CN206412780U - Metering switching device for large-scale nuclear power plant down-gateway - Google Patents

Abstract

The utility model is related to a kind of off line energy metering switching device of nuclear power station, particularly a kind of off line energy metering switching device of large nuclear power station, include a plurality of generating set outlet breaker auxiliary contacts and plurality of high voltage power distribution equipment breaker auxiliary contact, its structural feature is, also include logic control switching device, the logic control device includes breaker auxiliary contact On-off signal loop, logic control element and switching output loop, wherein a plurality of generating set outlet breaker auxiliary contacts and plurality of high voltage power distribution equipment breaker auxiliary contact are respectively connected to breaker auxiliary contact On-off signal loop, switching output loop is connected to each unit energy metering voltage circuit.Advantage is：Switching circuit is simplified, the application of a large amount of control cables is reduced while reliability is guaranteed.

Description

Metering switching device for large-scale nuclear power plant down-gateway

technical field

The utility model relates to a metering switching device for a gateway of a nuclear power station, in particular to a metering switching device for a gateway of a large nuclear power station.

Background technique

Large-scale nuclear power plants (referring to domestic mainstream units with an installed capacity of 1000 MW and above) send electric energy to the grid (on-grid electricity), while their generator excitation and other equipment also consume electric energy. Generally, the power consumption in the plant accounts for 5~5% of its power generation. 10%. As long as there is one generating set in the power station, the power generated by the unit on the high-voltage bus that is electrically connected to the unit will use the electric energy generated by the unit; on the contrary, if one or several units connected to each other on the high-voltage bus do not When one unit generates electricity, the factory power of the nuclear power unit must obtain power from the grid from the high-voltage power line. This power is called the off-grid electricity of the nuclear power unit, and the corresponding metering point is called the off-grid metering gateway. For nuclear power units of 1000MW and above, the off-grid metering gateway is on the booster transformer side of the unit.

Nuclear power plants need to pay corresponding electricity charges to the grid according to the electricity consumption at the metering gate. Since the electric energy metering device (electric energy meter) at the metering gate cannot distinguish whether the factory electricity is generated by the nuclear power plant itself or the off-grid electricity, it is necessary to configure an automatic switching device to distinguish. The device puts the gate metering device into use when using off-grid electricity, and cuts off the metering device when using the nuclear power plant's own electricity without metering. The final metering device measures all off-grid electricity.

At present, power plants and nuclear power plants generally connect the auxiliary contacts of circuit breakers and relays through control cables according to a certain logic to build automatic switching circuits: the switching circuits need to use auxiliary contacts of generator set outlet circuit breakers and high-voltage power distribution device circuit breakers. Contacts need to be connected in various series and parallel electrical connections in the circuit. In a conventional thermal power plant or a nuclear power plant with less than 4 units, since the distance between the units is not too far, when the cross-section of the control cable used is 4 square millimeters or more, the length of the control cable required for the corresponding control switching analog logic circuit can basically be Meet the requirements such as voltage drop required for switching control.

However, for large-scale nuclear power plants (such as the nuclear power plant currently under construction and planning in Fujian Province), the long-term scale is generally six 1000MW thermal power units, and the switching circuit control cables constructed according to the above principles will need to be very long (up to 7.5km). The resistance of such a long control cable will reach dozens of ohms, and the voltage drop generated by the loop on the cable will reach more than 10%, which will affect the drive of the relay action and reduce the reliability of the correct switching action. Figure 1 shows the electrical main wiring of a large nuclear power plant (six 1000MW units), and Figure 2 shows a schematic diagram of the switching circuit constructed by the downstream gateway metering relay of the large nuclear power plant. In the figure, ZJ1~ZJ6 are relays, others GCB1~GCB6 are auxiliary contacts of 1#~6# generating set outlet circuit breakers; 5011~5063 are auxiliary contacts of high voltage power distribution device circuit breakers; +KM/-KM are control power supplies.

It can be seen from the figure that if unit 1 generates power and unit 6 does not generate power and is connected to unit #1 at the high-voltage bus through the 5002 circuit breaker, then the locking circuit of unit #6 requires GCE1 unit, 5012, 5013, 5002, and 5062 , 5063 and other six circuit breaker auxiliary contacts in series. However, the distance between the units of large nuclear power plants is relatively large, and the distance between the cable trenches from unit 1 to unit #6 of the above-mentioned power plant is nearly 3km. In this way, the above-mentioned series circuit can reach a maximum length of 8.8km (generator auxiliary contact cable core length 2x3km + other five circuit breaker auxiliary contact cable core length 2x5x200m + network control room 800m).

