scholarly journals Distributed Control Strategy of Single-Phase Battery Systems for Compensation of Unbalanced Active Powers in a Three-Phase Four-Wire Microgrid

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8287
Author(s):  
Watcharakorn Pinthurat ◽  
Branislav Hredzak

Unbalanced active powers can affect power quality and system reliability due to high penetration and uneven allocation of single-phase photovoltaic (PV) rooftop systems and load demands in a three-phase four-wire microgrid. This paper proposes a distributed control strategy to alleviate the unbalanced active powers using distributed single-phase battery storage systems. In order to balance the unbalanced active powers at the point of common coupling (PCC) in a distributed manner, the agents (households’ single-phase battery storage systems) must have information on the active powers and phases. Inspired by supervised learning, a clustering approach was developed to use labels in order to match the three-phase active powers at the PCC with the agents’ phases. This enables the agent to select the correct active power data from the three-phase active powers. Then, a distributed power balancing control strategy is applied by all agents to compensate the unbalanced active powers. Each agent calculates the average grid power based on information received from its neighbours so that all agents can then cooperatively operate in either charging or discharging modes to achieve the compensation. As an advantage, the proposed distributed control strategy offers the battery owners flexibility to participate in the strategy. Case studies comparing performance of local, centralized, and the proposed distributed strategy on a modified IEEE-13-bus test system with real household PV powers and load demands are provided.

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 85 ◽  
Author(s):  
Pablo Quintana-Barcia ◽  
Tomislav Dragicevic ◽  
Jorge Garcia ◽  
Javier Ribas ◽  
Josep Guerrero

Energy management control is essential to microgrids (MGs), especially to single-phase ones. To handle the variety of distributed generators (DGs) that can be found in a MG, e.g., renewable energy sources (RESs) and energy storage systems (ESSs), a coordinated power regulation is required. The latter are generally battery-based systems whose lifetime is directly related to charge/discharge processes, whereas the most common RESs in a MG are photovoltaic (PV) units. Hybrid energy storage systems (HESS) extend batteries life expectancy, thanks to the effect of supercapacitors, but they also require more complex control strategies. Conventional droop methodologies are usually applied to provide autonomous and coordinated power control. This paper proposes a method for coordination of a single-phase MG composed by a number of sources (HESS, RES, etc.) using power line signaling (PLS). In this distributed control strategy, a signal whose frequency is higher than the grid is broadcasted to communicate with all DGs when the state of charge (SoC) of the batteries reaches a maximum value. This technique prevents batteries from overcharging and maximizes the power contribution of the RESs to the MG. Moreover, different commands apart from the SoC can be broadcasted, just by changing to other frequency bands. The HESS master unit operates as a grid-forming unit, whereas RESs act as grid followers. Supercapacitors in the HESS compensate for energy peaks, while batteries respond smoothly to changes in the load, also expanding its lifetime due to less aggressive power references. In this paper, a control structure that allows the implementation of this strategy in single-phase MGs is presented, with the analysis of the optimal range of PLS frequencies and the required self-adaptive proportional-resonant controllers.


2021 ◽  
Vol 11 (9) ◽  
pp. 3874
Author(s):  
Hyunwook Kim ◽  
Junghun Lee ◽  
Jaehyeong Lee ◽  
Gilsoo Jang

An increase in inverter-based resources (IBRs) can lower the inertia of a power system, which may adversely affect the power system by causing changes such as a frequency nadir reduction or an increased initial rate of change of frequency (RoCoF). To prevent this, an ancillary service called fast frequency response (FFR) helps the inertia response by using IBRs. The main resources used in FFR are variable-speed wind turbine generators (VSWTGs) or energy storage systems (ESSs), which can respond quickly through converter control. The control is applied to the frequency regulation service faster than the primary frequency response, so the second frequency nadir may fall below the first frequency nadir. This study proposed a novel coordinated control strategy to efficiently utilize energy to improve the frequency nadir through coordinated control of wind turbines based on permanent magnetic synchronous generators (PMSGs) and battery energy storage systems (BESSs). The simulation results confirmed that the two-bus test system was composed of PSCAD/EMTDC, and the frequency nadir increased by utilizing the same amount of energy as in traditional control systems.


2014 ◽  
Vol 573 ◽  
pp. 747-756 ◽  
Author(s):  
B. Karthik ◽  
Jerald Praveen Arokkia ◽  
S. Sreejith ◽  
S. Rangarajan Shriram

Application of Flexible AC Transmission Systems (FACTS) devices in a power system is a promising and more efficient way for the transfer and control of bulk amount of power. One of the problems encountered in power-systems operation is the generation of unbalanced voltages and currents in the presence of long transmission lines with few or no transpositions. This includes possible unbalances arising in source and load conditions, or indeed any items of plant such as shunt and series reactors. To improve or investigate these unbalance effects in any detail, a 3-phase load-flow solution that allows representation of all possible unbalances as they exist in the power-systems network without making any assumptions is essential. This paper deals with the three phase power flow incorporating Static Var Compensator (SVC). Here SVC is modeled using variable reactance modeling technique and incorporated into the single phase and three phase load flow. Newton Raphson power flow algorithm is adopted here. The performance of SVC to control the power flow and regulating voltage in the network is discussed. The performance analysis is carried out for 4 case studies namely single phase power flow, single phase power flow with SVC, three phase power flow and three phase power flow with SVC. The change in power flow and losses due to the unbalanced load condition in the three phases in illustrated. The studies are carried out in a standard 5 bus test system. Keywords: Three Phase Power flow, Static Var Compensator, Unbalanced system, Negative sequence components, Zero sequence components.


Sign in / Sign up

Export Citation Format

Share Document