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Huang X.,Henan Electrical Power Dispatching and Communication Center | Chai X.,Henan Electrical Power Dispatching and Communication Center
Advanced Materials Research | Year: 2012

The capacity of thermal power plants takes up 75 per cent of whole power generation capacity in China, and so a reserve of generation capacity margin that may adapt to the variations in power network load is of paramount importance. This paper proposes a concept: installed capacity margin, and basic mathematic modeling and example is analyzed. It would be supply theoretical help for real little thermal power plants shutdown schedules based on building detailed mathematical models after investigation of region-specific load structure characteristics and installed generator compositions. © (2012) Trans Tech Publications.


Huang X.,Henan Electrical Power Dispatching and Communication Center | Chai X.,Henan Electrical Power Dispatching and Communication Center
Lecture Notes in Electrical Engineering | Year: 2011

Power distribution network planning is an intricate combined optimization problem. The ant colony algorithm as a highly effective, random and heuristic global search technology can effectively solve large combined optimization problem. In this paper, special ant colony algorithm is presented to solve the obstacle bypass problem of network frame planning according to the characteristics of single stage power distribution network planning. The corresponding mathematical model is established, and the whole solution method is given out. The calculating result shows that this approach is feasible and effective. © 2011 Springer-Verlag.


Liu X.,Zhengzhou University | Ding C.,Zhengzhou University | Wang Z.,Henan Electrical Power Dispatching and Communication Center | Zhou P.,Henan Electrical Power Dispatching and Communication Center
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2011

It is investigated to apply Lyapunov direct method to the analysis and evaluation of power system small signal stability. Its criterion for linear system is introduced and the algorithm to solve Lyapunov functions is analyzed. The square integral of state deviation is introduced to evaluate the dynamic performance of system. The low frequency oscillation of four example systems is studied and results show that, the direct method can accurately and reliably estimate the small signal stability of power system; the index of square integral of power-angle deviation evaluates the dynamic performances of low frequency oscillation more comprehensively than the commonly-used minimum damping ratio.


Hu Y.,Henan Electrical Power Dispatching and Communication Center | Fu H.,Henan Electrical Power Dispatching and Communication Center | Zhang Y.,Henan Electrical Power Dispatching and Communication Center | Sun J.,Henan Electrical Power Dispatching and Communication Center | And 4 more authors.
Dianwang Jishu/Power System Technology | Year: 2011

After the building up and putting into operation of Nanyang ultra high voltage AC (UHVAC) substation, the electromagnetically coupled 1000/500 kV loop operation of the tie line connecting Hubei power grid and Henan power grid appears. In the viewpoint of transmission capability, security level and stability level, short-circuit current level, small signal stability, the operation characteristics of UHVAC electromagnetically coupled loop are overall analyzed, and a prominent problem is pointed out that the large-scale power transfer leads to the overload in transmission line belonging to lower voltage grade. For this reason, the security and stability control measures for the electromagnetically coupled 1000/500 kV loop operation of the tie line are researched, and after the comparisons of various conventional measures as well as the measure to coordinate with automatic generator control (AGC) a control measure, in which the coordinated AGC is comprehensively considered, is proposed. Implementation of the proposed control measure can effectively mitigate the cumbersomeness of security and stability control measure that is necessary to maintain power grid stability and offer a new idea for the secure dispatching of UHVAC power gird.


Fu H.-J.,Henan Electrical Power Dispatching and Communication Center | Sun J.-H.,Henan Electrical Power Dispatching and Communication Center | Wang J.G.,Henan Electrical Power Dispatching and Communication Center | Hu Y.-Y.,Henan Electrical Power Dispatching and Communication Center
Applied Mechanics and Materials | Year: 2013

With the HVDC system interconnected to power grid, the voltage stability problem of power grid has become increasingly prominent. This paper establishes the mathematical model of AC/DC hybrid power system and proposed an improved Continuation Power Flow (CPF) algorithm to calculate the static voltage stability limit of AC/DC hybrid system, the characteristics of this algorithm are as following: PQ decoupled power flow algorithm is used; Lagrange quadric interpolation is used in the process of predictor and step control; local parameter method is used in the correction. The iterations of AC/DC calculation alternate to solve power flow equations and select the step control near the critical power limit points to ensure the convergence of power flow solution. In order to verify the correctness of the proposed algorithm, this paper compares the calculation results by the improved algorithm and Matpower on the IEEE 14 bus-system. This paper calculates the static voltage stability limit of AC/DC hybrid power system under different DC control patterns of modified IEEE 14 bus-system and analyzes the impacts of different DC control pattern to the system voltage stability. © 2013 Trans Tech Publications Ltd, Switzerland.


