相角与中压侧B相二次电流基波相角差大于90度时，为变压器区内故障电流；当高压侧B相二次电流面积Sy高压侧B与中压侧B相二次电流面积Sy中压侧B的面积差ΔSb大于等于B相二次电流面积差整定值SB，并且，高压侧B相二次电流基波相角与中压侧B相二次电流基波相角差小于等于90度时，为变压器区外故障电流或和应涌流；The thirteenth step, when the secondary current area Sy of phase B on the high voltage side and the secondary current area S y of phase B on the high voltage side and the secondary current area Sy of phase B on the medium voltage side ΔSb is greater than or equal to the setting of the secondary current area difference of phase B value SB , and when the difference between the fundamental phase angle of the secondary current of phase B on the high voltage side and the fundamental phase angle of the secondary current of phase B on the medium voltage side is greater than 90 degrees, it is the fault current in the transformer area; when the secondary current of phase B on the high voltage side Current area Sy The area difference ΔS b of the secondary current area S y of the secondary current area Sy of the high voltage side B and the medium voltage side B of the medium voltage side Bis greater than or equal to the set value SB of the secondary current area difference of the B phase, and the secondary current area of the B phase on the high voltage side When the difference between the phase angle of the current fundamental wave and the phase angle of the B-phase secondary current on the medium voltage side is less than or equal to 90 degrees, it is the fault current or the inrush current outside the transformer area;
第十四步、当C相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，计算变压器的高压侧C相二次电流面积Sy高压侧C与变压器的中压侧C相二次电流面积Sy中压侧C的差ΔSc，计算时要采用高压侧C相二次电流、中压侧C相二次电流、低压侧C相二次电流；The fourteenth step, when the phase C phase difference current When the amplitude is greater than or equal to the differential current start-up setting value ΔI of the transformer protection, calculate the secondary current area Sy high-voltage side C of the high-voltage side of the transformer and the secondary current area Sy medium-voltage side C of the C-phase of the transformer The difference ΔSc of the high-voltage side C-phase secondary current should be used in the calculation , Secondary current of phase C on medium voltage side , C-phase secondary current on the low-voltage side ;
高压侧C相二次电流面积Sy高压侧C和变压器的中压侧C相二次电流面积Sy中压侧C的计算方法与第八步高压侧二次电流面积Sy高压侧A和中压侧A相二次电流面积Sy中压侧A的计算方法相同，高压侧C相二次电流面积Sy高压侧C与中压侧C相二次电流面积Sy中压侧C的面积差为ΔSc；High voltage side C phase secondary current area Sy high voltage side C and transformer medium voltage side C phase secondary current area Sy medium voltage side C calculation method and the eighth step high voltage side secondary current area Sy high voltage side A and The calculation method of the secondary current area S of phase A on the medium voltage sidey medium voltage side A is the same, the secondary current area S of phase C on the high voltage sidey high voltage side C and the secondary current area S of phase C on the medium voltage side Sy medium voltage side C The area difference is ΔSc ;
第十五步、当C相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，同时计算高压侧C相二次电流基波相角和中压侧C相二次电流基波相角，计算时要采用第四步调整后的高压侧C相二次电流、中压侧C相二次电流、低压侧C相二次电流；Step 15, when phase C phase difference current When the amplitude is greater than or equal to the differential current start-up setting value ΔI of the transformer protection, the fundamental phase angle of the secondary current of phase C on the high voltage side and the fundamental phase angle of the secondary current of phase C on the medium voltage side are calculated at the same time, and the fourth step is used in the calculation Adjusted high-voltage side C-phase secondary current , Secondary current of phase C on medium voltage side , C-phase secondary current on the low-voltage side ;
