Diversifying the Role of Distributed Generation Grid-Side Converters for Improving the Power Quality of Distribution Networks Using Advanced Control Techniques

Abstract

Diversifying the role of grid side converters (GSC) associated with distributed generation (DG) may have a technical and economic impact. The increasing number of residential photovoltaic systems can be exploited by distribution network (DN) operators in order to support and improve the power quality of the grid without considerable further capital investment. The GSC can support the grid during abnormal conditions but may also be used to improve the DN power quality by balancing out asymmetries and alleviating the grid from undesired harmonics. The proposed advanced control technique demonstrates through simulation and experimental results that the role of GSC can be upgraded to improve the power quality of the grid. Furthermore, the proposed control scheme is validated on a realistic low-voltage DN using data from the Cyprus Electricity Authority. Consequently, conventional practices by distribution network operators for improving the power quality can be reassessed as the necessary power electronics hardware for mitigating grid problems are already present within the GSCs of DG systems.

Photovoltaic reactive power compensation scheme: An investigation for the Cyprus distribution grid

“…An LCL filter is employed after the GSC to enable the injection of high quality currents. The control of GSC is designed in a synchronous reference frame (SRF), where an error signal is provided to a Proportional Integral (PI) controller along with the feedforward and cross-coupling terms [10]. The GSC control system mainly consists of an active/reactive power controller, a current controller, and a synchronization scheme [8,11].…”

“…The synchronization scheme, usually a Phase-Locked Loop (PLL), is the key element in the control process [14][15][16][17][18][19] since it extracts the necessary phase, frequency and amplitude information from the grid voltage. The extracted information is required for SRF transformations and implementation of current controller's feedforward terms [10,20]. This synchronization is achieved using an advanced PLL algorithm that can work under any abnormal grid condition [14] and the current controller that enables the injection of high quality current according to [10].…”

“…The extracted information is required for SRF transformations and implementation of current controller's feedforward terms [10,20]. This synchronization is achieved using an advanced PLL algorithm that can work under any abnormal grid condition [14] and the current controller that enables the injection of high quality current according to [10]. The design parameters for the power system, renewable energy system and tuning parameters for the current controller and PLL are listed in Table I.…”

Phase Balancing and Reactive Power Support Services for Microgrids

“…However, the development of these solutions come with a significant capital cost for the system operator or for the consumer. Another solution to compensate loading asymmetries and harmonic distortions at the building level is proposed in References [24][25][26]. The grid tied inverter of a PV or ESS is enhanced with advanced capabilities to compensate prosumer asymmetries.…”

A Sensor-less Control Scheme for Grid Tied Inverters to Provide Phase Balancing Services to the Distribution Grid

“…The inverter controller receives local measurements for the load currents and subsequently an adaptive observer and a triangular function are used respectively in order to analyze the distortion that needs to be compensated. In [9], the grid tied inverter compensates the asymmetric loading conditions of the prosumer by providing phase balancing services, while in [10] and [11] the grid tied inverter compensates both asymmetries and selected harmonics of the building load. In [9]- [11], a decoupling network is used to decompose the load currents to their positive and negative sequence components in order to enable phase balancing and active filtering operation.…”