34,308 research outputs found
New trends in active filters for improving power quality
Since their basic compensation principles were proposed around 1970, active filters have been studied by many researchers and engineers aiming to put them into practical applications. Shunt active filters for harmonic compensation with or without reactive power compensation, flicker compensation or voltage regulation have been put on a commercial base in Japan, and their rating or capacity has ranged from 50 kVA to 60 MVA at present. In near future, the term of active filters will cover a much wider sense than that of active filters in the 1970s did. The function of active filters will be expanded from voltage flicker compensation or voltage regulation into power quality improvement for power distribution systems as the capacity of active filters becomes larger. This paper describes present states of the active filters based on state-of-the-art power electronics technology, and their future prospects toward the 21st century, including the personal view and expectation of the author</p
Enhancing the stability of an autonomous microgrid using DSTATCOM
This paper proposes a method for power sharing in autonomous microgrid with multiple distributed generators (DG). It is assumed that all the DGs are connected through voltage source converter (VSC) and all connected loads are passive, making the microgrid totally inertia less. The VSCs are controlled by either state feedback or current feedback mode to achieve desired voltage-current or power outputs respectively. A modified angle droop is used for DG voltage reference generation. Power sharing ratio of the proposed droop control is established through deriva-tion and verified by simulation results. A distribution static compensator (DSTATCOM) is connected in the microgrid to provide ride through capability during power imbalance in the microgrid, thereby enhancing the system stability. This is estab-lished through extensive simulation studies using PSCAD
Optimal Voltage Regulation of Unbalanced Distribution Networks with Coordination of OLTC and PV Generation
Photovoltaic (PV) smart inverters can regulate voltage in distribution
systems by modulating reactive power of PV systems. In this paper, an
optimization framework for optimal coordination of reactive power injection of
smart inverters and tap operations of voltage regulators for multi-phase
unbalanced distribution systems is proposed. Optimization objectives are
minimization of voltage deviations and tap operations. A novel linearization
method convexifies the problem and speeds up the solution. The proposed method
is validated against conventional rule-based autonomous voltage regulation
(AVR) on the highly-unbalanced IEEE 37 bus test system. Simulation results show
that the proposed method estimates feeder voltage accurately, voltage deviation
reductions are significant, over-voltage problems are mitigated, and voltage
imbalance is reduced.Comment: IEEE Power and Energy Society General Meeting 201
Generation Adequacy and Investment Incentives in Britain: from the Pool to NETA
Three years after the controversial change of the British market design from compulsory Pool with capacity payments to decentralised energy-only New Electricity Trading Arrangements (NETA) market framework, we compare the two designs in terms of investment incentives. We review the biases of the Pool capacity payments design, the drought of investment following the introduction of NETA, and the reaction of the market during the first âstress-testâ of NETA during the winter 2003. In an energy-only market such as NETA, it is essential that price signals are right and the system operator has a crucial role in contracting ahead for reserve. We recommend that NETA adopt a single marginal imbalance price as dual imbalance pricing distorts price signals in times of scarcity. The lack of long-term contracting that causes hedging and financing difficulties for power projects can becompensated by vertical and horizontal reintegration at a cost of increased market power
Power Converters and Power Quality
This paper discusses the subject of power quality for power converters. The
first part gives an overview of most of the common disturbances and power
quality issues in electrical networks for particle accelerators, and explains
their consequences for accelerator operation. The propagation of asymmetrical
network disturbances into a network is analysed. Quantitative parameters for
network disturbances in a typical network are presented, and immunity levels
for users' electrical equipment are proposed. The second part of this paper
discusses the technologies and strategies used in particle accelerator networks
for power quality improvement. Particular focus is given to networks supplying
loads with cycling active and reactive power.Comment: 26 pages, contribution to the 2014 CAS - CERN Accelerator School:
Power Converters, Baden, Switzerland, 7-14 May 201
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