第十六步、当高压侧C相二次电流面积Sy高压侧C与中压侧C相二次电流面积Sy中压侧C的面积差ΔSc大于等于C相二次电流面积差整定值SC，并且，高压侧C相二次电流基波相角与中压侧C相二次电流基波相角差大于90度时，为变压器区内故障电流；当高压侧C相二次电流面积Sy高压侧C与中压侧C相二次电流面积Sy中压侧C的面积差ΔSc大于等于C相二次电流面积差整定值SC，并且，高压侧C相二次电流基波相角与中压侧C相二次电流基波相角差小于等于90度时，为变压器区外故障电流或和应涌流。The sixteenth step, when the secondary current area Sy of phase C on the high voltage side and the secondary current area Sy of phase C on the medium voltage side ΔSc is greater than or equal to the setting of the secondary current area difference of phase C value SC , and when the phase angle difference between the fundamental phase angle of the secondary current of phase C on the high-voltage side and the fundamental phase angle of the secondary current of phase C on the medium-voltage side is greater than 90 degrees, it is the fault current in the transformer area; when the secondary current of phase C on the high-voltage side Current area Sy The area difference ΔSc between the secondary current area Sy of the high-voltage side C and the secondary current area of the medium-voltage side C of the medium-voltage side C is greater than or equal to the setting value SC of the secondary current area difference of the C-phase, and the secondary current area of the C-phase on the high-voltage side When the difference between the phase angle of the current fundamental wave and the phase angle of the secondary current of phase C on the medium voltage side is less than or equal to 90 degrees, it is the fault current outside the transformer area or the inrush current.
本发明能准确鉴别变压器故障电流与和应涌流，避免了变压器差动保护的误动作，保证了电网主设备的正常运行。The invention can accurately identify transformer fault current and inrush current, avoids misoperation of transformer differential protection, and ensures normal operation of main equipment of power grid.
附图说明Description of drawings
图1是发明的变压器各侧一、二次电流正方向示意图。Fig. 1 is a schematic diagram of the positive direction of the primary and secondary currents on each side of the inventive transformer.
具体实施方式Detailed ways
下面结合附图对本发明进行详细说明：The present invention is described in detail below in conjunction with accompanying drawing:
一种变压器保护中的和应涌流与故障电流的鉴别方法，包括以下步骤：A method for discriminating an inrush current and a fault current in transformer protection, comprising the following steps:
第一步、获取Y-Y-Δ接线型式的变压器的高压侧二次电流采样值，获取Y-Y-Δ接线型式的变压器的中压侧二次电流采样值，获取Y-Y-Δ接线型式的变压器的低压侧二次电流采样值；The first step is to obtain the secondary current sampling value of the high-voltage side of the transformer with Y-Y-Δ connection type, obtain the sampling value of the secondary current of the medium-voltage side of the transformer with Y-Y-Δ connection type, and obtain the low-voltage side of the transformer with Y-Y-Δ connection type Secondary current sampling value;
第二步、将获取的高压侧二次电流采样值、中压侧二次电流采样值和低压侧二次电流采样值，分别进行差分滤波；The second step is to perform differential filtering on the acquired high-voltage side secondary current sampling value, medium-voltage side secondary current sampling value and low-voltage side secondary current sampling value respectively;
