Because of a lightning strike, short circuit fault, and switch operation, grounding grid will be impacted by high-frequency current, which makes the grounding grid appear uneven distribution of transient grounding pot...
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ISBN:
(纸本)9781728116952
Because of a lightning strike, short circuit fault, and switch operation, grounding grid will be impacted by high-frequency current, which makes the grounding grid appear uneven distribution of transient grounding potential, this kind of transient grounding potential rise will be coupled to the core wire through the outer surface of the cable and will invade the secondary system, which may have an impact on the normal operation of the secondary equipment and Endanger the safe and stable operation of substation or converter station. In addition, with the digitalization, electronization, and localization of the secondary equipment in the UHV converter station, a large number of precision secondary equipment used for protection, control and communication is placed in the high-voltage switching field of the converter station, which greatly increases the probability of interference with the secondary system of the UHV converter station. It is well known that using shielded cables and choosing correct grounding mode of the shielding layer is an important measure to improve the electromagnetic compatibility of converter stations. In this paper, based on a test method to research transient grounding potential rise in converter station, the transient overvoltage of multi-segment secondary cables and their shielding layer with different grounding modes are measured in the field of an AC filter in a UHV converter station. The test results show that the grounding of the shielding layer between the first and the last sections is the key to suppress transient overvoltage for the multi-segment control cable. The best grounding method is to increase the shielding layer and armor layer of the control cable between the on-site control cabinet to be grounded at the single end of the B-phase on-site control cabinet based on the cable grounding mode. That is to say, the cable of the shielding layer and the armor layer between the on-site control cabinet should consider the grounding at
Battery energy storage systems(BESSs)can provide instantaneous support for frequency regulation(FR)because of their fast response ***,purely pursuing a better FR effect calls for continually rapid cycles of BESSs,whic...
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Battery energy storage systems(BESSs)can provide instantaneous support for frequency regulation(FR)because of their fast response ***,purely pursuing a better FR effect calls for continually rapid cycles of BESSs,which shortens their lifetime and deteriorates the operational *** coordinate the lifespan savings and the FR effect,this paper presents a control strategy for the FR of BESSs based on fuzzy logic and hierarchical *** fuzzy logic controller improves the effect of FR by adjusting the charging/discharging power of the BESS with a higher response speed and precision based on the area control error(ACE)signal and the change rate of ACE in a non-linear *** controllers effectively reduce the life loss by optimizing the depth of discharge,which ensures that the state of charge(SOC)of BESS is always in the optimal operating range,and the total FR cost is the lowest at this *** proposed method can achieve the optimal balance between ACE reduction and operational economy of *** effectiveness of the proposed strategy is verified in a two-area powersystem.
Fully utilizing the flexibility provided by a district heating system(DHS)can promote wind power accommodation for an electric powersystem(EPS).However,for privacy or communication reasons,existing power and heat dis...
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Fully utilizing the flexibility provided by a district heating system(DHS)can promote wind power accommodation for an electric powersystem(EPS).However,for privacy or communication reasons,existing power and heat dispatch methods are not suitable for practical *** this paper,a general math formulation of the hierarchical dispatch method is proposed to coordinate EPS and DHS operators based on the feasible region of boundary variables(FRBV),and a method based on the simplicial approximation approach is proposed to obtain a conservative FRBV approximation of a DHS.A simulation based on a real 41-node DHS is constructed to determine the factors that may impact the boundaries of the FRBV,and then the performance of the simplicial approximation approach is displayed by visualizing the approximation process for the FRBV,and finally three dispatch methods are compared to show the advantages of the proposed hierarchical dispatch method.
Grid-connected LCL filter of voltage source PWM rectifier (VSR) can not only reduce the values of inductance, improve the system dynamic response, but also reduce the cost. However, LCL filter brings stability problem...
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The powersystem now is a typical complex system, which has inherent characteristics of SOC. Studying on cascading failures are necessary and meaningful to insure the grid's safety, national security and economic ...
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ISBN:
(纸本)9781479947249
The powersystem now is a typical complex system, which has inherent characteristics of SOC. Studying on cascading failures are necessary and meaningful to insure the grid's safety, national security and economic development. This paper firstly establishes the indices of powersystem development diagnosis, which are closely relevant to the trigger of powersystem evolution. Then a cascading failure model is proposed, considering planning and evolution of the powersystem. This model is based on OPA model, including both fast dynamics and slow dynamics. The slow dynamic process simulates the evolution of powersystem, which represents the functions of the planning department, while the fast dynamic process simulates power flow and cascading failures, which takes the effects of dispatch, relay protection and automation into consideration. Moreover, simulations are tested on the case of Kaifeng-Shangqiu powersystem in Henan Province of China, and evolution results are presented.
