Claims:We claim:
1. A photovoltaic system with indoor substation for greater reliability and safety, the system comprises:
a solar panel array of series parallel combination placed outside to absorb sunlight and generate electricity;
a power conditioning unit connected to the solar panel array to convert low voltage DC power from solar panel array into low voltage three phase AC power;
a transformer connected to the power conditioning unit to increase the low voltage three phase AC power to required voltage; and
a circuit breaker in connection with the transformer to protect the present system from damage caused by excess current from an overload or short circuit
characterized in that
the transformer used is a dry type transformer with no enclosure to provide extra cooling to the transformer; and
the power conditioning unit, the transformer and the circuit breaker is arranged in indoor substation.
2. The system as claimed in claim 1, wherein the power conditioning unit includes an inverter.
3. The system as claimed in claim 2, wherein the inverter is thyristor based inverter working on the principal of frequency modulation.
4. The system as claimed in claim 1, wherein the power conditioning unit is fed with 3 phase AC signal from the grid supply system to match frequency of output from the power conditioning unit with frequency of the grid voltage supply.
5. The system as claimed in claim 1, wherein the power conditioning unit introduces some harmonics that becomes an integral part of the AC supply output from the power conditioning unit.
6. The system as claimed in claim 1, wherein the connections between various equipment of the substation is done by cables running on cable trays inside the substation.
, Description:A PHOTOVOLTAIC SYSTEM WITH INDOOR SUBSTATION FOR GREATER RELIABILITY AND SAFETY
TECHNICAL FIELD
[0001] The present disclosure relates to a photovoltaic system with indoor substation for greater reliability and safety.
[0002] More particularly, the present disclosure relates to a photovoltaic system having power conditioning unit, transformer and circuit breaker employed in indoor subsystem instead of outdoor.
BACKGROUND
[0003] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0004] Energy demand has been increasing steadily along with the development of the state. Electric power is the easiest form of energy that can be utilized for different segments of industry for development of society. However, conventionally electrical power is generated by fossil fuel or gas and Hydropower. Hydropower is generated from large water sources dependent on rainfall on the vast catchment area and investment of large capital and infrastructure and rehabilitation of people. Fossil fuel plant needs huge capital and infrastructure, continuous supply of coal and maintenance with added problem of environment pollution and global warming. The other sources of power generation like Nuclear always puts additional problem of disposition of nuclear waste.
[0005] In view of limited conventional energy sources and their limited exploitation and increasing environmental pollution, production of energy based on new and renewable energy sources is given high priority and promotion. The alternative source of power like Solar and Wind energy attribute to Green energy generation that is harmless and environment friendly. Unlike the conventional power plants including wind energy (which is restricted to windy locations – seashores and mountain top) the Solar energy is abundantly available everywhere and generated in a decentralized manner.
[0006] Photo Voltaic System is the most efficient and convenient method of generation of electric energy from solar Irradiation. In a Photo Voltaic system of electric power generation, solar irradiation is captured by solar panels that convert the solar irradiation into low voltage DC electrical power.
[0007] This low voltage DC electrical power is converted into AC electric power which is modulated to be compatible with the requirement of utilities in terms of frequency and harmonics. This power is stepped up by a transformer and synchronized with the supply grid of the utility.
[0008] Thus a Photovoltaic power system basically comprises of Solar panels, Inverter, Transformer and Circuit breakers. While the inverter is necessarily indoor equipment, the Transformer and circuit breakers are conventionally outdoor equipment.
[0009] Conventionally, transformers are employed outside which make them vulnerable to lightening. Further, oil cooled transformer is frequently used outside which have higher chances of catching fire. The conventionally used system is not reliable as time to time maintenance is required for their proper working. Also, conventional systems are not completely safe.
[0010] Hence, there is a need to for designing a photovoltaic system with indoor substation for greater reliability and safety.
OBJECTS OF THE DISCLOSURE
[0011] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed hereinbelow.
[0012] General object of the present disclosure is to provide a photovoltaic system with indoor substation for greater reliability and safety.
[0013] Another object of the present disclosure is to provide a photovoltaic system with indoor substation which is maintenance free.
[0014] Another object of the present disclosure is to provide a photovoltaic system with indoor substation having a transformer which is less fire hazardous that conventional oil type transformer.
[0015] Yet another object of the present disclosure is to provide a photovoltaic system with indoor substation having a transformer with reduced ambient temperature, permitting higher range of temperature rise and higher level of harmonics from inverter.
