Some standard content:
National Standard of the People's Republic of China
Code for design of installation of shunt capacitorsGB50227—95
Editor: Ministry of Electric Power Industry of the People's Republic of ChinaApproval: Ministry of Construction of the People's Republic of ChinaEffective Date: July 1, 1996
GB50227--95
1.0.1This code is formulated to implement the technical and economic policies of the state in the design of shunt capacitors for power projects, and to ensure safety, reliability, advanced technology, economic rationality and convenient operation and maintenance. 1.0.2This code is applicable to the design of new and expanded projects of three-phase AC high-voltage and low-voltage shunt capacitors for reactive power compensation in substations and distribution stations of 220kV and below.
1.0.3The design of shunt capacitors should determine the compensation capacity, select wiring, protection and control, layout and installation methods based on the grid conditions, compensation requirements, environmental conditions, operation and maintenance requirements and practical experience at the installation site. 1.0.4 The equipment selection of shunt capacitor installation shall comply with the provisions of the current national product standards. 1.0.5 The design of shunt capacitor installation. In addition to the provisions of this specification, it shall also comply with the provisions of the relevant national standards and specifications.
2 Terms, symbols, and codes
2.1 Terms
2.1.1 Installation of high voltage shunt capacitors Installation of high voltage shunt capacitors A device consisting of high voltage shunt capacitors and corresponding primary and secondary supporting equipment, which can be operated independently or in parallel. 2.1.2 Installation of low voltage shunt capacitors Installation of low voltage shunt capacitors A device consisting of low voltage shunt capacitors and corresponding primary and secondary supporting equipment, which can be operated independently or in parallel. 2.1.3 Complete set of installation for shunt capacitors A complete set of shunt capacitors designed and assembled by the manufacturer and supplied to the user. 2.1.4 Single capacitor unit An assembly consisting of one or more capacitor elements assembled in a single housing and having lead terminals. 2.1.5 Capacitor bank A group of single capacitors electrically connected together. 2.1.6 Reactance ratio The ratio of the inductive reactance of the parallel reactor to the capacitive reactance of the parallel capacitor group, expressed as a percentage. 2.1.7 Discharge device, discharge component A device or component installed inside or outside the capacitor that can reduce the voltage between the capacitor terminals to a specified value within a specified time after the capacitor is disconnected from the power supply.
2.1.8 Series section
In a combination of multiple capacitors, a group of single capacitors connected in parallel. 2.1.9 Residual voltage The voltage remaining between the capacitor terminals or between the capacitor group terminals after a single capacitor or capacitor group is disconnected from the power supply. 2.1.10 Inrush transient current The transient overcurrent when a capacitor group is connected to the power grid. 2.1.11 External fuses are installed outside a single capacitor and connected in series with it. When a capacitor fails, the fuse of the capacitor is cut off. 2. 1.12 Internal fuses are installed inside a single capacitor and connected in series with a component or component group. When a component fails, the fuse of the component or component group is cut off.
2.1.13 Discharging capacity The capacity of the capacitor group that the discharger allows to be connected. 2.1. 14 Unbalance protection GB 50227—95
Protection formed by the current difference or voltage difference formed by the difference in capacitance between two related parts in the capacitor group. 2.2 Symbols
2.3 Codes
1C, 2C, 3C
Ci, Ca.C.
Occurrence n Capacitor capacity of subharmonic resonance Short-circuit capacity of busbar at the installation location of parallel capacitor device Harmonic order
Reactance
Per-unit value of inrush current peak
Capacitor bank
Parallel capacitor device grouping circuit number
Single capacitor number
Shenlian reactor or current limiting coil
Isolating switch or knife switch
Circuit breaker
Earthing switch
Current transformer
Discharger, discharge element
3 Basic requirements for grid access
Electromagnetic influence coefficient taken into account in inrush current calculation Capacitor bank capacity
Capacitor terminal operating voltage
Bus voltage of parallel capacitor device
Number of connected sections per phase of capacitor bank
Arrester
Fuse
AC contactor
Thermal relay
Indicator light
Open triangle voltage
Phase unbalanced voltage
Bridge differential current
Neutral point unbalanced current
3.0.1 The design of high-voltage parallel capacitor device connected to the power grid should determine the optimal compensation capacity and distribution method according to the principles of comprehensive planning, reasonable layout, hierarchical compensation and local balance.
