Instructor:
The purpose of studying in Hebei Agricultural University is to improve my academic qualifications. Secondly, with the progress of science and technology, I feel that my knowledge is relatively poor and I can't better meet the needs of my work. I hope to improve my knowledge and cultural level through study. Thirdly, during my study in school, because all the theoretical knowledge I have learned comes from books, it is far from reality, so my knowledge is not well mastered. Now, the whole university study course has all ended and started.
Course design purpose: 1. Consolidate and expand the professional theoretical knowledge and apply it flexibly in the practice of curriculum design; 2. Learn and master the basic methods of electrical design of power plants and substations, and establish correct design ideas; 3. Cultivate the ability to analyze and solve problems independently and the basic skills to solve practical engineering design; 4. Learn the skills of consulting relevant design manuals, specifications and other reference materials.
procedure
catalogue
chapter one
chapter two
chapter three
chapter four
chapter five
Chapter vi
Chapter VII
The first chapter is the original data given in the design of electrical main wiring and transformer selection analysis task book. According to the status and construction scale of substation in power system, the reliability, flexibility and economy of substation operation are comprehensively considered, and the best main wiring scheme is determined through comprehensive demonstration.
The first section of the original data analysis 1. The station is connected to the system through two lines 1 10KV, and supplies power to local users at 35KV and 10KV respectively. 2. Task: 1 10KV transformer relay protection. 3. Environmental parameters: altitude
Section 2 Determination of Electrical Main Wiring Scheme
Scheme I, Scheme II and Scheme III
Comparison of main wiring schemes Determination of economic reliability scheme of main transformer for switch
Scheme 1: 1 1,1/0kv4, 35kv5,10kv2,4,0.7× 4 = 2.8 is the worst, with the largest total transformer capacity and the most switches. It is best to fully consider the transformer, and the switch can still guarantee power supply during maintenance and testing. 1 10kv terminal substation adopts double circuit 1 10kv incoming line, which should be an important substation, and the design idea should be based on reliability. So choose scheme one as the final scheme. Although the construction investment of the first scheme is large, in the later operation process, a main transformer can be removed when the load is small, thus reducing the loss.
In the second scheme, there are 7 sets, 1 10kv5 sets, 35kv and 10kv 1 sets and 2 sets, and 1 is the best, and the total capacity of the transformer is the smallest. The medium, 35kv and 10kv loads supply power respectively, which will not affect each other in case of failure. However, when the equipment is overhauled, the power supply will inevitably be interrupted. There are 7 sets in Scheme III, including 1 10kv4 sets, 35kv2 sets, 10kv 1 set and 1.6 sets, which are between Scheme I and Scheme II. Worst of all, when the high-voltage side fails, the low-voltage side will inevitably interrupt the power supply.
Section 3 Capacity Calculation and Main Transformer Selection
1. Based on the annual load growth rate of 6%, consider 8 years. 2. Two transformers run in parallel, and each transformer bears 70% of the load. 3.35kV load is KVA, 10kv load is KVA, and the total load is KVA. 4. Transformer capacity: 1) Load forecast: 35kv load:10000kVA× (1+6%) 8 =15036.30kVA; 10kv load: 3600kva× (1+6%) 8 = 5413.07kva, and * * is 20449.77KVA. 2) The calculation of active and reactive losses of transformers is not calculated because the proportion is small and the capacity margin considered by this station is relatively large. 3) Selection of transformer in substation. Because the design specification has given the power consumption of 160KVA, it can be directly selected. From the analysis of the main wiring scheme, it is more reliable to connect the transformer in the substation to the 35KV bus, so SL7- 160/35 is selected.
Selection and determination of transformer: Select and determine the load capacity of main transformer. The model1# b20449.77× 0.5× 0.7 = 7157.42kva 8000kva szl7-8000/1102 # b is the same as 1 # B 3. B5413.07× 0.5× 0.7 =1894.57kva 2000kva sl7-2000/354 # b and 3 # B transformer160kva160kva sl7-/kl. Loss (KW) Impedance voltage (%) No-load current (%) Connection group High and low voltage No-load SZL7-8000/1038.5155010.51.4d/kloc
Chapter II Calculation of Short-circuit Current
The purpose of short-circuit current calculation in the first section is to determine whether it is necessary to limit short-circuit current in line connection, to ensure that all kinds of electrical equipment and wires can work safely and reliably under normal operation and fault conditions, to provide a basis for selecting relay protection mode and setting calculation, and to check the short-circuit current calculation used for dynamic stability and thermal stability of wires and appliances and the breaking current of appliances. We should consider the long-term development plan for 5- 10 years.
