Photovoltaic Training - Session 3 - Plant Operation

Photovoltaic Systems Training

Session 3 ‐ Plant Operation

http://www.leonardo-energy.org/training-pv-systems-design-construction-operation-and-maintenance

Javier Relancio & Luis RecueroGeneralia Group

September 21st 2010

PHOTOVOLTAIC SYSTEM

Design, Execution, Operation & Maintenance

PLANT OPERATION

Javier Relancio. Generalia Group. 21/09/2010www.generalia.es

2 http://www.leonardo-energy.org/training-pv-systems-design-construction-operation-and-maintenance

INDEX

Control & Telecommunication system

Control system components & infrastructures

Control system gathered data management

Plant security

Security systems


INDEX




Plant security

Security systems


Monitoring:

To control, using specially designed devices,

the state & evolution of one or various

physiologic (or others) parameters to detect

possible malfunctions

Reasons for monitoring & control:

1.- To invoice the produced energy

2.- To detect incidences & malfunctions

3.- To guarantee the plant owner

Remote control:

Group of devices which allow us to modify the state of the equipments and devices of the

plant, from a remote location

a) Availability

b) Performance Ratio

c) Production (kWh./kWp)5

Control & Telecommunication Systems: Introduction

DC / ACInverter

Photovoltaic Array Electricity

Grid

EnergyMeter

6

This presentation is based in Grid Connected PV Facilities

Both the meters and the inverters have communications outputs to allow the monitoring

of their parameters

We can also use: calibrated cells, temperature sensors, etc

Transformer

The remote control and monitoring depend on the available mechanisms.

Both in grid connected and stand alone PV facilities, electronic devices with communication

ports and dataloggers are used in order to gather the information from the different

equipment more important parameters

Control & Telecommunication Systems: Introduction


Requirements:

Reliability: redundancy. Stable communications (wire)

Robustness: gathering errors, incidences & alarms

Solutions:

To be found in the market

Already developed.

From each manufacturer or generic (Many inverter & meter

manufacturers)

Customized solutions

They are more scalable and can be updated

7

Monitoring System

The monitoring system features will depend on the capability for

each plant to afford its cost


INDEX




Plant security

Security systems


Element Parameters Incidences

Panels ‐ String current

‐ Irradiance

‐ Module malfunctioning

‐ Isolating error

Inverter ‐ Instant power

‐ Produced energy

‐ CO2 Emissions

‐ Electronic failure (low

performance)

‐ Electric failure (stop)

Meter ‐ Produced kWh

‐ Load profile

‐Meter stop

Transformer

grid

‐ Phase voltage

‐ Frequency

‐ grid out of range

PV Facility main elements

Element Parameter Alerts / Warnings

Calibrated cell ‐ Radiation ‐ Low production, when high

radiation

Meteo Station ‐Wind speed

‐ Temperature

‐ High wind speed

Current sensors ‐ Current

‐ Voltage

‐ Overvoltage

‐ System breakdown

Protections ‐ State (ON / OFF) ‐ Trigger

Other elements within a PV facility


Sensors

Inverter

Meter

Communications

Options:

1. Design

- Wire

- Wireless

2. Logic

- Without logic:

Converter

- With logic:

Datalogger

Control Room

Server

Display

Internet

Alarms

1.Data gathering

2.Data Analysis

3.Alert generation

4.Internet communication

5.Logs

Visualization

1. Locals:

Siren

2. SMS

3. E-mail

1. BBDD

2. Web

3. Tunnel

1. VPN

2. VNC

Datalogger

RS232/485

Ethernet

RS232/485

Monitoring System. Topology


Monitoring system: Routine

Data gathering & Analysis

Correct

Performance: average or higher than average

Incidences & parameters log

Performance: lightly lower than average

Parameter analysis

Include modifications in preventive maintenance

Actions/Modifications on the system

- In situ or by Remote control

- Report generation

- Corrective maintenance order

Performance: lower than average

Failure diagnosis Alarm


Gateway Server

ON/OFF switches for system reclosing (i.e. in case of breakdown)

Tracker Control

Monitoring System

Security system

REMOTE PC

INTERNET

13

Remote control system. Basic topology


Gateway Server

Tracker

Monitoring

system

Security

System

PC REMOTO

INTERNET - Updates

- Modifications

- Configuration

- New meters & inverters

- Updates

- Modifications

- Configurations

- Updates

- Modifications

- Configuration

An advanced remote control system requires larger bandwidth and robustness

14

Remote control system. Advanced topology


Internal communications

Data transference between devices, dataloggers, Server & Gateway.