3.0.2 The installed capacity of capacitors in substations should be calculated and determined according to the reactive power planning of the local power grid and the provisions of the current national standards "Technical Guidelines for Voltage and Reactive Power of Power Systems" and "National Power Supply and Use Rules". When the design calculation conditions are not met, the installed capacity of capacitors can be determined according to 10% to 30% of the transformer capacity. 3.0.3 The grouping capacity of capacitors shall be determined according to the principle of increasing the capacity of a single group and reducing the number of groups. When the grouping capacitors are operated in various capacity combinations, resonance shall not occur, and the voltage content of any harmonic of the busbars on each side of the transformer shall not exceed the relevant provisions of the current national standard "Power Quality-Public Grid Harmonics". The capacity of the resonant capacitor can be calculated as follows: Qex = S.
Where Qex is the capacity of the capacitor with nth harmonic resonance (Mvar); Sa is the busbar short-circuit capacity (MVA) at the installation point of the parallel capacitor device, the harmonic number, that is, the ratio of the harmonic frequency to the fundamental frequency of the power grid, and K is the reactance ratio.
GB50227-95
3.0.4 The high-voltage parallel capacitor device shall be installed on the main load side of the transformer. When conditions are not met, it can be installed on the low-voltage side of the three-winding transformer.
3.0.5 When there is no high-voltage load in the distribution station, the parallel capacitor device shall not be installed on the high-voltage side. 3.0.6 The installation location and installed capacity of the low-voltage parallel capacitor device should be based on the original toilet installation quantity of decentralized compensation and line loss reduction. The power factor after compensation should comply with the provisions of the current national standard "National Power Supply and Use Rules". 4 Electrical wiring
4.1 Wiring method
4.1.1 For high-voltage parallel capacitor devices, when there is no power supply line or there is a power supply line on the same voltage bus, each group circuit can be directly connected to the bus and connected to the transformer through the main circuit (Figure A.0.1-1 and Figure A.0.1-2). When there is a power supply line on the same voltage bus, the wiring method of the dedicated bus for capacitors can be set when it is technically and economically reasonable (Figure A.0.1-3). 4.1.2 The wiring method of the high-voltage capacitor group shall comply with the following provisions: 4.1.2.1 The capacitor group should adopt single star wiring or double star wiring. In a power grid with a non-directly grounded neutral point, the neutral point of the star-connected capacitor group should not be grounded.
4.1.2.2 When each phase or each bridge arm of the capacitor bank is composed of multiple capacitors in series, the wiring method of first parallel connection and then series connection should be adopted. 4.1.3 Low-voltage capacitors or capacitor banks can be connected in a delta connection or a star connection with an ungrounded neutral point. 4.2 Supporting equipment and its connection
4.2.1 The grouping circuit of the high-voltage parallel capacitor device can be connected in a way that the high-voltage capacitor bank is connected to the supporting equipment (Figure A.0.2), and install the following supporting equipment:
(1) Isolating switch, circuit breaker or drop-out fuse. (2) Series reactor.
(3) Lightning arrester for operating overvoltage protection. (4) Fuse for single capacitor protection. (5) Discharger and grounding switch.
(6) Primary equipment and secondary equipment for relay protection, control, signal and electrical measurement. 4.2.2 The wiring of low-voltage parallel capacitor device (Figure A.0.3) should be equipped with the following supporting components; when the AC contactor used has the function of limiting inrush current and the capacitor cabinet has harmonic over-value protection, the corresponding current limiting coil and thermal relay may not be installed. (1) Main circuit knife switch and sub-circuit AC contactor or other components with the same function. (2) Lightning arrester for operating overvoltage protection. (3) Fuse for short-circuit protection.
(4) Thermal relay for overload protection.
（5）Current limiting coil for limiting inrush current.
（6）Discharge device.
（7）Hydronic content over-limit protection, automatic switching controller, protection elements, signal and measuring meters and other supporting devices. 4.2.3 The Shenlian reactor should be installed on the neutral point side of the capacitor bank. When installed on the power supply side of the capacitor bank, the dynamic stability current and thermal stability current should be verified.
4.2.4 When the capacitor is equipped with a fuse, each capacitor should be equipped with a spray-type fuse; it is strictly prohibited to share a spray-type fuse for multiple capacitors.
4.2.5 When the shell of the capacitor is directly grounded, the fuse should be connected to the power supply side of the capacitor. When the capacitor is installed on an insulating frame (stand) and the number of series sections is two or more, at least one series section of the fuse should be connected to the power supply side of the capacitor.
4.2.6 The capacitor bank should be equipped with a discharger or discharge element. 884
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4.2.7 The discharger should be connected in parallel with the capacitor bank. When the discharger adopts star connection, the neutral point should not be grounded. 4.2.8 The external discharge device installed on the low-voltage capacitor bank can adopt delta connection or ungrounded star connection and be directly connected to the capacitor.
