1, line protection
Line protection is generally provided by two different manufacturers, each manufacturer provides a set, each set of protection integrated with the main protection and backup protection function modules. The main protection is divided into vertical high frequency protection and longitudinal differential protection. Longitudinal high frequency protection is divided into high frequency distance protection and high frequency direction protection. It is divided into blocking type and permissible type according to different transmission signals of the channel. The 500kV line protection adopts the permissible high frequency protection, and the 220kV adopts the blocking high frequency protection; the backup protection mainly has the zero sequence protection and the distance protection. With the large-scale popularization of line fiber-optic composite overhead ground lines, 500kV line protection longitudinal differential protection has been widely used, and the application of longitudinal high-frequency protection is relatively small, and will gradually be replaced. Each line can be protected by two sets of fiber length differential protection, or a set of fiber length differential protection and a set of fiber distance protection.
All protection devices include three components: analog input, digital input and digital output. Let's take the 500kV line longitudinal fiber protection as an example to describe the specific components of the above three parts.
(1) Analog input. Includes current and line voltage for the side and middle circuit breakers.
(2) Digital input. Including protection function platen opening, inspection platen opening, remote transmission (other protection actions transmit the remote transmission signal to the opposite side protection by means of the line protection channel), phase separation trip position (side and middle circuit breaker phase separation positions are connected in series) ), signal reset, start printing.
(3) Switch output. Including split-phase trip, three-phase trip, remote transmission (received remote signal from the opposite line protection, this signal is connected to the remote measuring trip device), protection signal (including protection action signal, abnormal signal, channel alarm, etc.) ).
2, over voltage and far jump protection
The pass voltage and far jump protection devices are generally provided by line protection manufacturers. Over-voltage protection protects the receiver from direct judgment and trip logic, over-voltage trip and signaling.
Overvoltage and far-hop protection analog inputs include the current of the side and middle circuit breakers (also the sum current of the two), the line voltage (for local current, voltage, power factor and power judgment); the digital input includes functions The pressure plate is opened, the pressure plate is opened, the three-hop position (for long jump, judged by the jump lock), the communication receiving (this line protection receives the remote transmission signal after the opposite side), the channel fault, the signal Reset, start printing; switch output includes protection trip, over-voltage start long jump (open to the line line protection remote transmission), protection signal (protection action signal, abnormal signal and device fault alarm signal, etc.).
3, circuit breaker protection
Each circuit breaker is equipped with a circuit breaker protection device to realize breaker failure protection, automatic reclosing, charging over current protection, dead zone protection and synchronous detection, and no pressure detection. In the design of the line spacing, in order to facilitate the test of the circuit transformer during the line power failure maintenance, the general current transformer is installed close to the line side, and the line circuit breaker is installed close to the bus line side. When a fault occurs between the circuit breaker and the current transformer, the fault point is outside the line protection range within the protection range of the busbar, the busbar protection action, the line protection does not operate, and the fault point is still not removed. This fault is called the line dead zone. Failure, rely on the circuit breaker dead zone protection cut. When the charging overcurrent protection policy is running, it will be out of operation, and only when the power is supplied to the bus or bus line is temporarily put into operation.
The circuit breaker protection analog input includes the power of the circuit breaker and the voltage on both sides of the circuit breaker; the switch input includes the function pressure plate opening, the maintenance platen opening, the phase split trip position opening, the protection phase splitting trip and the three-phase trip input (using In the start failure and reclosing), the lock recloser (operation box TJR contact), the low air pressure lock recloser (the circuit breaker mechanism body is not stored and locked latching reclosing), signal reset, start printing; the switch output includes split phase trip Three-phase tripping (breaker single-set configuration, so split-phase trip and three-phase trip outlet have two groups, corresponding to two coils of the circuit breaker), failure exit (failure to initiate adjacent line protection or component protection), reclosing exit , protection signal (protection action signal, reclosing action signal, abnormal signal, device failure alarm signal, etc.).
4, the operation box
The function of the operation box is to communicate the protection, the connection between the automation device and the circuit breaker, and the rest of the protection and automation devices cooperate to operate the circuit breaker according to the protection action situation and the remote control command in the background, and provide the protection and the required cooperation of other devices. point.
For each circuit breaker of 500kV and above, a circuit breaker with two trip coils and one closing coil shall be equipped to complete the trip and exit of the line and auxiliary protection. Shuangtao protection shall respectively act as a trip coil. .
220kV line protection configuration
1, line protection
The 220kV line protection has more reclosing function modules than the 500kV line protection. The protection configuration is the same as the 500kV line protection. The line protection can be double-set using fiber longitudinal differential protection or high frequency protection, or one set of fiber longitudinal differential protection. One set uses high frequency protection.
The following takes the high-frequency protection of 220kV line as an example to describe the protection analog input, digital input and digital output. The analog input includes line current, line voltage and bus voltage; the switch input includes function pressure plate opening, maintenance platen opening, channel test button, receiving (receiving, transmitting machine receiving output contact), channel abnormal alarm, Other protection stop letters (operation box TJR contact), lock recloser, low air pressure lock reclose, split phase trip position contact, signal reset, start printing; switch output includes split phase trip, three phase trip, reclose, Sending (receiving, sending and receiving of the transmitter is completed by protection), protection signal (protection action signal, reclosing action signal, protection abnormal signal, device alarm signal).
2, circuit breaker protection
The 220kV circuit breaker protects only the malfunction protection and charging over current protection function modules. At present, in the six unified standards, the circuit breaker failure protection device has been eliminated, and the function of failure protection is completed by the mother-to-child protection. Before the introduction of the six unified standards, the circuit breaker failure protection device has one-to-one correspondence failure prevention start-up protection according to the principle of dual configuration, and also has a set of failure protection devices to start two sets of busbar protection.
3, the operation box
As with the 500kV line, each circuit breaker is configured with a two-trip coil and a closing coil scoring phase operation box.
Line protection group screen solution
1.3/2 circuit breaker wiring
(1) Line protection A screen. Line protection device A (including main protection, backup protection) + over voltage and far jump protection device A.
(2) Line protection B screen. Line protection device B (including main protection, backup protection) + over voltage and far jump protection device B.
(3) Circuit breaker protection screen. Circuit breaker protection device (separate by circuit breaker) + phase separation operation box.
The specific group screen scheme is shown in Figure 2-1.
Figure 2-1 Screen diagram of the 500kV line protection group screen.
2. Double busbar wiring
The 220kV line protection has two schemes of two-sided screen and three-sided screen group screen. The difference between them is whether the split-phase operation box is a separate group screen or a double-sided screen.
(1) Two-sided screen scheme.
1) Line protection A screen. Line protection device A + voltage switching box 1 + sub-operation box.
2) Line protection B screen. Line protection device B+ voltage switching box 2.
The specific group screen scheme is shown in Figure 2-2.
(2) Three-sided screen solution
1) Line protection A screen. Line protection device A + voltage switching box 1.
2) Line protection B screen. Line protection device B + voltage switching box 2.
3) Line auxiliary screen. Split phase operation box.
Figure 2-3 shows the specific group screen scheme.
    Figure 2-3 220kV three-sided screen group screen solution.
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