第三步、将差分滤波后的高压侧二次电流采样值、差分滤波后的中压侧二次电流采样值和差分滤波后的低压侧二次电流采样值，分别进行全波傅立叶数字滤波，得到变压器高压侧二次电流基波幅值和相角、变压器中压侧二次电流基波幅值和相角、变压器低压侧二次电流基波幅值和相角；The third step is to perform full-wave Fourier digital filtering on the sampled value of the secondary current on the high-voltage side after differential filtering, the sampled value of the secondary current on the medium-voltage side after differential filtering, and the sampled value of the secondary current on the low-voltage side after differential filtering. Obtain the fundamental wave amplitude and phase angle of the secondary current at the high voltage side of the transformer, the fundamental wave amplitude and phase angle of the secondary current at the medium voltage side of the transformer, and the fundamental wave amplitude and phase angle of the secondary current at the low voltage side of the transformer;
高压侧二次电流基波幅值和相角的计算方法为：The calculation method of the fundamental wave amplitude and phase angle of the secondary current on the high voltage side is:
先设定变压器高压侧二次电流每周波的采样点数为N，则变压器高压侧二次电流采样点的电流采样值为i（k），k=0，1，2，…N-1，采样间隔为Δt；First set the number of sampling points of the secondary current cycle cycle of the high voltage side of the transformer as N, then the current sampling value of the secondary current sampling point on the high voltage side of the transformer isi (k ),k = 0, 1, 2, ... N-1, sampling The interval is Δt;
根据如下傅立叶变换公式：According to the following Fourier transform formula:
其中：in:
ω—变压器高压侧二次电流周波的角频率；ω —the angular frequency of the secondary current cycle on the high voltage side of the transformer;
求出基波的正弦系数后，则基波分量的复数形式为：After calculating the sine coefficient of the fundamental wave, the complex number form of the fundamental wave component is:
高压侧二次电流基波幅值为：The amplitude of the fundamental wave of the secondary current on the high voltage side is:
高压侧二次电流基波相角为：The fundamental phase angle of the secondary current at the high voltage side is:
利用以上同样方法，计算出变压器中压侧二次电流基波幅值和相角，以及变压器低压侧二次电流基波幅值和相角；Using the same method above, calculate the amplitude and phase angle of the secondary current fundamental wave on the medium voltage side of the transformer, and the amplitude and phase angle of the secondary current fundamental wave on the low voltage side of the transformer;
第四步、利用Y-Δ变换方法，调整变压器各侧电流幅值及相角；将Y-Y-Δ接线型式的变压器的Y接法的高压侧二次电流转换为Δ接法的高压侧二次电流，将Y-Y-Δ接线型式的变压器的Y接法的中压侧二次电流转换为Δ接法的中压侧二次电流，Y-Y-Δ接线型式的变压器的Δ接法的低压侧二次电流侧不变；将变压器中压侧电流幅值按照变压器变比折算至变压器高压侧，将变压器低压侧电流幅值按照变压器变比折算至变压器高压侧；由此得到滤波及转换后的：高压侧A相二次电流、高压侧B相二次电流、高压侧C相二次电流、中压侧A相二次电流、中压侧B相二次电流、中压侧C相二次电流、低压侧A相二次电流、低压侧B相二次电流、低压侧C相二次电流；The fourth step is to use the Y-Δ transformation method to adjust the current amplitude and phase angle of each side of the transformer; convert the secondary current of the high-voltage side of the Y-connection method of the YY-Δ connection type transformer to the secondary current of the high-voltage side of the Δ connection method Current, convert the secondary current on the medium-voltage side of the Y-connection method of the YY-Δ connection type transformer to the secondary current on the medium-voltage side of the Δ connection method, and the secondary current on the low-voltage side of the Y-connection method of the transformer with the YY-Δ connection type The current side remains unchanged; the current amplitude of the medium-voltage side of the transformer is converted to the high-voltage side of the transformer according to the transformation ratio of the transformer, and the current amplitude of the low-voltage side of the transformer is converted to the high-voltage side of the transformer according to the transformation ratio of the transformer; thus obtained after filtering and conversion: high voltage Side A phase secondary current , High voltage side B-phase secondary current , Secondary current of phase C on the high voltage side , Secondary current of phase A on medium voltage side , B-phase secondary current on medium voltage side , Secondary current of phase C on medium voltage side , A-phase secondary current on the low-voltage side , B-phase secondary current on the low-voltage side , C-phase secondary current on the low-voltage side ;
