System and method for polarity and configuration of transformer primary current correction zero-sequence differential protection

Abstract

The invention discloses a system and method for correcting the polarity and configuration of zero-sequence differential protection of a transformer primary current. A high-voltage side circuit breaker is connected to a high-voltage side winding of a transformer, one end of an output end of a voltage regulating power supply is connected to a line between the high-voltage side circuit breaker and the high-voltage side winding of the transformer, a transformer high-voltage side current transformer is arranged on the line between the high-voltage side circuit breaker and the high-voltage side winding of the transformer, a neutral point of the high-voltage side of the transformer and the other end of the output end of the voltage regulating power supply are connected to a grounding grid, a transformer high-voltage side neutral point zero-sequence current transformer is arranged on the line between the neutral point of the high-voltage side of the transformer and the grounding grid, and a transformer low-voltage winding is connected to a low-voltage side circuit breaker. Before the transformer is put into operation, the system and method judge the correctness of the protection polarity and configuration to ensure that the transformer zero-sequence differential protection is correct and effective.

Description

Technical Field

[0001] The invention belongs to the technical field of power commissioning and power testing, and relates to a system and method for correcting polarity and configuration of zero-sequence differential protection for primary current of a transformer. Background Art

[0002] Large transformer zero-sequence differential protection protects single-phase winding grounding faults, and has the advantages of being unaffected by the transformer magnetic circuit and high sensitivity. When the transformer is operating normally, the zero-sequence current is very small, and the braking current and operating current of the protection device are also very small. The operating current during operation cannot be used to judge the protection polarity and configuration correctness.

[0003] At present, the commonly used method is to use the no-load impact current to determine the protection polarity and configuration. The disadvantage is that the impact current is related to the voltage phase of the closing impact, the size cannot be controlled, the time is short, and the protection polarity and configuration correctness cannot be accurately determined, resulting in a high protection false operation rate.

[0004] A method for correcting the polarity and configuration of zero-sequence differential protection of a large transformer by primary current flow is provided. The method of applying power supply is used to judge the protection polarity and configuration correctness through the current of the primary circuit, which is of great significance. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a system and method for correcting the polarity and configuration of zero-sequence differential protection of a transformer primary current. Before the transformer is put into operation, the system and method judge the correctness of the protection polarity and configuration to ensure that the zero-sequence differential protection of the transformer is correct and effective.

[0006] To achieve the above-mentioned object, the system for correcting the polarity and configuration of zero-sequence differential protection for primary current of a transformer described in the present invention comprises a neutral point on the high-voltage side of the transformer, a transformer protection device, a high-voltage side winding of the transformer, a low-voltage winding of the transformer, a high-voltage side circuit breaker, a low-voltage side circuit breaker and a voltage regulating power supply;

[0007] The high-voltage side circuit breaker is connected to the high-voltage side winding of the transformer, one end of the output end of the voltage regulating power supply is connected to the line between the high-voltage side circuit breaker and the high-voltage side winding of the transformer, a transformer high-voltage side current transformer is arranged on the line between the high-voltage side circuit breaker and the high-voltage side winding of the transformer, the neutral point of the high-voltage side of the transformer and the other end of the output end of the voltage regulating power supply are connected to the grounding grid, a transformer high-voltage side neutral point zero-sequence current transformer is arranged on the line between the neutral point of the high-voltage side of the transformer and the grounding grid, and the low-voltage winding of the transformer is connected to the low-voltage side circuit breaker;

[0008] The transformer protection device is connected to the current transformer at the high voltage side of the transformer and the neutral point zero-sequence current transformer at the high voltage side of the transformer.

[0009] Self-generated zero-sequence current of the current transformer on the high-voltage side of the transformer Among them, U is the output voltage of the voltage-regulated power supply, Z0 is the zero-sequence impedance of the transformer, and n1 is the transformation ratio of the current transformer on the high-voltage side of the transformer.

[0010] Secondary current of zero-sequence current transformer at neutral point on high voltage side of transformer Among them, U is the output voltage of the voltage-regulated power supply, Z0 is the zero-sequence impedance of the transformer, and n2 is the transformation ratio of the zero-sequence current transformer at the neutral point on the high-voltage side of the transformer.

[0011] The method for polarity and configuration of transformer primary current correction zero-sequence differential protection according to the present invention comprises the following steps:

[0012] 1) Prepare for the polarity test of through-current differential protection;

[0013] 2) Disconnect the high-voltage side circuit breaker and the low-voltage side circuit breaker;

[0014] 3) Connect one end of the voltage regulating power supply output end to the line between the high-voltage side circuit breaker and the current transformer on the high-voltage side of the transformer, connect the other end of the voltage regulating power supply output end to the grounding grid, and connect the neutral point on the high-voltage side of the transformer to the grounding grid;

[0015] 4) Adjust the amplitude of the voltage regulating power supply so that the secondary current amplitude of the zero-sequence current transformer at the neutral point of the high-voltage side of the transformer is greater than N;