Calculation of circuit component parameters in the second quarter 1. Equivalent network figure 2- 1 main wiring figure 2-2 equivalent network figure 2-3 equivalent network 2 under minimum operation mode. Common reference value (SJ = 100 MVA), reference voltage UJ (kV) 6.3 10.5 37 65437 0 reference current Ij (Ka) 9.165.5010.56 0.502 0.25. 0.397 1. 10 6538Sj reference current ij =- reference reactance XJ = 2) line impedance x 1 = 0.4× 65 = 26 ohms 3) transformer reactance is xb 1 = xb2, Xb3 = xb4xb1= ud%/100× SJ/se =10.5/100×100/8 =1.3638. Kloc-0/ 15kV So, Three-phase short-circuit current I(3)= 15/26√3 = 2.55 Ka Two-phase short-circuit current I(2)=I(3) √3/2 =2.55× 1.73 The impedance diagram is simplified from Figure 2-4 (a) to Figure 2-4 (b). 100× UE2/SE， X2 =10.5/100×1102/8 = 65438+conversion formula 105.4 1 = 0.63ka two-phase short-circuit current I (2) = = =1.52× 0.63 = 0.96 ka3) D3 ka3) When D3 is short-circuited: Up = 37kv D3, the impedance diagram is simplified from Figure 2-5 (a) to Figure 2-5 (b), Figure 2-5 (a) and Figure 2-5 (b). X1= 26 Ω X6 = 79.41Ω According to the conversion formula of transformer reactance, xd = udx4 = 6.5/100× 352/2 = 39.81ω x4 = x5x4//x5x7 =/. 125.32 = 0.53ka two-phase short-circuit current I (2) = 0.886i (3) = 0.886× 0.53 = 0.47ka three-phase short-circuit capacity s (3) = √ 3upi (3) =1.73x/kloc-0. = 1.52×0.53 =0.8 1kA 3。 Calculation of short circuit current in minimum operation mode. The lowest operation mode of this station is B 1 and B3 off or B2 and B4 off. Accordingly, the equivalent network is shown in Figure 2-6, Figure 2-6, 1). Up = 37kV x1= 26Ω when D2 is short-circuited. According to the conversion formula of transformer reactance nominal value XD = UD%/ 100× UE2/SE, X2 =10.5/100×1102/8 =158.81Ω three-phase short circuit184.81. = 0.886×0.36 = 0.32 ka Three-phase short-circuit capacity S (3) = √ 3upi (3) = 1.73× 37×. =1.52× 0.36 = 0.55ka2) In case of short circuit at point D3: up =10.5kvx1= 26ω x2 =158.81ω According to the conversion formula XD = UD%/ω. X4 = 6.5/100× 352/2 = 39.81ω three-phase short-circuit current I (3) = up/√ 3/x =15/1.73/224.62 = 0.22.
4. Short-circuit current calculation result table Short-circuit number branch name Short-circuit current (KA) Minimum operation mode Short-circuit current (kA) Effective value of full short-circuit current (kA) Short-circuit capacity (MVA) D (3) D (2) D (3) D (2) D (3) D (3) D (2) D (2)
Chapter III Selection and Design of Conductors and Electrical Appliances (No Dynamic Thermal Stability Check)
The first section is the calculation of maximum continuous working current 1. 110kv+10kv bus conductor selection bus maximum continuous working current calculation igmax =1.05se/√ 3ue =1.05x016000//kloc-0. 0 = 88.28 a 1 # B, 2#B transformer lead maximum continuous working current is 2.35kV bus 1 conductor selection. Calculation of the maximum continuous working current of bus igmax =1.05se/√ 3UE =1.05x16000/138.73a/35 = 277.46a1#. 2. The flexible conductor is selected for the 35KV lead of the main transformer according to the economic power density. The maximum continuous working current of the 35KV lead under the maximum operation mode is calculated as 1.05 times of the rated current of the transformer, and the maximum continuous working current of the selected 35kV bus conductor is calculated as igmax =1.05se/√ 3UE =1.05× 4000/1.73. 3#B transformer igmax =1.05se/√ 3ue =1.05× 2000/1.73/35 = 34.68a.
