Applied Science and Innovative Research ISSN 2474-4972 (Print) ISSN 2474-4980 (Online) Vol. 7, No. 1, 2023 www.scholink.org/ojs/index.php/asir 92 Original Paper Local Grid Planning and Design Lifan Yang1 1 Xihua University, Chengdu Sichuan, 610039, China Received: February 13, 2023 Accepted: February 24, 2023 Online Published: February 28, 2023 doi:10.22158/asir.v7n1p92 URL: http://doi.org/10.22158/asir.v7n1p92 Abstract This design is based on Etap simulation software to complete the following steps: analysis of original data, determination of power grid voltage level and preliminary selection of power grid connection scheme, technical and economic operation of optimal scheme, operation characteristics and material statistical calculation. Through this design, I have mastered the general principles and common methods of power network planning and design. I am skilled in using Etap simulation software to cultivate my analytical ability in various aspects of technology and economy, improve my ability of calculation, data analysis and arrangement, and design specification compilation. Keywords Power system, Etap simulation, relay protection 1. Introduction The electric power industry is the basic industry for the development of the national economy. The fundamental task of power system planning, design and operation is to rationally develop and utilize power resources under the overall arrangement of the national economic development plan, and use less investment and operating costs to meet the growing needs of various sectors of the national economy and people’s lives. Need, provide sufficient, reliable and qualified electrical energy. The static insulation level of the vacuum interrupter is the basis for improving the overall insulation reliability of the vacuum circuit breaker, and the optimization of the internal insulation structure of the vacuum interrupter is the main way to improve its static insulation level. Therefore, this article will try to optimize the internal structure of a 3.6kV vacuum interrupter to improve its insulation level. This design is based on ETAP simulation software to complete the planning of the power grid and the design of relay protection configuration. ETAP is the abbreviation of comprehensive analysis software system for electric power analysis and electric energy management. ETAP is a comprehensive power and electrical analysis and calculation software with comprehensive functions, which can provide a comprehensive analysis platform and www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 93 Published by SCHOLINK INC. solution for the planning, design, analysis, calculation, operation and simulation of power generation, transmission and distribution, and industrial power electrical systems. ETAP is OTI The power and electrical system comprehensive calculation and analysis software and real-time online control and smart grid system products developed and produced by the group company are also an all-round comprehensive engineering company for power system planning, design, analysis, operation, training and computer simulation. 2. Research Background 2.1 Basic Background Information The relative geographical locations and distances of the involved power plants and substations are shown in Figure 1. The specific system situation is the number of installed units as Figure 2 shown, capacity: 2×300 (MW), rated voltage (kV): 21kV rated power factor: equivalent system S: power plant A is connected to a system S through 500kV, and the total installed capacity of the system is 2000MW. The average power factor is 0.92, the maximum integrated load is 1900MW, cosφN=0.9. The specific load data of the project at each location is shown in Figure 2. The grid voltage is determined as shown in Figure 3. The calculation method and principle of electric energy loss fee are as follows: (1) The maximum power loss of the entire network is obtained from the power flow calculation results; (2) According to the annual maximum load utilization hours and load power factor given in the appendix, (3) Calculate the entire power grid Annual power loss (kWh/year); (4) Calculate the power loss fee based on the