In addition to the above protection function, each microcomputer protection measurement and control device has RS485 communication interface, realize the communication with the power monitoring system, realizes the independent operation circuit monitoring function, realize the switch status, and the switch circuit monitoring is more complete; built-in hop function, users can choose whether to invest. The newly configured microcomputer protection measurement and control device AM5SE series protection function is rich, and each menu can be freely set in Chinese or English, conducive to operation and maintenance.

5. Design of 10kV plant

        The newly configured AM5SE series computer integrated protection measurement and control device and drawings are designed by Acrel Co., LTD. The schematic design of the secondary circuit must be based on the original 10kV high voltage cabinet secondary drawings. The terminal row layout is based on the drawing design, and the drawing design must meet the requirements of relevant regulations. For the drawing design with the same load nature, the terminal number and line number are highly uniform and have certain rules. The accuracy of the drawing design determines whether the construction and commissioning is smooth and the safe production after operation.

6. Power protection and transformation process of 6 10kV plant

        The 10kV plant must meet the construction conditions: detailed construction plan and drawings; equipment managers shall complete the acceptance of new equipment; construction personnel to complete the safety education; and complete tools and materials. Construction is carried out in strict accordance with the scheme and drawings, to ensure the smooth completion of each link.

6.1 10kV plant power protection hardware transformation

        The renovation construction of 10kV plant mainly has three links: the replacement of the terminal row in the switch cabinet, the removal of the old comprehensive protection measurement and control device, and the installation and assembly line and cable arrangement of the new comprehensive protection device.

6.1.1. Replace the terminal row

        Terminal replacement needs to be replaced one by one, to replace one terminal; forbidden to replace two or more terminals at the same time to prevent misconnection, cause miswiring, replace the terminal row in a switch cabinet alone, and effectively prevent miswiring; AC power supply, DC power supply, trip circuit, signal circuit to add isolation, should be isolated to prevent the short connection between the terminals should be pressed without loosening. To replace the terminal row, to ensure that the original loop terminal and line number remain unchanged, and the next step of wiring and line check work can be carried out smoothly.

6.1.2 Demolition of the old comprehensive protection measurement and control device

        According to the construction plan and drawings, remove the components to be abolished, including the old integrated protection measurement and control devices, intermediate relays in the switchgear, voltage relays, time relays and other components, and related secondary cables. When dismantling, pay attention to prevent artificial damage to components and mistakenly remove useful secondary cables. Organize and abolish the components and classify, specify local storage, to prevent the work site chaos, the construction site should meet the 6S requirements.

6.1.3 Installation and assembly line and cable arrangement of comprehensive protection measurement and control device

        Due to the different sizes of new and old comprehensive protection measurement and control devices, the size of the installation window on the switch cabinet panel does not meet the size of the new comprehensive protection measurement and control device. The installation window on the switch cabinet panel must be cut and expanded to install the new comprehensive protection measurement and control device and prevent the scraping panel when cutting. The cable connected to the new device shall be a new cable, and all the unused cables shall be removed to prevent the existence of a parasitic circuit. The wiring shall be conducted in strict accordance with the design drawings to prevent leakage, misconnection and misswitching. The cable wiring of the new device should be neat, unified, reasonable wiring, convenient for inspection and maintenance.

6.2 Power protection and commissioning of 10 k V plant

        Protection and debugging are mainly divided into four links: secondary loop line check, loop function verification, static debugging of the protection device and transmission test. Carefully check each terminal and each line number according to the construction drawings. Focus on checking the CT secondary circuit without open circuit, PT secondary circuit, polarity and wiring should be correct; check the telemetry, remote communication, remote control wiring should be correct; check the DC control circuit without short circuit, no short circuit between ground circuit LN; measure the DC control circuit insulation resistance meets the requirements (1000V); measure whether the AC / DC circuit with electricity. It is worth noting that, because the outsourcing unit is not familiar with the secondary circuit of the factory, it is easy to miss and misconnect in the transformation process.

        The AC voltage and DC control loops are powered on to verify the functions of each loop. Check that the telemetry, remote signaling, and remote control signals are correct, the meters, indicator lights, lighting, and heater circuits are normal; the anti-jump function of the switch body is correct. Power on the control loop to further verify that the wiring of each loop is correct.

        The static debugging of the protection device is to carry out the sampling inspection of the device, the uploading and checking of the fixed value, and the function inspection of the device. Check the line protection device AM5SE-F, transformer protection device AM5SE-T, motor protection device AM5SE-M, standby self-switching device AM5SE-B, and PT monitoring by means of applying current on the CT secondary side and applying voltage analog to the PT cabinet terminal. The device AM5SE-UB, voltmeter, ammeter, and monitoring system are displayed correctly, and the phase sequence and phase of the AC voltage and AC current loop are verified to be correct. Set the fixed value according to the fixed value single-pair protection device and check it to ensure that the fixed value is correct. The protection function inspection is to verify the correctness of the action logic and action time of the AM5SE series microcomputer protection measurement and control device by adding analog quantity, there will be no rejection and malfunction, and the action time should meet the requirements. The static debugging of the protection device ensures that the protection device can respond sensitively to faults, and send out alarm signals and trip instructions reliably and quickly.

        The data connection between the comprehensive protection measurement and control device and the power monitoring system is correct, and the operation status, setting value, event record and other information on the protection device can be collected in real time in the background. The protection device is connected to the background, which improves the management of the relay protection system and the automation level of fault information processing.

        The transmission test is to simulate the amount of fault collected by the protection device, and the protection device should exit the trip switch to verify the correctness of the device protection logic, trip circuit and signal circuit; and to verify that the switch can be properly opened and closed remotely through the operation of the host computer. A complete transmission test should be done for each set of protection devices to ensure that the protection logic of each switch cabinet protection device, the protection outlet tripping, the remote opening and closing switch, and the correct signal indication.

6.3 Problems encountered in the transformation and optimization

        After the transformation of the new comprehensive protection measurement and control device was completed, during the transmission test, it was found that the switch could only be closed once. If it was closed again, it could only be closed after restarting the control power supply. Through analysis, it is found that there is no normally closed point in the closing coil of the circuit breaker. Since the closing relay is set in the protection device to ensure that the circuit breaker can be closed reliably, at this time, since there is no normally closed point in the closing coil of the circuit breaker, after closing If there is no breakpoint, the energy of the closing and holding relay cannot be released, so it needs to be restarted and the closing and holding relay can be released before the next closing. After many times of communication with the circuit breaker manufacturer and the relevant personnel of the hydropower station, a set of normally closed points are connected in series before the closing coil, thus solving the above problems. Taking the AM5SE-T transformer protection measurement and control device as an example, the secondary diagram of the opening and closing circuit of the hydropower station reconstruction is shown in Figure 2.