Preventing relay protection from causing expansion accidents and improving the correct operation rate of protection devices to improve the safe operation level of the power grid.
I. Strengthening the operation and management of relay protection and safety automatic devices The relay protection of power systems is an organic whole. The relay protection profession should implement unified leadership and hierarchical management. Set up relay protection professional institutions in the network bureau, provincial bureau, prefecture (city) power bureau and power plant. The network bureau and the provincial bureau respectively set up the relay protection department as the functional organization of the relay protection technology management, fulfilling the functions of professional management, realizing the professional leadership of the whole network and the province's relay protection, and being responsible for the system under its jurisdiction. The calculation of electric protection and the operation management. The ground (city) power bureau relay protection calculation and technical management, generally located in the dispatching station. Set up a relay protection team at the local (city) power bureau, the maintenance branch of the power plant, or the substation area (the maintenance department) to be responsible for the operation, maintenance and calibration of the relay protection equipment of the whole or the whole plant.
The technical protection of relay protection work is very strong. The problem of one line and one contact may cause a major accident. Therefore, the relay protection organization must be equipped with professional and technical personnel with strong professionalism, careful and meticulous work, and diligent research techniques. The relay protection departments at all levels must establish a post responsibility system to enable each responsibility to be implemented to individuals. Leaders of all units should pay attention to the work of relay protection, enrich the technical strength, mobilize all levels of relay protection staff, and maintain the stability of the relay protection team.
For the fixed value management of relay protection, the system relay protection setting plan should be compiled or revised regularly in conjunction with the development of the power system. The basis for the preparation of the tuning plan: the system operation mode and operating parameters approved by the leader, including the normal and actual possible maintenance operation modes, maximum active and reactive power flow (including the inrush current value if necessary, the self-starting current value of the motor, etc.) , minimum operating voltage, phase sequence components of non-full-phase operating lines, optimal reclosing time, specific requirements for de-listing, etc. The equipment and parameters required for important generators and systems above 110kV must be measured. After the preparation of the tuning plan, it should be fully checked by the person in the relay protection department, and then discussed by the dispatching (value), operation, biotechnology, safety supervision and other departments, and approved by the chief engineer. The original calculation of the calculation shall be organized into a book and kept in a safe place for checking in daily operation or accident handling. The adjustment of the setting value of the site protection device shall be carried out in accordance with the requirements of the protection device setting notice and shall be completed in accordance with the specified date.
For the protection devices in operation, regular inspections shall be carried out in accordance with the relevant regulations. The grassroots bureaus and plant relay protection departments shall reasonably arrange the annual, quarterly and monthly protection devices according to the seasonal characteristics, load conditions and the maintenance of the primary equipment. plan. Regular inspection work should ensure the quality of inspection, master the progress, and complete in time. After the relay protection device is inspected, it shall be clarified to the operating personnel and fill in the relay protection work record. It is strictly forbidden to put unprotected equipment into operation during operation, and the important main protection withdrawal operation must be approved by the chief engineer. When the protection device malfunctions, it shall promptly report to the higher-level relay protection department and the regulatory authority, and retain the original status of the site, and conduct on-site inspection after the accident in time. The inspection project is determined according to the specific situation of the incorrect operation. The inspection work shall be agreed with the higher-level relay protection and safety supervision department, and there shall be a transfer institute and a power test institute to participate in the analysis to find out the causes of incorrect actions and formulate countermeasures. The operation department should strengthen the inspection of equipment in peacetime, and carry out equipment safety inspection and protection transmission test before the peak load comes.
For new construction, relay protection and automatic devices must be put into operation at the same time as the project. After the newly installed protection device is completed, it shall be checked and accepted to prevent incorrect operation or accident due to poor installation and debugging. Within one year after the new installation protection is put into operation, before the secondary circuit is changed, the accident is caused by poor installation and commissioning, and the responsibility is the infrastructure unit. The operating unit shall conduct the first periodic inspection within one year of the investment, and an accident shall occur after the inspection or after one year of operation, and the responsibility shall be the operating unit.
Second, to prevent direct failure of personnel caused by relay protection accidents (a) to prevent accidental touch relays in the relay protection disk before and after the disk should have obvious equipment name number. If there is 2 or more circuit protection devices on a disk, the plate should be painted with obvious dividing lines. There should be sufficient separation distance between the trip platens. The trip platen with too close spacing should try to add an insulating cover to prevent accidental tripping when switching the platen. Transistor protection should also be fitted with a protective platen. It is advisable to make obvious special signs for the lead-out plates, terminals, cable leads, etc. of other devices. Relays that are not likely to trip after being touched should have obvious warnings on their lids and bottom plates. The line grounding test trip button shall be fitted with a cover and there shall be a warning sign on the cover. Marks should be made on the terminals that need to be tested regularly (for example, terminals that periodically test whether the intermediate relay coil is disconnected, etc.) to prevent accidental contact with other terminals. Before the protection device and the standby power supply are automatically reclosed, check whether there is DC positive power supply at the tripping plate terminal, check that the outlet is not in the working state, or check that the starting relay is not in the operating state.
