附 录附录A 外文资料Design of Mv/Lv Substation TransformerAbstract：A substation is a part of an electrical generation, transmission, and distribution system. Substations generally have switching, protection and control equipment, and transformers. The low voltage distribution networks are supplied from MV/LV substation transformer that represent the last step of bringing transformation to the low voltage and ensuring the protection and monitoring of the network. There are three types of MV/LV substation: pole-mounted transformer substation, the substation in an envelope and substation in masonry. This paper presents a general description for different MV/LV substation and a methodology to design the various elements making up the public distribution substation (choice of the emplacement, engineering, power transformer, choice of MV cells, circuit breakers, fuses, disconnect switch, conductors,...etc). Keywords: Substation transformer MV cells Substation in masonry Pole-mounted transformer substation 1. Introduction A substation is a part of an electrical generation, trans-mission, and distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. Electric power may flow through several substations between generating plant and consumer, and its voltage may change in several steps. Substations generally have switching, protection and control equipment, and transformers. Distribution circuits are fed from a transformer located in an electrical substation, where the voltage is reduced from the high values used for power transmission. Distribution networks are typically of two types, radial or interconnected. A radial network leaves the station and passes through the network area with no normal connection to any other supply. This is typical of long rural lines with isolated load areas. An interconnected network is generally found in more urban areas and will have multiple connections to other points of supply. These points of connection are normally open but allow various con-figurations by the operating utility by closing and opening switches. Operation of these switches may be by re-mote control from a control center or by a lineman. The benefit of the interconnected model is that in the event of a fault or required maintenance a small area of network can be isolated and the remainder kept on supply. The MV/LV substations are a node of a network, which includes a set of equipment designed to protect and facilitate the operation of the electrical energy . The MV/LV substations provide the interface between the distribution MV and LV. The MV / LV adapts to all modes of operation and why should fulfill the following functions: ● Distribute the power and protect the LV departures; ● Isolate the MV/LV substation in case of default; ● Manage the MV network in case of default and the position by remote control. MV/LV substation transformer has two purposes: - The interconnection between the lines of the same voltage level, it helps to distribute the power of the different lines from substations. - The transformation of electrical power, processors can switch between voltage levels to another. So, we can classify the MV/LV substations over the networks on which they are used as well as the functions they perform. The realization of MV/LV substations needs prior knowledge: ● Standards of reference and statutory instruments (voltage, quality of supply, short-circuit power, ..., etc); ● Needs to be performing (power plant availability, operation); ● Specific needs-related uses (voltage variations tolerated, compensation of reactive power, immunity to interference receivers, regulations related to facility security); ● Constraints, installation and environment . This paper presents the different MV/LV substation transformer and a methodology to design the various elements making up the public distribution substation.2. The Birth of MV/LV Substation TransformerThe decision of a MV or LV supply will depend on local circumstances and considerations such as those mentioned above, and will generally be imposed by the utility for the district concerned. When a decision to supply power at MV has been made, there are two widely-followed methods of proceeding:● The power-supplier constructs a standard substation close to the consumer’s premises, but the MV/LV transformer is located in transformer chamber inside the premises, close to the load centre. ● The consumer constructs and equips his own substation on his own premises, to which the power supplier makes the MV connection . 2.1. Project StudiesThe consumer must provide certain data to the utility at the earliest stage of the project. the power-supplier must indicate: ● The type of power supply proposed, and define the kind of power-supply system: over headline or under-ground-cable network, the service connection details: single-line service, r。