The secondary circuit of the power plant generally adopts DC220V or DC110V. The resistance of intermediate relay ZJ1~ZJ6 is generally about 300 ohms. The resistance of the 8.8km control cable core (4 mm2) is nearly 37.84 ohms, which causes a voltage drop of more than 10%. This will affect the normal action of the relay (on or off), thereby affecting the stability and reliability of the automatic switching circuit, which needs to be improved.

Contents of the invention

The purpose of the utility model is to provide a large-scale nuclear power plant down-gate metering switching device that can ensure the stability and reliability of the automatic switching circuit according to the deficiencies of the prior art.

The purpose of this utility model is achieved by the following approach:

The metering switching device at the gateway of a large nuclear power plant includes a plurality of auxiliary contacts of the generator set outlet circuit breaker and a plurality of auxiliary contacts of the circuit breaker of the high-voltage power distribution device. The key point of its structure is that it also includes a logic control switching device. The logic control device includes There are a circuit breaker auxiliary contact switch input circuit, a logic control unit and a switching output circuit, among which a plurality of generator set outlet circuit breaker auxiliary contacts and a plurality of high-voltage power distribution device circuit breaker auxiliary contacts are respectively connected to the circuit breaker auxiliary contact switch input circuit , switch the output circuit and connect it to the metering voltage circuit at the gate of each unit.

The utility model adopts a logic control switching device to replace the traditional relay, thereby simplifying the switching circuit. The logic control switching device uses the auxiliary contacts of each circuit breaker directly as the switching value of the logic control unit, and the logic control unit constructs the logic control unit according to the switching circuit in the prior art, which can status, it can be judged whether there is a generating set in the nuclear power plant that is generating electricity. , it means that the nuclear power unit is in shutdown state and needs external power supply. Further, according to the input state of the auxiliary contact of the circuit breaker of the high-voltage power distribution device: if there is an input switch, it means it is in the closed state, and if there is no input switch, it means it is in the off state; according to the existing switching circuit logic relationship, it is judged whether the shutdown unit is connected to the nuclear power plant. The other generating units in the system are electrically connected. If there is a connection, the electric energy generated by the generator set will be sent to the shutdown unit. If there is no connection, it will be switched to the metering circuit of the downstream gateway by switching the output circuit. Therefore, the metering switching device for the gateway of the large nuclear power plant described in the utility model effectively simplifies the switching circuit, and the logic control switching device realizes automatic switching of the output contacts, realizes the disconnection of the voltage circuit of the metering device, and thus realizes intelligent switching. The longest control cable of the switching circuit of the device is only 2km, and the voltage drop generated by the circuit on the cable is below 2.5%, which ensures reliability and reduces the application of a large number of control cables.

The utility model can be further specifically described as:

The logic control unit is either a logic control loop or a PLC controller.

Since the logic control unit is constructed based on the principle of the original switching circuit, it can be embodied in the form of a circuit, or a PLC controller can be used. The PLC controller is a conventional commercially available programmable controller. It only needs to use the principle of the original switching circuit to construct a logic judgment process to realize the logic control function described in the utility model, and the PLC control The device is small in size and easy to operate, which can further simplify the switching circuit and improve the reliability of the switching circuit.

To sum up, the utility model provides a large-scale nuclear power plant down-gate metering switching device, which effectively simplifies the switching circuit, and automatically switches the output contacts by the logic control switching device to realize intelligent switching. The longest control cable of the switching output loop is only 2km, the voltage drop of the loop on the cable is below 2.5%, the reliability is guaranteed, and the application of a large number of control cables is also reduced.

Description of drawings

Fig. 1 is the electrical main wiring diagram of the large-scale nuclear power plant described in the background technology;

Fig. 2 is a schematic diagram of the switching circuit constructed by the downstream gateway metering relay of the large-scale nuclear power plant described in the background technology;

Fig. 3 is a schematic diagram of the principle structure of the metering switching device for the gateway of the large-scale nuclear power plant shown in the present invention.