In the field work, the “Safety Regulations for Field Protection of Relay Protection†must be strictly observed. Complete safety technical measures and organizational measures should be done before work, including the isolation of the working part from the live equipment, the specific location of the secondary wiring demolition, the working procedures, the main test wiring, etc., together with the relevant drawings, the relevant staff will discuss, and then Site execution. When working in the secondary circuit with equipment charging, the person in charge of work must write a written work plan and secondary special work ticket for relay protection in advance. There must be special person supervision during the work on site, and work steps or test methods should not be changed at will. Before the work, the on-duty operators are required to make the prescribed safety measures: there should be a “Working here†sign on the work plate or other appropriate place, and the relay protection plate running on both sides of the work plate, there should be a cloth or a partition behind the plate. The board is blocked, there should be a transparent cloth in front of the plate, or a temporary cover, or other obvious warning measures. Relay protection personnel must not modify safety measures at will. When working on the relay protection disk, especially when there are several circuits on a disk and the device is compact, there should be obvious isolation measures for the adjacent relay protector terminal block, such as adding temporary insulation sleeve. , cover or other protective measures to prevent accidental accidental tripping with a screwdriver, pliers, wrench, etc. In order to drill holes and drill holes on the running relay protection disk, and can not power off, only the electric working age can be used and anti-seismic measures are taken. Special attention should be paid to relays that operate instantaneously, such as zero-sequence currents, current-balanced relays, etc. It is generally necessary to disable protection before it can work.
The full-time or part-time technical personnel of relay protection shall, when the new equipment is put into production, introduce the operating principle and precautions in operation to the duty officer and strengthen the technical training for the relevant personnel.
(2) Preventing accidental verification of relay protection It is necessary to strictly implement the “Regulations on the Verification of Relay Protection Devices and Systems Automatic Devices†or the implementation rules of the on-site inspection regulations formulated in accordance with the ministerial regulations. All units must use a unified relay protection test procedure, a unified test method and quality requirements, and can not be used for each person. For all kinds of protection devices, there should be a set of test record forms including all the inspection items specified in the inspection regulations. The format should be concise and clear, and easy to check.
The instrument for relay protection test must be checked regularly to ensure compliance with the standard. The polarity meter should prove that its polarity indication is correct before use. The name and number of the instrument used in this test should be recorded in the relay protection test. . The staff must work on the secondary circuit, and must take the drawings and check the work before they start working to prevent the work by memory. If the instrument staff is working in the utility circuit of the instrument and relay protection, the instrument work should be carried out after the relay protection personnel do measures to prevent the relay protection from malfunctioning. When the test requires the DC power supply to be cut off, it is better to cut off the positive and negative power supplies at the same time. If there is no such device, the positive power supply should be disconnected first, then the negative power supply should be disconnected; when recovering, the negative power supply should be given first, then the positive power supply. Prevent accidents caused by parasitic backlash.
The test shall be carried out item by item, and the test item shall be recorded immediately in the test record form. At the end of the work, the test record should be collected and the test data must be completed before leaving the site. The test report should be written in time and reviewed. Through the whole set of transmission test, the operation of each component of the protection device is checked. The whole set of simulation test (including the transmission switch) must simulate the actual situation of the device according to the schematic diagram, according to the test procedure, operation rules, setting requirements and related drawings. Etc. Prepare the entire group of trials. When carrying out load inspection on relays with AC voltage and AC current loops, the current and voltage loops should be prevented from mixing, causing short circuit of the voltage loop and large current flowing through the zero sequence current loop, resulting in incorrect operation of the zero sequence protection. Strengthen the inspection and adjustment of the mechanical part of the relay, improve the quality of the mechanical part of the relay, overcome the tendency of only paying attention to the electrical test and ignoring the adjustment of the mechanical part. Regularly check the setting value of the AC relay. It is advisable to connect the test power supply to the terminal block of the protection disk. Check the original value first. If there is a big difference from the previous test value, you must find out the cause and adjust it to avoid the test wiring. Improper misunderstanding.