[0016] 5) Check the secondary self-generated zero-sequence current of the current transformer on the high-voltage side of the transformer collected in the transformer protection device and the secondary current amplitude of the neutral point zero-sequence current transformer on the high-voltage side of the transformer. When the secondary current amplitude of the neutral point zero-sequence current transformer on the high-voltage side of the transformer is consistent with the actual value, and the secondary self-generated zero-sequence current of the current transformer on the high-voltage side of the transformer is zero, go to step 6); otherwise, eliminate the fault and then go to step 4);

[0017] 6) Check the secondary self-generated zero-sequence current of the current transformer on the high-voltage side of the transformer collected in the transformer protection device and the secondary current phase of the neutral point zero-sequence current transformer on the high-voltage side of the transformer. When the secondary current phase of the neutral point zero-sequence current transformer on the high-voltage side of the transformer meets the polarity requirements of the transformer protection device and the secondary self-generated zero-sequence current of the current transformer on the high-voltage side of the transformer is zero, go to step 7); otherwise, eliminate the defect and go to step 4);

[0018] 7) The primary current correction zero-sequence differential protection polarity and configuration test are completed.

[0019] N=20mA.

[0020] The present invention has the following beneficial effects:

[0021] The system and method for correcting the polarity and configuration of zero-sequence differential protection by primary current of a transformer described in the present invention, during specific operation, applies a voltage-regulated power supply to a circuit consisting of a current transformer on the high-voltage side of the transformer, a winding on the high-voltage side of the transformer, and a zero-sequence current transformer on the neutral point of the high-voltage side of the transformer, and tests whether the polarity and configuration of the zero-sequence differential protection of the transformer are correct through a transformer protection device, wherein the current of the tested protection device is greater than 20 mA. Before the transformer is put into operation, a method of applying power is adopted to judge the correctness of the protection polarity and configuration through the current of the primary circuit, so as to avoid malfunction of the zero-sequence differential protection during the operation of the transformer, and ensure that the zero-sequence differential protection of the transformer is correct and effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Figure 2 It is a flow chart of the present invention.

[0024] Among them, 1 is the current transformer on the high-voltage side of the transformer, 2 is the neutral point zero-sequence current transformer on the high-voltage side of the transformer, 3 is the transformer protection device, 4 is the high-voltage side winding of the transformer, 5 is the low-voltage winding of the transformer, 6 is the high-voltage side circuit breaker, 7 is the low-voltage side circuit breaker, and 8 is the voltage regulating power supply. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0026] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0027] refer to Figure 1The system for correcting the polarity and configuration of the zero-sequence differential protection for primary current of the transformer described in the present invention comprises a current transformer 1 on the high-voltage side of the transformer, a zero-sequence current transformer 2 on the neutral point of the high-voltage side of the transformer, a transformer protection device 3, a high-voltage side winding 4 of the transformer, a low-voltage winding 5 of the transformer, a high-voltage side circuit breaker 6, a low-voltage side circuit breaker 7 and a voltage regulating power supply 8;

[0028] The high-voltage side circuit breaker 6 is connected to the high-voltage side winding 4 of the transformer, one end of the output end of the voltage regulating power supply 8 is connected to the line between the high-voltage side circuit breaker 6 and the high-voltage side winding 4 of the transformer, a transformer high-voltage side current transformer 1 is arranged on the line between the high-voltage side circuit breaker 6 and the high-voltage side winding 4 of the transformer, the neutral point of the high-voltage side of the transformer and the other end of the output end of the voltage regulating power supply 8 are connected to the grounding grid, a transformer high-voltage side neutral point zero-sequence current transformer 2 is arranged on the line between the neutral point of the high-voltage side of the transformer and the grounding grid, and the transformer low-voltage winding 5 is connected to the low-voltage side circuit breaker 7;

[0029] The transformer protection device 3 is connected to the transformer high-voltage side current transformer 1 and the transformer high-voltage side neutral point zero-sequence current transformer 2.

[0030] Self-generated zero-sequence current of current transformer 1 on the high-voltage side of the transformer Among them, U is the output voltage of the voltage regulating power supply 8, Z0 is the zero-sequence impedance of the transformer, n1 is the transformation ratio of the current transformer 1 on the high-voltage side of the transformer; the secondary side current of the zero-sequence current transformer 2 at the neutral point of the high-voltage side of the transformer Wherein, U is the output voltage of the voltage regulating power supply 8, Z0 is the zero-sequence impedance of the transformer, and n2 is the transformation ratio of the neutral point zero-sequence current transformer 2 on the high-voltage side of the transformer.