comprehensive cost electricity price of the power system (take 0.35 yuan/kWh). The relationship between maximum load loss hours, maximum load utilization hours, and power factor is shown in Figure 4. Figure 1. Relative Geographical Location and Distance of Power Plants and Substations Project Place 1 2 3 Load MW Max 180 15 10 Minimum 90 7 5 Power Factor Max 0.9 0.9 0.9 Minimum 0.85 0.85 0.85 www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 94 Published by SCHOLINK INC. Load Category Ⅰ% 50 40 30 Ⅱ% 30 40 50 Ⅲ% 20 20 20 Maximum Load Time(h) 5500 5500 5500 LV Bus Voltage(kV) 110 10 10 Regulator Requirements Inverse Regulation Figure 2. Load Data and Related Requirements of Areas to be Planned Rated Voltage (kV) Transmission Power (kW) Conveying Distance (km) 35 2000～10000 20～50 60 3500～30000 30～100 110 10000～50000 50～150 220 100000～500000 100～300 Figure 3. Suitable Transmission Capacity and Transmission Distance for Various Voltage Levels cos maxT 0.80 0.85 0.90 0.95 1.00 2000 1500 1200 1000 800 700 2500 1700 1500 1250 1100 950 3000 2000 1800 1600 1400 1250 3500 2350 2150 2000 1800 1600 4000 2750 2600 2400 2200 2000 4500 3150 3000 2900 2700 2500 5000 3600 3500 3400 3200 3000 5500 4100 4000 3950 3750 3600 6000 4650 4600 4500 4350 4200 6500 5250 5200 5100 5000 4850 7000 5950 5900 5800 5700 5600 7500 6650 6600 6550 6500 6400 8000 7400 7350 7250 Figure 4. Relationship between Maximum Load Loss Time, Maximum Load Utilization Time and Power Factor 2.2 Basic Design Method This power system planning is based on the given original data of power plants and substations (substations) to complete the following design. The specific design steps are as follows: 1. Based on the www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 95 Published by SCHOLINK INC. ETAP simulation platform, complete the planning and design of the power grid, and output power flow simulations under various operating modes Report. 2. Based on the ETAP simulation platform, complete the grid voltage regulation calculation and output the simulation report. 3. Based on the ETAP simulation platform, complete the coordinated design of relay protection, and output the STAR simulation report of each short-circuit point. 3. Design Options 3.1 Balance of Electric Power The balance of electric power is divided into the balance of active power and the balance of reactive power. The calculation method of active power balance is to first calculate the installed capacity of the generator SN=2X300=600MW, and take 8% of the factory power load. The calculation of reactive power balance and load is 𝑄综合 = 𝐾1∑𝑄𝑖𝑚𝑎𝑥+𝐾2∑𝑄𝑖𝑒 𝑛 𝑖=1 𝑛 𝑖=1 𝑄𝑚𝑎𝑥 = 𝑃𝑚𝑎𝑥 𝐶𝑜𝑠𝛷𝑚𝑎𝑥 ∗ 𝑆𝑖𝑛𝛷𝑚𝑎𝑥 Therefore, substation one, substation two, and substation three are 𝐶𝑜𝑠𝛷𝑚𝑎𝑥 = 0.9, 𝑆𝑖𝑛𝛷𝑚𝑎𝑥 = 0.44 Therefore, its power can be calculated as 𝑄1𝑚𝑎𝑥 =454.55𝑀𝑉𝑎𝑟, 𝑄2𝑚𝑎𝑥 =37.88𝑀𝑉𝑎𝑟, 𝑄3𝑚𝑎𝑥 =25.25MVar while the apparent power is 𝑆𝑠 = 1900 0.9 = 2111.11MVA，𝑆1 = 180 0.9 = 200MVA，𝑆2 = 15 0.9 = 16.67MVA at the same time 𝑆3 = 10 0.9 = 11.11MVA Generator set A300MW unit power is 𝑄1 = 300 0.85 *2=705.88MVar The integrated power is 𝑄综合 = 0.95∑𝑄MAX+0.2∑𝑆 = 537.25𝑀𝑉𝑎𝑟 The unit power is 𝑄装 = 705.88MVa The difference is 𝛥𝑄 = 𝑄装− 𝑄综合 = 705.88 − 537.25 = 168.63M Therefore, the reactive power of the installed generator capacity of the system is sufficient. www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 96 Published by SCHOLINK INC. 3.2 Determination of Power Grid Level and Preliminary Selection of Grid Wiring Scheme 3.2.1 Preliminary Selection of Grid Wiring Schem The preliminary selection of grid connection scheme 1 is shown in Figure 5, the preliminary selection of grid wiring scheme 2 is shown in Figure 6, and the preliminary selection of grid wiring scheme 3 is shown in Figure 5. Option 1 Wiring Option 2 Wiring www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 97 Published by SCHOLINK INC. Option 3 Wiring Figure 5. Preliminary Selection of Grid Wiring Scheme 3.2.2 Preliminary Comparison of Grid Wiring Schemes According to the summary of the ETAP power flow analysis report, the specific data of each scheme is shown in Figure 6. Plan Line Length (km) Total Demand 𝑀𝑊 Loss 2kmMW  Number of Switches Advantages