Synchronous Active Proportional Resonant-Based Control Technique for High Penetration of Distributed Generation Units into Power Grids

This paper deals with a synchronous active proportional resonant-based (SAPR) control technique for interfaced converters, enhancing the stable operation of the power grid under high penetration of distributed generation sources. By considering the grid specifications and load currents, both d and q axis of converter currents are obtained in terms of active and reactive power and also angular speed using small-signal linearization method. Then, swing equation is analyzed in detail to achieve the reference current components in the current control loop of the interfaced converter. By using the obtained swing equation and a non-ideal proportional resonant (PR) controller, a new control technique is proposed, which introduces the behavior of synchronous power generators based on power electronic converters in distributed generation (DG) technology. The effectiveness of the proposed control technique is verified through stringent simulation studies in MATLAB/SIMULINK. Index Terms—Distributed generation (DG), synchronous active PR-based (SAPR), synchronous power generator.Smart and Sustainable Insular Electricity Grids Under Large-Scale Renewable Integratio

Influence of an inverter based DG on a double-ended fault location scheme

This paper describes the influence of Distributed Generation (DG) on a double ended fault location based on measuring the high frequency fault transients. The additional non-fundamental frequency current components from DG will influence the accuracy of an impedance based fault location technique based on non-fundamental frequencies. A double-ended impedance based fault location technique that utilizes the high frequency content (up to 5 kHz) is studied. The study showed that double-ended method is still able to locate a fault with a maximum error of 4% compared to the case without DG which showed a percentage error up to 2%

Cooperative Control And Advanced Management Of Distributed Generators In A Smart Grid

Smart grid is more than just the smart meters. The future smart grids are expected to include a high penetration of distributed generations (DGs), most of which will consist of renewable energy sources, such as solar or wind energy. It is believed that the high penetration of DGs will result in the reduction of power losses, voltage profile improvement, meeting future load demand, and optimizing the use of non-conventional energy sources. However, more serious problems will arise if a decent control mechanism is not exploited. An improperly managed high PV penetration may cause voltage profile disturbance, conflict with conventional network protection devices, interfere with transformer tap changers, and as a result, cause network instability. Indeed, it is feasible to organize DGs in a microgrid structure which will be connected to the main grid through a point of common coupling (PCC). Microgrids are natural innovation zones for the smart grid because of their scalability and flexibility. A proper organization and control of the interaction between the microgrid and the smartgrid is a challenge. Cooperative control makes it possible to organize different agents in a networked system to act as a group and realize the designated objectives. Cooperative control has been already applied to the autonomous vehicles and this work investigates its application in controlling the DGs in a micro grid. The microgrid power objectives are set by a higher level control and the application of the cooperative control makes it possible for the DGs to utilize a low bandwidth communication network and realize the objectives. Initially, the basics of the application of the DGs cooperative control are formulated. This includes organizing all the DGs of a microgrid to satisfy an active and a reactive power objective. Then, the cooperative control is further developed by the introduction of clustering DGs into several groups to satisfy multiple power objectives. Then, the cooperative distribution optimization is introduced iii to optimally dispatch the reactive power of the DGs to realize a unified microgrid voltage profile and minimize the losses. This distributed optimization is a gradient based technique and it is shown that when the communication is down, it reduces to a form of droop. However, this gradient based droop exhibits a superior performance in the transient response, by eliminating the overshoots caused by the conventional droop. Meanwhile, the interaction between each microgrid and the main grid can be formulated as a Stackelberg game. The main grid as the leader, by offering proper energy price to the micro grid, minimizes its cost and secures the power. This not only optimizes the economical interests of both sides, the microgrids and the main grid, but also yields an improved power flow and shaves the peak power. As such, a smartgrid may treat microgrids as individually dispatchable loads or generators

Non-isolated high gain DC-DC converter by quadratic boost converter and voltage multiplier cell

