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This paper presents a two-stage optimization approach to mitigate the rapid voltage fluctuations and minimize the power losses of distribution systems due to the high penetration of photovoltaic (PV) generation. The first stage is a day-ahead optimal strategy which aims to minimize the total voltage deviations and power losses within the constraints of the daily maximum allowable number of operations...
Unbalanced operation between panel-level modular inverters constrains the operating range of grid-tied cascaded H-bridge Photovoltaic (PV) inverter system when the active and reactive power of the architecture changes. The main objective of this paper is to propose a distributed control approach for balancing reactive power among inverters. The distributed controller allows fully decentralized architecture...
The transition from centralized grid control towards distributed and cellular control requires new methods and intelligent solutions for power generation, storage and transmission. Due to temporary occurrence of reversed power flow during low load conditions in distribution grids, the grid voltage may reach or may exceed voltage limits. Data centers and telecom facilities, which are equipped with...
In this study, an adaptive capacitor switching algorithm is developed to optimize the use of switched capacitors as the availability and output of individual wind turbines change within wind farms. Wind farms are typically required to be able to operate within a power factor range of ± 0.95. To achieve this range of operation, switched capacitor banks are used to supply bulk reactive power to the...
As the penetration of small scale generators increases in distribution networks, the controllability of these systems, especially at Low Voltage (LV) level, is becoming more and more important. Several research studies proposed the adoption of the On-Load-Tap-Changer at the Secondary Substation transformer to enhance the voltage control, thus several commercial products are now available. This paper...
This paper presents a new application of modular multilevel cascaded converters (MMCC) for combined active harmonic current elimination and reactive power compensation in a power distribution line. A technique for simultaneous extracting harmonic components and reactive element in the load current is presented. A novel voltage control scheme for balancing the module intra-cluster capacitor voltages...
This paper proposes a novel reactive power control strategy based on virtual flux droop method. Firstly, flux droop control method is derived, where comlicated multiple feedback loops and parameter regulation are avoided. Next, the factors influencing reactive power sharing are theoretically analysed in virtual flux control. Then, a novel reactive power droop controller is designed which consists...
The total real power injected by distributed renewable energy sources (RES) in the low voltage (LV) grids can cause voltage rise effects during light load scenarios. Integrating RES in microgrid architectures can result in improved power quality of the electrical grid, by avoiding the voltage rise effect from occurring and also by providing ancillary services to the grid. In this paper, a cascaded...
This paper reports simple and effective control logic for connecting abrupt, steep and short-term power sources (for example, regenerative power from electric railway vehicles) to distribution lines with renewable energy units connected. With conventional centralized control systems, power conditioner units were unable to keep voltage of the distribution line within an acceptable range when extremely...
The rapidly rising penetration level of distributed generators (DGs) increases the risk of unacceptable voltages in distribution systems. The conventional voltage regulation devices are limited by physical constraints in their ability to perform voltage/var control in response to photovoltaic (PV) output fluctuations. However, the reactive power capability of PV inverters alongside with conventional...
Many utilities may prefer that various distributed generation (DG) systems, particularly photovoltaic (PV) systems in this study, connected to their network are able to maintain a fixed power factor or higher (e.g., unity power factor) as a current source. On the contrary, some utilities may require that such a DG system participates in controlling reactive power for regulating voltage. Furthermore,...
This paper attempts to thoroughly evaluate the long-term performance of the most well-established voltage control strategies applied in active medium-voltage (MV) networks. This is attained by performing an exhaustive probabilistic analysis to consider and assess the impact of generation and demand uncertainties on the network operation. More specifically, Monte Carlo-based time-series simulations...
In this paper, proposed an adaptive droop control method using estimated the line impedance in real time and compensate for the mismatch in voltage drops across line impedance, to enhance reactive power sharing accuracy in island microgrids. The block of line parameter estimation using the current and voltage parameters in the microgrid and estimation algorithm recursive least squares method (LSM)...
In this paper, proposed an adaptive droop controller using compensate for the mismatch in voltage drops across line impedance, to enhance reactive power sharing accuracy in island microgrid. Communication is used to facilitate the tuning of adaptive controller for the change of load. The method will ensure in accurate reactive power sharing even the communication is interrupted if the load does not...
The increasing proliferation of distributed generations (DGs) in distribution networks has brought several management and operation challenges. To improve energy efficiency and voltage profiles of the distribution grids under different operating conditions, this paper propose a distributed optimal reactive power control solution combined with gradient algorithm. In the proposed method, each DG or...
The mathematical model of the power system load node is proposed. The main elements of the model are synchronous and asynchronous motors, a power transformer, power transmission lines and capacitor banks. The voltage instability of the electrical grid and the starting transients of the asynchronous motors are considered in the proposed model, in contrast to the counterparts. On the basis of this model...
Power Quality within LV distribution and Smart Grid systems is an important issue. Open Unified Power Quality Conditioner (Open UPQC) is a possible solution to improve power quality level within distribution smart grid networks. This paper presents the ICT-based power control in order to manage cooperation between series and shunt units of Open UPQC. The cooperation is meant to improve system functionality...
With decreasing generation of central conventional power plants and increasing number of decentral renewable energy sources (RES), there is arising discussion on distribution grids providing flexibility in terms of control of active and reactive power exchange at connection points to higher voltage grids by control of RES. In this work, a new methodology is developed to estimate flexibility potential...
This paper investigates the loadability increase that can be obtained in radial transmission lines by means of a synchronous condenser connected at the receiving end of the line. In this configuration, the reactive power reserve at the receiving node can be used (at least in the best part) to control the reactive power flow in the radial line. This way, the voltage drop across the line can be controlled,...
Many state of the art voltage control algorithms aim at reducing voltage rise in distribution grids caused by distributed in-feed, e.g. Photovoltaics (PV), by reactive power control strategies or active power curtailment. Due to the R/X-ratio, the effectiveness of reactive power on the voltage is generally more effective in medium voltage networks (MV) compared to low voltage networks (LV). For small...
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