05-10-2016, 09:25 AM
1457757214-50KVAGSCsystem.pdf (Size: 847.55 KB / Downloads: 6)
The DSP based three phase Grid Support Conditioner (GSC) utilizes a bi-directional inverter
module to supply conditioned power to a dedicated local load and operates as a single
conversion on-line UPS. The inverter module can operate either in a ‘stand alone’ mode or in
a ‘grid tied’ mode with a utility mains supply. The power to the local load will usually be
supplied from the utility grid and can be supplemented from the renewable input via the
inverter. Any excess renewable energy can be exported into the utility supply to realise the
highest overall efficiency for the system. Battery charging will automatically occur from the
utility supply to maintain the battery bank at its float voltage. In the event that the utility
voltage or frequency moves out of its operating range or was lost, the utility supply will be
disconnected and the load will be supplied directly from the battery via the inverter with no
interruption to the power fed to the load (stand alone mode).
Operation with a backup genset can be provided as an optional extra to ensure that the
batteries are not subjected to excessive discharge cycles state during periods of extended
utility supply outages. The backup genset will also start if the inverter is overloading during
excessive peak load demands. Once the utility is back online, the control will unload the
genset and switch over to the utility supply. The genset will proceed through its shutdown
sequence and then switch off.
SYSTEM COMPONENTS:-
The overall system can consist of up to six main cards as described below:
a) Digital Signal Processor card (DSP)
b) Multi Interface Card (MIC)
c) Input Extender Card (IEC)
d) Keypad & Display Interface (KDI)
e) Power Driver Card (PDC)
f) Solar Driver Card (SDC)
a) Digital Signal Processor Card (DSP)
The DSP card contains the main control processor for the hybrid system along with the
complete 3 phase PWM generation for the inverter module. It includes hardware for serial
communications to a dedicated modem as well as modbus based communication ports for the
Keypad & Display Interface including local serial communications. It utilizes 12 bit signal
processing for very fast and accurate sampling and control.
b) Multi Interface CARD (MIC)
The Multi Interface Card (MIC) monitors all the AC resource parameters such as voltage,
current, and frequency; and DC parameters such as battery volts, current, temperature, solar,
wind charge currents and various other digital inputs. It also is the main digital I/O portal for
all the system control. Gain and offsets are handled in the digital domain making the setup of
the card very easy to accomplish. It includes LED status indicators for all actions of the
hybrid control as to assist in debugging problems with the system.
c) Input Extender Card (IEC)
The Input Extender Card (IEC) provides a suitable interface for dedicated external
monitoring devices such as Solar Radiation, Wind Speed, Fuel Flow and Fuel Level along
with dedicated site kWh metering from an external meter
d) Keypad & Display Interface (KDI)
The Keypad & Display Interface Module operates in conjunction with the front panel keypad
membrane panel and a 40 x 4 character liquid crystal display (LCD) to provide a HMI
(human-machine-interface) to the outside world. All modes of operation, fault conditions,
instantaneous system parameters, set points and system events can be accessed via this
medium.
e) IGBT Power Driver Cards (DRV-1,2,3)
Each Half-Bridge IGBT Power Driver Card (PDC) receives low voltage PWM drive signals
from the DSP card via the Drive Interface Card (DIC) and provides the necessary isolated
gate drive for up to two parallel, half-bridge IGBT modules. Peak current protection of the
IGBT modules is provided by monitoring the saturation voltage of the individual top and
bottom IGBT and inhibiting the drive if the voltage exceeds a preset limit. All the drive
signals to the card are optically isolated for high noise immunity. Each phase of the inverter
requires two of these cards.
f) Solar Driver Card (SDC)
This card provides the required isolated drive to control an IGBT connected in series with the
PV input into the DC link (battery bank). On standard PWM Solar Charge systems, it
regulates the average flow of current into the DC Link (battery bank) by pulsing the IGBT
ON and OFF at approximately 100Hz based on an isolated drive signal derived from the
MIC. On integrated MPPT charger systems, it receives a 16kHz PWM signal from the
DSP to perform the necessary MPPT control.
SYSTEM BLOCK DIAGRAM
GSC SYSTEM
The block diagram below shows the basic components of the Grid Support Conditioner
system. Please note that the diesel generator is only required as a backup option in some