and disadvantages Plan 1 160 88.491 61064.3 18 Advantages: the line is short, the loss is very small, and the wiring is more flexible Cons: less reliable www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 98 Published by SCHOLINK INC. Plan 2 160 191.65 65484 18 Advantages: more reliable power supply, simple circuit structure Disadvantages: difficult maintenance, large loss Plan 3 258.81 176.07 66790.1 28 Advantages: good stability, easy maintenance; Disadvantages: longer lines, more protection devices Figure 6. Preliminary Comparison of Grid Wiring Schemes There are four preliminary comparison indicators for the grid connection scheme, namely line length, path length, load moment and number of high-voltage switches. The smaller the four indicators, the better the technical and economic performance. After the initial comparison of the above-mentioned preliminary plans through these indicators, the first plan has excellent values. Next, we will use Etap to analyze the operation of each scheme under load short circuit, equivalent grid short circuit, one generator short circuit and busbar (BUS) short circuit. According to the summary of some data in the Etap short-circuit analysis report, the following table is obtained as shown in Figure 7. Voltage kV Option One Option Two Option Three Operating Status Load1 Load2 Load3 Load1 Load2 Load3 Load1 Load2 Load3 Load one Short circuit 0 5.39 5.39 0 5.42 5.42 0 6 6 load two short circuit 59.28 0 5.39 59.31 0 5.39 65.88 0 5.99 Load three short circuit 59.28 5.39 0 59.31 5.39 0 66.02 6 0 Equivalent grid short circuit 12.62 1.15 1.15 35.36 3.21 3.21 12.81 1.08 1.16 A generator short circuit 58.33 5.3 5.3 57.79 5.25 5.25 57.11 5.23 5.19 www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 99 Published by SCHOLINK INC. BUS1 short circuit 0 0 0 0 0 0 0 0.33 0.35 BUS2 short circuit 37.12 0 3.37 28.73 0 2.61 2.1 0 0.19 BUS3 short circuit 37.12 3.37 0 28.73 2.61 0 3.8 0.33 0 Figure 7. Summary of Short Circuit Situation of Each Scheme From Figure 7 we can analyze and get: 1) In the case of short-circuit of each load, the voltage levels of the three schemes are roughly the same, and the scheme three is better. 2) In the case of a short circuit in the equivalent network, the voltage level of Scheme 2 far exceeds that of Scheme 1 and Scheme 3 3) In the case of a short circuit of a generator, the voltage levels of the three schemes are roughly the same, and scheme one is superior. 4) In the case of short-circuit of the three busbars directly linked to the load. Option one is better. Based on the above analysis, the design of scheme one is simple, the cost is the lowest, and the loss is small, but the stability is not as good as scheme two and scheme three. The second scheme has better stability, but the loss is the highest. Although the third option has the longest line, it has the best stability and is easy to repair and maintain because of the structure of the ring network. Therefore, option three is adopted. 4. Economic Calculation Analysis 4.1 Selection of Conductor Sections for Overhead Transmission Lines 1) Select wire cross-section for economical current density. For overhead transmission lines of 35kV and above, the conductor cross section is generally selected according to the economic current density, and is verified by techniques such as mechanical strength, heat generation and corona. The formula for calculating the wire cross-section of the economic current density is S = P √3JVn cosϕ (mm2) In the formula, P is the active power passing through the line (kW); VN line rated voltage (kV); is the power factor of the power passing through the line; J is the economic current density. As shown in Figure 8 Generator A to bus one: Line6, Line1.Bus 1 to bus 2: Line3, Line7. Busbar 2 to busbar 3: Line4, Line8Bus three to generator A: Line2, Line5. www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 100 Published by SCHOLINK INC. Model Cross-sectional Area(𝑚𝑚2) Resistance(Ω) Reactance(Ω) Active Power (MW) Reactive Power ( arMV ) Line1 CHLORINE-7 34.4 1.05 0.296 0.42 0 Line2 CHLORINE-7 34.4 1.05 0.296 0.42 0 Line3 CHLORINE-7 34.4 1.05 0.296 0.42 0 Line4 CHLORINE-7 34.4 1.05 0.296 0.42 0 Line5 CHLORINE-7 34.4 1.05 0.296 0.42 0 Line6 CHLORINE-7 34.4 1.05 0.296 0.42 0 Line7 CHLORINE-7 34.4 1.05 0.296 0.42 0 Line8 CHLORINE-7 34.4 1.05 0.296 0.42 0 Figure 8. Option 3 Line Information 2) Check the cross section of the wire according to the mechanical strength For lines crossing canals, highways, communication lines, and residential areas, the conductor interface shall not be less than 35mm; for lines passing through other areas, the minimum cross-section is generally stipulated as: 35Kv and above for lines; 35Kv and below for lines. 