Multiterminal Medium Voltage DC Distribution Network Hierarchical Control

Abstract

In this research study, a multiterminal voltage source converter (VSC) medium voltage DC (MVDC) distribution network hierarchical control scheme is proposed for renewable energy (RE) integration in a co-simulation environment of MATLAB and PSCAD/EMTDC. A DC optimal power flow (DC OPF) secondary controller is created in MATLAB. In PSCAD/EMTDC, the main circuit containing the adaptive DC voltage droop with a dead band and virtual synchronous generator (VSG) based primary controller for the VSCs is implemented. The simulation of the MVDC network under the proposed hierarchical control scheme is investigated considering variations in wind and solar photovoltaic (PV) power. The network is also connected to the standard IEEE-39 bus system and the hierarchical scheme tested by assessing the effect of tripping as well as restoration of the REs. The results show that during random variations in active power such as increasing wind and PV power generation, a sudden reduction or tripping of wind and PV power, the primary controller ensures accurate active power sharing amongst the droop-based VSCs as well as regulates DC voltage deviations within the set range of 0.98–1.02 pu with an enhanced dynamic response. The DC OPF secondary control optimizes the system’s losses by 38% regularly giving optimal droop settings to the primary controllers to ensure proper active power balance and DC voltage stability. This study demonstrates that the hierarchical control strategy is effective for RE integration in the MVDC distribution network.

On the Efficiency in Electrical Networks with AC and DC Operation Technologies: A Comparative Study at the Distribution Stage

“…Presently electrical distribution networks are essential systems in economic development around the word [1,2]; these grids are also responsible for distributing energy from large-scale power systems to all end users at medium and low voltage levels [3], which implies that in terms of size, the distribution networks are the lengthiest infrastructure inside of the power system [4,5]. This is important since higher losses can be presented at distribution networks in comparison to power systems (transmission and sub-transmission networks), e.g., in the Colombian context, energy losses at distribution networks can be between 6% and 18% while losses at transmission networks can be between 1% and 2% [6].…”

A Mixed-Integer Conic Formulation for Optimal Placement and Dimensioning of DGs in DC Distribution Networks

“…Direct current (DC) distribution networks have attracted much attention in recent years in specialized literature [1], since these networks have better voltage profiles [2] and low energy losses [3]. They are easily controllable since frequency or reactive power are nonexistent concepts in these electrical networks [4].…”

“…They are easily controllable since frequency or reactive power are nonexistent concepts in these electrical networks [4]. In the literature, multiple approaches regarding DC networks have been described, such as control methodologies for power electronic converters that interface renewable energies [5] and batteries [6], optimization approaches associated with power losses minimization [2] and analysis of convergence algorithms for power flow analysis [7].…”

Hybrid GA-SOCP Approach for Placement and Sizing of Distributed Generators in DC Networks

“…Recently, the study and analysis of direct current (DC) networks have increased, due to the development of power electronics, advances in renewable generation, and the advantages over alternative current (AC) networks [1,2]. Initially, the DC networks began to operate at high-level voltages in the power transmission for long-distance between systems, since it allows for reducing transmission power losses, enhancing grid stability systems, easily incorporating off-shore wind systems, and managing power flow both direction simply [3][4][5]. Consecutively, the integration of the DC networks has been widened to medium-and low-voltage level applications, generating concepts, such as the microgrids [6,7].…”