A relay protection system for transmission lines containing current limiting reactors

Abstract

The present invention discloses a relay protection system for a power transmission line including a current limiting reactor, including voltage transformers and current transformers respectively arranged on both sides of an overhead line; voltage transformers and current transformers arranged on the side not connected to the overhead line of the current limiting reactor; line protection devices with integrated current limiting reactor protection functions respectively arranged on both sides of the entire power transmission line including the current limiting reactor; after the line protection of one side is actuated, the circuit breaker on this side is tripped, and the circuit breaker on the opposite side is tripped in parallel. The present invention only needs to increase a system measurement point once, does not need to increase a relay protection device, does not need to change the original line protection setting value, the protection range includes not only the original overhead line, but also the current limiting reactor, and is suitable for two operating modes of the current limiting reactor being put into operation and being withdrawn.

Description

Technical Field

[0001] The invention belongs to the field of relay protection of electric power systems, and relates to a relay protection system for a power transmission line including a current limiting reactor. Background Art

[0002] With the continuous development and expansion of the power grid, the electrical connection is becoming closer and closer. The 500kV power grid sites in developed areas are densely distributed, and the short-circuit current level of the main hub 500kV substation is constantly increasing. The short-circuit current of the 500kV busbar of the substation has approached or exceeded the interrupting capacity of the circuit breaker, and it is urgent to limit the short-circuit current level. Adding current-limiting reactors to the relevant 500kV lines can effectively reduce the short-circuit current and affect the power grid power flow distribution.

[0003] The installation of transmission line current limiting reactors can extend the electrical distance between sites without changing the structure of the power grid. However, after the installation of line current limiting reactors, the system positive sequence and zero sequence parameters will change, thereby changing the line impedance. Chinese patent application number 200910034668.7, published on December 14, 2011, the name of the invention is a series capacitor compensation line distance protection method combined with a phase comparison relay. The patent discloses a series capacitor compensation line distance protection method combined with a phase comparison relay. The disadvantage is that it is only applicable to transmission lines where the series devices are capacitive series devices.

[0004] Chinese patent application number 201610958677.5, published on January 18, 2017, the name of the invention is a distance protection method for a transmission line containing series equipment. The patent discloses a distance protection method for a transmission line containing series equipment, which calculates the equivalent impedance of the series equipment in real time, and uses the calculated equivalent impedance to accurately calculate the measured impedance of the transmission line containing the series equipment, and finally compares the positional relationship between the measured impedance and the distance protection action area to determine whether the distance protection should be activated. . Its disadvantage is that the zero-sequence compensation coefficient is not easy to adjust. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a relay protection system for a transmission line containing a current limiting reactor, which can adapt to two operating modes of the current limiting reactor being put into operation and being withdrawn without adding a relay protection device.

[0006] In order to achieve the above object, the solution of the present invention is:

[0007] A relay protection system for a power transmission line including a current limiting reactor, wherein the power transmission line including the current limiting reactor includes two sections, the first section is the current limiting reactor, and the second section is an overhead line; the relay protection system includes:

[0008] A voltage transformer PT1 and a current transformer CT1 are arranged at the connection between the first section and the second section, and a first line protection device with an integrated current limiting reactor protection function;

[0009] A voltage transformer PT2 and a current transformer CT2 are arranged on the side of the overhead line of the second section which is not connected to the current limiting reactor of the first section, and a second line protection device with integrated current limiting reactor protection function;

[0010] A voltage transformer PT3 and a current transformer CT3 are arranged on the side of the current-limiting reactor of the first section which is not connected to the overhead line of the second section;

[0011] A communication connection is provided between the first line protection device and the second line protection device;

[0012] The first line protection device is connected to the voltage of the voltage transformer PT1, the current of the current transformer CT1, the voltage of the voltage transformer PT3 and the current of the current transformer CT3, and receives the voltage of the voltage transformer PT2 and the current of the current transformer CT2 from the second line protection device through a communication connection;

[0013] The second line protection device is connected to the voltage of the voltage transformer PT2 and the current of the current transformer CT2, and receives the voltage of the voltage transformer PT3 and the current of the current transformer CT3 from the first line protection device through a communication connection.

[0014] In a preferred scheme, the first line protection device uses the voltage of the voltage transformer PT1 and the current of the current transformer CT1 to configure conventional protection functions; the second line protection device uses the voltage of the voltage transformer PT2 and the current of the current transformer CT2 to configure conventional protection functions; the conventional protection functions include distance protection, zero-sequence overcurrent protection and reclosing function.

[0015] In a preferred solution, the first line protection device and the second line protection device use the current of the current transformer CT3 and the current of the current transformer CT2 to form differential protection, and the protection range is the entire line including the current limiting reactor.

[0016] In a preferred solution, the first line protection device uses the current of the current transformer CT1 and the current of the current transformer CT3 to form differential protection, and the protection range is the first section current limiting reactor.

[0017] In a preferred solution, the first line protection device utilizes the voltage of the voltage transformer PT1 and the current of the current transformer CT1 to form a distance protection whose protection range is directed to the first section current limiting reactor.

[0018] In a preferred solution, the second line protection device utilizes the voltage of the voltage transformer PT2 and the current of the current transformer CT2 to form a distance protection whose protection range is directed to the first section current limiting reactor.

[0019] In a preferred solution, after the first line protection device or the second line protection device is actuated, the actuation signal is transmitted to the opposite side protection device through a communication connection for joint tripping.