AbstractA novel non-isolated DC-DC converter is proposed by combining quadratic boost converter with voltage multiplier cell. The proposed converter has low semiconductor device voltage stress and switch utilization factor is high. The superiority of the converter is voltage stress of the semiconductor devices depends on voltage multiplier (VM) cell. By increasing the VM cell the stresses across the devices reduce drastically. The proposed converter has same number of components compared to certain voltage lift converters taken for comparison. A detailed comparative study is made on the proposed converter with few voltage lift converters in the literature, conventional boost with VM cell and quadratic boost converter. A 40W prototype is constructed with 12V input voltage and 96V output voltage to verify the performance and validate the theoretical analysis of the proposed converter

High frequency impedance based fault location in distribution system with DGs

Distributed Generations (DGs) with power electronic devices and their control loops will cause distortion to the fault currents and result in errors for power frequency measurement based fault locations. This might jeopardize the distribution system fault restoration and reduce the grid resilience. The proposed method uses high frequency (up to 3kHz) fault information and short window measurement to avoid the influence of DG control loops. Applying the DG high frequency impedance model, faults can be accurately located by measuring the system high frequency line reactance. Assisted with the DG side recorded unsynchronized data, this method can be employed to distribution systems with multiple branches and laterals

Influence of an inverter based DG on a double-ended fault location scheme

This paper describes the influence of Distributed Generation (DG) on a double ended fault location based on measuring the high frequency fault transients. The additional non-fundamental frequency current components from DG will influence the accuracy of an impedance based fault location technique based on non-fundamental frequencies. A double-ended impedance based fault location technique that utilizes the high frequency content (up to 5 kHz) is studied. The study showed that double-ended method is still able to locate a fault with a maximum error of 4% compared to the case without DG which showed a percentage error up to 2%

Grid frequency and voltage support using photovoltaic systems with energy storage assist

An optimized operating scheme for a grid-connected community based photovoltaic (PV) system is described. The system can participate in grid ancillary services like frequency and voltage regulation functions based on the Smart Grid framework. The proposed model comprises of a PV plant with Li-ion batteries coupled to the grid by means of a three-phase inverter. A two-way communication between the PV plant and the grid is assumed. The PV/storage plant provides constant updates on its current kW/kVar capability and the grid transmits the demand for specific amounts of power and for specific lengths of time. The battery charging energy can originate from either the PV system or the grid depending on the prevailing energy prices. The batteries are discharged when two conditions are met: the grid requests energy from the community-based PV system and if the PV system itself fails to meet the requested kW or kVar demand. The PV plant and the battery storage are integrated with the grid with the help of dc-dc and dc-ac converters in such a way that bi-directional flow of active and reactive powers can be achieved. Controllers integrating energy sources respond to the received signals and attempt to fulfill the grid demand. The system response is almost instantaneous and thus can be very helpful in grid frequency and voltage support --Abstract, page iii

Solid state transformer technologies and applications: a bibliographical survey

This paper presents a bibliographical survey of the work carried out to date on the solid state transformer (SST). The paper provides a list of references that cover most work related to this device and a short discussion about several aspects. The sections of the paper are respectively dedicated to summarize configurations and control strategies for each SST stage, the work carried out for optimizing the design of high-frequency transformers that could adequately work in the isolation stage of a SST, the efficiency of this device, the various modelling approaches and simulation tools used to analyze the performance of a SST (working a component of a microgrid, a distribution system or just in a standalone scenario), and the potential applications that this device is offering as a component of a power grid, a smart house, or a traction system.Peer ReviewedPostprint (published version

Power System Simulation, Control and Optimization

This Special Issue “Power System Simulation, Control and Optimization” offers valuable insights into the most recent research developments in these topics. The analysis, operation, and control of power systems are increasingly complex tasks that require advanced simulation models to analyze and control the effects of transformations concerning electricity grids today: Massive integration of renewable energies, progressive implementation of electric vehicles, development of intelligent networks, and progressive evolution of the applications of artificial intelligence