4.2.9 The power supply side and neutral point side of the high-voltage capacitor bank should be equipped with maintenance grounding switches. 4.2.10 The operation overvoltage protection and lightning arrester wiring method of the high-voltage parallel capacitor device should comply with the following provisions: 4.2.10.1 The group circuit of the high-voltage parallel capacitor device should be equipped with operation overvoltage protection. 4.2.10.2 When the circuit breaker only has a single-phase heavy breakdown, the neutral point lightning arrester wiring method (Figure A.0.4-1) or the relative ground lightning arrester wiring method (Figure A.0.4-2) can be used. 4.2.10.3 When the probability of two-phase heavy breakdown of the circuit breaker is extremely low, two-phase heavy breakdown fault protection may not be set. When it is necessary to limit the overvoltage between the capacitor and the power supply side to the ground, the protection method shall comply with the following provisions: (1) When the reactance rate is 12% or above, the method of connecting the arrester in parallel with the reactor and the neutral point arrester can be adopted (Figure A.0.4-3).
(2) When the reactance rate is not more than 1%, the method of connecting the arrester in parallel with the capacitor bank and the neutral point arrester can be adopted (Figure A.0. 4-4).
(3) When the reactance rate is 4.5% to 6%, the arrester wiring method should be determined by simulation calculation. 5 Selection of electrical appliances and conductors
5.1 General provisions
5.1.1 The equipment selection of parallel capacitor devices should be selected according to the following conditions: (1) Grid voltage and capacitor operating conditions. (2) Grid harmonic level.
(3) Busbar short-circuit current.
(4) The boosting effect of capacitors on short-circuit current. (5) Compensation capacity and expansion planning, wiring, protection and capacitor bank switching methods. (6) Environmental conditions such as altitude, temperature, humidity, dirt and ground sac intensity. (7) Layout and installation methods.
(8) Product technical conditions and product standards. 5.1.2 The selection of electrical appliances and conductors for parallel capacitor devices shall meet the requirements of normal operation, overvoltage conditions and short-circuit faults under local environmental conditions.
5.1.3 The steady-state overcurrent of electrical appliances and conductors in the total circuit and group circuit of the parallel capacitor device shall be 1.35 times the rated current of the capacitor bank.
5.1.4 The external insulation coordination of high-voltage parallel capacitor devices shall be consistent with other electrical equipment of the same voltage level in substations and distribution stations. 5.1.5 The combined structure of the parallel capacitor complete set shall be convenient for transportation and on-site installation. 5.2 Capacitors
5.2.1 The selection of capacitors shall comply with the following provisions: 5.2.1.1 Single capacitors, collective capacitors and single capacitors with a capacity of 500kvar or more can be selected to form capacitor banks. 5.2.1.2 Capacitors installed in severe cold, high altitude, humid tropical areas and polluted, flammable and explosive environments shall meet special requirements. 5.2.1.3 Capacitors installed indoors should preferably use capacitors with flame-retardant dielectrics. 5.2.1.4 Capacitor banks with two sections in series installed on the same insulating frame (station) should preferably use single-tube capacitors. 5.2.2 The selection of capacitor rated voltage shall comply with the following requirements: 5.2.2.1 The operating voltage at the point where the capacitor is connected to the power grid shall be taken into account. 5.2.2.2 The long-term power frequency overvoltage that the capacitor withstands during operation shall not be greater than 1.1 times the rated voltage of the capacitor. 885
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5.2.2.3 The operating voltage rise of the capacitor caused by the series reactor should be taken into account, and the voltage rise value is calculated as follows: U
V3s'i-K
Where U. Capacitor terminal operating voltage (kV); U. Bus voltage of a parallel capacitor (kV) S The number of series sections per phase of the capacitor group.
5.2.2.4 The capacity of the capacitor should be fully utilized and safety should be ensured. 5.2.3 The insulation level of the capacitor should be selected according to the requirements of the place where the capacitor is connected to the power grid. 5.2.4 The overvoltage value and overcurrent value of the capacitor should comply with the provisions of the current national product standards. (5.2.2)
5.2.5 The selection of the rated capacity of a single capacitor should be determined according to the design capacity of the capacitor group and the number of capacitors in parallel per phase, and it is advisable to select from the priority values of the rated capacity series of the capacitor product. 5.2.6 Self-healing capacitors are suitable for low-voltage capacitors. 5.3 Circuit Breakers
5.3.1 The selection of circuit breakers for high-voltage parallel capacitor devices shall not only comply with the relevant standards for circuit breakers, but also comply with the following provisions: 5.3.1.1 When closing, the contact bounce time should not be greater than 2ms, and there should not be too long pre-breakdown; the closing pre-breakdown time of a 10kV low-oil circuit breaker shall not exceed 3.5ms.
