Aiming at the problem that the proportion of new energy is gradually increasing and the frequency quality is getting worse, a comprehensive control strategy for primary frequency regulation of energy storage system ba...
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Aiming at the problem that the proportion of new energy is gradually increasing and the frequency quality is getting worse, a comprehensive control strategy for primary frequency regulation of energy storage system based on fuzzy control is proposed. Firstly, the influence of energy storage virtual droop, virtual inertia and virtual negative inertia control on the frequency response of the system is analyzed, and the fuzzy control is used to realize the smooth switching and complementary advantages between the control modes; Then, the feedback control strategy of SOC is designed by using logistics function, and the self-recovery control strategy of energy storage SOC is introduced to make the energy storage SOC reach the ideal state and improve the frequency modulation ability of energy storage. Finally, the simulation results show the effectiveness of the proposed method.
The performance of the negative sequence pilot protection (NSPP) is less deteriorated by the phase-ground shunt capacitance since the negative sequence current loops in phase-phase lines. Hence NSPP is a good candidat...
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ISBN:
(纸本)9781424452293
The performance of the negative sequence pilot protection (NSPP) is less deteriorated by the phase-ground shunt capacitance since the negative sequence current loops in phase-phase lines. Hence NSPP is a good candidate for the main protection in UHV lines with the special characteristic of larger charging current. But as we all known, NSPP is not suit to the open-phase operations in transmission line, which limited its wide applications in HV/EHV lines in history. In response to this question, the performance of NSPP in transmission line with open-phase operation is analyzed, and the mal-operation reason of the NSPP relay is discovered. Then an improved algorithm for faults detection is proposed in open-phase line, and the simulation results verified its validity. The work in this paper is only the basic steps, the more research, such as the sensitivity and transient characteristics of ground fault detections in open-phase line should be discussed further.
power grid and communication network, which depends on each other to provide proper functionality, are becoming more and more coupled together. Failure of a fraction of nodes in communication networks may lead to a fa...
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power grid and communication network, which depends on each other to provide proper functionality, are becoming more and more coupled together. Failure of a fraction of nodes in communication networks may lead to a failure even a cascade of failures in power grid. Wide area protection is highly dependent on communication. The failure of communication in some part of wide area protection system will affect the realization of the function to prevent cascading outages and result in serious consequences. Based on Manchester, OPA and hidden failure cascading failure models and considered the feature of relay protection, an improved cascading failure model is established. Then it is used to analyze the dynamic process of communication fails in wide area protection system and IEEE 30 bus system is employed to demonstrate the efficiency of the proposed method. Results show that communication failure in protection system will accelerate the cascading outages of power grid. Effective solutions to reduce the communication risk are discussed. The work of this paper is available for reference to analyze the process of cascading outages and design protection system preventing cascading outages.
Body: power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic st...
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Body: power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic stress and Lorentz force. Noise has become a bad environmental pollution source in some situations, and its vibration and noise reduction has become an urgent problem need to be solved. The shapes, materials, magnetostriction and joints forms of iron cores, the limitations of test, modeling, and experimental measurement of vibration and noise characteristic, are all the difficult reasons to analyze the vibration and acoustic noise of transformers and reactors. 1. The magnetostrictive modeling can be divided into two steps based on the magnetic field force and materials deformation, so the magnetic field force will be fed into the structural finite element with Maxwell electromagnetic force produced on the interface between the iron core and the air to calculate the deformation of the magnetic materials and to make the model more general and consistent. In order to fully verify the correctness of the model in the magnetostrictive analysis, and to ensure the simplicity of test and avoid unnecessary interference factors, the most simple magnetostriction tests will be carried out by using a single closed circle or rectangular electrical steel sheet, as shown in Fig. 1(a). The tests will measure the relationship between magnetostriction and magnetic field of different magnetic materials, different saturations, different sizes and different shapes. 2. The joint is a necessary form for the stacking of large transformer iron cores, and the main joint form is the step jiont at present. The introduction of the joints causes the magnetic force lines to flow through the different laminations and to make the local magnetic field complicated. From simple to complex process is adopted in this paper, and the verification is gradually complicated. Based on the study of a
To achieve a fast approach to the dynamic reactive power optimization model, a mixed integer nonlinear programming model was set up, with consideration of the discrete reactive powerequipment operation limit and powe...
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The development of digital substation provides new opportunity for integrated protection. However, the realization of integrated protection is constrained by serial communication between process level and bay level. B...
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Regarding the power transmission mode from energy base to load center as the heart of the matter, a joint optimal operating model for both sending- and receiving- end power grids is established. In this model, the car...
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Due to the power electronic devices in doubly fed induction generators (DFIG), it is very time consuming to simulate the electromagnetic transients of DFIG using its detailed model. Thus it is necessary to have approp...
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ISBN:
(纸本)9781629936017
Due to the power electronic devices in doubly fed induction generators (DFIG), it is very time consuming to simulate the electromagnetic transients of DFIG using its detailed model. Thus it is necessary to have appropriately simplified model of DFIG that maintains desirable accuracy. In this paper, the piecewise averaged model of PWM converters is introduced and applied to the modelling of DFIG. The proposed model divides the simulation time interval into switching periods and recalculates the averaged state equations of PWM converters in each switching cycle. In addition, a predictorcorrector based EMTP algorithm is designed to iteratively solve the model. Instead of treating switching events at the time points when they happen, the new algorithm solves all the switching instants in a switching cycle at the same time, which avoids frequency modification of the system conductance matrix and speeds up EMT simulations of DFIG. simulation results of a single-machine infinity bus system with a DFIG show that the proposed model and algorithm can achieve satisfactory accuracy and efficiency.
With high speed data sampling technology development, fault generated high-frequency signals can be got, in which fault generated traveling waves reflects fault location, fault type and faulted equipment so on from di...
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With high speed data sampling technology development, fault generated high-frequency signals can be got, in which fault generated traveling waves reflects fault location, fault type and faulted equipment so on from different ways of traditional power-frequency information. Fault generated traveling waves may help to improve protection relaying. The paper will review fault generated traveling waves and its physical base at first. Then two cases will be presented to exemplify the advantage of traveling waves based protection relaying. One is that fault generated traveling waves with the speed of light can be used to protect UHV long transmission lines independent of capacitive charging current. The other is traveling wave will be applied to detect single-phase-to-ground fault in power distribution system with neutral non-effectively grounded. At last the paper will conclude with implementation of traveling wave based protection relaying.
The battery differences not only affect the reliability and security of battery packs but also accelerate the decline of the packs' life. Although battery management systems (BMS) and equalization circuit can be u...
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ISBN:
(纸本)9781728149318
The battery differences not only affect the reliability and security of battery packs but also accelerate the decline of the packs' life. Although battery management systems (BMS) and equalization circuit can be used to balance the differences, only the whole battery pack can be protected with high-cost and complex circuits. Dynamic reconfigurable battery management system (DRBMS) based on networked control has a simple principle and can shield the differences of battery cells. This paper designs experiments for the dynamic reconfigurable battery network technology and makes a contrast with the traditional BMS. Through the analysis of voltage, SOC difference and dynamic resistance during charging and discharging, the results show that DRBMS has better voltage and capacity equalization effect than BMS. The cells of paralleled battery packs can be fully charged/released in DRBMS. It is also verified that DRBMS is applicable on decommissioned bus battery packs which are of larger differences and the ladder utilization.
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