1

A write up on a 5 MW solar plant visit Shivana samudra Banglore

STATION EQUIPMENTS

Solar power plant Equipments Familiarized

Solar Panels Array Junction Box Inverters Step up transformers Relays Battery charging units Signal conditioning device SCADA systems

SOLAR PANELS

Solar panels

2

A solar panel is a set of solar photovoltaic modules electrically connected and mounted on a supporting

structure. A photovoltaic module is a packaged, connected assembly of solar cells. The solar panel can be used as a

component of a larger photovoltaic system to generate and supply electricity in commercial and residential

applications. Here a panel consists of 60 cells in series and each of them having capability of supplying 36v output.

In this power plant 12 panels are included in a single structure.Such two structures are connected together to form

an array. There are 990 total arrays are mounted in the plant. Output from 288 panels is connected to one array

junction box. This will give a total output of 63.5KW.For connecting each panel to the AJB 65sqmm cables are

used. For connecting these AJB s to inverters 95 sqmm cables are used.

ARRAY JUNCTION BOX

Array junction box

Array Box is a junction box which allows several photovoltaic strings (from 8 to 32) to be connected in

parallel. The total DC power is then distributed to the photovoltaic inverter. It includes photovoltaic string

protection, overvoltage protection and a DC output switch disconnector. They are well adapted for Power plants as

well as for photovoltaic large buildings The Array Box also integrates a monitoring module and communicates

through Modbus protocol with the monitoring devices (iRIO, XLRIO) located in the inverter substation. For each

string of panels, Array Box realizes DC current measurement (0 to 20A per string). The DC voltage (up to

1000Vdc) is also measured and abnormal behavior or failures are detected. Array Box can also propose safety

opening control and remote control of the switch disconnector.In Shivanasamudra power plant a panel consists of

60 cells in series and each of them having capability of supplying 36v output. Here 12 panels are included in a

3

single structure. Such two structures are connected together to form an array. There are 990 total arrays are there in

this plant.A total output from 288 panels is connected to one array junction box. This will give a total output of

63.5KW

Benefits Minimize Power Plant downtime

Ensure the security of the plant

Opt for a preventive maintenance rather than a curative maintenance

Reduce the on-the-field operation time

INVERTERS

Inverter

The output of array junction boxes is connected to common bus bars and again they coupled to an inverter.

Inverter converts DC output of the array junction box to alternating current. The output of the inverter is 415 V.

Benefits

True bankability

Higher return on investment

Designed for reliability

Flexible

Easy to service

Easy to install

4

STEP UP TRANSFORMERS

Fig 7.1 Step-Up transformer

A step up transform increased input voltage in a circuit. A transformer is a simple passive device created

from wound coils of wire on two separate circuits. Constructing it with fewer wire coils on the output as compared

to the input, the output voltage is increased proportionately. In the solar power plant the outputs of the solar cells

inverted and we will get a Ac of 415 v.This 415 v is stepped up to 11 KV and again stepped up to 66 KV for

feeding to the grid.

5

Name plate details of the transformer in the power plant

6

RELAYS

Relays

A relay is an electrically operated switch. The three basic types of relays include reed relays, mechanical

relays and solid-state relays. Many relays use an electromagnet to operate a switching mechanism mechanically, but

other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power

signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be

controlled by one signal. A type of relay that can handle the high power required to directly control an electric

motor or other loads is called a contractor. Solid-state relays control power circuits with no moving parts, instead

using a semiconductor device to perform switching. Relays with calibrated operating characteristics and sometimes

multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power

systems these functions are performed by digital instruments still called "protective relays".

7

BATTERY CHARGER

Battery charger

In the plant a 100V dc battery charger is used to extensively for the purpose of charging the batteries to

provide back up for the station auxiliaries

8

RID EXPORT CONDITIONERS

Grid export conditioners

The dc output of the AJB is converted to AC and stepped up to 11 KV and fed to a system called grid export

conditioner. This will monitor various parameters like voltage, current, frequency and power before supplying it to

the grid.A total of 12 conditioners are being used.

9

10

SCADA SYSTEMS

SCADA user interface

The operation of the whole plant is monitored and controlled by SCADA system provided by the vendors of

grid conditioners.

As we can see above the 5 MW total output of the plant is segmented in to 5 groups each of them having 1

MW.Again they are feeding the conditioning device. Through the conditioning device they will feed the step-up

transformer equipped with buchholz relay and then breaker. At the end each 1MW combines to form 5MW and

supplied to the grid. We can also monitor how much co2 emission we prevented using the solar panels.