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Many power systems are facing power quality problems and transmission equipment are stressed with heavy power flows over long distances. Distributed generation (DG) units can minimize the burden on transmission networks by supplying local loads and providing ancillary services. However, increased penetration of DG units in the distribution networks require new operating conditions to ensure safe and...
Reactive power has a significant influence on the reliability and security of power systems because it perturbs voltages throughout the system. An appropriate and applicable power system operation is totally important to prevent voltage collapse or instability, decrease system losses and avoid equipment damage, such as overheating of transformers, generators and motors. This operational regime can...
This paper introduces a novel backward/forward sweep algorithm for both fundamental and harmonics flow calculation in distribution network. In this algorithm, the fundamental and harmonic currents of each branch are calculated by equivalent current injection method. The relationship between branch currents and harmonic currents of each order on a radial feeder can be calculated by summing the injection...
Wind energy is the most promising renewable energy source that can reduce the consumption of fossil resources and helps to meet the requirement in the reduction of emissions in electricity generation. In terms of percentage of yearly growth of installed capacity, wind energy has been the fastest growing energy technology during the past twenty years. Due to the intermittent characteristics of wind...
Distributed Generation (DG) based on renewable energy resources has become extremely attractive due to their significant ability to reduce greenhouse gas emissions and decrease the dependency on fossil fuels. However, in modern power systems these DGs should participate with the main conventional power plants and other system's equipments in the power system security and reliability by providing the...
The deregulation of electricity market has brought more challenges to the system operator to handle system contingencies. In the deregulated market, congestions are encountered with higher frequency than before. Congestion can lead to price volatility and system instability, which can deteriorate the electricity market operation. Therefore proper congestion management methods should be developed to...
In Microgrid energy is normally transmitted from source to grid through converters and this makes the output components of microsources (MSs) easier to control. Control technologies for Microgrid are focused on the output of the inverter part. There are two fundamental approaches: PQ control and droop control. For different co-operation between MSs and energy storage devices, there are several control...
The use of wind power to generate electricity is probably the most widely used renewable energy sources around the globe. The major reason may well be of its well developed technology in comparison with other form of renewable. The percentage of wind power installation with respect to the total power generation, also known as the penetration factor, is increasing rapidly year by year in many countries...
Power companies around the world are incorporating wind power into their electricity networks. Wind power is an intermittent source of energy and their technical and financial impacts on the transmission and distribution networks are not totally known. Due to this situation, it is necessary to study the influences of wind energy on electric network. The objective of this paper is to investigate the...
This paper presents a dynamic wind power generation model with the Weibull Distribution Function being used to analysis the wind distribution problem. The Monte Carlo simulation method is applied to consider random output of wind power generation. The nodal prices ensure a competitive market and efficient allocation while the access charge allows the transmission provider to recover the full embedded...
In power systems with conventional power plants, provision of ancillaries ensures safe system operation without significant compromise in return of investment cost as intended reduction in generator output power implies to less use of gas, fossil or nuclear fuels. While with renewable power generations, always there is a conflict of interest between transmission system operators (TSOs) and wind or...
To increase the stability and efficiency of the Grid with wind power integration, one of the solutions is to control the active power output of wind farms. This paper focuses on wind farms with DFIG wind turbines, and analyzes the stability of DFIGs working in different control strategies. An optimized control strategy is proposed that guides the active power output of a DFIG wind farm to follow the...
This paper proposes a wavelet transform approach for the evaluation of harmonic contents of power system waveforms. In this approach, the discrete wavelet packet transform is presented to decompose the waveform, and then based on the decomposed coefficient the harmonic contents include frequencies, amplitudes and phases are calculated by continuous wavelet transform. The wavelet transform is introduced...
This paper applies the panel unit root test, heterogeneous panel cointegration test and panel causality analysis to investigate the relationship and direction of causality between electricity consumption and economic growth for 28 provinces in China during period of 1985–2008. The empirical results show that there are cointegration relationship and long-run bidirectional causality between electricity...
In recent years wind generation penetration level in both transmission and distribution networks has been increasing. The increase in integration is mainly due to environmental concern and the push for carbon-free power generation. In some remote areas economic factor could also be a major one. The size of wind turbines and wind farms are increasing and the influence of wind generation on voltage...
It is acknowledged that Distributed Generation, in spite of the benefits that it provides, causes harmonics problems due to the power converter interfaces. In this paper, a generic approach is adopted to reduce the harmonic injection from converter-connected DG units, using a phase-shifting technique. By changing the vector group between transformers that connect with either converter-connected DG...
This paper investigates the possibility of using HVDC networks to create a large power pool that may facilitate the following objectives: increased connection of renewable power to the ac network without the need for bulky storage systems; improve the resiliency of the ac networks attached to this power pool against power and frequency instability problems during local loss of generation or major...
As an important component of distribution network, micro-grid is the necessarily development trend for future. Micro-grid has greatly improved the random problems of distributed generation (DG). However, DGs, the power electronic equipments inevitably bring about power quality problems, especially voltage flicker and harmonics. This paper tries to study the operating regulations of micro-grid in order...
Available Transfer Capability (ATC) is a measure of the transfer capability remaining in the physical transmission network for further commercial activity over and above already committed uses. Putting forward against the defect that the traditional contingency selection method uses single index to enumerate states or disturbances, this paper introduces the active power behavior index and the voltage-reactive...
With the deepening reform to power industries, power systems are going to gradually open the demand side and the power consumers have to face the changes of their role in the market, and make a preliminary long-term forecasting for the electricity prices. In order to consider the relations between the spot market and the long-term contract market, this paper builds a multi-electricity price grey model...
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