第五步、获取Y-Y-Δ接线型式的变压器保护的差电流启动整定值ΔI；The fifth step is to obtain the differential current start-up setting value ΔI of the transformer protection of the Y-Y-Δ connection type;
第六步、计算A相相差电流、B相相差电流和C相相差电流，计算公式如下：Step 6. Calculate the phase difference current of phase A , Phase B phase difference current Phase difference current with phase C ,Calculated as follows:
第七步、分别获取：变压器的高压侧A相二次电流面积与变压器的中压侧A相二次电流面积差的A相二次电流面积差整定值SA；变压器的高压侧B相二次电流面积与变压器的中压侧B相二次电流面积差的B相二次电流面积差整定值SB；变压器的高压侧C相二次电流面积与变压器的中压侧C相二次电流面积差的C相二次电流面积差整定值SC；The seventh step is to obtain: the setting value SA of the secondary current area difference of phase A between the secondary current area of phase A on the high voltage side of the transformer and the secondary current area of phase A on the medium voltage side of the transformer; The setting value SB of the difference between the secondary current area of the secondary current area and the secondary current area of the phase B of the medium-voltage side of the transformer; the secondary current area of the C-phase of the high-voltage side of the transformer The setting value SC of the secondary current area difference of phase C of the area difference;
第八步、当A相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，计算变压器的高压侧A相二次电流面积Sy高压侧A与变压器的中压侧A相二次电流面积Sy中压侧A的差ΔSa，计算时要采用高压侧A相二次电流、中压侧A相二次电流、低压侧A相二次电流；The eighth step, when phase A phase difference current When the amplitude is greater than or equal to the differential current startup setting value ΔI of the transformer protection, calculate the secondary current area Sy high voltage side A of the high voltage side of the transformer and the secondary current area Sy medium voltage side A of the A phase of the transformer The difference ΔSa of the high-voltage side A-phase secondary current should be used in the calculation , Secondary current of phase A on medium voltage side , A-phase secondary current on the low-voltage side ;
高压侧二次电流面积Sy高压侧A的计算方法为：The calculation method of the high-voltage side secondary current area Sy high-voltage side A is:
先设定变压器高压侧电流每周波的采样点数为N，变压器高压侧电流采样点的电流采样值i（k），k=0，1，2，…N-1，采样间隔为Δt，利用矩形（或梯形）法，计算出两个采样点之间的间隔面积，计算公式如下：First set the number of sampling points of the transformer high-voltage side current per cycle as N, the current sampling valuei (k ) of the transformer high-voltage side current sampling point,k = 0, 1, 2, ... N-1, the sampling interval is Δt, use the rectangular (or trapezoidal) method to calculate the interval area between two sampling points, the calculation formula is as follows:
ΔS0=i(0)*Δt；ΔS0 =i (0)*Δt;
ΔS1=i(1)*Δt；ΔS1 =i (1)*Δt;
ΔS2=i(2)*Δt；ΔS2 =i (2)*Δt;
……；...;
ΔSN-1=i(N-1)*Δt；ΔSN -1 =i (N -1)*Δt;
获取相差电流大于或等于变压器保护的差电流启动整定值ΔI时刻的采样点为x；The sampling point at which the phase difference current is greater than or equal to the start-up setting value ΔI of the transformer protection difference current isx;
则y时刻变压器高压侧A相二次电流面积：Then the secondary current area of phase A on the high voltage side of the transformer at timey :
中压侧A相二次电流面积Sy中压侧A的计算方法为：The calculation method of secondary current area Sy of medium voltage side A of medium voltage side A is:
先设定变压器中压侧电流每周波的采样点数为N，变压器中压侧电流采样点的电流采样值i（k），k=0，1，2，…N-1，采样间隔为Δt，利用矩形（或梯形）法，计算出两个采样点之间的间隔面积，计算公式如下：First set the number of sampling points of the current cycle of the medium-voltage side of the transformer as N, the current sampling valuei (k ) of the current sampling points on the medium-voltage side of the transformer,k = 0, 1, 2, ... N-1, and the sampling interval is Δt, Use the rectangular (or trapezoidal) method to calculate the interval area between two sampling points, the calculation formula is as follows:
ΔS0=i(0)*Δt；ΔS0 =i (0)*Δt;
ΔS1=i(1)*Δt；ΔS1 =i (1)*Δt;
ΔS2=i(2)*Δt；ΔS2 =i (2)*Δt;
……；...;
ΔSN-1=i(N-1)*Δt；ΔSN -1 =i (N -1)*Δt;
获取相差电流大于或等于变压器保护的差电流启动整定值ΔI时刻的采样点为x；The sampling point at which the phase difference current is greater than or equal to the start-up setting value ΔI of the transformer protection difference current isx;
则y时刻变压器中压侧A相二次电流面积：Then the secondary current area of phaseA on the medium voltage side of the transformer at time y:
高压侧A相二次电流面积Sy高压侧A与中压侧A相二次电流面积Sy中压侧A的面积差为ΔSa；The area difference between the high-voltage side A-phase secondary current area Sy high-voltage side A and the medium-voltage side A-phase secondary current area Sy medium-voltage side A is ΔSa ;
第九步、当A相相差电流幅值大于或等于变压器的差电流启动整定值ΔI时，同时计算高压侧A相二次电流基波相角和中压侧A相二次电流基波相角，计算时要采用第四步调整后的高压侧A相二次电流、中压侧A相二次电流、低压侧A相二次电流；The ninth step, when the phase A phase difference current When the amplitude is greater than or equal to the differential current start-up setting value ΔI of the transformer, the fundamental phase angle of the secondary current of phase A on the high-voltage side and the fundamental phase angle of the secondary current of phase A on the medium-voltage side are calculated at the same time, and the fourth step is used to adjust the calculation After the high voltage side A phase secondary current , Secondary current of phase A on medium voltage side , A-phase secondary current on the low-voltage side ;
第十步、当高压侧A相二次电流面积Sy高压侧A与中压侧A相二次电流面积Sy中压侧A的面积差ΔSa大于等于A相二次电流面积差整定值SA，并且，高压侧A相二次电流基波相角与中压侧A相二次电流基波相角差大于90度时,为变压器区内故障电流；当高压侧A相二次电流面积Sy高压侧A与中压侧A相二次电流面积Sy中压侧A的面积差ΔSa大于等于A相二次电流面积差整定值SA，并且，高压侧A相二次电流基波相角与中压侧A相二次电流基波相角差小于等于90度时，为变压器区外故障电流或和应涌流；Step 10. When the area difference ΔS a of the secondary current area Sy of the secondary current area of phase A on the high voltage side and the secondary current area Sy of phase A on the medium voltage side is greater thanor equal to the setting value of the secondary current area difference of phase A SA , and, when the difference between the fundamental phase angle of the secondary current of phase A on the high voltage side and the fundamental phase angle of the secondary current of phase A on the medium voltage side is greater than 90 degrees, it is the fault current in the transformer area; when the secondary current of phase A on the high voltage side Area Sy The area difference ΔS a between the secondary current area Sy of the high-voltage side A and the medium-voltage side A phase of the medium-voltage sideA is greater than or equal to the setting value SA of the secondary current area difference of the A-phase, and the secondary current of the A-phase on the high-voltage side When the difference between the fundamental wave phase angle and the fundamental wave phase angle of the A-phase secondary current on the medium voltage side is less than or equal to 90 degrees, it is the fault current outside the transformer area or the inrush current;
第十一步、当B相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，计算变压器的高压侧B相二次电流面积Sy高压侧B与变压器的中压侧B相二次电流面积Sy中压侧B的差ΔSb，计算时要采用高压侧B相二次电流、中压侧B相二次电流、低压侧B相二次电流；The eleventh step, when the phase B phase difference current When the amplitude is greater than or equal to the differential current starting setting value ΔI of the transformer protection, calculate the secondary current area Sy high voltage side B of the high voltage side B of the transformer and the B phase secondary current area Sy medium voltage side B of the transformer The difference ΔSb of the high-voltage side B-phase secondary current should be used in the calculation , B-phase secondary current on medium voltage side , B-phase secondary current on the low-voltage side ;