3) Check the cross section of the wire according to the heat generation The selected cross-section of the wire must be checked for heat generation according to the power transmission capacity of various possible normal operation modes and accident operation modes. Under normal circumstances, the maximum temperature of aluminum, aluminum alloy and steel-reinforced aluminum wire does not exceed, and does not exceed under accidental conditions. 4) Check the cross section of the wire according to the corona The corona phenomenon will cause power loss and interfere with the surrounding communication lines. Increasing the cross section of the wire can reduce the electric field intensity on the surface of the wire, so that the working voltage of the line is lower than the critical voltage for corona generation. For lines with a voltage level of 110KV greater than, there will be no corona phenomenon. Because our voltage level is 110kv, and the selected lines are all greater than 110kv, so there is no corona phenomenon. 4.2 Calculate the Maximum Voltage Loss of the Line After the line parameters are determined, recalculate the power distribution (using the maximum load) and find out the maximum voltage loss of each scheme. It should be noted that when calculating the voltage loss here, only the preliminary calculation is carried out, that is, the power loss of the line is not considered, and the voltage of each node is calculated by the rated voltage of the grid, that is, the calculation formula of the voltage is N PR QX V V    www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 101 Published by SCHOLINK INC. In order to ensure the user’s power quality, under normal circumstances, the maximum voltage loss from the power point to the load point in the network should be less than 10% of the rated voltage; under fault conditions, it should be less than 20%. If the maximum voltage loss of a scheme exceeds the index requirement when it is normal or faulty, the scheme should be eliminated. According to the Etap power flow analysis report, the branch loss summary is as follows. Line Head-end Bus Flow(Mvar) Terminal-head Bus Flow(Mvar) Loss(kvar) Bus Voltage Drop(%) Line1 -136.771 -8.089 137.432 8.198 Line2 -101.721 12.069 102.090 -12.092 Line3 61.910 -34.335 -61.732 34.227 Line4 -96.926 14.213 97.266 -14.248 Line5 -101.721 12.069 102.090 -12.092 Line6 -136.771 -8.089 137.432 8.198 Line7 61.910 -34.335 -61.734 34.227 Line8 -96.926 14.213 97.266 -14.248 Figure 9. Effect of Contact Thickness on Electric Field Distribution After increasing the thickness of the contact, because the inertia during the opening and closing process is greater, the erosion caused by the bouncing process is likely to increase the unevenness of the contact surface, and the maximum value of the field strength inside the arc extinguishing chamber rises sharply, which is not conducive to The internal insulation capacity of the arc extinguishing chamber is improved; after increasing the thickness of the contact, the distance between the back of the moving contact and the end of the floating shield is reduced, because the overall length of the arc extinguishing chamber is still suitable, and the field strength in the gap between the two is not obvious increase. It can be seen from Figure 9 that appropriately increasing the thickness of the contacts can make the electric field distribution inside the arc extinguishing chamber more uniform, so the thickness of the moving and static contacts is increased from 10mm to 12mm. 4.3 One-time Equipment Investment Cost Calculation Since the network wiring