17-11-2012, 11:46 AM
U.P.Power Corporation Ltd
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INTRODUCTION
220 KV /132 KV/ 33KV Substation is the one of oldest and important Substation of U.P.Power Corporation Ltd. commissioned in 1977. This Substation feeds power to almost 40% area of state capital at different voltage levels. Almost 1,75,000 MWH power exported from this S/S monthly on different voltage levels.
This Substation is situated in Sarojininagar area on Kanpur Road approximately 14 Kms. from Lucknow Junction Railway Station. This Substation has 4 voltage levels namely 220KV, 132 KV, 33KV & 11KV. At 220 KV voltage level this S/S import Power from 2x240MVA T/F’s at 400 KV S/S situated adjacent to this S/S. Also UNCHAHAR Thermal Power Plant exports power to this S/S and is the major power exporter for this S/S.
At 220 KV Voltage Level there are 5 transmission lines namely 220 KV Gomtinagar, 220KV Rai-Bareli, 220 KV Unnao I, 220Kv Unnao II & 220 KV Hardoi Road.
Also there are 3 nos. Power Transformer having capacity 2x100MVA+1x160 MVA with voltage ratio of 220KV/132KV. They takes power from 220 KV bus and delivers at 132 KV to 132 KV Bus. These transformers are running at 70% loading in normal conditions.
At 132 KV Voltage level there are 8 nos. transmission lines which transfer the power at this voltage level to various 132KV S/S namely 132 KV SGPGI, 132 KV TRT, 132 KV Unnao, 132 KV Sandila and 132 KV Railway. Also there are 2x40 MVA T/F’s having voltage ratio 132KV/33KV connected from 132 KV Bus and delivers power to 33 KV bus.
There are 8 nos. 33 KV lines to distribute the power at 33 KV Voltage level. There are 2x3MVA T/F’s having voltage ratio 33/11KV for step down the voltage to meet the supply requirement of Substaion auxiliaries and colony.
There are 3shifts for the operation purpose of Substation round the clock. Each shift consists of 1 No. Junior Engineer and 2 Nos. Sub Station Operator for data logging and operation of Equipments. Also there is adequate strength of maintenance personnel for attending the fault and its rectification.
POWER SECTOR OF INDIA
The power sector constitutes the backbone of our economy. Adequate Electrical Power with a high degree of reliability and quality is the key to our economic growth. The economic growth rate of 8-9% on a sustained basis is necessary for India to meet the aspirations of its people for reasonably good quality of life. Development of basic infrastructure is an essential prerequisite to sustain this growth. Keeping in view the central position of power sector in the domain of infrastructure, the government of India has set the objective of providing access to uninterrupted quality power supply at affordable costs to all by the year 2012. The responsibility for translating this version into reality vests with the power sector and perticularily the power distribution sector functionaries.
In the last 20 yrs. , the Indian power sector has witnessed tremendous growth in size and capacity. Our current installed capacity for power generation exceeds 125,000 MW and the aim is to increase it to 2,12,000 MW by the year 2012. However , in spite of such massive expansion, the power sector in India has not been able to match the rapidly growing demand for reliable and cost effective supply. Demand for power has continued to grow at a compound annual rate of about 8% and has completely outstripped the supply leading to an ever widening gap. The power sector faces many challenges today in its march towards meeting its goal of “power to all”.
Elements of a substation
Substations generally contain one or more transformers, and have switching, protection and control equipment. In a large substation, circuit breakers are used to interrupt any short-circuits or overload currents that may occur on the network. Smaller distribution stations may use recloser circuit breakers or fuses for protection of branch circuits. Substations do not (usually) have generators, although a power plant may have a substation nearby. A typical substation will contain line termination structures, high-voltage switchgear, one or more power transformers, low voltage switchgear, surge protection, controls, grounding (earthing) system, and metering. Other devices such as power factor correction capacitors and voltage regulators may also be located at a substation
Distribution substation:-
A distribution substation transfers power from the transmission system to the distribution system of an area. It is uneconomical to directly connect electricity consumers to the high-voltage main transmission network, unless they use large amounts of power, so the distribution station reduces voltage to a value suitable for local distribution.
The input for a distribution substation is typically at least two transmission or subtransmission lines. Input voltage may be, for example, 33 kV, or whatever is common in the area. The output is a number of feeders. Distribution voltages are typically medium voltage, between 0.4 and 11 kV depending on the size of the area served and the practices of the local utility.
The feeders will then run overhead, along streets (or under streets, in a city) and eventually power the distribution transformers at or near the customer premises.
Besides changing the voltage, the job of the distribution substation is to isolate faults in either the transmission or distribution systems. Distribution substations may also be the points of voltage regulation, although on long distribution circuits (several km/miles), voltage regulation equipment may also be installed along the line.
Elements of a substation in detail:-
Instrument transformers
Purpose:-
The voltage transformers and current transformers continuously measure the voltage and
current of an electrical system and are responsible to give feedback signals to the relays to enable them to detect abnormal conditions. The values of actual currents in modern
distribution systems varies from a few amperes in households, small industrial/commercial houses, etc. to thousands of amperes in power-intensive plants, national grids, etc., which also depend on the operating voltages. Similarly, the voltages in electrical systems vary from few hundreds of volts to many kilo volts. However, it is impossible to have monitoring relays designed and manufactured for each and every distribution system and to match the innumerable voltages and currents being present.
Hence the voltage transformers and current transformers are used which enable same types of relays to be used in all types of distribution systems ensuring the selection and cost of relays to be within manageable ranges.
Basic theory of operation:-
The transformer is one of the high efficient devices in electrical distribution systems,
which are used to convert the generated voltages to convenient voltages for the purpose
of transmission and consumption. A transformer comprises of two windings viz., primary
and secondary coupled through a common magnetic core.
When the primary winding is connected to a source and the secondary circuit is left open,
the transformer acts as an inductor with minimum current being drawn from the source. At the same time, a voltage will be produced in the secondary open-circuit winding due to the magnetic coupling.
POTENTIAL TRANSRORMER
Voltage transformers:-
Voltage transformers (VTs) or potential transformers (PTs) are another type of instrument transformer, used for metering and protection in high-voltage circuits. They are designed to present negligible load to the supply being measured and to have a precise voltage ratio to accurately step down high voltages so that metering and protective relay equipment can be operated at a lower potential. Typically the secondary of a voltage transformer is rated for 69 or 120 Volts at rated primary voltage, to match the input ratings of protection relays.