5.3.1.2 There should be no heavy breakdown when breaking.
5.3.1.3 It should be able to withstand the combined effect of closing surge current, power frequency short-circuit current and capacitor commercial frequency surge current. 5.3.1.4 Circuit breakers that are switched on and off more than three times a day should have the performance of frequent operation. 5.3.2 The circuit breaker in the main circuit of the high-voltage parallel capacitor device should have the ability to cut off all connected capacitor banks and break the short-circuit current of the main circuit. When conditions permit, the circuit breaker of the group circuit can use a switch device that does not bear the short-circuit current. 5.3.3 The connection and breaking capacity and short-circuit strength of the switch for switching low-voltage capacitors shall meet the use conditions of the installation point. When the capacitor is cut off, no heavy breakdown should occur, and it should have the performance of frequent operation. 5.4 Fuse
5.4.1 The fuse used for capacitor protection should be a spray-type fuse. 5.4.2 The time-current characteristic curve of the fuse should be selected on the left side of the 10% burst probability curve of the protected capacitor shell. The deviation of the time-current characteristic curve shall comply with the relevant provisions of the current national standard "Technical Conditions for Ordering Fuses for Single Protection of High-voltage Shunt Capacitors".
5.4.3 The rated current of the fuse to be blown should not be less than 1.43 times the rated current of the capacitor, and should not be greater than 1.55 times the rated current.
The rated voltage, withstand voltage, breaking performance, fusing characteristics, current resistance, mechanical properties and electrical life of the fuse selected in the design shall all comply with the provisions of the current national standard "Technical Conditions for Ordering Fuses for Single Protection of High-voltage Shunt Capacitors". 5.5 Series Reactor
5.5.1 For the selection of series reactors, dry-type air-core reactors or oil-immersed iron-core reactors should be used, and the selection should be based on technical and economic comparisons. 5.5.2 The reactance ratio of the series reactor should comply with the following provisions: 5.5.2.1 When used only to limit inrush current, the reactance ratio should be 0.1%~~1% 5.5.2.2 For harmonic suppression, when the background harmonics at the place where the shunt capacitor device is connected to the power grid are 5th or above, 4.5%~6%When the background harmonics at the place where the shunt capacitor device is connected to the power grid are 3rd and above, 12% is appropriate. Alternatively, two reactance rates of 4.5%~6% and 12% can be used.
5.5.3The closing inrush current limit of the shunt capacitor device should be 20 times the rated current of the capacitor bank; when it exceeds, a series reactor should be installed to limit it. The calculation of the inrush current when the capacitor bank is put into the power grid shall comply with the provisions of Appendix B of this specification. 5.5.4The rated voltage and insulation level of the series reactor shall comply with the requirements of the grid voltage and installation method at the access point. 5.5.5The rated current of the shunt reactor shall not be less than the rated current of the connected capacitor bank, and its allowable overcurrent value shall not be less than the maximum overcurrent value of the capacitor bank.
GB50227-95
5.5.6When a current limiting reactor is installed in the transformer circuit, its influence on the capacitor group circuit and the effect of raising the bus voltage should be taken into account. 5.6 Discharger
5.6.1 When a voltage transformer is used as a discharger, a fully insulated product should be used, and its technical characteristics should comply with the provisions of the discharger. 5.6.2 The insulation level of the discharger should be consistent with the insulation level of the power grid at the access point. The rated terminal voltage of the discharger should match the rated voltage of the capacitor connected in parallel.
5.6.3 The discharge performance of the discharger should be able to meet the requirement that after the capacitor bank is disconnected from the power supply, the residual voltage on the capacitor bank will be reduced to 50V or less within 5s.
5.6.4 When the discharger is equipped with a secondary line diagram and used for protection and measurement, it should meet the requirements of secondary load and voltage ratio error. 5.7 Lightning Arrester
5.7.1 When the lightning arrester is used to limit the operational overvoltage protection of parallel capacitor devices, a gapless metal oxide arrester should be selected. 5.7.2 The number of arresters connected in parallel with capacitor banks, arresters connected in parallel with series reactors, and neutral point arresters shall be determined by simulation calculation based on the specific conditions of the engineering design. 5.8 Conductors and others
5.8.1 The connection line from a single capacitor to the busbar or fuse shall be a soft conductor, and its long-term allowable current shall not be less than 1.5 times the rated current of the single capacitor.