[0020] Beneficial effects of the invention: The relay protection system for a transmission line containing a current limiting reactor disclosed by the invention only needs to add a system measurement point once, without adding a relay protection device or changing the original line protection setting. The protection range includes not only the original overhead line but also the current limiting reactor, and is suitable for two operating modes: the current limiting reactor is put into operation and the current limiting reactor is withdrawn. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a relay protection system for a transmission line including a current limiting reactor. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] like Figure 1 Shown is a schematic diagram of an embodiment of a relay protection system for a transmission line containing a current limiting reactor of the present invention. Among them, the transmission line containing the current limiting reactor includes two sections, the first section is the current limiting reactor, and the second section is the overhead line. The relay protection system for the transmission line containing the current limiting reactor includes: a voltage transformer PT1 and a current transformer CT1 configured at the connection between the first section and the second section, and a first line protection device with an integrated current limiting reactor protection function; a voltage transformer PT2 and a current transformer CT2 configured on the side of the overhead line in the second section that is not connected to the current limiting reactor in the first section, and a second line protection device with an integrated current limiting reactor protection function; a voltage transformer PT3 and a current transformer CT3 configured on the side of the current limiting reactor in the first section that is not connected to the overhead line in the second section; the first line protection device A communication connection is set between the protection device and the second line protection device; the first line protection device is connected to the voltage of the voltage transformer PT1, the current of the current transformer CT1, the voltage of the voltage transformer PT3 and the current of the current transformer CT3, and receives the voltage of the voltage transformer PT2 and the current transformer CT2 from the second line protection device through the communication connection; the second line protection device is connected to the voltage of the voltage transformer PT2 and the current transformer CT2, and receives the voltage of the voltage transformer PT3 and the current transformer CT3 from the first line protection device through the communication connection.

[0024] In a preferred embodiment, the first line protection device uses the voltage of the voltage transformer PT1 and the current of the current transformer CT1 to configure conventional protection functions; the second line protection device uses the voltage of the voltage transformer PT2 and the current transformer CT2 to configure conventional protection functions; the conventional protection functions include distance protection, zero-sequence overcurrent protection and reclosing function.

[0025] In a preferred embodiment, the first line protection device and the second line protection device use the current of the current transformer CT3 and the current of the current transformer CT2 to form differential protection, and the protection range is the entire line including the current limiting reactor.

[0026] In a preferred embodiment, the first line protection device uses the current transformer CT1 current and the current transformer CT3 current to form a differential protection, and the protection range is the first section current limiting reactor.

[0027] In a preferred embodiment, the first line protection device utilizes the voltage of the voltage transformer PT1 and the current of the current transformer CT1 to form a protection range of distance protection directed to the first section current limiting reactor.

[0028] In a preferred embodiment, the second line protection device utilizes the voltage of the voltage transformer PT2 and the current of the current transformer CT2 to form a protection range of distance protection directed to the first section current limiting reactor.

[0029] In a preferred embodiment, after the first line protection device or the second line protection device is actuated, the actuation signal is transmitted to the opposite side protection device through a communication connection for joint tripping. The devices may establish a communication connection through an optical fiber channel, and after the first line protection device or the second line protection device is actuated, the actuation signal is transmitted to the opposite side protection device through the optical fiber channel for joint tripping.

[0030] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A relay protection system for a power transmission line containing a current limiting reactor, wherein the power transmission line containing the current limiting reactor comprises two sections, the first section is the current limiting reactor, and the second section is an overhead line; characterized in that: The relay protection system comprises: A voltage transformer PT1 and a current transformer CT1 are arranged at the connection between the first section and the second section, and a first line protection device with an integrated current limiting reactor protection function; A voltage transformer PT2 and a current transformer CT2 are arranged on the side of the overhead line of the second section which is not connected to the current limiting reactor of the first section, and a second line protection device with integrated current limiting reactor protection function; A voltage transformer PT3 and a current transformer CT3 are arranged on the side of the current-limiting reactor of the first section which is not connected to the overhead line of the second section; A communication connection is provided between the first line protection device and the second line protection device; The first line protection device is connected to the voltage of the voltage transformer PT1, the current of the current transformer CT1, the voltage of the voltage transformer PT3 and the current of the current transformer CT3, and receives the voltage of the voltage transformer PT2 and the current of the current transformer CT2 from the second line protection device through a communication connection; The second line protection device is connected to the voltage of the voltage transformer PT2 and the current of the current transformer CT2, and receives the voltage of the voltage transformer PT3 and the current of the current transformer CT3 from the first line protection device through the communication connection; The first line protection device uses the voltage of the voltage transformer PT1 and the current of the current transformer CT1 to configure a conventional protection function; the second line protection device uses the voltage of the voltage transformer PT2 and the current of the current transformer CT2 to configure a conventional protection function; the conventional protection function includes distance protection, zero-sequence overcurrent protection and reclosing function; The first line protection device and the second line protection device use the current of the current transformer CT3 and the current of the current transformer CT2 to form differential protection, and the protection range is the entire line including the current limiting reactor; The first line protection device uses the current of the current transformer CT1 and the current of the current transformer CT3 to form a differential protection, and the protection range is the first section current limiting reactor; The first line protection device uses the voltage of the voltage transformer PT1 and the current of the current transformer CT1 to form a protection range of distance protection pointing to the first section current limiting reactor; The second line protection device utilizes the voltage of the voltage transformer PT2 and the current of the current transformer CT2 to form a protection range of distance protection directed to the first section current limiting reactor.

2. A relay protection system for a power transmission line containing a current limiting reactor as claimed in claim 1, characterized in that: After the first line protection device or the second line protection device is actuated, the actuation signal is transmitted to the opposite side protection device through the communication connection for joint tripping.

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