8. Eaton Elect BOS Presentation for NSC conference, June '14

© 2013 Eaton. All Rights Reserved.

Electrical BOS solutions for UK grid-connected PV systems

Richard Molloy

Segment Sales – Renewable Energy

25th June 2014

2© 2013 Eaton. All Rights Reserved.

Presentation overview

• Introduction• Electrical BOS – a

definition• Component overview –

typical SLD• Design considerations• Examples• G59/3 update• Future trends


Electrical Balance Of System

• The electrical infrastructure required to gather and combine the DC power generated by multiple panels and provide a single AC power feed to the building and/or the grid


Electrical SLD, 1.3MW Eaton Beaver PlantPanels & racking

DC combiners

Inverters

AC Switchgear & transformer

Building / Grid connection & metering

DC cable

AC cable


System design topology

• Decision to be made at early stage of system design between using a few central inverters or multiple string inverters

• Each type has BOS design differences in downstream element but basic premise is the same


Design considerations

• General:• Space / location• Access for installation and maintenance• UV stability• Cable routing• Ongoing production processes• Security

• Electrical:• AC switchgear loading – must use 0% diversity factor• Cable volt drop <1% increases cable size

• Ensure terminal capacities can accept large cables


Design considerations – large sites

• Fault levels can be high• Ensure protective devices have sufficient fault current

breaking capacity• Especially problematic for string-inverter based sites

• Inter-tripping requirements – HV connected sites• The DNO is likely to have specific MV inter-tripping

requirements and this varies by DNO

• Site earthing requirements• Ensure earthing is considered up-front

• Lead times• Many BOS items can be on extended lead times


UK grid integration project locations


Complete containerised solution


1.5MW substation with t/x & POC


PV Distribution Board, 50 to 250kWp +

• Includes lockable rotary isolator, G59 protection relay, contactor, MID certified kWh meter with RS485 comms and commissioning socket

• Available from 50kWp up to 250kWp +

• Options for number / size / type of inverter inputs


160kW PV-DB with 100mA Type A TP RCBOs


EREC G59/3

• Released Sept. ‘13 – mandatory w.e.f. 1st Dec. ’14• Many minor revisions over G59/2 – plus some

substantial ones• New performance requirements for ‘type tested’

generator units (inverters)• Type testing of inverters now accepted for a wider

range of applications (versus requirement for dedicated additional protection and witness testing)

• Changes to testing & commissioning requirements• Section 12 – all very substantially revised and much of this section is new

• Changes to test sheet templates


Future trends

• On-going reductions in cost• Standardisation of site electrical design• Increase in DC voltage• Increase in AC connection voltage• Introduction of grid stability requirements

• Real-time reactive power control• Variable export power limits• Large scale energy storage solutions

8. Eaton Elect BOS Presentation for NSC conference, June '14

Engineering

Transcript of 8. Eaton Elect BOS Presentation for NSC conference, June '14