5.8.2 The conductor cross-section of the busbar and the voltage-equalizing line of the capacitor bank shall be consistent with the conductor surface of the grouping circuit. 5.8.3 The long-term allowable current of the neutral point connection line of the double star capacitor bank and the bridge connection line of the bridge-connected capacitor bank shall not be less than the rated current of the capacitor bank.
5.8.4 All connecting conductors of the parallel capacitor device shall meet the requirements of dynamic stability and thermal stability. 5.8.5 The support insulators used for high-voltage parallel capacitor devices shall be selected and calibrated according to technical conditions such as voltage level, leakage distance, and mechanical load.
5.8.6 The current transformer used for unbalanced protection of high-voltage capacitor banks shall meet the following requirements: 5.8.6.1 The rated voltage shall be selected according to the grid voltage at the connection point. 5.8.6.2 The rated current shall not be less than the maximum steady-state unbalanced current. 5.8.6.3 It shall be able to withstand short-circuit current and high-frequency surge current under fault conditions. And protective measures such as installation of intermittent or lightning arresters shall be adopted.
5.8-6.4 The accuracy level can be determined according to the requirements of relay protection. 5.8.7 The voltage transformer used for unbalanced protection of high-voltage capacitor banks shall meet the following requirements: 5.8.7.1 The insulation level shall be selected according to the grid voltage at the connection point. 5.8.7.2 The rated voltage shall not be lower than the maximum unbalanced voltage. 5.8.7.3 When the secondary line is used as the discharge circuit of the capacitor, the discharge capacity requirements shall be met. 5. 8.7.4 The accuracy level can be determined according to the voltage measurement requirements. 6 Protection devices and switching capacity
6.1 Protection devices
6.1.1 Capacitor fault protection methods should be configured according to local practical experience. 6.1.2 Capacitor banks should be equipped with unbalanced protection and should comply with the following provisions: 6.1.2.1 For single star-connected capacitor banks, open triangle voltage protection can be used (Figure A.0.5-1). 6.1.2.2 For single star-connected capacitor banks with two or more series sections, voltage differential protection can be used (Figure A.0.5-2). 6.1.2.3 For single star-connected capacitor banks that can be connected into four bridge arms per phase, bridge differential current protection can be used (Figure A, 0.5-3). 6.1.2.4 For double star-connected capacitor banks, neutral point unbalanced current protection can be used (Figure A.0.5-4). 887
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For capacitor banks with external fuse protection, the unbalanced protection shall be set according to the permissible overvoltage value of a single capacitor. For capacitor banks with internal fuse protection and no fuse protection, the unbalanced protection shall be set according to the permissible overvoltage value of the internal components of the capacitor. 6.1.3 High-voltage parallel capacitor devices can be equipped with quick-break protection and overcurrent protection with short delay, and the protection action is tripping. The action current value of the quick-break protection, under the minimum operating mode, when a two-phase short circuit occurs in the end leads of the capacitor bank, the protection coefficient shall meet the requirements: the action time limit shall be greater than the capacitor combination gate inrush time. The action current of the overcurrent protection device shall be set to be greater than the long-term maximum overcurrent allowed by the capacitor bank. 6.1.4 High-voltage parallel capacitor devices should be equipped with overload protection, with time limit action on signal or tripping. 6.1.5 High-voltage parallel capacitor devices should be equipped with busbar overvoltage protection, with time limit action on signal or tripping. 6.1.6 High-voltage shunt capacitor devices should be equipped with busbar undervoltage protection and time-limited tripping action. 6.1.7 Oil-immersed iron core series reactors with a capacity of 0.18MVA and above should be equipped with gas protection. Light gas action is on signal, and heavy gas action is on tripping.
6.1.8 Low-voltage shunt capacitor devices should have short-circuit protection, overvoltage protection, undervoltage protection, and should have overload protection or harmonic over-value protection.
6.2 Switching device
6.2.1 High-voltage shunt capacitor devices can choose automatic switching or manual switching according to their role in the power grid, equipment conditions and operating experience, and should comply with the following regulations:
6.2.1.1 Shunt capacitor devices that also serve as power grid voltage regulation can use automatic switching according to the combination of voltage, reactive power and time. 6.2.1.2 When the main transformer of the substation is equipped with an on-load voltage regulating device, automatic switching can be used to comprehensively adjust the capacitor bank and the transformer tap.
6.2.1.3 In addition to the above, the parallel capacitor devices of the substation can be automatically switched according to the voltage, reactive power (current), power factor or time as the control quantity.
