SUNSYS HES L - 551697A - SOCOMEC
21
EN
3.6. Modes of operation
The system is designed to operate in the following modes of operation:
Figure 10. Modes of operation of SUNSYS HES L
3.6.1.
On Grid Mode
SUNSYS HES L is a Grid Follower, meaning output voltage and frequency are imposed by the mains. The C-Cab operates
according to active and reactive power set-points, provided by PMS/EMS, to exchange active and reactive power with the
mains, both in injection and absorption.
When operating in On-Grid, the C-Cab is a grid-tied AC current generator controlled as a Current Source Inverter. AC
current exchanged with the mains is controlled by an inner current control loop, driven by P and Q set-points.
During this Operation Mode all the criteria defined in the Grid Codes are met, from the point of view of both Interface
Protection Requirements and Grid Support Functionalities.
When operating in On-Grid Mode, it provides Grid Support functionalities being properly a grid support utility interactive
device as defined by UL1741SA 2nd rev. August 03 2020.
The converter has also been designed to UL1741 CRD (March 2019, Power Controls Systems) with two modes of
operations being possible:
- Unrestricted Mode
: The ESS may import active power from Area EPS while charging and may export active power to the
Area EPS while discharging.
- Import Only Mode
: The ESS may import active power from the Area EPS for charging purposes but shall not export
active power from the ESS to the Area EPS.
3.6.2.
Off-Grid Mode
SUNSYS HES L is a Grid Former, meaning output voltage and frequency are imposed by C-Cab itself.
In this operating mode the C-Cab is controlled as a Voltage Source Inverter. Active power and reactive power exchanged
with the bus depend on loads and generators connected to AC bus (Microgrid).
The C-Cab is disconnected from the grid and it autonomously manages the microgrid parameters such as voltage,
frequency and phase accurately. The Off-Grid Mode is also called grid-forming mode.
For specific Seamless Islanding operation, it is necessary to add a cabinet, in addition to the C-Cab, that includes:
•
A protective relay*
at PCC (Point of Common Coupling) connected on the C-CAB (Ethernet and dry contact) and use for :
- Grid reconnection : Synchronism Check
- Unintentional islanding Detection with ROCOF (81R), Fast ROCOF (81 RF) and Vector Shift (78) capabilities
•
A motorized Breaker**
with additional relay (Mx) with the capabilities to perform an opening in below than 50ms
•
Additional measurement***
connected to the C-CAB for load and other sources (Renewable, Genset, …
•
Synchro Compact Core
– CRE Technology card