(3) Preventing the relay protection from misaligning the newly installed relay protection and the setting value of the automatic device, or when the system needs to change the relay protection and the automatic device setting value, the person responsible for the setting shall calculate according to the relevant data, and another Audited by a professional accountant. An approved setting is required for both new adjustments and changes. When performing the tuning calculation, attention should be paid to the sensitivity of each component, such as the grounding direction component, the oscillating blocking component, the negative sequence voltage blocking component, and the minimum precise operating current of the distance component. When setting the quick-break protection of the line, pay attention to the cooperation with the characteristics of the fuse fuse on the line. In the protection setting of the standby power automatic closing device, it should be considered to prevent malfunction due to the influence of the automatic starting current and the non-periodic component, and malfunction due to the inrush current of the transformer, and the stepping trip due to the permanent failure. After the preparation of the relay protection setting plan, relevant operational departments should be organized for discussion and review. The main content of the review is the sensitivity and possible consequences of the relay protection device, the cooperation with the regional system and the plant power system. Regularly prepare the system relay protection setting plan. When there is a major change in the maximum and minimum operating mode load currents, a comprehensive review is required for the tuning plan. For those who need to change the protection setting value as the operation mode changes, it is necessary to be programmed into the “Registration Operation Procedure for Relay Protectionâ€, and each setting value should be clearly marked and submitted to the duty personnel in detail.
The relay protection test personnel must carry out the adjustment test according to the requirements in the setting book, and repeatedly check whether the rheological and compressive transformation ratio is consistent with the setting book. If in doubt, it must be inquired to the tuning unit, and it must not be ambiguous. Regardless of the permanent or temporary change of the relay protection and the setting value of the automatic device, it must be part of the system operation. There must be a dispatch order or the permission of the dispatcher on duty, and there must be a written record after execution. The dispatching room and the control room of the factory and the factory shall have the current setting book, and the operation drawing board reflecting the setting value of the relay protection, and keep the setting value of the drawing board consistent with the actual situation at any time. The factory, the relay protection special value personnel and the operation duty personnel should regularly check the calibration order of the unit, the setting record and the scale value of the protection device, so that the three are consistent. Expired orders must be properly disposed of in a timely manner. The unit that operates and maintains the protection device must communicate with each other. If there are changes in equipment parameters (such as rheology, pressure change, etc.), the unit of calculation must be notified in advance.
(4) Prevent miswiring Before construction, organize the construction personnel to learn the wiring diagram, expansion diagram and terminal wiring diagram. If the project is reconstructed, the original drawings should be learned and checked with the on-site wiring. To change the wiring of the secondary circuit, it is necessary to have the approved construction drawing (or the transaction application form), and strictly follow the construction of the figure. When disassembling the wiring, check with the original drawing first. After the wiring is changed, check with the new drawing. After the simulation test must be done. Replace the relay protection components, or due to the test requirements, because the exchange switch, switch auxiliary contacts, current and voltage transformers, etc. should be temporarily disconnected from the secondary circuit line head, although the wiring is not changed, the drawings should be accompanied by the work and checked with the field wiring. Nothing wrong. Before the disconnection, the corresponding terminals should be recorded. After the wiring, check whether the matching is consistent. The connection and disconnection should be carried out under the supervision of a special person. If there is any doubt in the restoration of the wiring, a load test must be performed to confirm that the wiring is correct. When the new equipment is put into operation, the positive and negative fuses should be removed, the switches should be opened and closed, and the circuit operation of the lock (such as air pressure lock) should be simulated to check whether there is a parasitic circuit. Newly installed relay protection or change the connection of the secondary circuit wiring. After the work is completed, it must be tested to prove that there is no error in the wiring (such as hexagonal diagram, differential flow differential pressure, etc.) before it can be put into operation. The measured differential current differential pressure shall be converted to the value at the rated load current and within the allowable range of the procedure. Wiring on the relay protection panel should have a clear terminal number, and the terminal number must match the design drawing. Various measures must be taken to eliminate the parasitic loop; the signal loop must be strictly separated from the protection loop; a separate fuse should be used in each switch (including the operating loop, protection and automatic devices) to ensure that the fuse is disconnected. There is no stringing phenomenon in its circuit. The protection devices acting on several switches (such as bus differential, transformer differential, etc.) should be obtained from independent insurance. The DC power supply for each switch should be taken from each switch's own DC power supply. The DC power supply acts as a common DC power source to prevent malfunction or rejection. Do not operate more than two switches or connect two different circuits when using a pair of contacts or a platen. The DC link insulation monitoring device should be put into operation to prevent the two points of DC from being grounded and the protection to malfunction. It is not allowed to simply use the bulb as a monitoring device to prevent two-point grounding caused by the grounding of the low internal resistance monitoring device itself when the DC link is grounded.
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