[0031] refer to Figure 2 The method for transformer primary current correction zero-sequence differential protection polarity and configuration of the present invention comprises the following steps:

[0032] 1) Prepare for the polarity test of through-current differential protection;

[0033] 2) Disconnect the high-voltage side circuit breaker 6 and the low-voltage side circuit breaker 7;

[0034] 3) Connect one end of the output end of the voltage regulating power supply 8 to the line between the high-voltage side circuit breaker 6 and the current transformer 1 on the high-voltage side of the transformer, connect the other end of the output end of the voltage regulating power supply 8 to the grounding grid, and connect the neutral point on the high-voltage side of the transformer to the grounding grid;

[0035] 4) Adjust the amplitude of the voltage regulating power supply 8 so that the secondary side current amplitude of the zero-sequence current transformer 2 at the neutral point of the high voltage side of the transformer is greater than 20mA;

[0036] 5) Check the secondary self-generated zero-sequence current of the transformer high-voltage side current transformer 1 and the secondary current amplitude of the transformer high-voltage side neutral point zero-sequence current transformer 2 collected in the transformer protection device 3. When the secondary current amplitude of the transformer high-voltage side neutral point zero-sequence current transformer 2 is consistent with the actual value, and the secondary self-generated zero-sequence current of the transformer high-voltage side current transformer 1 is zero, go to step 6); otherwise, eliminate the fault and then go to step 4);

[0037] 6) Check the secondary self-generated zero-sequence current of the transformer high-voltage side current transformer 1 and the secondary current phase of the transformer high-voltage side neutral point zero-sequence current transformer 2 collected in the transformer protection device 3. When the secondary current phase of the transformer high-voltage side neutral point zero-sequence current transformer 2 meets the polarity requirement of the transformer protection device 3 and the secondary self-generated zero-sequence current of the transformer high-voltage side current transformer 1 is zero, go to step 7); otherwise, eliminate the defect and go to step 4);

[0038] 7) The primary current correction zero-sequence differential protection polarity and configuration test are completed.

Claims

1. A method for transformer primary current correction zero-sequence differential protection polarity and configuration, characterized in that: A system based on transformer primary current correction zero-sequence differential protection polarity and configuration, the system comprising a transformer high-voltage side neutral point, a transformer protection device (3), a transformer high-voltage side winding (4), a transformer low-voltage winding (5), a high-voltage side circuit breaker (6), a low-voltage side circuit breaker (7) and a voltage regulating power supply (8); A high-voltage side circuit breaker (6) is connected to a high-voltage side winding (4) of a transformer; one end of an output end of a voltage regulating power supply (8) is connected to a line between the high-voltage side circuit breaker (6) and the high-voltage side winding (4) of the transformer; a transformer high-voltage side current transformer (1) is provided on the line between the high-voltage side circuit breaker (6) and the high-voltage side winding (4) of the transformer; a neutral point of the high-voltage side of the transformer and the other end of the output end of the voltage regulating power supply (8) are connected to a grounding network; a transformer high-voltage side neutral point zero-sequence current transformer (2) is provided on the line between the neutral point of the high-voltage side of the transformer and the grounding network; and a transformer low-voltage winding (5) is connected to a low-voltage side circuit breaker (7); The transformer protection device (3) is connected to the transformer high-voltage side current transformer (1) and the transformer high-voltage side neutral point zero-sequence current transformer (2); Self-generated zero-sequence current of the current transformer (1) on the high-voltage side of the transformer Wherein, U is the output voltage of the voltage regulating power supply (8), Z0 is the zero-sequence impedance of the transformer, and n1 is the transformation ratio of the current transformer (1) on the high-voltage side of the transformer; Secondary current of the zero-sequence current transformer (2) at the neutral point on the high-voltage side of the transformer Wherein, U is the output voltage of the voltage regulating power supply (8), Z0 is the zero-sequence impedance of the transformer, and n2 is the transformation ratio of the zero-sequence current transformer (2) at the neutral point of the high-voltage side of the transformer; The following steps are involved: 1) Prepare for the polarity test of through-current differential protection; 2) Disconnect the high-voltage side circuit breaker (6) and the low-voltage side circuit breaker (7); 3) connecting one end of the output end of the voltage regulating power supply (8) to the line between the high-voltage side circuit breaker (6) and the current transformer (1) on the high-voltage side of the transformer, connecting the other end of the output end of the voltage regulating power supply (8) to the grounding grid, and connecting the neutral point on the high-voltage side of the transformer to the grounding grid; 4) adjusting the amplitude of the voltage regulating power supply (8) so that the amplitude of the secondary side current of the neutral point zero-sequence current transformer (2) at the high voltage side of the transformer is greater than N; 5) Check the secondary self-generated zero-sequence current of the transformer high-voltage side current transformer (1) and the secondary current amplitude of the transformer high-voltage side neutral point zero-sequence current transformer (2) collected in the transformer protection device (3); when the secondary current amplitude of the transformer high-voltage side neutral point zero-sequence current transformer (2) is consistent with the actual value and the secondary self-generated zero-sequence current of the transformer high-voltage side current transformer (1) is zero, go to step 6); otherwise, eliminate the fault and then go to step 4); 6) Check the secondary self-generated zero-sequence current of the transformer high-voltage side current transformer (1) and the secondary current phase of the transformer high-voltage side neutral point zero-sequence current transformer (2) collected in the transformer protection device (3); when the secondary current phase of the transformer high-voltage side neutral point zero-sequence current transformer (2) meets the polarity requirement of the transformer protection device (3) and the secondary self-generated zero-sequence current of the transformer high-voltage side current transformer (1) is zero, go to step 7); otherwise, eliminate the defect and go to step 4); 7) The primary current correction of zero-sequence differential protection polarity and configuration test are completed; N=20mA.

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