The document describes a proposed solution to problems with unreliable grid performance from voltage fluctuations and harmonic loads. The solution uses a series inverter topology with a phase locked loop to synchronize with the grid voltage and compensate for changes. Sensors measure real-time power values which are communicated via DSPs between inverters for coordinated control. The goals are to accurately measure power in real-time, transmit measurements between inverters, and develop control algorithms to compensate for grid voltage fluctuations.

1. • Unreliable grid experiences sag, swell, frequency
deviation, harmonic distortion => Unreliable
Performance of sensitive loads
• Reactive loads require power factor correction
circuits => Additional Cost
• Harmonic-inducing loads contaminate grid current
=> Inefficiency
S
Main
DSP
DSP
Communication
Network
Sensor
Network
Boost converter
Boost converter
DC/AC
Inverter
Series
DC/AC
Inverter
Parallel
Boost
converter
Boost
converter
DC/AC
Inverter
Series
PV
PV
Grid
DC/AC
Inverter
Parallel
Load
DSP
DSP DSP
• Phase locked loop will be embedded in the series invertor
• Synchronize input grid signal with generated signal
• Compensating voltage changes by tracking the grid voltage in
relation to the signal of the grid
• Measure and provide real time power
measurements to the DSPs
• Use LEM Voltage Transducer to step down
the voltage to +/- 1.5V
• External +/- 15V DC source to shift up the
voltage to 0V ~3V.
1
3
2 • Transmit different current and voltage values
from different boards to main controller
• Explore more effective communication
protocol to use for the project.
Compensates for grid
voltage disturbances
Series invertor Parallel invertor
Compensates for load
harmonic and reactive
currents
Current Problem
Proposed Solution
FYP Group:EEE-14A100 Students: Luo Jin Wei, Wivaldy Lee Wen Yi, Stephanie Kek Sok Hui
Diploma in Clean Energy Engineering (DCEG) Supervisor: Dr Chia Chew Lin Co-supervisor: Arun Nagendra, Naga Brahmendra
*PLL is implemented inside the series inverter
Our Objectives
• To design and build the sensing network will provide the accurate, precise real
time power measurement
• To build and develop a communication system which will transmit real time power
measurements between multiple DSPs for Inverter control coordination
• To develop control algorithm that will compensate any grid voltage fluctuations
via tracking of grid and inverters' voltage and phase.
S
S
S S S S S
*S => Sensor
1
2
3
Reference: “Single-Phase Inverter-Control Techniques for Interfacing Renewable Energy Sources With Microgrid-Part II: Series-connected Inverter
Topology to Mitigate Voltage-Related Problems Along With Active Power Flow Control,” IEEE Trans. Power Electron., Vol. 26, No. 3 , MARCH 2011