6.2.1.4 When the high-voltage parallel capacitor device is switched no more than three times a day, manual switching should be adopted. 6.2.2 The low-voltage parallel capacitor device should be automatically switched. The control quantity of automatic switching can be reactive power, voltage, time, and power factor.
6.2.3 The automatic switching device should have a locking function to prevent the capacitor bank from being closed by mistake when the protection trips, and should have control, regulation, locking, communication and protection functions according to the operation needs; a selection switch for changing the switching mode should be set. 6.2.4 It is strictly forbidden to set an automatic reclosing switch for parallel capacitor devices. 7 Control circuits, signal circuits and measuring instruments 7.1 Control circuits and signal circuits
7.1.1 The shunt capacitor device of the 220kV substation should be controlled in the main control room, and the shunt capacitor devices of other substations and distribution stations can be controlled locally.
7.1.2 The circuit breaker of the high-voltage shunt capacitor device should adopt a one-to-one control method, and its control circuit should have a locking function to prevent the switching equipment from tripping.
7.1.3 A locking device should be installed between the circuit breaker of the high-voltage shunt capacitor device and the corresponding disconnector and grounding switch. 7.1.4 The high-voltage shunt capacitor device should be equipped with a circuit breaker position signal, an abnormal operation warning signal and an accident trip signal. 7.1.5 The low-voltage shunt capacitor device should have a capacitor switching and disconnection signal. 7.2 Measuring instruments
7.2.1 The busbar connected to the high-voltage shunt capacitor device should have a voltmeter that switches and measures the line voltage. 7.2.2 The main circuit of the high-voltage shunt capacitor device should be equipped with a reactive power meter, a reactive watt-hour meter and an ammeter for each phase. 7.2.3 When shunt capacitors and shunt reactors are connected to the main circuit, the main circuit should be equipped with a bidirectional reactive power meter, and reactive watt-hour meters for measuring capacitance and inductance respectively. 888
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7.2.4 Only one ammeter may be installed in the group circuit of the high-voltage shunt capacitor device. When the shunt capacitor device and the power supply line are connected to the same bus, a reactive watt-hour meter should be installed in the group circuit of the high-voltage shunt capacitor device. 7.2.5 The low-voltage shunt capacitor device should have an ammeter, a voltmeter and a power factor meter. 8 Layout and installation design
8.1 General provisions
8.1.1 The layout and installation design of high-voltage parallel capacitor devices should be conducive to phased expansion, ventilation and heat dissipation, operation inspection, maintenance and replacement of equipment.
8.1.2 The layout type of high-voltage parallel capacitor devices should be selected according to the environmental conditions of the installation site, equipment performance and local practical experience, and outdoor or indoor layout should be selected. Outdoor layout is suitable for general areas; indoor layout is suitable for special areas such as severe cold, damp heat, wind and sand, and special environments such as pollution flash, flammable and explosive.
Parallel capacitor devices arranged indoors should be equipped with measures to prevent flashover accidents caused by condensation. 8.1.3 The layout type of low-voltage parallel capacitor devices should be determined according to the environmental conditions applicable to the equipment. 8.1.4 Indoor high-voltage parallel capacitor devices and switch cabinets of power supply lines should not be arranged in the same room. Low-voltage capacitor cabinets and low-voltage distribution panels can be arranged in the same room, but the capacitor cabinets should be arranged at the end of the same row of cabinets. 8.1.5
8.1.6 The copper and aluminum conductors in the high-voltage parallel capacitor device should be connected by installing copper-aluminum transition joints. 8.1.7 The steel structure components such as the frame (platform) of the capacitor group, the cabinet structure, and the support (platform) of the series reactor should be galvanized or other effective anti-magnetic measures.
8.1.8 The treatment of the ground below and around the high-voltage capacitor group should comply with the following provisions: 8.1.8.1 On the ground within 1m of the outer contour of the outdoor capacitor group, a pebble layer or crushed stone layer should be laid. The thickness should be 100mm and should not be higher than the surrounding floor.
8.1.8.2 Measures should be taken to prevent liquid overflow on the ground below the indoor capacitor group. Concrete floor can be used for other parts of the house; the surface layer should be plastered with cement mortar and pressed. bzxZ.net
8.1.9 The ground of the low-voltage capacitor room should be concrete floor; the surface layer should be plastered with cement mortar and pressed. 8.1.10 The waterproofing standard of the roof of the capacitor shall not be lower than that of the indoor power distribution room. 8.2 Arrangement and installation design of high-voltage capacitor banks 8.2.1 The arrangement of capacitor banks should be separated by phases and independent frames (racks). When the number of capacitors is small or the site is limited, a three-phase common frame can be set.
