Recent years, technologies for new energy have developed rapidly since the energy crisis and the environmental pollution got worse. And the solar energy generation technology tends towards the stage of a large number ...
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Recent years, technologies for new energy have developed rapidly since the energy crisis and the environmental pollution got worse. And the solar energy generation technology tends towards the stage of a large number of applications in engineering from the research stage. This paper designed a grid-connected PV system firstly, then introduced the operation principle of the various parts as well with the control strategy of the power flow. The design of energy storage is of great significance as the output power of PV cells array is greatly affected by the light intensity and the temperature change. Battery is used as the energy storage device normally in the traditional energy storage system. In this paper, it used the Ultracapacitor as the energy storage device after comparing with the battery, and designed the charge-discharge control strategy according to the characteristics of the ultracapacitor. Finally it verified the feasibility of the energy storage control strategy through the simulation models which was built based on the PSCAD/EMTDC platform.
In this paper probabilistic estimation of PCC loss is approached in distribution systems. For the difficulty of directly solving the impedances of the star-connected equivalent model, a port-based model is adopted for...
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ISBN:
(纸本)9781424449347
In this paper probabilistic estimation of PCC loss is approached in distribution systems. For the difficulty of directly solving the impedances of the star-connected equivalent model, a port-based model is adopted for voltage magnitude calculation under four fault types (TPF, SLGF, LLF and DLGF). The specific energy (SE) function is used to evaluate voltage sags involving the voltage magnitude and sag duration simultaneously, and PCC loss is directly computed from the trip probability density, which derives from the normal probability distribution function of SE. The distribution characteristic of balanced and unbalanced faults is also considered. The estimation method for PCC loss is proved fast and effective by IEEE RBTS system.
The integration of a large number of wind farms will have a significant impact on the reliability performance of the electric generation and transmission systems. In this paper, an adequacy evaluation model of wind po...
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The integration of a large number of wind farms will have a significant impact on the reliability performance of the electric generation and transmission systems. In this paper, an adequacy evaluation model of wind power integration in power system based on the sequential Monte-Carlo simulation approach is presented. This model is applied to simulate power system including wind power generation. Depth first search algorithm is used to find out each connected block of network. In the section of active power correction and dispatching, a reduction of load minimum as goal function linear programming model is presented. Corresponding software is programmed according to the Matlab7. The calculations to IEEE-RTS79 test system which wind farm model added is carried out. The reliability index from calculated examples show the value of wind power, and will provide the valuable reference for wind farm operation and planning.
This paper proposed a new technology for HVDC start-up and operation using VSC-HVDC system. The new concept of the technology is to start HVDC when its receiving side is passive network. The motivation of choosing thi...
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This paper proposed a new technology for HVDC start-up and operation using VSC-HVDC system. The new concept of the technology is to start HVDC when its receiving side is passive network. The motivation of choosing this technology is to enable HVDC to operate under small amount of power delivery condition as the receiving side is passive network. A physical model of starting HVDC by VSC-HVDC is developed. Moreover, a control system is designed in dq reference frame. In order to testify this technology, the dynamic performance of starting HVDC using VSC-HVDC is investigated. Simulation results obtained using PSCAD/EMTDC show that with the use of the proposed technology, the HVDC system can start successfully and feed small amount of power to passive network. The technology proposed exerts the advantage of VSC-HVDC system and increases the availability ratio of supplying power to passive network.
In the control of electric power systems, especially in the wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its correspondi...
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ISBN:
(纸本)9781424449347
In the control of electric power systems, especially in the wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be detected quickly and defined exactly. In our researches, global information will be introduced into the backup protection system, basing on discriminant analysis theory of multivariate statistical analysis theory, we are going to seek after for the statistical laws of electrical quantities' marked changes by analyzing and computing real-time PMU measurements, so that we can carry out fast and exact identification of faulty components and faulty sections, and finally accomplish fault isolation. Multivariate statistical analysis theory is an efficient theory that can resolve different kinds of complex problems. It has been applied successfully to many researches of various fields. Discriminant analysis is an important theory in multivariate statistical analysis theory. A common approach to discriminant analysis is to apply the decision theory framework. In the study of electric power systems, discriminant analysis theory must also have a good prospect of application.