Section 2 Selection of Conductors
Without considering the simultaneous coefficient, Tmax is calculated as 3000 h.1. 1 10kv bus conductor selection, please refer to Figure 5-4 and Figure 5- 1 in Graduation Design Guide for Electrical Parts of Power Plants and Substations. It is concluded that TMAX = 3000 h and the economic current density of steel-cored aluminum stranded wire is J = 1.53a/mm2 SJ = ig. See Figure 5-4 and Figure 5- 1 of the Guide for Graduation Design of Electrical Parts of Power Plants and Substations for conductor selection of 2.35kv bus, and it is concluded that Tmax=3000h, and the economic current density of steel-core aluminum stranded wire is j =1.53a/mm2 SJ = ig/j = 277.46//kloc-0. 3. See Figure 5-4 and Figure 5- 1 for the conductor selection of10kV bus, and it is concluded that TMAX = 3000 h and the economic current density of steel-core aluminum stranded wire is j =1.53a/mm2 SJ = ig/j = 242.77. 4. The transformer leads shall be 1) 1#B+0 # B, and the 2#B transformer 1 10kv side leads shall be made of LGJ-95 steel-core aluminum stranded wire; 2) LGJ-1# B and 2#B transformers are selected as the 35kv side leads; 3) The 35KV side leads of 3 # B and 4 # B transformers are made of LGJ-95 steel-core aluminum stranded wires; 4) LGJ- 120 steel-core aluminum stranded wire is selected for the 35KV side lead of 4)3 # B transformer.
Section 3 Selection of Electrical Equipment
1. The selection of circuit breaker and current transformer shall meet the conditions of selecting circuit breaker. Refer to Guiding Opinions on Graduation Design of Electrical Parts of Power Plants and Substations, and select the following schedule:No. Circuit Breaker Form, Model, Rated Voltage (kv) Rated Current (A) Breaking Current (KA) Working Current (A) Current Transformer 1DL Low Oil Circuit Breaker SW7-1KLOC-0/065438. 5.8 88.28 lcw-1/kloc-0 2dl low oil circuit breaker ditto 88.28 ditto 3DL low oil circuit breaker ditto 44. 14 ditto 4DL low oil circuit breaker ditto 44. 14 ditto 5DL low oil circuit breaker sw3-35351000. 5438+038.73 LCW-35 6DL oil-free circuit breaker ditto 138.73 ditto 1DL oil-free circuit breaker ditto 7DL oil-free circuit breaker SW3-35 35 600 6.634.68 ditto 8DL oil-free circuit breaker ditto 34.68 ditto 9DL vacuum circuit breaker Zn-65438. +0010 600 8.72121010/0 dl vacuum circuit breaker ditto 12 1.38 ditto 35kx outlet switch sw3-. /7 = 29.7 A LCW-35 10 kV outlet switch Zn-10/kloc-0 300 3 242.77/10 = 24.28 a LFC-10 technical parameters current transformer serial number rated voltage (kV Accuracy grade rated current primary and secondary load impedance ω 1s thermal stability multiple dynamic stability multiple 65485 7DL 35 34.68 ditto 0.5 40/5 8DL 34.68 ditto 0.540/59dl10/21.38lfc-/kloc-. kloc-0/25/50.675 165 10dl 12 1.385 2 65 100 10 242.77/ 10 = 24.28 a LFC- 10 0.5 350/50.6 75 155 2。 The selection of disconnector should meet the selection and modeling conditions of disconnector. Refer to Guiding Opinions on Graduation Design of Electrical Parts of Power Plants and Substations, and select the following schedules: serial number, installation location, model, rated voltage (kv) and rated current (a) on both sides of GW5-1DL-4DL1KLOC-0/06025DL-8DL. Station transformers GW4-35 35 600 39DL, GW1-1010 600 410 kV outgoing switch GW1-KLOC-0/0 400 53. The selection of PT for voltage transformer shall meet the conditions of selecting according to voltage transformer. Refer to the Guidance for Graduation Design of Electrical Parts of Power Plants and Substations, and select the following schedule: serial number, installation location, type, model (unit), rated voltage, kv, rated transformation ratio110kV outdoor single-phase JCC1-1kloc-0/65438. +00000/√ 3:100/√ 3/100kv outdoor single-phase JCC1-10365438+. 