Hu Y.-M.,Beijing Jiaotong University | Wu J.-Y.,Beijing Jiaotong University | Li F.,China Electric Power Research Institute | Fu H.-J.,Henan Electrical Power Dispatching and Communication Center
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

In order to optimize the operation patterns of Henan power grid after putting the ±800 kV UHVDC from Hami to Zhengzhou into operation, the relationship between DC system control modes and voltage stability of receiving-end power network is analyzed in detail, and the regularity of different control modes impacting the voltage stability of AC bus at converter station is revealed and simulated based on the planning data of Henan power grid in 2014. Simulation results show that the Ha-Zheng UHVDC taking CP-CV control mode i.e. constant power at rectifier side and constant voltage at inverter side will be conducive to voltage stability of receiving-end power network; after putting Ha-Zheng UHVDC into operation, the operation patterns of multi-channel transferring HVDC power from Henan to Central China Grid combined with partly internal consumption are favorable to improve the static voltage stability. The analysis results provide theoretical basis for future optimizing operation and scheduling of Henan power grid.


Zhang Y.,Tsinghua University | Wu W.,Tsinghua University | Zhang B.,Tsinghua University | Wan Y.,Jiangxi Electrical Power Dispatching and Communication Center | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

This paper presents an early warning and preventive control system for transient stability. This system has been used in several provincial power grids. Firstly, the framework and the main modules of the proposed system are introduced. Secondly, the key technologies of the system are also presented. An algorithm is implemented to calculate total transfer capacity (TTC) under four different power increasing strategies. The preventive control algorithm, which is based on transient energy function sensitivity, is also realized. Thirdly, some engineering-oriented methods are introduced to solve practical problems, which emerge in real application. There are several examples: a node-breaker model is implied to adapt to the changing operation mode, a scheme is presented to avoid misjudge of stability in the case of island, generation areas and load areas can be automatically divided with new method. © 2010 State Grid Electric Power Research Institute Press.


Zhou H.,Hohai University | Huang X.,Henan Electrical Power Dispatching and Communication Center | Wu L.,Hohai University | Ju P.,Hohai University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

In dynamic equivalents of power systems, if the excitation systems of the coherent generators are of the same type, the equivalent excitation system has the same type and the same model, and the equivalent parameters could be obtained with the weighted summation. However, the excitation systems of the coherent generators may be different. For this case, the uniform stand transfer function as the model of equivalent excitation system are proposed, and the parameters of the equivalent excitation systems are estimated by piecewise linear polynomial function (PLPF) method. The simulation results show that the frequent and time domain characteristics are very proximal before and after excitation system aggregation. This proves the effectiveness and adaptability of the proposed method. ©2010 State Grid Electric Power Research Institute Press.


Xu H.,North China Electrical Power University | Ma J.,North China Electrical Power University | Fu H.,Henan Electrical Power Dispatching and Communication Center | Hu Y.,Henan Electrical Power Dispatching and Communication Center | Sun S.,Henan Electrical Power Dispatching and Communication Center
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

Because load model is the aggregation of various load components with considerable uncertainties, it is very important to investigate the effects of load model on power system small signal stability. A method using sensitivity factors is proposed to study the load model impact on system eigenvalues for small signal stability assessment. The method is based on state space description of composite load model. It is based on analytical form of the partial derivative matrix of system differential and algebraic equations with respect to the state and algebraic variables of the load model sub-matrix. Finally, a method to analyze the effects of the uncertainty in load model on the distribution of system eigenvalues is given. This method can be used to effectively describe how oscillation modes in multi-machine systems are affected as the parameter of load model is varying within the uncertainty scope. The effectiveness of the proposed method is illustrated by case studies using the classic two-area four-machine system. © 2010 State Grid Electric Power Research Institute Press.


Shen W.,Tsinghua University | Wu W.,Tsinghua University | Zhang B.,Tsinghua University | Hao J.,Henan Electrical Power Dispatching and Communication Center
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

It is a time-consuming task to manually edit the power grid one-line diagram in an EMS. An automatic diagram generating method is proposed. The automatic diagram generation problem can be divided into two sub-problems: the substation placement and transmission lines layout. The gravitation-repulsion method is used to optimize substation placement. This method can efficiently calculate a good scheme. Based on this initial scheme, a genetic algorithm is also used to revise the solution. To solve the transmission lines layout problem, the labyrinth exploration method is used to make the lines connecting two substations straight and even. The software developed based on the proposed method has been embedded in a commercial grade EMS and proved practical. ©2010 State Grid Electric Power Research Institute Press.

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