Substation Design
Power system is the system of production and consumption of electricity generation, transmission, transformation, distribution and electricity and other aspects of the composition. Its primary function is the energy conversion means through natural generation power into electrical energy, and then by transmission and distribution substation and supplies power to each user. The main structure of the power system has power (hydropower, thermal power plants, nuclear power plants, etc.), substations (boost substation, load center substation, etc.), transmission and distribution lines and load centers. Each power point is also interconnected to achieve energy exchange between different regions and regulation to improve security of supply and economy. Substation transmission line network consisting of the electricity network and is usually called.
Substation is from the main terminal , the main transformers, high and low voltage power distribution equipment , relay protection and control systems, the power and DC systems , remote and communication systems , the necessary reactive power compensation device and the main control room and other components . Among them, the main terminal , the main transformers, high and low voltage power distribution equipment , such as belonging to a system ; protection and control systems, the DC system , remote and communication systems are secondary system . Main connection is the most import
ant part of the substation . It determines the function of the substation , construction, investment , operation quality , maintenance conditions and supply reliability. Generally divided into several basic forms single busbar , double busbar , a half breaker and ring wiring and so on. Substation main transformer is the most important equipment , which directly affects the performance and configuration of the advanced nature of the substation , economy and reliability . General need to install substation main transformer 2 to 3 sets ; 330 kV and below , the main transformer is usually a three-phase transformer , its capacity by 5 to 10 years into the expected load selection . In addition, substations and other equipment selection and the overall layout of the site selection also have specific requirements. Substation
relay protection subsystem (including transmission lines and bus protection ) and component protection ( including transformers , reactors and reactive power compensation device protection ) categories. Substation control mode is generally divided into the direct control and optional control two categories.
Transformer substation is the main equipment is divided into two-winding transformer, three-winding transformers and autotransformers that high and low voltage windings for each phase of a shared, taking a header from the middle of the high voltage winding qualify as a low-voltage winding of the tran
sformer. V oltage is proportional to the level of the winding turns, the current is inversely proportional to the number of turns. Transformers can be classified according to their role and step-down transformer step-up transformer. The former is used to send end substation power system, which is used by the end of the substation. V oltage transformer and voltage of the power system needs to adapt. In order to maintain acceptable voltage under different load conditions may need to switch the transformer tap. By way of transformer tap switch with load-load and no-load regulating transformer no-load tap changer. OLTC is mainly used by the end of the substation.
V oltage and current transformers. Their operating principle is similar to the transformer, which the operating voltage of high voltage equipment and busbar, high current that the device and the bus load or short-circuit current measurement instruments according to a predetermined ratio becomes low voltage relay protection and control equipment and a small current . Operation at rated voltage transformer secondary voltage l00V, current transformer secondary current is 5A or 1A. Current transformer secondary winding is often connected with the load close to a short circuit, please note: never let it open, otherwise it will endanger due to high voltage equipment and personal safety or to the current transformer burned.
Switchgear includes circuit breakers, isolating switches, load switches, high voltage fuses are disconn
ected and close the circuit devices. Breakers are generally composed of a contact system, arc system, operation mechanism, release, housing and so on. The role of the circuit breaker is turned off and the load circuit, and cut off the fault circuit
to prevent the accident and ensure safe operation. The high-voltage circuit breakers to breaking 1500V, current 1500-2000A arc, which can be stretched to 2m arc continues to burn is not extinguished. It is a high voltage circuit breaker interrupter must be addressed. Blowing arc extinction of the arc principle is diminished heat free cooling, on the other hand by blowing arc elongated arc reinforced composite and diffusion of charged particles, while the arc gap of charged particles disperse quickly restore the dielectric strength of the medium.
Isolation switch (knife) primary role is to isolate the voltage at the device or line maintenance, to ensure safety. It does not disconnect the load current and short-circuit current, should be used in conjunction with the circuit breaker. After a power outage should pull isolation switch before pulling circuit breakers, power transmission should be fit after isolation switch is closed circuit breaker. If misuse will cause equipment damage and personal injury.The ability to be able to disconnect the load switch without disconnecting the load current fault current in normal operation, generally used for high-voltage transformer fuse with or without outlet voltage 10kV and above regular operations.
In order to reduce the area substation positive development in recent years, sulfur hexafluoride enclosed Switchgear (GIS). It is the circuit breakers, disconnectors, busbar, grounding switches, transformers, bushing or cable terminals were installed in their prime in concentrated form a seal between the overall enclosure filled with sulfur hexafluoride gas as insulating medium. This combination has a compact structure, small appliances and light weight without affecting atmospheric conditions, long maintenance intervals, no electric shock and electrical noise, etc., have been put into operation before the development of 765kV substation. Currently, its disadvantage is expensive, require high manufacturing and maintenance processes. Ready for operation management of substation is to achieve safe, reliable, reasonable and an important guarantee of economic power. So substation design must meet the requirements, so based on evidence.