Five-level active neutral-point-clamped (ANPC) converter is a newly emerging topology which can overcome the drawbacks of traditional neutral-point clamped (NPC) converters and flying-capacitor (FC) converters. Its dc...
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With the development of smart grid, the self-healing ability of protection device becomes much more important. Pilot protection is of good selectivity, but it needs a highly reliable communication network. Once the co...
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ISBN:
(纸本)9781785618260
With the development of smart grid, the self-healing ability of protection device becomes much more important. Pilot protection is of good selectivity, but it needs a highly reliable communication network. Once the communication line between two devices is out of work, pilot protection will be forced out of operation. Since there are many ring structures in communication network, circuitous routes can be found to help pilot protection remain operational. In this paper, ant colony algorithm (ACA) are used to find the optimal circuitous route, and simulation results show the method is fast and accurate. To the actual communication network of powersystem, each node is just connected to a few other nodes, so the search process often come to dead ends. Use penalty functions can reduce the probability of coming to a dead end and improve the algorithm efficiency. The whole route accelerating penalty function is most efficient.
This study utilizes hot dry rock(HDR)geothermal energy,which is not affected by climate,to address the capacity allocation of photovoltaic(PV)-storage hybrid powersystems(HPSs)in frigid plateau *** study replaces the...
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This study utilizes hot dry rock(HDR)geothermal energy,which is not affected by climate,to address the capacity allocation of photovoltaic(PV)-storage hybrid powersystems(HPSs)in frigid plateau *** study replaces the conventional electrochemical energy storage system with a stable HDR plant assisted by a flexible thermal storage(TS)*** HPS consisting of an HDR plant,a TS plant,and a PV plant is *** approaches are introduced to establish the game pattern model of the proposed HPS as the *** annualized income of each player is used as the payoff ***,non-cooperative game and cooperative game approaches for capacity allocation are proposed according to the interests of each player in the proposed ***,the proposed model and approaches are validated by performing calculations for an HPS in the Gonghe Basin,Qinghai,China as a case *** results show that in the proposed non-cooperative game approach,the players focus only on the individual payoff and neglect the overall system *** proposed cooperative game approach for capacity allocation improves the flexibility of the HPS as well as the payoff of each game ***,the HPS can better satisfy the power fluctuation rate requirements of the grid and increase the equivalent firm capacity(EFC)of PV plants,which in turn indirectly guarantees the reliability of grid operation.
Wind powergeneration uncertainty has imposed great challenge on powersystems' operation and should be considered when making an operation *** this paper,we focus on optimal power flow(OPF) problem in radial powe...
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ISBN:
(纸本)9781467374439
Wind powergeneration uncertainty has imposed great challenge on powersystems' operation and should be considered when making an operation *** this paper,we focus on optimal power flow(OPF) problem in radial power networks while considering wind powergeneration *** cope with this uncertainty,the stochastic AC-constrained OPF(ACOPF) problem considering both continuous and discrete devices is formulated based on our previous *** second order cone relaxation is employed to relax the original mixed integer nonconvex nonlinear programming(MINNLP) problem to a mixed integer second order cone programming(MISOCP) problem which can be solved by commercial solvers with high computation *** modified IEEE 33 bus distribution system is studied in this paper which validate the effectiveness of the proposed model.
The identification of load model parameters from practical measurement data has become an essential method to build load models for powersystemsimulation,analysis and *** practical situations,the accuracy of the loa...
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The identification of load model parameters from practical measurement data has become an essential method to build load models for powersystemsimulation,analysis and *** practical situations,the accuracy of the load model parameters identification results is impacted by data quality and measurement accuracy,which leads to the problem of *** this paper,an identifiability analysis methodology of load model parameters,by estimating the confidential intervals(CIs)of the parameters,is *** load model structure and the combined optimization and regression method to identify the parameters are first ***,the definition and analysis method of identifiability are *** CIs of the parameters are estimated through the profile likelihood method,based on which a practical identifiability index(PII)is defined to quantitatively evaluate ***,the effectiveness of the proposed analysis approach is validated by the case study results in a practical provincial power *** results show that the impact of various disturbance magnitudes,measurement errors and data length can all be reflected by the proposed ***,the proposed PII can provide guidance in data length selection in practical load model identification situations.
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