Generator transformer bank main transformer differential protection framework

Abstract

The utility model belongs to the technical field of power transmission and transformation, and particularly discloses a differential protection framework for a main transformer of a generator transformer bank. By changing the current taking position of a main transformer protection device in a line and adaptively adding and deleting a current transformer for main transformer protection of a generator outlet circuit breaker, only the generator outlet circuit breaker trips when an excitation branch has a short-circuit fault, and a main transformer high-voltage side circuit breaker is kept in a closed state; and the high-voltage station service working transformer can still take power from the network side to ensure the load demand of station service power. A power generation enterprise suitable for the system adopts the following wiring modes: the current construction scale is two generator sets; each generator is provided with a generator outlet circuit breaker (GCB); the whole plant is not provided with a start-up (shutdown) transformer; the two machines are connected with each other through high-voltage factory buses and are standby for each other during shutdown.

Description

Technical Field

[0001] The utility model belongs to the technical field of power transmission and distribution, and specifically discloses a main transformer differential protection architecture of a generator transformer group. Background Art

[0002] Transformer differential protection is the main protection of the transformer, which is mainly used to protect various phase-to-phase short-circuit faults occurring inside the windings and lead-out lines of double-winding or three-winding transformers, and can also be used to protect single-phase turn-to-turn short-circuit faults of transformers. Existing power generation enterprises generally establish a main transformer protection architecture covering external power transmission and in-plant power supply in accordance with the requirements of the "Electric Power Industry Standard of the People's Republic of China: Selection and Calculation Procedures for Current Transformers and Voltage Transformers (DL / T866-2015)". This architecture has been proven to be effective under most operating conditions and has played a protective role for the main transformer. However, if the following wiring type is adopted: the current construction scale is two generator sets; all generators are equipped with generator outlet circuit breakers (GCB); there is no standby (shutdown) transformer in the whole plant; the high-voltage plant busbars of the two machines are interconnected and serve as each other's shutdown standby; when a short circuit occurs in the generator excitation branch line, the above architecture also senses the abnormal current signal and causes the high-voltage side circuit breaker of the main transformer to trip, and the high-voltage plant working transformer also loses power at the same time, causing the accident to expand. Utility Model Content

[0003] In order to solve the technical problems listed in the background technology, the utility model provides a main transformer differential protection architecture for a generator transformer group. The specific technical solution is as follows:

[0004] A main transformer differential protection architecture of a generator transformer group comprises a generator output trunk line, a generator excitation branch line, a high-voltage plant transformer branch line and a main transformer protection device; the generator output trunk line comprises a generator, a generator outlet circuit breaker, a main transformer and a main transformer high-voltage side circuit breaker which are sequentially connected by conductors along the current direction; the generator excitation branch line comprises an excitation transformer and a rectifier which are sequentially connected by conductors along the current direction; the high-voltage plant transformer branch line comprises a high-voltage plant transformer and a 10kV working busbar which are sequentially connected by conductors along the current direction; wherein, the excitation shunt point of the generator excitation branch line on the generator output trunk line is located between the generator and the generator outlet circuit breaker, and the plant shunt point of the high-voltage plant transformer branch line on the generator output trunk line is located between the generator outlet circuit breaker and the main transformer; the differential protection in the main transformer protection device is connected to the measuring points on the conductors through different current transformers, respectively, and the measuring points are distributed in the section from the main transformer high-voltage side to the main transformer high-voltage side circuit breaker, the section from the plant shunt point to the high-voltage plant transformer, and the section from the excitation shunt point to the generator outlet circuit breaker.

[0005] Preferably, the conductors between the generator excitation branch line, the high-voltage plant transformer branch line and the generator outlet to the main transformer are all closed busbars, and the current transformers at the measuring points on the conductors are installed in the closed busbars.

[0006] The design of the installation location of this current transformer is based on the consideration that the current transformers provided by GCB manufacturers are limited by manufacturing space and manufacturing costs, and it is difficult to add new current transformers to realize the protection wiring rewiring function. The simplest method is to add current transformers to the supply scope of the closed busbar manufacturer, which is also convenient for later transformation to realize the function of main transformer differential protection wiring rewiring.