高压侧B相二次电流面积Sy高压侧B和变压器的中压侧B相二次电流面积Sy中压侧B的计算方法与第八步高压侧A相二次电流面积Sy高压侧A和中压侧A相二次电流面积Sy中压侧A的计算方法相同，高压侧B相二次电流面积Sy高压侧B与中压侧B相二次电流面积Sy中压侧B的面积差为ΔSb；The calculation method of the secondary current area Sy of phase B on the high voltage side, the secondary current area S y of phase B on the high voltage side and the secondary current area Sy of phase B on the medium voltage side of the transformer, and the eighth step: the secondary current area Sy of phase A on the high voltage side A and medium voltage side A phase secondary current area Sy medium voltage side A is calculated in the same way, high voltage side B phase secondary current area Sy high voltage side B and medium voltage side B phase secondary current area Sy medium voltage side The area difference ofB is ΔSb ;
第十二步、当B相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，同时计算高压侧B相二次电流基波相角和中压侧B相二次电流基波相角，计算时要采用第四步调整后的高压侧B相二次电流、中压侧B相二次电流、低压侧A相二次电流；The twelfth step, when the phase B phase difference current When the amplitude is greater than or equal to the differential current start-up setting value ΔI of the transformer protection, the fundamental phase angle of the secondary current of the B-phase on the high-voltage side and the fundamental phase angle of the secondary current of the B-phase on the medium-voltage side are calculated at the same time, and the fourth step is used in the calculation Adjusted high-voltage side B-phase secondary current , B-phase secondary current on medium voltage side , A-phase secondary current on the low-voltage side ;
第十三步、当高压侧B相二次电流面积Sy高压侧B与中压侧B相二次电流面积Sy中压侧B的面积差ΔSb大于等于B相二次电流面积差整定值SB，并且，高压侧B相二次电流基波相角与中压侧B相二次电流基波相角差大于90度时，为变压器区内故障电流；当高压侧B相二次电流面积Sy高压侧B与中压侧B相二次电流面积Sy中压侧B的面积差ΔSb大于等于B相二次电流面积差整定值SB，并且，高压侧B相二次电流基波相角与中压侧B相二次电流基波相角差小于等于90度时，为变压器区外故障电流或和应涌流；The thirteenth step, when the secondary current area Sy of phase B on the high voltage side and the secondary current area S y of phase B on the high voltage side and the secondary current area Sy of phase B on the medium voltage side ΔSb is greater than or equal to the setting of the secondary current area difference of phase B value SB , and when the difference between the fundamental phase angle of the secondary current of phase B on the high voltage side and the fundamental phase angle of the secondary current of phase B on the medium voltage side is greater than 90 degrees, it is the fault current in the transformer area; when the secondary current of phase B on the high voltage side Current area Sy The area difference ΔS b of the secondary current area S y of the secondary current area Sy of the high voltage side B and the medium voltage side B of the medium voltage side Bis greater than or equal to the set value SB of the secondary current area difference of the B phase, and the secondary current area of the B phase on the high voltage side When the difference between the phase angle of the current fundamental wave and the phase angle of the B-phase secondary current on the medium voltage side is less than or equal to 90 degrees, it is the fault current or the inrush current outside the transformer area;