100/335kV bus outdoor single-phase jdj-35335 35000/√ 3:100/√ 3/100/3410kv bus indoor single-phase jdj-103/kloc 100 4. Select the serial number, type and model of high-voltage current-limiting fuse (only), rated voltage and rated current of kv A 1.35kV transformer RW3-353 350.52 10kV transformer RN2310.53 transformers RW3-353 3555 5. Lightning arresters at all levels are power plants and power plants. According to the insulation level and service conditions of the protected equipment, the form and rated voltage of lightning arrester are selected. The arc extinguishing voltage and power frequency discharge voltage of the limited arrester are verified according to the use situation. Lightning arrester number, model, technical parameters (KV), number of installation sites, arc voltage, power frequency discharge voltage, impulse discharge voltage, residual voltage,100170-19526526510kV system side selection results. 184-10413413435kv side and outlet 3fz-1012.726-314545/kloc-0. Selection and installation position of rated voltage of grounding switch model. Long-term passing current A 1 10kv side jw2-110 (w)11004060035kv side isolating switch.
Chapter IV Configuration and Setting Calculation of Relay Protection
A, according to the technical specification for relay protection and safety automatic device protection configuration. 1. Transformer relay protection: longitudinal differential protection, gas protection, current quick break protection, composite overcurrent protection (backup protection), serial number protection, configuration protection function and operation principle, export mode relay model 1, longitudinal differential protection, transformer internal fault protection, such as disconnection, interlayer and turn-to-turn short circuit, and other unbalanced current starting protection on both sides of transformer. Disconnect the switches on both sides of the transformer. BCH-22 gas protection transformer is short-circuited, and severe heating produces gas start protection. Light gas signal, heavy gas disconnect the switches on both sides of the transformer. 3 The overload current that may flow out in the accident state of overcurrent protection acts on signal 4. Current quick-break protection and interphase short circuit disconnect circuit breaker 2. Relay protection for 35KV lines and 10KV lines: current quick-break protection, overcurrent protection, single-phase grounding protection serial number protection configuration protection function Export relay model 1 current quick-break protection and interphase short-circuit disconnection circuit breaker 2. Over-current protection and interphase short circuit disconnect insulation monitoring signal of single-phase grounding protection of line breaker 3 bus.
Section 4 Protection Principles
Section 5 Protection Configuration Diagram
Section 6 setting calculation setting calculation of current quick-break protection 1. 1 # b, 2 # b setting calculation of current quick-break protection 35kv system and 10kv system are all ungrounded, so the current quick-break protection wiring is of two-phase double relay type. The setting calculation of this connection mode is based on the phase current connection. 1) When avoiding external short-circuit of transformer, the maximum short-circuit current flowing through the protection device IDZ = KKI (3) D.max Chapter 5 Lightning protection planning and design According to the requirements of Technical Specification for Overvoltage Protection Design of Power Equipment, the lightning protection and grounding facilities are configured as follows: In order to prevent lightning from directly hitting substation equipment and its structure, electrical buildings, etc., independent lightning rods are required for substation transformation, and the impact grounding resistance should not exceed/kloc- In order to prevent the lightning rod from falling and causing counterattack accidents, the distance SK between the independent lightning rod and the distribution structure in the air should not be less than 5 meters.
Chapter VI Description of Protection Action
Chapter VII Conclusion According to the basic requirements of the task book, I consulted the teaching materials and a large number of laws, regulations and related materials. After two weeks of hard work, the design task was finally completed and the design results were formed. Looking back now, there are ups and downs, joys and sorrows, especially the theoretical basis is not too hard, which is even more difficult.
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