Post on 21-May-2020
Next generation PV Systems must be flexible to accommodate large-scale plants in a variety of locations throughout the globe. Utility-scale inverters will maximize the degree of system integration so that fewer additional components are required.
MAXIMUM INTEGRATION OF COMPONENTS SIMPLIFIES PLANNING AND DESIGN WHILE REDUCING BALANCE-OF-SYSTEM COSTS BY INCLUDING:» Integrated control power transformer (green power) » Integrated housekeeping transformer for customer loads» Integrated tracker supply transformer » Two managed switches support with selectable
redundancy protocols (RSTP or MRP)
THE INVERTER’S ROLE IN LIFETIME PROJECTSECURITY AND PROFITABILITY KEN CHRISTENSEN, GLOBAL PRODUCT MANAGER, SMA AMERICA
OPTIMIZATION OFUTILITY-SCALE PV SYSTEMS
Project developers, EPCs, utilities, financiers and other PV project stakeholders are relying on utility-scale photovoltaic systems for long-term energy production and profitability. These systems have proven to be viable sources of electricity as their power-producing capacity is realized. However, PV system technology must continue to advance and decrease the cost of producing electricity in order for this trend to continue. Utility-scale PV systems must be optimized to provide maximum energy harvest at the lowest overall cost, while also minimizing risk to investors.
PLANNING & DESIGN
INSTALLATION &COMMISSIONING
LIFETIMEOPERATION &
MAINTENANCE
LOGISTICS
The project lifecycle is a value chain that begins with system design and extends throughout the 20+ year lifetime operation of the PV plant. Optimized inverter solutions bring value to every stage of the process and contribute to greater PV project profitability.
A complete DC to AC solution from one source reduces project management and logistical costs. The compact design of next generation inverters along with the optimal power block size allow for a higher power density which reduces transportation and shipping costs.
Optimized PV systems utilizing advanced inverter technology benefit from increased construction velocity through reduced site work, installation labor, and special equipment requirements. PV systems must enable fast, worry-free commissioning around the globe and must meet any foreseeable grid connection requirements.
Meeting the needs of utilities and grid operators ensures consistent energy production without delays, contributing to overall system profitability. In addition, a high level of serviceability from an experienced partner who offers comprehensive O&M is critical to lifetime system optimization.
OPTIMAL BLOCK SIZE WILL REDUCE THE INSTALLED COSTS OF A PV SYSTEM
The specific cost of an inverter will reduce to the point that the AC and DC switchgear have to be increased in size. At that point, the inverter specific cost increases exponentially.
DC home runs increase linearly until the cable diameter increases, to the point where the cable becomes difficult to work with. At that point, construction and labor costs increase dramatically.
The ideal block size to optimize system costs globally is 1.9 to 2.2MVA.
EXPANDED ENERGY HARVEST WITH HIGHER DC: AC RATIOS » Increased Energy » Time-of-Day (TOD) Optimization» Eliminate DC Curtailment
As the DC: AC ratio increases, the time that the PV system delivers maximum power also increases. In addition, more energy is produced later in the day when electricity is most valuable. The result is an overall increase in energy production and reduced system capital expenditures which both contribute to greater system profitability.
Utility-Enabled Inverters» Remotely controllable parameters» VAR production technology» Sub-cycle control capabilities
High Speed Communication Network» 1 ms propagation /
processing delays
Intelligent Power Control – Utility Cornerstone» Fast response control network
and inverters» Advanced grid integration features» Abnormal voltage and
frequency assistance» Coordinated inverter and
storage controls» Balancing distributed generation
(DG) assets
ELEMENTS FOR ADVANCED GRID INTERACTION
A comprehensively engineered solution suite with a maximum degree of system integration will optimize and secure the entire PV system for the life of the plant.
Reduced capital costs, reduced operational costs and at the same time increased energy yields over the complete lifetime makes PV projects profitable at all project stages.
Optimized solutions will minimize the project risk during all stages: from the predictable and reliable speed to energization throughout the lifetime of the investment.
INVERTER DESIGNSH E A V I LY I M P A C TTHE OPTIMIZATION OF THEENTIRE PV SYSTEM
OPTIMAL BLOCKLOWER COSTS
PV GRIDMANAGEMENT FUNCTIONS» Remote on/off» Active power (P) set point (kW)» Reactive power (Q) set point (kVAR)» Reactive power fixed power
factor: Cos(φ)» Q-on-demand» Reconnect delay control» Reconnect ramp rate control
» Ride-through (LVRT, HVRT, ZVRT)» Setpoint slew-rate control» Scheduled commands / ”supermodes”» Autonomous frequency / watt control» Closed-loop Watt / VAR control» Closed-loop volt / VAR control PV Power plant optimization and profitability
is further enhanced with ongoing operations and maintenance performed by a strong service organization that can draw on comprehensive bench strength.
Adding storage to a PV power plant enables frequency response and other advanced grid stabilization functions. This diagram depicts the frequency response requirements of many less-tolerant grids such as those on an island.
GRID STABILIZATION - FREQUENCY SUPPORT
TechnologyLeadership
ProfessionalServices
PVExperience
PV Focus
SystemPerformance
Operations &Maintenance
Quality
FinancialStrength
ApplicationEngineering
Safety
InverterExperts
Commitment
Bankability
IndustryStandards BOS
Experts
Technicians
Capacity
Reliability
MediumVoltage
GridManagement
Experts
MasterElectricians
Tools &Training
Spare PartsManagement
3rd PartyContract
Management
Logistics/AssetManagement
ProjectManagement
O&MO&M
PROJECT LIFECYCLEBLO
CK SIZE
UNITS TO
COM
MISSIO
N
UNITS TO
TRANSPO
RT
UNITS TO
MAIN
TAIN
FOUN
DATION
S TO PO
UR
EQUIPM
ENT TO
SET
THE TWO FACTORS THAT HAVE THE GREATEST IMPACT ON THE OPTIMAL BLOCK SIZE ARE THE INVERTER COST AND DC HOMERUN COST
2012 2015
SYSTEM COST1000Vdc, 360Vac System
Block Size (MWac)
Total System CostInverterMV TransformerMV SwitchgearSkidDC Homerun
SYST
EM C
OST
DC: AC Ratio