[0016] Yet another object of the present disclosure is to provide a photovoltaic system with indoor substation having no need for maintenance of cable used for interconnecting inverter, transformer and circuit breaker.
[0017] Still yet another object of the present disclosure is to provide a photovoltaic system with indoor substation having protection from lightning flash.

SUMMARY
[0018] This summary is provided to introduce a photovoltaic system with indoor substation. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0019] The present subject matter discloses a photovoltaic system with indoor substation for greater reliability and safety. The present system comprises a solar panel array of series parallel combination placed outside to absorb sunlight and generate electricity, a power conditioning unit connected to the solar panel array to convert low voltage DC power from solar panel array into low voltage three phase AC power, a transformer connected to the power conditioning unit to increase the low voltage three phase AC power to required voltage and a circuit breaker in connection with the transformer to protect the present system from damage caused by excess current from an overload or short circuit.
[0020] In an aspect, the transformer used is a dry type transformer with no enclosure to provide extra cooling to the transformer.
[0021] In an aspect, the power conditioning unit, the transformer and the circuit breaker is arranged in indoor substation.
[0022] In an aspect, the power conditioning unit includes an inverter.
[0023] In an aspect, the inverter is thyristor based inverter working on the principal of frequency modulation.
[0024] In an aspect, the power conditioning unit is fed with 3 phase AC signal from the grid supply system to match frequency of output from the power conditioning unit with frequency of the grid voltage supply.
[0025] In an aspect, the power conditioning unit introduces some harmonics that becomes an integral part of the AC supply output from the power conditioning unit.
[0026] In an aspect, the connections between various equipment of the substation is done by cables running on cable trays inside the substation.
[0027] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of a systems that are consistent with the subject matter as claimed herein, wherein:
[0029] FIG. 1 illustrates layout plan inside the indoor substation of a photovoltaic system.
DETAILED DESCRIPTION
[0030] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0031] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0032] Photo Voltaic cells absorb the sunrays and generate electricity. Large number of solar cells are grouped together to form a solar panel. The combined electrical power output of the individual cell is known as the power output of a solar Panel. Thousands of panels are arranged in arrays of series parallel combination so as to form the consolidated power output from the solar field.
[0033] Reference may be made to figure 1 illustrating present sytsem according to an embodiment. The power generated by solar panel array is DC power of varying magnitude. The magnitude of the power depends on the level of solar irradiation impinged and absorbed by different solar panels. The low voltage DC power is fed to power conditioning unit. The power conditioning unit has thyristor based inverter working on the principle of frequency modulation. The power conditioning unit convert the DC power from solar field into low voltage 3 phase AC power . The power conditioning unit is also fed with a 3-phase AC signal from the Grid supply system which acts as a reference. The frequency of the AC power output from the power conditioning unit is modulated so that frequency of the output is matched with the frequency of the grid voltage supply. During conversion of the solar power from DC power from Solar field to AC power by power conditioning unit, some harmonics are also generated, which becomes an integral part of the AC supply output from the power conditioning unit.
[0034] AC Power from the power conditioning unit is fed to the transformer for increasing the voltage to a higher level equal to the required voltage of the utility.
[0035] In the present subject matter, a dry type transformer is utilized in-lieu of conventional oil type transformer. In the system, the basic advantages of Dry type transformer are availed. The basic advantage of Dry type transformer is that it is maintenance-free transformer. In addition, since there is no oil inside the transformer, there is no chance of fire hazard. By putting, the transformer inside control room it is also not effected by the lightning strike, which is otherwise a potential danger to the working of the transformer.
[0036] The present subject matter, employes a Dry type transformer with no enclosure in the transformer. This gives added advantage of extra cooling to the transformer due to more cooling surface area of the transformer i.e the transformer can be overloaded in terms of extra current due to harmonics in the input power from the power conditioning unit. The input to the transformer is AC power at low voltage from power conditioning unit and the output is AC power at high voltage equaling the utility supply voltage.
[0037] All the connections between different equipment viz. connections from power conditioning unit to the transformer, from transformer to circuit breaker (used for synchronizing) are done by Cables running on cable trays inside the indoor substation. So, there is no chance of cable fault, which could otherwise generate a short circuit on the transformer.
[0038] The present system utilize the Open type Dry type transformer for extra safety and reliability. Extra safety and reliability features are brought in terms of additional withstand capacity, lightning strike, short circuiting, over loading, higher harmonics.
[0039] Further, it will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope.
[0040] Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.
[0041] Further, it will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope.
[0042] Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.
[0043] The above description does not provide specific details of the manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[0044] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0045] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0046] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.