变电站设计
电力系统是由发电、输电、变电、配电和用电等环节组成的电能生产与消费系统。它的功能是将自然界的一次能源通过发电动力装置转化成电能，再经输电、变电和配电将电能供应到各用户。电力系统的主体结构有电源（水电站、火电厂、核电站等发电厂），变电所（升压变电所、负荷中心变电所等），输电、配电线路和负荷中心。各电源点还互相联接以实现不同地区之间的电能交换和调节，从而提高供电的安全性和经济性。输电线路与变电所构成的网络通常称电力网络。
变电所由主接线，主变压器，高、低压配电装置，继电保护和控制系统，所用电和直流系统，远动和通信系统，必要的无功功率补偿装置和主控制室等组成。其中，主接线、主变压器、高低压配电装置等属于一次系统；继电保护和控制系统、直流系统、远动和通信系统等属二次系统。主接线是变电所的最重要组成部分。它决定着变电所的功能、建设投资、运行质量、维护条件和供电可靠性。一般分为单母线、双母线、一个半断路器接线和环形接线等几种基本形式。主变压器是变电所最重要的设备，它的性能与配置直接影响到变电所的先进性、经济性和可靠性。一般变电所需装2～3台主变压器；330 千伏及以下时，主变压器通常采用三相变压器，其容量按投入5 ～10年的预期负荷选择。此外，对变电所其他设备选择和所址选择以及总体布置也都有具体要求。变电所继电保护分系统保护（包括输电线路和母线保护）和元件保护（包括变压器、电抗器及无功补偿装置保护）两类。
变压器是变电站的主要设备，分为双绕组变压器、三绕组变压器和自耦变压器即高、低压每相共用一个绕组，从高压绕组中间抽出一个头作为低压绕组的出线的变压器。电压高低与绕组匝数成正比，电流则与绕组匝数成反比。变压器按其作用可分为升压变压器和降压变压器。前者用于电力系统送端变电站，后者用于受端变电站。变压器的电压需与电力系统的电压相适应。为了在不同负荷情况下保持合格的电压有时需要切换变压器的分接头。按分接头切换方式变压器有带负荷有载调压变压器和无负荷无载调压变压器。有载调压变压器主要用于受端变电站。
电压互感器和电流互感器。它们的工作原理和变压器相似，它们把高电压设备和母线的运行电压、大电
流即设备和母线的负荷或短路电流按规定比例变成测量
仪表、继电保护及控制设备的低电压和小电流。在额定运行情况下电压互感器二次电压为l00V，电流互感器二次电流为5A或1A。电流互感器的二次绕组经常与负荷相连近于短路，请注意：绝不能让其开路，否则将因高电压而危及设备和人身安全或使电流互感器烧毁。
reactive翻译隔离开关（刀闸）的主要作用是在设备或线路检修时隔离电压，以保证安全。它不能断开负荷电流和短路电流，应与断路器配合使用。在停电时应先拉断路器后拉隔离开关，送电时应先合隔离开关后合断路器。如果误操作将引起设备损坏和人身伤亡。负荷开关能在正常运行时断开负荷电流没有断开故障电流的能力，一般与高压熔断丝配合用于10kV及以上电压且不经常操作的变压器或出线上。开关设备包括断路器、隔离开关、负荷开关、高压熔断器等都是断开和合上电路的设备。断路器一般由触头系统、灭弧系统、操作机构、脱扣器、外壳等构成。断路器的作用是切断和接通负荷电路，以及切断故障电路，防止事故扩大，保证安全运行。而高压断路器要开断1500V，电流为1500-2000A的电弧，这些电弧可拉长至2m仍然继续燃烧不熄灭。故灭弧是高压断路器必须解决的问题。吹弧熄弧的原理主要是冷却电弧减弱热游离，另一方面通过吹弧拉长电弧加强带电粒子的复合和扩散，同时把弧隙中的带电粒子吹散，迅速恢复介质的绝缘强度。
隔离开关（刀闸）的主要作用是在设备或线路检修时隔离电压，以保证安全。它不能断开负荷电流和短
路电流，应与断路器配合使用。在停电时应先拉断路器后拉隔离开关，送电时应先合隔离开关后合断路器。如果误操作将引起设备损坏和人身伤亡。负荷开关能在正常运行时断开负荷电流没有断开故障电流的能力，一般与高压熔断丝配合用于10kV及以上电压且不经常操作的变压器或出线上。为了减少变电站的占地面积近年来积极发展六氟化硫全封闭组合电器（GIS）。它把断路器、隔离开关、母线、接地开关、互感器、出线套管或电缆终端头等分别装在各自密封间中集中组成一个整体外壳充以六氟化硫气体作为绝缘介质。这种组合电器具有结构紧凑体积小重量轻不受大气条件影响，检修间隔长，无触电事故和电噪声干扰等优点，具有发展前765kV已在变电站投入运行。目前，它的缺点是价格贵，制造和检修工艺要求高。
做好变电所的运行管理工作，是实现安全、可靠、合理、经济供电的重要保证。