of each scheme is different, the main wiring of the power plant and the substation may also be different, so the number and type of lines and high-voltage circuit breakers of each scheme are different. When comparing the schemes, only the investment costs of the two types of equipment are taken into account. The comprehensive investment per unit length of various wire lines of different voltage levels (that is, including all costs of materials and installation) can be checked from the table. High-voltage circuit breakers should be selected and verified, but this is generally done in the design of power plants and substations. In grid planning, it is only necessary to determine their type, www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 102 Published by SCHOLINK INC. and then calculate the gas investment cost according to the voltage level and the number of units (intervals). The comprehensive investment for one interval of circuit breakers of various types and different voltage levels can be obtained from the table. 4.4 The Annual Operating Cost of the Grid The annual power loss of the power grid. The annual power loss of each line segment is calculated according to the maximum load loss time method, and the sum of the annual power loss of each line segment is the annual power loss of the entire network (the power loss of the transformer is not included here). 𝛥𝑊𝐿 =∑𝛥𝑊𝑖 = 𝐿 𝑖=1 ∑𝛥𝑃𝑖𝑚𝑎𝑥× 𝜏𝑖(𝑘𝑊 • ℎ) 𝐿 𝑖=1 In the formula, is the active load when the i-th line is at its maximum load, and it is calculated with the rated voltage of the network, is the maximum load loss time of the i-th line, which can be obtained from the table. 𝛥𝑊𝐿 = 𝛥𝑃𝑖𝑖𝑚𝑎𝑥 5. Detailed Technical Calculation of the Optimal Solution 5.1 Determination of Transformer Capacity 1) Determination of transformer capacity Generally, two transformers are selected for connecting the voltage busbar of the power plant to the system, and the capacity of one transformer is selected according to the capacity that can bear 70% of the power plant capacity. When the generator is connected to the transformer unit, a margin of 10% is left after deducting the factory load of the unit according to the rated capacity of the generator. (2) Determination of the capacity of the main transformer of the substation There are generally two main transformers connected to the substation and the system. When a main transformer is out of service, the remaining transformer capacity should guarantee 70%-80% of the total load (calculated by the maximum load of the substation), or the main production electricity of important users. After the transformer capacity is selected, its nameplate parameters can be found according to the attached table, so as to calculate the impedance and admittance of the transformer. Look up the table to select a transformer with appropriate capacity. The selected capacity of the power plant transformer is 60MW, the selected capacity of the substation 1 transformer is 31.5MW, the selected capacity of the substation 2 and 3 transformers is 40MW, and the selected capacity of the system S transformer is 63MW. Record the parameters of each transformer in a form. Transformer impedance calculation formula: RT = 1 2 × PSVN 2 1000SN 2 , XT = 1 2 × VS%VN 2 100SN 2 2 imax imax imax i2 N P Q P R V    www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 103 Published by SCHOLINK INC. The parameters of each transformer are recorded in Figure 10 through Etap: Capacity(M VA) Number of Windings Rated Voltage (KV) Loss (Kvar) short circuit voltage (%) No-load current(%) TR (Ω) TX (Ω) T1 300 2 220/10 137.432 12.498 0.25 0.02 50 T2 300 2 220/10 -13.255 12.498 0.25 0.02 50 T3 300 2 220/10 -8.910 12.498 0.25 0.02 50 T4 300 2 220/21 -239.522 12.5 0.25 0.02 50 T5 300 2 121/10.5 -239.522 12.5 0.25 0.02 50 T6 300 2 500/220 -303.933 12.5 0.25 0.02 50 Figure 10. Transformer Parameters 5.2 Power Flow Calculations for Maximum and Minimum Load Cases Four operating conditions are set for the load, which are Power flow calculations under maximum load conditions www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 104 Published by SCHOLINK INC. Power flow calculations for minimum