1 project overview
Liu Yang Coal Mine is located in the east of qianxi county, Guizhou Province, about 25 kilometers away from the county seat. It has jurisdiction over Sheikh Township, Zhongshan Town and Guli Town. There are four 1 10kV substations in qianxi county, namely Qianxi 1 10kV substation, and its main transformer capacity is16mva+10mva; Gan Tang 1 10kV substation, with a main transformer capacity of 20MVA；; Linquan 1 10kV substation has a main transformer capacity of 20MVA. The main transformer capacity of Tailai 1 10kV substation is 100 mA. Qianxi county has five 35kV substations, namely Renhe (1MVA), Yuduo (1MVA), Zhong Ping (1. 15MVA), Zhongshan (1MVA) and Sheikh (2MVA).
2 Determination of power load
According to the selection of main equipment in the mine and the statistics of electricity load in the whole mine, the load power in the later stage of the mine is calculated. In order to improve the power factor of mine power, reduce the power loss and improve the utilization rate of electrical equipment, a 3600kvar high-voltage capacitor installed on the mine high-voltage bus is designed. After compensation, the mine load is:
(1) Under normal water inflow, the active power is 7872.2kW；; The reactive power is 2534.3kvar；; The apparent power is 8270.1kva; ; The natural power factor is 0.95.
(2) Maximum water inflow: active power is 9953.9kW；; Reactive power 4137.8kvar; ; The apparent power is10779.7kva; ; The natural power factor is 0.92.
3 Determination of power supply point
The maximum calculated power load (maximum water inflow) of Liuyang mine in the later period is 10779.7kVA, which is about 9km away from Tailai10/0kv substation and 5.05km away from Gan Tang10/0kv substation. It is about 5.8km from Concord 35kV substation and 8.5km from Gaoshan 35kV substation.
Because Qianxi 1 10kV substation is too far away from this mine, if it supplies power to this mine, the engineering quantity is very large, so we will not consider introducing mine power supply for the time being. Tailai substation has no spare outlet interval, so it can't supply power to this mine. According to the existing and planned power supply conditions and power load near the above mines, the following two mine power supply schemes are proposed.
(1) Scheme 1
The mine adopts 35kV power supply, that is, a 35/ 10kV substation is built in the industrial site of Liu Yang Mine. The primary power supply comes from Gan Tang 1 10kV substation, with a voltage of 35kV, conductor model of LGJ-240 and line length of about15.05km.: The other loop power supply comes from the 35kV substation of Gaoshan Mine, with a voltage of 35kV, the conductor model is LGJ-240, and the line length is about 8.5km.
(2) Scheme II
The mine adopts 35kV power supply, that is, a 35/ 10kV substation is built in the industrial site of Liu Yang Mine. The primary power supply comes from Gan Tang 1 10kV substation with a voltage of 35kV, the conductor type is LGJ-240, and the line length is about15.05km. The other loop power supply comes from Xiehe 35kV substation, and the power supply comes from the 35kV bus section of Tailai1kloc-0/0kv substation. The voltage is 35kV, the conductor type is LGJ- 185, and the line length is 5.8km.
(3) Economic and technical comparison between the two schemes.
Economy: From the investment point of view, both schemes consider 35/ 10kV substation, so part of the investment in substation is the same. Line part: In the first scheme, in addition to the power line of the mine, the power line of the 35kV substation of Gaoshan Mine needs to be reconstructed, * * 30.55km, and in the second scheme, 20.85km. Option 2 requires less investment.
Technically speaking, scheme 2 needs the professional knowledge of substation managers more than scheme 1 for better management; After verification, the first and second schemes can meet the requirements of mine power supply quality. In addition, mine gas power generation can also be used as a supplementary power supply in the future, and the quality and reliability of mine power supply will be greatly improved. Therefore, this design chooses Scheme 2 as the power supply scheme of Liuyang Mine.
Selection of conductor, lightning conductor and tower of 4 35kV line
There are many mountains, ditches and trees in Guizhou, and the changes of topography, landforms and geology are also complicated, which brings certain difficulties to the erection of transmission lines. The path of transmission lines should make full use of hilltops and hillsides, cut down less trees and occupy less farmland. Anti-pollution and shockproof are considered for the line, and synthetic insulators are used.
