Microgrid Laboratory (eACCESS-MGL)

PV MODULES

These PV Modules operate to produce electric energy from solar energy. The electric energy is in the form of DC quantity so in this application, a converter which can convert this DC voltage into AC voltage is required. SCU Microgrid Laboratory implements 10 x 540 Wp Photovoltaic Module (Monocrystalline type)

BATTERIES

The batteries are functioned as energy storage elements. When the system under islanding mode, the system relies on energy from the batteries and PV modules. The batteries can be charged by energy from utility or from PV-modules. 12 units of 12V 100 Ah Lead Acid Battery are installed in SCU Microgrid Laboratory as the energy storage elements.

PV INVERTER

This inverter has capability to convert the DC voltage as the output of PV modules into AC voltage which will be transferred into the busbar. The inverter must also be functioned as maximum power point tracker to maximize the PV output power. A 4 kW three-phase inverter is used in the SCU Microgrid Laboratory. This type of such an inverter is grid follower inverter, it will act as a controlled current source so its required voltage reference from grid or from grid former inverter.

BATTERY INVERTER

This inverter has capability to convert the DC voltage from the batteries into AC. Three single-phase inverters are use to operate in three phase system. These inverters can be operated as grid former inverter or grid follower inverter. When the microgrid is connected to the grid, the battery inverters operate as grid follower inverters. Meanwhile under islanding mode of operation, such inverters operate as grid former inverters.

HOME MANAGER

This will monitors all energy flows in the system, automatically identifies potential savings and facilitates efficient use of solar energy. Intelligent energy management is thus becoming even easier and more cost-effective

SCADA SYSTEM

SCADA system must be capable to function for monitoring and controlling the system on different modes of operations. The quantities of voltages, currents, real power, reactive power, temperature and irradiation of the system must be able to be displayed on monitor graphically or in measurement numbers. Based on the measurements as the data, SCADA controls the status of the circuit breaker via the PLC.

Supervisory Control and Data Acquisition (SCADA) is a system of collecting information or data from the results of electricity measurements and then sending it to a central computer which will regulate, process, and control the data. The SCADA system is needed to handle a plant system by controlling, monitoring, marking, recording and retrieving data with a high level of complexity. The proposed SCADA system consists of a Master Terminal Unit (MTU), Human Machine Interface (HMI), Front End Processor (FEP), Data Communication Media, Remote Terminal Unit (RTU), and plants.

This SCADA system is formed by four components that have synergistic functions with each other, these components are:

• Transducer, instrumentation equipment in the form of sensors used to read analog or digital signals that are measured in the form of current, voltage, irradiance, temperature or other measurements
• Actuators (controlled contactors) are used to control equipment such as power flow connected to a PLC (RTU).
• Remote Terminal Unit (RTU), computer-based equipment that is placed at certain locations and places in the field. The RTU acts as a local data collector that gets its data from sensors and sends commands directly to the equipment in the field which functions to control the actuators and read signals from the sensors and communicate with the control center.
• The communication network is used to connect the RTU with the central station for MTU control, which can be a cable or radio network
• The Master Terminal Unit (MTU) is a computer that is used as a central processing unit for the SCADA system. This MTU provides a Human Machine Interface (HMI) for the user, and automatically adjusts the system according to the input from the sensor received.

Supervision and control functions in the SCADA system:

• Tele-signaling (TS) functions for sending signals to changes in state on the sensors that have been placed (current, voltage, irradiance, temperature). With this, it is expected that the real power, reactive power, power flow and irradiance conditions and temperature can be known in real time.
• Tele-control (TC) functions to operate the desired power flow and respond to what is desired
• Tele-metering (TM) which functions to read the desired data. The results of this monitoring are not only used as data loggers for the operation of the power flow, but can also be used in relation to remote control

One of the important things in a SCADA system is data communication between the remote system (remote station / RTU) and the control center. Communication on SCADA systems uses a special protocol, although there are also general protocols that are used. One of the protocols used in the SCADA system for electric power systems must comply with IEC Standards including IEC 60870-5-101 which is based on serial communication and IEC 60870-5-104 which is based on Ethernet communication.