第十四步、当C相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，计算变压器的高压侧C相二次电流面积Sy高压侧C与变压器的中压侧C相二次电流面积Sy中压侧C的差ΔSc，计算时要采用高压侧C相二次电流、中压侧C相二次电流、低压侧C相二次电流；The fourteenth step, when the phase C phase difference current When the amplitude is greater than or equal to the differential current start-up setting value ΔI of the transformer protection, calculate the secondary current area Sy high-voltage side C of the high-voltage side of the transformer and the secondary current area Sy medium-voltage side C of the C-phase of the transformer The difference ΔSc of the high-voltage side C-phase secondary current should be used in the calculation , Secondary current of phase C on medium voltage side , C-phase secondary current on the low-voltage side ;
高压侧C相二次电流面积Sy高压侧C和变压器的中压侧C相二次电流面积Sy中压侧C的计算方法与第八步高压侧二次电流面积Sy高压侧A和中压侧A相二次电流面积Sy中压侧A的计算方法相同，高压侧C相二次电流面积Sy高压侧C与中压侧C相二次电流面积Sy中压侧C的面积差为ΔSc；High voltage side C phase secondary current area Sy high voltage side C and transformer medium voltage side C phase secondary current area Sy medium voltage side C calculation method and the eighth step high voltage side secondary current area Sy high voltage side A and The calculation method of the secondary current area S of phase A on the medium voltage sidey medium voltage side A is the same, the secondary current area S of phase C on the high voltage sidey high voltage side C and the secondary current area S of phase C on the medium voltage side Sy medium voltage side C The area difference is ΔSc ;
第十五步、当C相相差电流幅值大于或等于变压器保护的差电流启动整定值ΔI时，同时计算高压侧C相二次电流基波相角和中压侧C相二次电流基波相角，计算时要采用第四步调整后的高压侧C相二次电流、中压侧C相二次电流、低压侧C相二次电流；Step 15, when phase C phase difference current When the amplitude is greater than or equal to the differential current start-up setting value ΔI of the transformer protection, the fundamental phase angle of the secondary current of phase C on the high voltage side and the fundamental phase angle of the secondary current of phase C on the medium voltage side are calculated at the same time, and the fourth step is used in the calculation Adjusted high-voltage side C-phase secondary current , Secondary current of phase C on medium voltage side , C-phase secondary current on the low-voltage side ;
第十六步、当高压侧C相二次电流面积Sy高压侧C与中压侧C相二次电流面积Sy中压侧C的面积差ΔSc大于等于C相二次电流面积差整定值SC，并且，高压侧C相二次电流基波相角与中压侧C相二次电流基波相角差大于90度时，为变压器区内故障电流；当高压侧C相二次电流面积Sy高压侧C与中压侧C相二次电流面积Sy中压侧C的面积差ΔSc大于等于C相二次电流面积差整定值SC，并且，高压侧C相二次电流基波相角与中压侧C相二次电流基波相角差小于等于90度时，为变压器区外故障电流或和应涌流。The sixteenth step, when the secondary current area Sy of phase C on the high voltage side and the secondary current area Sy of phase C on the medium voltage side ΔSc is greater than or equal to the setting of the secondary current area difference of phase C value SC , and when the phase angle difference between the fundamental phase angle of the secondary current of phase C on the high-voltage side and the fundamental phase angle of the secondary current of phase C on the medium-voltage side is greater than 90 degrees, it is the fault current in the transformer area; when the secondary current of phase C on the high-voltage side Current area Sy The area difference ΔSc between the secondary current area Sy of the high-voltage side C and the secondary current area of the medium-voltage side C of the medium-voltage side C is greater than or equal to the setting value SC of the secondary current area difference of the C-phase, and the secondary current area of the C-phase on the high-voltage side When the difference between the phase angle of the current fundamental wave and the phase angle of the secondary current of phase C on the medium voltage side is less than or equal to 90 degrees, it is the fault current outside the transformer area or the inrush current.