The maximum calculated power load of the mine 35kV substation in the later period is/kloc-0 10779.7kVA It is designed to supply power to the Liu Yang mine 35kV substation from Gan Tang10kV substation and Sheikh 35kV substation. LGJ-240； is selected according to the economic current density and the allowable voltage drop. As the conductor model from Gan Tang 1 10kV substation to mine 35kV substation; LGJ- 185 is selected as the conductor model of the line from Concord 35kV substation to mine 35kV substation. Among them, the line length from Gan Tang 1 10kV substation to Liuyang mine is 15.05km, and the line length from Xiehe mine 35kV substation to Liuyang mine 35kV substation is 5.8km Both lines are equipped with 8-core OPGW composite optical fiber ground wires, which not only serve as lightning protection for the lines, but also provide a channel for communication between the mine substation and the superior substation. Install zinc oxide arrester at the beginning and end of 35kV line.
Determination of 35kV Substation in Minmetals
There is a 35/ 10kV substation in the mine industrial square, and the site selection takes into account such factors as convenient transportation, proximity to the load center, flood control and drainage. According to statistics, the maximum active load at 10kV side in the early stage is 6 195.5W, and the apparent power is 67 17kVA (after capacitor compensation). At the later stage, the maximum active load on 10kV side is 9953.9kW, and the apparent power is 10779.7kVA (after capacitor compensation). Determination of the number of main transformers;
Scheme 1: two main transformers SZ11-10000/35,35.5%/10.5kv, 10000kVA are selected. In the early stage, two main transformers were used, and one was reserved. When the working transformer fails, the standby transformer is automatically put into operation, which can meet the requirements of the whole mine. The load factor is 0.67 and the guarantee factor is 1.49. In the later stage, the two main transformers run separately and are standby for each other. The load factor of two main transformers working at the same time is 0.54, and the accident assurance factor of one main transformer working during maintenance or failure is 0.93. It can meet the power demand of the first and second load of the whole mine. The advantages are simple wiring, simple control and management operation, convenient operation and less investment. The disadvantage is that the ability to adapt to load changes is small, and the cost of collecting basic electricity fee according to the installation capacity of main transformer in the early stage is high.
Option 2: Choose SZ 1 1-8000/35, 35.5%/ 10.5kV and 8000kVA, and install two main transformers in the early stage. Under normal circumstances, two main transformers are in use and one is standby. When the working transformer fails, the standby transformer will be automatically put into operation, which can meet the power supply demand of the whole mine load. The load factor is 0.84 and the guarantee factor is 1. 19. Add a main transformer in the later stage. Under normal circumstances, two main transformers are running and one is standby. When any working main transformer fails, the standby main transformer will be put into operation automatically. The load coefficient of two main transformers working at the same time is 0.673, and the guarantee coefficient of any transformer when it fails is 1.48, which can meet the needs of the whole mine load. Its advantages are high ability to adapt to load changes, and low cost of collecting basic electricity fee according to the installation capacity of main transformer in the early stage. The disadvantages are complicated wiring, inconvenient management and operation, large investment, high load rate of main transformer in the early stage, and high cost of collecting basic electricity fee according to the installation capacity of main transformer in the later stage.
Because the installation of two main transformers in the substation is simple and convenient, and it is not easy to cause misoperation, this design is designed according to the first scheme. The 35kV and 10kV systems in the substation are all connected in sections by single bus, and two 35kV power sources are used at the same time. KYN6 1-40.5 armored removable metal enclosed switchgear and ZN85 vacuum circuit breaker are selected for the 35kV distribution equipment in the substation. 10kV power distribution equipment adopts KYN28A- 12 armored removable metal enclosed switchgear and VS 1 vacuum circuit breaker. The 35kV switchgear adopts single-row and double-channel layout, and the 10kV switchgear adopts double-row and double-channel layout.
There are two station transformers in the substation, which are located in 35kV I bus section and 10kV II bus section respectively. Transformer in substation are SC9-50/35, 35/0.4, 50kVA and SC9-50/ 10,10.4 and 50kVA respectively. The station power supply is equipped with a station power supply screen, and the power supply enters the line twice, which can be mutually standby and automatically switched. The operating power supply of the substation is a microcomputer high-frequency switch DC screen, and a set of maintenance-free lead-acid battery is installed with a voltage of 220V V. According to the DC load of the substation, the battery capacity is 100Ah. There are two low-voltage power transformers in the substation. According to the statistics of power load, two transformers S11-1250/10,10.4 kV, 1250kVA are selected, and the two transformers work separately as backup. Ground power supply, lighting, work and safety power supply.