8.2.2 The frame (rack) of the capacitor bank arranged in layers should not exceed three layers, and each layer should not exceed two rows. Partitions should not be set around or between layers. 8.2.3 The minimum design size of the capacitor bank installation should comply with the provisions of Table 8.2.3. Table 8.2.3 Minimum size of capacitor bank installation design (mm) Name
Minimum size
Capacitor (outdoor, indoor)
Distance between rows
Capacitor bottom to ground
Clear distance from frame (stand) top to eaves
8.2.4 For capacitor banks arranged indoors and outdoors, maintenance passages shall be set around or on one side, and their width shall not be less than 1.2m. When capacitors are arranged in double rows, maintenance walkways may be set between the frame (stand) and the wall or between the frames (stands), and their width shall not be less than 1m. Note: ①Maintenance passages refer to passages for inspection during normal operation, maintenance and repair after power outage, and replacement of equipment. ②Maintenance walkways refer to passages used for maintenance and repair after power outage. 8.2.5The insulation level of capacitor banks shall be coordinated with the insulation level of the power grid. When the insulation level of the capacitor is consistent with that of the power grid, the capacitor shell and frame (stand) should be reliably grounded; when the insulation level of the capacitor is lower than that of the power grid, the capacitor should be installed on an insulating frame (stand) consistent with the insulation level of the power grid, and the capacitor shell should be reliably connected to the frame (stand). 889
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8.2.6 There should be a certain degree of slack between the capacitor bushings and the connection lines from the capacitor bushings to the busbar or fuse. It is strictly forbidden to directly use the capacitor bushings to connect or support the hard busbar. The shell connection wire of the single-bushing capacitor group should be connected to the bright terminal with a soft wire.
8.2.7 The ratio of the maximum to minimum capacitance between any two line terminals of the three-phase capacitor group and the ratio of the maximum to minimum capacitance between each series section of each capacitor group should not exceed 1.02. 8.2.8 When the parallel capacitor is not equipped with a grounding switch, the busbar contact surface and grounding connection terminal for hanging the grounding wire should be set. 8.2.9 The busbar of the capacitor group shall meet the requirements of mechanical strength to prevent the connection line from the fuse to the busbar from loosening. 8.2.10 The installation position and angle of the fuse shall meet the following requirements: 8.2.10.1 It shall be installed on the side with a passage. 8.2.10.2 Vertical installation is strictly prohibited. The installation angle and spring tension position shall meet the product technical requirements of the manufacturer. 8.2.10.3 After the fuse is blown, the tail wire shall not be placed on the capacitor shell. 8.2.11 For parallel capacitor devices, anti-intrusion blocking, pens and net fences can be set according to the activities of small animals such as birds, mice, snakes, etc. in the surrounding environment.
8.3 Arrangement and installation design of series reactors 8.3.1 Oil-diffused iron core series reactors should be arranged outdoors; when ordinary equipment is used in industrial and mining enterprises with heavy pollution, they should be arranged indoors. For oil-immersed iron core series reactors installed indoors, when the oil volume exceeds 100kg, explosion-proof intervals and oil storage facilities should be set up separately. 8.3.2 Dry-type hollow series reactors should be arranged horizontally or in a triangle in a phase-by-phase arrangement outdoors. The installation design sequence for three-phase stacking should comply with the manufacturer's regulations.
8.3.3 When the insulation level of the series reactor to the ground is lower than that of the power grid, it should be installed on an insulating platform consistent with the insulation level of the power grid. 8.3.4 The distance between the dry-type hollow series reactor and the metal components around it, on the top, below it and in the foundation, as well as the distance between the metal components forming a closed loop, should meet the requirements for electromagnetic induction prevention. 8.3.5 The grounding of the supporting insulator of the dry-type hollow series reactor should be radial or open ring, and should be connected to the main grounding grid at least at two points.
8.3.6 The assembled parts of the dry-type hollow series reactor should be connected with stainless steel bolts; when a rectangular busbar is used to connect with adjacent equipment, the rectangular busbar should be installed vertically.
9 Fire prevention and ventilation
9.1 Fire prevention
9.1.1 The fire clearance distance between the outdoor high-voltage parallel capacitor device and other buildings or main electrical equipment shall be consistent with the provisions of the distribution device of the corresponding voltage level. When the provisions cannot be met, a fire wall shall be installed. When the outer wall of the adjacent building is a fire wall, the fire clearance distance may not be restricted. When connected with other buildings, a fire wall shall be installed between them; the fire wall and the enclosure within 2m on both sides shall not have doors or holes.