对于变压器中压侧或低压侧无电源时，可利用变压器三侧的复合电压（低电压和负序电压）构成或逻辑解除第十步、第十三步和第十六步中的高压侧二次电流相角与中压侧二次电流相角差的条件；这样可避免在区内故障时发生拒动；When there is no power supply on the medium-voltage or low-voltage side of the transformer, the composite voltage (low voltage and negative sequence voltage) on the three sides of the transformer can be used to form or logically release the two voltages on the high-voltage side in the tenth, thirteenth and sixteenth steps. The condition of the difference between the phase angle of the secondary current and the phase angle of the secondary current of the medium voltage side; this can avoid the failure to operate when there is a fault in the area;
低电压和负序电压的计算方法为：The calculation method of low voltage and negative sequence voltage is:
基波电压可利用第三步的全波傅立叶数字滤波，滤出基波电压；The fundamental voltage can be filtered out by the third step of full-wave Fourier digital filtering;
正、负序电压计算方法为：The calculation method of positive and negative sequence voltage is:
其中：a=ej120°为矢量运算因子；Where:a=ej 120° is the vector operation factor;
当变压器中压侧无电源时，可经过复合电压（低电压和负序电压）解除闭锁，此时只需判定电流面积差超过整定值，不再判别高中压侧电流角度，保护装置即可输出跳闸信号，跳开变压器各侧断路器。对于变压器低压侧有电源情况，同样可以得出上述结论，但此时角度判别为高低压侧电流角度差。When there is no power supply on the medium voltage side of the transformer, the blocking can be released through the compound voltage (low voltage and negative sequence voltage). At this time, it is only necessary to determine that the current area difference exceeds the set value, and no longer judge the current angle of the high and medium voltage side, and the protection device can output Trip signal to trip the circuit breakers on each side of the transformer. For the case where there is a power supply on the low-voltage side of the transformer, the above conclusion can also be drawn, but at this time, the angle is judged as the current angle difference between the high and low voltage sides.
利用Y-Δ变换将变压器Y侧的电流转换为Δ；Δ侧不变，调整变压器各侧电流幅值及相位，然后计算差电流；对于Y-Y-Δ-11接线型式的变压器，其电流变换公式如下表：Use Y-Δ conversion to convert the current on the Y side of the transformer to Δ; the Δ side remains unchanged, adjust the current amplitude and phase of each side of the transformer, and then calculate the difference current; for the transformer with Y-Y-Δ-11 connection type, its current conversion formula As shown in the following table:
利用下式计算差电流：Calculate the differential current using the following formula:
式中：、、—为A、B、C相差电流；In the formula: , , — is the phase difference current of A, B, and C;
、、—为变换前变压器高压侧A、B、C相电流； , , — is the A, B, and C phase currents on the high voltage side of the transformer before transformation;
、、—为变换前变压器中压侧A、B、C相电流； , , — is the A, B, and C phase currents on the medium-voltage side of the transformer before transformation;
、、—为变换后变压器高压侧A、B、C相电流； , , — is the A, B, and C phase currents on the high-voltage side of the transformer after transformation;
、、—为变换后变压器中压侧A、B、C相电流； , , — is the A, B, and C phase currents on the medium-voltage side of the transformer after transformation;
、、—为变压器低压侧A、B、C相电流； , , — is the A, B, and C phase currents at the low-voltage side of the transformer;
其他接线组别的变压器根据变压器各侧相位情况，同样可以推导出其变换公式。Transformers of other wiring groups can also derive their transformation formulas according to the phase conditions of each side of the transformer.
SA、SB和SC的整定值按照变压器接入系统情况计算后进行整定。The setting values of SA , SB and SC are set according to the conditions of the transformer connected to the system.
ΔI的整定参照目前变压器差动保护整定原则进行整定。The setting of ΔI is set according to the current setting principles of transformer differential protection.
| Application Number | Priority Date | Filing Date | Title |
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| CN201510101914.1ACN104779582B (en) | 2015-03-09 | 2015-03-09 | A kind of discrimination method of in tranformer protection and echo surge current and fault current |
| Application Number | Priority Date | Filing Date | Title |
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| CN201510101914.1ACN104779582B (en) | 2015-03-09 | 2015-03-09 | A kind of discrimination method of in tranformer protection and echo surge current and fault current |
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| CN104779582B CN104779582B (en) | 2017-09-26 |
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| CN201510101914.1AActiveCN104779582B (en) | 2015-03-09 | 2015-03-09 | A kind of discrimination method of in tranformer protection and echo surge current and fault current |
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| CN116112972A (en)* | 2023-01-12 | 2023-05-12 | 南京国电南自电网自动化有限公司 | A line differential protection method suitable for saving 5G communication traffic |
| CN116404612A (en)* | 2023-06-06 | 2023-07-07 | 三峡智能工程有限公司 | Method and system for preventing generator differential protection misoperation caused by emergency current |
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