Below in conjunction with embodiment the utility model is described further.

detailed description

Best practice:

Referring to Figure 3, the metering switching device at the gateway of a large nuclear power plant includes a plurality of auxiliary contacts of the outlet circuit breaker of the generating set and a plurality of auxiliary contacts of the circuit breaker of the high-voltage power distribution device, and also includes a logic control switching device. The logic control device includes There are a circuit breaker auxiliary contact switch input circuit, a logic control unit and a switching output circuit, among which a plurality of generator set outlet circuit breaker auxiliary contacts and a plurality of high-voltage power distribution device circuit breaker auxiliary contacts are respectively connected to the circuit breaker auxiliary contact switch input circuit , switch the output circuit and connect it to the metering voltage circuit at the gate of each unit. Wherein the logic control unit is a PLC controller.

The working principle of the metering switching device at the gateway of the large-scale nuclear power plant is as follows, see Figure 3:

1. The auxiliary contacts of each circuit breaker are directly connected to the digital input module of the PLC as a digital value.

2. The programmable logic controller (PLC) judges whether there is a generating set in the nuclear power plant that is generating electricity according to the state of the switched value. If the auxiliary contact switch of GCE1 has an input, it means that the No. 1 nuclear power unit is generating electricity.

3. The programmable logic controller (PLC) intelligently judges the shutdown of a certain generating set in the nuclear power plant according to the status of the connected switch. If there is no input to the auxiliary contact switch of GCE6, it means that the No. 6 nuclear power unit is in a shutdown state and needs external power supply.

4. According to the status of the switch value, it is judged whether the shutdown unit is electrically connected to the generating unit in the nuclear power plant. Taking the shutdown of No. 6 unit as an example, No. 6 unit needs to use factory power. If unit 6 is connected to unit 1 on the high-voltage bus through the circuit breaker, that is, circuit breakers 5011 and 5061 are in the closed position at the same time or circuit breakers 5012, 5013, 5062 and 5063 are in the closed position at the same time, then it is judged that the 6th unit of the shutdown Unit No. 1 is connected to Unit No. 1 on the high-voltage bus.

5. If it is judged that there is a connection, that is, the shutdown unit (No. 6 unit) is using the power generated by the generator set (No. 1 unit) in the station (the Y contact shown in the figure), at this time the switching output circuit is cut off (the PLC output contact is disconnected) and measured The metering circuit of the gateway metering device (N contact shown in the figure). On the contrary, if there is no connection, switch to the metering circuit of the gateway port to use the power of the grid.

The utility model has the advantages of: 1. It improves the reliability of the metering switching circuit at the gateway of the large-scale nuclear power plant: it is guaranteed that as long as there is one generating set in the large-scale nuclear power plant to generate electricity, the set that is electrically connected to the set on the high-voltage bus is used by the factory. At this time, the switching device cuts off the metering circuit of the metering device at the gateway of the metering gateway; on the contrary, if one or more units connected to each other on the high-voltage bus does not generate electricity, then the nuclear power The factory power of the unit obtains the electric energy of the power grid from the high-voltage power line. At this time, the switching device connects the metering circuit of the metering device at the gateway of the metering gateway, and accurately measures the power of the power grid. 2. Reduce a large number of control cables and reduce the overall investment. According to statistics, after adopting the switching device of the above-mentioned logic control, the nuclear power plant of the above-mentioned scale can reduce the control cables by 12km. The comprehensive cost is 20,000 yuan lower than that of the current relay switching device.

The undescribed part of the utility model is the same as the prior art.

Claims (2)

1. The metering switching device at the gateway of a large nuclear power plant includes a plurality of auxiliary contacts of the outlet circuit breaker of the generating set and a plurality of auxiliary contacts of the circuit breaker of the high-voltage power distribution device. It is characterized in that it also includes a logic control switching device. The logic control device It includes a circuit breaker auxiliary contact switch input circuit, a logic control unit and a switching output circuit, in which a plurality of generator set outlet circuit breaker auxiliary contacts and a plurality of high-voltage power distribution device circuit breaker auxiliary contacts are respectively connected to the circuit breaker auxiliary contact switch input The switching output circuit is connected to the metering voltage circuit at the gate of each unit. 2. The metering switching device for the gateway of a large-scale nuclear power plant according to claim 1, wherein the logic control unit is either a logic control loop or a PLC controller.