load conditions Figure 11. Power Flow Calculation 变压器 kV % 大小 角度 MW Mvar MW Mvar MW Mvar 安培 %PF %分接头 220.000 99.821 1.5 0 0 0 0 -129.417 -4.978 340.5 99.9 86.061 -24.145 235.0 -96.3 -129.417 -4.978 340.5 99.9 86.061 -24.145 235.0 -96.3 86.713 58.245 274.6 83.0 220.000 99.558 1.4 0 0 0 0 -85.781 24.083 234.9 -96.3 -106.174 10.389 281.2 -99.5 -85.781 24.083 234.9 -96.3 -106.174 10.389 281.2 -99.5 7.235 4.514 22.5 84.8 376.675 -73.457 1011.6 -98.2 220.000 99.914 1.5 0 0 0 0 -109.101 8.824 287.5 -99.7 106.575 -10.396 281.3 -99.5 -109.101 8.824 287.5 -99.7 106.575 -10.396 281.3 -99.5 5.052 3.146 15.6 84.9 21.000 100.816 7.3 240.000 20.000 0 0 240.000 20.000 6567.6 99.7 21.000 100.816 7.3 240.000 20.000 0 0 240.000 20.000 6567.6 99.7 220.000 100.281 1.6 0 0 0 0 130.005 5.053 340.5 99.9 109.520 -8.825 287.5 -99.7 109.520 -8.825 287.5 -99.7 130.005 5.053 340.5 99.9 -239.525 3.772 626.9 -100.0 -239.525 3.772 626.9 -100.0 110.000 97.383 -0.6 0 0 86.622 53.683 -86.622 -53.683 549.3 85.0 10.000 99.364 1.2 0 0 7.234 4.483 -7.234 -4.483 494.5 85.0 10.000 99.779 1.4 0 0 5.052 3.131 -5.052 -3.131 343.9 85.0 * 500.000 100.000 0.0 -376.489 82.742 0 0 -376.489 82.742 445.1 -97.7 潮流报告 母线 电压 发电 负荷 潮流 ID ID Bus1 Bus6 Bus2 Bus6 Bus2 Bus7 Bus2 Bus1 Bus3 Bus1 Bus3 Bus8 Bus10 Bus3 Bus6 Bus2 Bus6 Bus2 Bus9 Bus4 Bus6 Bus5 Bus6 Bus6 Bus1 Bus3 Bus3 Bus1 Bus4 Bus5 Bus7 Bus1 Bus8 Bus2 Bus9 Bus3 Bus10 Bus2 变压器 kV % 大小 角度 MW Mvar MW Mvar MW Mvar 安培 %PF %分接头 220.000 99.532 1.2 0 0 0 0 -136.771 -8.089 361.2 99.8 61.910 -34.335 186.7 -87.5 -136.771 -8.089 361.2 99.8 61.910 -34.335 186.7 -87.5 149.722 84.847 453.7 87.0 220.000 99.370 1.1 0 0 0 0 -61.734 34.227 186.4 -87.5 -96.926 14.213 258.7 -98.9 -61.734 34.227 186.4 -87.5 -96.926 14.213 258.7 -98.9 13.256 6.512 39.0 89.8 304.063 -103.391 848.2 -94.7 220.000 99.688 1.2 0 0 0 0 -101.721 12.069 269.7 -99.3 97.266 -14.248 258.8 -98.9 -101.721 12.069 269.7 -99.3 97.266 -14.248 258.8 -98.9 8.911 4.357 26.1 89.8 21.000 100.559 7.0 240.000 20.000 0 0 240.000 20.000 6584.4 99.7 21.000 100.559 7.0 240.000 20.000 0 0 240.000 20.000 6584.4 99.7 220.000 100.025 1.3 0 0 0 0 137.432 8.198 361.2 99.8 102.090 -12.092 269.7 -99.3 102.090 -12.092 269.7 -99.3 137.432 8.198 361.2 99.8 -239.522 3.894 628.5 -100.0 -239.522 3.894 628.5 -100.0 110.000 96.056 -2.5 0 0 149.473 72.393 -149.473 -72.393 907.5 90.0 10.000 99.087 0.8 0 0 13.255 6.420 -13.255 -6.420 858.1 90.0 10.000 99.499 1.0 0 0 8.910 4.315 -8.910 -4.315 574.5 90.0 * 500.000 100.000 0.0 -303.933 109.918 0 0 -303.933 109.918 373.2 -94.0 潮流报告 母线 电压 发电 负荷 潮流 ID ID Bus1 Bus6 Bus2 Bus6 Bus2 Bus7 Bus2 Bus1 Bus3 Bus1 Bus3 Bus8 Bus10 Bus3 Bus6 Bus2 Bus6 Bus2 Bus9 Bus4 Bus6 Bus5 Bus6 Bus6 Bus1 Bus3 Bus3 Bus1 Bus4 Bus5 Bus7 Bus1 Bus8 Bus2 Bus9 Bus3 Bus10 Bus2 www.scholink.org/ojs/index.php/asir Applied Science and Innovative Research Vol. 7, No. 1, 2023 105 Published by SCHOLINK INC. 6. Conclusion This design is completed by using Etap simulation software: determination of power network voltage level, design of network connection mode, selection of electrical equipment, etc., and calculation of power flow and voltage regulation is carried out, and then the best power grid connection is obtained through technical and economic comparison plan. References Liu, T. Q. (2005). Power system analysis theory. Wuchang: Science Press. Ji, W. (1998). Power System Design Manual. Beijing: China Electric Power Press. Liu, Z. Y. (1998). General cost of power transmission and transformation project of State Grid Corporation of China_ 110kV transmission line volume (2010 edition). China Electric Power Press. Liu, T. Q., & Qiu, X. Y. (2013). Power System Analysis (2nd ed.). Science Press. Cao, S. M. (March 1998). Reference materials for power system curriculum design and graduation design. Beijing: China Electric Power Press. Ge, D. F. (December 1998). Electrical Design Manual of Electric Power Engineering. Beijing: China Electric Power Press. Liu, T. Q. (June 2011). Power System Steady State Analysis Theory (2nd ed.). Beijing: Science Press. Zhang, D. S. (March 2014). Design Manual for High Voltage Transmission Line of Electric Power Engineering. Beijing: China Electric Power Press.