[0007] Compared with the prior art, the utility model has the following advantages:

[0008] The utility model provides a main transformer differential protection architecture for a generator transformer group, so that when a short circuit occurs in the generator excitation branch line, only the generator outlet circuit breaker trips, while the main transformer high-voltage side circuit breaker remains connected, and the high-voltage plant working transformer can still ensure the load demand of the plant power by drawing power from the grid side. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Schematic diagram of the differential protection architecture of the main transformer of the generator transformer group in the embodiment of the utility model. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on this embodiment, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0011] like Figure 1As shown, an embodiment of the utility model provides a main transformer differential protection architecture of a generator transformer group, including a generator output trunk line, a generator excitation branch line, a high-voltage plant transformer branch line and a main transformer protection device (any main transformer is equipped with two sets of the main transformer protection devices); the generator output trunk line includes a generator (100MW~1000MW), a generator output circuit breaker (GCB), a main transformer and a main transformer high-voltage side circuit breaker connected in sequence along the current direction by a conductor; the generator excitation branch line includes an excitation transformer and a rectifier connected in sequence along the current direction by a conductor; the high-voltage plant transformer branch line includes a high-voltage transformer connected in sequence along the current direction by a conductor The high-voltage plant transformer and the 10kV working bus are connected, and the high-voltage plant transformer is also connected to the power grid through a backup circuit; wherein, the excitation shunt point of the generator excitation branch line on the generator output trunk line is located between the generator and the generator outlet circuit breaker, and the plant shunt point of the high-voltage plant transformer branch line on the generator output trunk line is located between the generator outlet circuit breaker and the main transformer; the differential protection in the main transformer protection device is connected to the measuring points on the conductor through different current transformers, respectively, and the measuring points are distributed in the section from the high-voltage side of the main transformer to the circuit breaker on the high-voltage side of the main transformer, the section from the plant shunt point to the high-voltage plant transformer, and the section from the excitation shunt point to the generator outlet circuit breaker.

[0012] The conductors between the generator excitation branch line, the high-voltage plant transformer branch line and the generator outlet to the main transformer are all closed busbars. The current transformers at the measuring points on the conductors are installed in the closed busbars. The current transformers TA01 and TA02 on the conductors between the original generator outlet and the excitation shunt point are changed to standby (the first main transformer protection device corresponds to the newly added current transformer TA03, and the second main transformer protection device corresponds to the newly added current transformer TA04), cancelled or changed to other uses. The current transformers TA03 and TA04 are installed in the closed busbar, and the corresponding measuring points are located in the section from the excitation shunt point to the generator outlet circuit breaker.

[0013] Since the differential protection configurations of the main transformers of the two generator sets are the same, the attached figure only illustrates the differential protection architecture of the main transformer of one generator transformer set.

[0014] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A main transformer differential protection architecture of a generator transformer group, comprising a generator output trunk line, a generator excitation branch line, a high-voltage plant transformer branch line and a main transformer protection device; the generator output trunk line comprises a generator, a generator output circuit breaker, a main transformer and a main transformer high-voltage side circuit breaker sequentially connected by conductors along the current direction; the generator excitation branch line comprises an excitation transformer and a rectifier sequentially connected by conductors along the current direction; the high-voltage plant transformer branch line comprises a high-voltage plant transformer and a 10kV working busbar sequentially connected by conductors along the current direction; wherein, The excitation shunt point of the generator excitation branch line on the generator output trunk line is located between the generator and the generator output circuit breaker, and the plant shunt point of the high-voltage plant transformer branch line on the generator output trunk line is located between the generator output circuit breaker and the main transformer; it is characterized in that the differential protection in the main transformer protection device is connected to the measuring points on the conductor through different current transformers, and the measuring points are distributed in the section from the high-voltage side of the main transformer to the circuit breaker on the high-voltage side of the main transformer, the section from the plant shunt point to the high-voltage plant transformer, and the section from the excitation shunt point to the generator output circuit breaker.

2. A generator transformer group main transformer differential protection architecture according to claim 1, characterized in that: The conductors between the generator excitation branch line, the high-voltage plant transformer branch line and the generator outlet to the main transformer are all closed busbars, and the current transformers at the measuring points on the conductors are installed in the closed busbars.

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