When the high-voltage parallel capacitor device is installed indoors, the floor, partition wall, door and hole of the building shall meet the fire prevention requirements. 9.1.2 The fire-fighting facilities and fire-proof passages of the high-voltage and low-voltage parallel capacitor devices shall meet the following requirements: 9.1.2.1 Fire-fighting facilities must be installed nearby. 9.1.2.2 Fire-fighting passages should be installed between the outdoor high-voltage large container devices connected to different main transformers. 9.1.3 The frames (stands) and cabinets of capacitor banks shall be made of non-combustible or difficult-to-combust materials. 9.1.4 The capacitor room shall be a Class C production building, and its fire resistance level shall not be lower than Class II. 9.1.5 When the length of the high-voltage capacitor room exceeds 7m, two exits shall be provided. The door of the high-voltage capacitor room shall open outwards. When the partition wall between two adjacent high-voltage capacitor rooms needs to have a door, a Class B fire door shall be used, and it shall be able to open on both sides. High-voltage capacitor rooms should not be equipped with daylighting glass windows. 9.1.6 The roads related to the capacitor bank shall comply with the following provisions: B90
GB 50227—95
9.1.6.1 The channel from the high-voltage capacitor room to the outside of the house shall be fireproofed at the junction inside and outside the house. 9.1.6.2 The distance between the edge of the cable trench and the outer corridor of the high-voltage capacitor group frame (station) rack should not be less than 2m: the cables leading to the capacitor group should be laid in pipes.
9.1.6.3 The trench cover in the low-voltage capacitor room should not be made of combustible materials. 9.1.7 The assembled parallel capacitor should be equipped with an oil storage tank or oil retaining wall, and the impregnant and cooling oil should not be released into the surrounding environment. 9.1.8 In the northern region, the high-voltage parallel capacitor device should be arranged on the leeward side of the maximum frequency wind direction of the substation in winter, and in the southern region, it should be arranged on the leeward side of the maximum frequency wind direction of the substation all year round. 9.2 Ventilation
9.2.1 The ventilation volume of the high-voltage capacitor room should be calculated based on the elimination of indoor residual heat, which includes the heat dissipation of the equipment and the solar radiation heat transmitted through the protective structure.
9.2.2 The exhaust temperature of the high-voltage capacitor room in summer should not exceed 40℃. 9.2.3 The ventilation volume of the series reactor room should be calculated based on the elimination of indoor waste heat, but the waste heat does not include solar radiation heat. The exhaust air temperature should not exceed 45°C, and the inlet and exhaust air temperature difference should not exceed 15°C. 9.2.4 The room for high-voltage parallel capacitor installation should adopt natural ventilation. When natural ventilation cannot meet the requirements, natural air intake and mechanical exhaust can be used.
9.2.5 The air inlet and outlet of the high-voltage parallel capacitor room should take measures to prevent small animals such as birds, rats, snakes and rain and snow from entering. 9.2.6 In areas with strong wind and sand, dust prevention measures should be set up in the high-voltage capacitor room; filtering devices should be installed at the air inlet. 9.2.7 The layout of the high-voltage parallel capacitor device should reduce the impact of solar radiation heat on the capacitor, and it should be arranged in a direction with good ventilation in summer.
9.2.8 According to the local temperature conditions, a thermal insulation layer or heat insulation layer should be set on the roof of the high-voltage capacitor room. 891
GB 50227-95
Appendix A Parallel capacitor device wiring diagram
A.0.1 Connection to the power grid (Figure A.0.1-1~Figure A.0.1-3). A.0.2 Connection of high-voltage capacitor bank and supporting equipment (Figure A.0.2). To main transformer
3~66kv
Figure A.0.1-1
On the same voltage bus
Access method when there is no power supply line
To main transformer
3~~66kv
Outgoing line
Figure A.0.1-3 Access method for setting up a dedicated
bus for capacitors
A.0.3 Connection of low-voltage parallel capacitor device (Figure A.0.3). Note: C,~~C. circuits are the same as C circuit. To the main transformer
3~B6kV
Figure A.0.1-2 Connection method when there is
power supply line on the same voltage bus
To 3~66kV bus
Figure A.0.2 Connection method of high-voltage capacitor bank and supporting equipment Note: The lightning arrester wiring is connected according to the method selected in the engineering design. A.0.4 Connection method of lightning arrester for operation overvoltage protection (Figure A.0.4-1~~A.0.4-4) 892
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