Topology:

Wireless: Bluetooth, wifi, GSM/GPRS/UMTS, etc..

Wired: RS232, RS485, Ethernet, Optical Fiber, etc..

Converters’ usage: Moxa, etc..

External communications

To communicate remotely

Topologies: RTB, ADSL, Satellite, GSM/GPRS/UMTS…

Redundancy & robustness

15

Communications


Telephone

Network (PSTN)

GPRS UMTS Radio Satellite

Coverage

Bandwidth

Reliability /

Robustness

Cost

(Installing)

Cost

(Operation)

Communications


GatewayConversor Ethernet –RS232/485

Meter BUS

Meter BUS

The electrical company remote meter reading, which is already being done in some countries,

as Spain, allows the electrical company (or the grid manager):

Avoid having dedicated staff to read the meter locally for invoicing

Receiving data from the meters, that well processed, can improve the grid performance

Modem GSM

Generator

GSM Modem

Electrical company

Gateway

Server

RS232/485

Remote Meter Reading(From the electrical company)

* In the future PLC communications could be applied


Using the same system in different facilities

A system that works perfectly for a solar facility, may not work properly in a different one

due to different devices, SW versions, communication buses, countries, etc..

Solutions compatibility

Mixing commercial solutions from different manufacturers may produce system

malfunctions due to devices response times, transference times, bandwidths, etc..

Many solutions are still under development.

Coverage failure

Isolated areas. Without Telephone Network (PSTN), ADSL, UMTS or GPRS coverage

Losing the communication channel would mean losing 90% of the system features

18

Usual problems


INDEX




Plant security

Security systems


It is the last device in the system. The one that meters the energy

injected to the grid

We have to control that we are injecting the maximum energy to the

grid

We need references:

Radiation (calibrated cell) & temperature

Others: experience, reference facilities, etc

Operation orientated monitoring

Objective:

Maximize

productivity

The most important device is the meter

Example: If the temperature is raising continuously, it could mean:

A sporadic technical failure – REPAIR

A design failure – REDESIGN

The plant could stop.

The inverter can help to prevent future malfunctions


To detect incidences as soon as possible (Real Time)

To predict some incidences & breakdowns

To solve some incidences & breakdowns

To warn the staff in the plant

The local plant staff can NEVER be replaced by any software or remote

control

It is essential to have spare parts and equipments at the plant

High electrical risk: training and protections

21

Operation Key points


Example: Valdecarábanos Solar Plant. Spain

Operation orientated monitoring


Devices:

Inverter, suntracker, protections, monitoring system, security system

NEVER the meters

Reasons:

1. Save costs.

2. Legal requirement:

Requirement from the Electric Company: remote control of the

isolation cells (of the transformer)

Depending on each country regulations, the PV plants over a

certain output power could be obliged to be attached to a

generation control center

23

Remote control system

Used to remotely control the devices in the plant

It will usually be linked with the monitoring system

Maintenance types

Corrective: to solve an incidence

Preventive: to prevent a possible incidence, before it happens.

Elements to maintain

Inverter

Suntracker

Panels (maintenance is required to a lesser extent): cleaning up,

replacement…

24

Data sending for maintenance


According to its seriousness:

Warning: minor failures. Many warnings can be expected. Generally, not

important

Alarm: serious failures. They should be minimized. They are important, and

could imply the plant stop

According to its origin:

Internal: from the inverter

External: from the plant.

DC side: from the panels to the inverter.

AC side: from the inverter to the grid

25

Inverter maintenance

Failure classification:


Isolation failure (cable without enough protection)

External failure: from the plant.

Low DC Voltage:

External failure: AC side problem (in the modules array)

MPP Tracking failure

External failure: a wrong configuration could produce a

deviation from the MPPT

Internal failure: Programming/Firmware problem

Grid voltage or frequency out of range

External failure: from the inverter to the grid

Temperature limit

26

Inverter maintenance

Usual incidences:


Orientation/Position failure

To check if it is synchronized or not

In case of strong wind, to check if it is in

protection state or not

Motor overvoltage failure.