This paper design an integrative ancillary fuzzy logic controller for the Voltage Source Converter based HVDC transmission system, VSC-HVDC, to improve the stability of the AC/ DC system by damping the oscillation eff...
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This paper design an integrative ancillary fuzzy logic controller for the Voltage Source Converter based HVDC transmission system, VSC-HVDC, to improve the stability of the AC/ DC system by damping the oscillation effectively after disturbance. The fast control capability of the VSC-HVDC and the process of area mode oscillations are analyzed. No detailed model of the system is required for the design of the proposed control scheme. The controller judges the operation states and the control effect and synthetically adjusts its active power and reactive power order in an adaptive way by using fuzzy rules, so as to damp out the area mode oscillation. An IEEE 4-generator AC/DC power system is built in PSCAD. Integrative ancillary fuzzy logic controllers is designed in Matlab and interfaced with PSCAD. Simulation results have shown that the integrative controller can enhance the dynamic stability of interconnected power systems effectively and is robust to the variation of system operating conditions and oscillation modes.
In this paper, the equivalent model of a local HVDC transmission system is set up based on Real-Time Digital Simulator (RTDS). A realistic DC line fault on the pole 2 of the HVDC project is simulated successfully by u...
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In this paper, the equivalent model of a local HVDC transmission system is set up based on Real-Time Digital Simulator (RTDS). A realistic DC line fault on the pole 2 of the HVDC project is simulated successfully by use of the RTDS model connected with actual physical control and protection devices. And then, a complete evaluation theory of simulation errors is proposed. In the theory, residuals similarity is used to characterize the global error of dynamic simulation, and frequency, damping and amplitude similarity are used to characterize features errors respectively. The comparison analysis has been carried out between the simulation results and the fault recordings by the simulation similarity computation procedure based on LabVIEW. It is proved that the simulation results of existing models are almost the same as the fault recordings, and the simulation model of HVDC transmission system established can reflect operation characteristics of real network exactly. The realistic faults can be reproduced by the simulation experiment accurately.
The reliability of electricity supply is required by users increasingly, and whether to invest the reliability and voltage quality has been a point of contention. Thus, the assessment of voltage sag becomes acute. In ...
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ISBN:
(纸本)9781424449347
The reliability of electricity supply is required by users increasingly, and whether to invest the reliability and voltage quality has been a point of contention. Thus, the assessment of voltage sag becomes acute. In this paper, the acceptable indices considering system performance and user characteristics are proposed for comprehensive assessment of voltage sag, including the reliability of the system and economy of users. The comprehensive assessment strategy, based on analytic hierarchy process (AHP), is applied to the assessment process for integrate the independent variables of the indices function. All the factors of users can be collected accurately from historic data, and the effectiveness of the method proposed in this paper is proved by the analysis of IEEE RBTS system.
Information security risk assessment combined with powercontrol process is not a properly resolve problem, the lack of asset identification method accord with characteristics of power information systems is one of th...
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ISBN:
(纸本)9781424449347
Information security risk assessment combined with powercontrol process is not a properly resolve problem, the lack of asset identification method accord with characteristics of power information systems is one of the main factors. Network-based substation automation systems (SAS) are typical power information systems, based on the analysis of difficulties on asset identification, a complete information asset identification method is introduced from three aspects, includes asset classification, task identification, and asset valuation. In the asset classification, combined with the IEC 61850 standard, a structured asset model is defined based on association of actual intelligent electronic devices and virtual logical nodes. In the task identification, take functions of substation automation as the object of task, the concept of function graph is defined to reflect the logical relations between functions and assets, as well as the logical relation between the assets. In the asset valuation, two levels of asset value include function level and substation level, are defined to quantify the information security properties of assets and the effects of possible accidents. Finally, an evaluation instance is constructed from IEC 61850 standard, the proposed method is applicable to asset identification of network-based SAS.
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