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This paper proposes a control architecture of distributed generators (DGs) inverters and shunt active power filters (APFs) in microgrids to compensate voltage harmonics in a coordinated way. For this, a hierarchical control structure is proposed that includes two control levels. The primary (local) control consists of power controllers, selective virtual impedance loops and proportional-resonant (PR)...
This paper discusses the Alberta's experience of coordinating High Voltage Direct Current (HVDC) line operation with under-voltage Remedial Action Scheme (RAS). The integration of two 500 kV HVDC transmission projects in the Alberta Interconnected Electric System (AIES) has some impacts on AC system voltage recovery after clearing three phase faults. The resuming of power transfer on HVDC inverters...
The operation of a photovoltaic (PV) generating system under intermittent solar radiation is a challenging task. Furthermore, with high penetration levels of photovoltaic energy sources being integrated into the current electric power grid, the performance of the conventional synchronous generators is being changed and grid inertial response is deteriorating. This paper proposes a combined virtual...
Recently, Queensland state of Australia has seen a rapid growth in rooftop solar photovoltaic (PV) installations. However, the growth can be throttled due to voltage violation constraints at the distribution feeder level. Consequently, distribution utilities in Queensland have set a guideline for new PV inverter connections. During light load condition and under high availability of PV power, voltage...
Increased integration of distributed energy resources (DER) depends on addressing a number of technical challenges, both on the planning side—the interconnection process—and likewise how the DER interacts with distribution operations. These two domains are obviously linked. This paper presents the results of the first phase of a project considering the testing and demonstration of DER and a real-time...
Modernized grid needs ancillary service as a variety of distributed energy resources are connected. Vehicle-to-grid (V2G) application is one of promising distributed energy resources, which enables to transfer bidirectional power between batteries of plug-in electric vehicle and the grid as well as offer ancillary service to the grid. Benefits of V2G application are voltage and frequency regulation,...
An Anti-Windup (AW) scheme is developed in this paper for Proportional Resonant (PR) controllers in the current control loop of a voltage source converter with an LCL filter. The innovation of this scheme lies in the fact that the anti-windup feedback signal is distributed to each input of the integrator. By controlling the percentage of this distribution, one can effectively adjust the phase shift...
Solar storms can affect the terrestrial power grid by inducing potential differences between points on the earth. These can couple into the power system through earthed structures such as transformer earths, which in turn can result in transformer saturation through geomagnetically induced current (GIC). For systems such as voltage-source converter (VSC) HVDC, this causes a variety of problems. This...
Optimization of distributed power assets is a powerful tool that has the potential to assist utility efforts to ensure customer voltages are within pre-defined tolerances and to improve distribution system operations. While convex relaxations of Optimal Power Flow (OPF) problems have been proposed for both balanced and unbalanced networks, these approaches do not provide universal convexity guarantees...
The wide application of distributed generations (DGs) and microgrids (MGs) infuses new vitality into the voltage control of the inverter, which represents a traditional power electronic research area. In this paper, a self-synchronized resonance voltage control algorithm is proposed to satisfy the requirement of an inverter's seamless switching from grid-connected (GC) mode to stand-alone (SA) mode,...
This paper studies the distributed photovoltaic (PV) hosting capacity in distribution feeders by using the stochastic analysis approach. Multiple scenario simulations are conducted to analyze several factors that affect PV hosting capacity, including the existence of voltage regulator, PV location, the power factor of PV inverter and Volt/VAR control. Based on the conclusions obtained from simulation...
Fuel cell is an emerging energy source, which is characterized with advantages feature like non dependency of environment conditions, clean source of power generation etc. Use of fuel in grid independent operation may be attributed with challenges like load transients and voltage unbalancing. The paper presents and innovative approach to mitigate the challenges face during the grid independent operation...
In this paper, a stochastic optimization framework is developed to reduce congestion on distribution feeders using batteries, under offline and online design paradigms. Our design is customized, implemented, tested, and analyzed in a real-world testbed that was built based on a university-utility collaboration in California. Our proposed method seeks to optimize peak load at the feeder while taking...
Distributed energy resources (DERs) and smart loads have the potential to provide flexibility to the distribution system operation. A coordinated optimization approach is proposed in this paper to actively manage DERs and smart loads in distribution systems to achieve the optimal operation status. A three-phase unbalanced Optimal Power Flow (OPF) problem is developed to determine the output from DERs...
Power systems are under a huge transformation because of the growing penetration of renewable sources. In this sense, microgrids may become a reality, since local sources and manageable loads and batteries may help the system to be self-sustainable under emergency conditions. This paper proposes a three phase power flow for microgrids which considers the droop method. Hence, frequency and voltage...
This paper presents a novel model for the short circuit analysis of PV inverter during transient period based on the dynamic phasor sequence component (DPSCs), especially the subtransient period (the first cycle after fault occurred). The model of photovoltaic (PV) inverter is presented as state space equations with DPSCs. The unbalanced fault condition can be given as the input vector in the state...
One solution towards a resilient electric distribution system during extreme weather conditions and other natural disasters is microgrid with distribution automation. This low voltage bottom-up black start capability and feeder reconfiguration capability allow true realization of the full potentialities of distributed generation. This paper exploits the black start of a low voltage network supported...
In this paper, we present a day-ahead optimal scheduling for reactive power of PV inverters and tap position of on-load tap changer (OLTC) in distribution network. We used a pattern search optimization algorithm based on the forecasted load demand and PVs active power generation. While the objective is to minimize the node voltage deviation and network losses, the maximum number of tap operation is...
The decrease in PV panel cost has globally increased the residential PV installations in the distribution grid. Studies have shown that high PV penetration can cause overvoltage, voltage deviation and reverse power flow concern in the distribution grid. To avoid the grid concerns, the utilities typically limit the PV penetration in the distribution feeder. However, the PV hosting capacity limits of...
The paper proposes a control strategy for managing the load associated to the HVAC system of a building. The idea is to use the thermal energy stored into the building to contribute to frequency response during emergency conditions and improve islanding transition. The frequency dynamics of a Microgrid, following a disturbance on the main grid, can be improved using load response. A test network model...
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