Coordinated Control of Voltage Balancers for the Regulation of Unbalanced Voltage in a Multi-Node Bipolar DC Distribution Network

In a bipolar DC distribution network, the unbalanced load resistance, line resistance and renewable energy source will cause an unbalanced current for each node of the neutral line and lead to its unbalanced voltage. This is a unique power quality problem of bipolar DC distribution networks, which will increase the power loss in the network and lead to overcurrent protection of the neutral line in serious cases. A voltage balancer can be adopted to suppress the unbalanced voltage and current. However, the existing literature does not consider the consistent application of multiple voltage balancers in a multi-node bipolar DC distribution network. This paper creatively proposes a consensus control topology combining primary control and secondary control in a radial multi-node bipolar DC distribution network with voltage balancers. In this paper, the formulas for the positive and negative current and duty cycle of a bipolar DC distribution network with voltage balancers are derived, and improved voltage balancer modeling based on a consensus algorithm is built. The radial multi-node bipolar DC distribution network is established in MATLAB/Simulink. The simulation results compare the consensus control with the traditional droop control and verify the effectiveness of the new control structure with voltage balancers.

Simulation of PEM fuel cell integrated DVR using SRF-ANFIS controller for power quality enhancement

Voltage related Power Quality (PQ) problems are attracting the eyes of researchers, as these cause huge loss in productivity and profitability for both utilities and consumers. Dynamic Voltage Restorer (DVR) is a well-known custom power device that provides an economical solution for the alleviation of power quality problems. Generally, battery energy storage is used as an input for DVR, but batteries are still bulky and costly and must be disposed once their chemicals are used, which limits the compensation capability of DVR. Nowadays, Fuel Cell (FC) technologies have attracted much attention owing to their high efficiencies and low emissions. This project aims to model and simulate Proton Exchange Membrane Fuel Cell (PEMFC) and is used as a DC input source for DVR. The suitable boost converter is designed and modelled to lift up the fuel cell output voltage suitable as DC link voltage for DVR. Adaptive Neuro Fuzzy Inference System (ANFIS) controller uses Synchronous Reference Frame Theory (SRF) algorithm to generate d and q axis components of reference signal for Voltage Source Converter (VSC) of DVR. This PEMFC DVR is verified for balanced and unbalanced voltage sag, swell, and harmonics using MATLAB/SIMULINK. A simulation result proves that this PEMFC DVR is capable of providing a technically advanced and economic solution for balanced and unbalanced voltage sag and swell. During compensation, the DVR DC input voltage is also preserved as constant, which enhances the compensation capability of DVR.