Reducer breakdown

Limiting movement sensor

Overpass the end charging sensors without

activating the stop signal

27

Suntracking maintenance


INDEX




Plant security

Security systems


Reasons:

Expensive elements: inverters, panels, cable, etc

Many thefts

To avoid production losses (there are insurances which cover these losses)

Isolated areas

Long unattended periods (unless local staff is employed)

Great communication problems

The perfect solution does not exist.

But the best would be the combination of:

Local staff

Remote security systems

Security in the plant: Introduction


The possible security systems could be:

Local staff

Video surveillance system (CCTV)

Perimeter sensors

Panel sewing

String controllers

Infrared / Microwave controllers

Security in the plant: Possibilities

The security systems keep evolving as the thieves develop new techniques


Security in the Plan: General scheme

Source: PYSEC Seguridad

Solar plant security system

Real time mobile phone access

Real time internet access

Domo video camera

ADSL / GPRS

Control room

Optical Fiber

Acoustic & Luminous waning

Video analysis. Intrusion detection

Night mode video cameras

Local authorities warning system


INDEX




Plant security

Security systems


Advantage

Very dissuasive solution

Drawbacks

The most expensive solution (in the Long Term)

It may reduce the plant profitability

Options

Employees

Outsourcing

The optimal solution would be Local Staff & Video surveillance

Local staff (In the plant)


IP - based

Versatility

Good quality

Good transmission

Less wiring

CCTV

Closed TV Circuit

It requires dedicated

transmission buses

Video surveillance system

Source: Condev

CCTV vs IP

Recommended: IP

System

Digital Video Recorder (Encoder/Decoder)

D1 Real Time Quality

Great storage capacity

Optional:

Alarms & relays management

Remote control

Video analyzer

Using specialized software

Expensive

Movement detection

D1 Quality

- Full D1 video is 720x480.

- Cropped D1 is 704x480.

- Half D1 video is 352x480

Video Surveillance System: elements


Video cameraThey can be IP or analogical

Quality: Up to D1 (Real time)

Long distance(Several Km*)Optical Zoom: 60x

InfraredLong distance

Night viewing (when the risk is higher)

Range: 1.5Km (0.00001 lux).

PTZ Control Automatic or Manual orientation & zoom control (Joystick).

* According to specs, up to 15 km.

Video Surveillance System: elements

Perimeter sensor system

Best solution: optical fiber system

Passive system: immune to storms or electrical

systems

False alarms discrimination

Alarm if the fiber is cut

Alarm if a movement is detected

Options:

At the wall. More vulnerable

Buried. More expensive (trench)

Temperature range: -30º to 75º

Movement/Passage areas

Anti – Intrusion systems

Rubber tube Metallic tube


Presence sensor

Detects:

Infrared: thermal energy variations

Microwaves: movements

Configurable:

Alarm only if double detection

Problems in foggy areas

Alarm if any detection

False alarms

Anti-intrusion system


Panel sewing (with optical fiber)

Attached to every panel (at the backside)

Alarm if the fiber is cut

Difficult execution

Temperature range: -30º a +75º

Another option could be a conductive wire system

Depending on the wire impedance

Immune to sabotage

Anti-theft system


String Controller

Both for monitoring and security systems

During the days

It controls the power (Current/Voltage) on the panel strings

It protects the plant with integrated fuses

During the night

It detects if the electrical cable is cut/broken

Even if there is no voltage or current

This is quite a new system

Anti-theft system


Local alarm:

Siren, Lighting, Speakers

Dissuasive

Local staff:

SMS, E-Mail, Phone call

To control, or to warn the authorities

Warning the authorities:

Private entity or the public authorities

We have to consider the distance from the authorities to

the plant

Siren

Study the inputs

-Plant visibility

-Distance to the

security entity

-Etc.

Two options:

- Dissuasive: to

avoid being stolen

- To try to catch the

thief

Alarm management


Other possibilities

Virtual patrols

Nowadays, a possibility that can mean an important saving in physical surveillance is the

called "virtual patrol“

The virtual patrol simulates an ordinary guard patrol, but it is done from a remote central

of the surveillance company using a system of video cameras

Security for rooftop facilities

Usually, for this type of projects, no surveillance system is installed but the ones already

used by the clients, as this facilities are normally located in urban zones.

If the facility is located in an isolated area and the roof is not very high or difficult to

access, it is recommended to apply one of the security systems described within this

presentation

It is also recommended to have the “all risk insurance” in force.


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End of Session 3


Thank you for attending

Technology

Photovoltaic Training - Session 3 - Plant Operation