The development and utilization level of energy is an important symbol of the technology and living standards of the society. Integrated Energy System (IES) is important to improve energy efficiency and promote the large-scale development of the Renewable Energy Source (RES). In the meanwhile, it also can improve the utilization of the social infrastructure and secure the energy supply. It has become a significant research topic in the international energy field. Photovoltaics, wind turbines and other renewable energy source of electricity are coupled with energy storage system to supply power to the local consumers in the IES, which can reduce the energy transmission losses and the large disturbances impact from the main grid. Since the inverse distribution of the output power of some renewable energy distributed generation and the load demand, the research of the energy storage system control to achieve the target of high efficient local utilization of the renewable energy and avoid a large excess power flowing into the network is one of the development priorities of the integrated energy system. For the control method of the energy storage system, the most important part is the dispatchment control strategy of the energy storage system. It is expected that the energy system can discharge more energy during the peak load period and discharge less during the valley load period. Directing at this aim, this paper uses fixed threshold and dynamic threshold method to calculate the discharge threshold power to control the discharge power of the storage system respectively. Comparing the energy management results, the dynamic threshold method is confirmed to have higher energy management efficiency.
Abstract.Transformer oil quality has a great impact on the production of UHV; The traditional single tank type or inverted tank type oil filter can be used for transformer oil filter in UHV Substation. The disadvantage of this method is the low degree of automation, high labor costs, error prone and low efficiency. Therefore, the research and application of the automatic intelligent oil filter system has broad prospects. This paper introduces a kind of intelligent oil filtering system based on PLC and configuration software designed to liberate workers on site, reduce error rate and improve production efficiency.
Islanding in power system can be intentional or unintentional. In the past most of the methods were developed for the phenomenon of unintentional islanding. Recently as the distributed generator (DG) sources are able to control voltage and frequency in the islanded part, the phenomenon of unintentional islanded is not common. If the autonomous operation of sources or intentional islanding is desired, then a fast islanding detection technique is necessary . The main philosophy of detecting an islanding situation is to monitor the DG output parameters and system parameters to decide whether or not an islanding situation has occurred from change in the parameters. islanding detection techniques can be classified as remote techniques and local techniques, and local techniques can be divided into passive methods, active methods and hybrid methods. In this paper, several remote and local techniques (passive, active, and hybrid methods) for islanding detection are briefly described. The advantage and limitation of each technique are also introduced. Meanwhile, the comparison of these methods is also discussed.
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