共查询到20条相似文献，搜索用时 718 毫秒
1.
The voltage instability of power system often occurs when the active power on one or more weak branches exceeds its transfer capability. A preventive control model for static voltage stability is proposed using the active power transfer capability of weak branches as static voltage stability constraints. A local line based voltage stability index is used to determine the critical contingencies, weak branches and transfer capability of each weak branch. A static security analysis method, which is based on DC power flow equations, is used to establish the non linear active power flow expressions on weak branches following each critical contingency. The active power constraints on weak branches can be obtained from the active power flow expressions and transfer capabilities of weak branches. A quadratic optimal model for preventive control including the proposed active power constraints on weak branches is presented. The simulation results for IEEEE14 bus system and IEEE118 bus system demonstrate the correctness and effectiveness of the proposed preventive control model. 相似文献
2.
Zhao Youxin Li Wenyuan 《保鲜与加工》1991,(1):1-5
A method introducing fictious variables for resolving the linear model of reactive power and voltages control in power systems is presented. The method theoritically guarantees the resolvability and optimizition of linear programming model. This method has been proved successful by IEEE 6 -node test system and the several practical power systems such as 49-node, 155 -node systems. 相似文献
3.
Chen Wanming Zhou Jiaqi 《保鲜与加工》1992,(3):37-42
An A. C. load flow analysis of the reliability evaluation of composite generation and transmission systems is presented on the basis of a fast outage simulation algorithm and an optimal model of active and reactive power adjustment after outage contingencies. The information of the first -level outage events is utilized for simulating higher -level outage events in the fast outage simulation algorithm ; the optimal model is satisfactory in speed and accuracy with the application of concentric relaxation and linear increment constraint on the comprehensive adjustment of active and reactive power. As an example. the IEEE Reliability Test System is tested and the results show that the method is accurate and well-matched in speed with the method studied by R. Bllinton, et al. 相似文献
4.
Based on the reactive surplus of Chongqing 220 kV main electric power network under low water and low load, and on state of higher system voltage, a thorough research is done on voltage and reactive power of the system power network by means of calculation,analysis and experiments. A main network calculating equivalence model of power network in Chongqing is constructed. And reactive power optimizing calculation is figured out on the Chongqing power network on condition that the loss minimum of the active power network is object function. Several optimizing compensatory schemes are put forward. Based on the calculation result and the analysis of all schemes, the most reasonable and feasible optimizing scheme could be achieved. Meanwhile, the feasibility that the system voltage could be adjusted when generator operating under excitation was demonstrated. According to the experience of under-excitation operation of the same type units , it decreases the system voltage, improves Chongqing power network running performance, and strengthens the coordination and stabilization of system. 相似文献
5.
In power system,traditional method of nonsinusoidal power measurement is not feasible for containing non integer harmonics condition. A method of power measurement based on Prony algorithm is presented. At first, identify all modes of integer and non interger harmonics from voltage and current signals, using Prony method. Futher more, calculate active and reactive power in each harmonics frequency, using the modes of harmonics. Based on the defination of IEEE active power, a expression of Budeanu power is given in non integer harmonics condition. At last, active and reactive power of energy gird are calculated. The results of simulation prove that this method is feasibility. The method of power measurement based on Prony algorithm has high precision, especially for non integer harmonics condition. 相似文献
6.
Zhao Youxin 《保鲜与加工》1988,(4)
A new approach based on sensitivity method for the optimal power flow is presented in the paper. This method has the following advantages: it is suitable to solve a 200-node power system on the microcomputer; the convergence is easy to reach and the computation speed is quick; it is possible to reduce 8-14% power loss and to get maximum economic benefit by using this method; in power system dispatch center it can be used as an on-line voltage and reactive power control program to keep good voltage level. The proposed method has been proved successful by IEEE 118-node test system and the several real power systems such as 49-node, 61-node, 99-node and 200-node systems. 相似文献
7.
This paper presents a new rnethod for analysis and computation of steady-statereal power security region by linear programming.In this method based on the D.C load flow,theupper and lower bounds of the hyper-cuboid explicit steady-state security region are chosen asunknown variables.The objective function is the total amount of the adjustable generations withweighting factors.The model of the steady-state real power security region is changed in to the proposed linearprogramming methed for ealculation.The numerieal exarnples are tested on IEEE 6-bus and 30-bussample systems.The computational resuIts showed the proposed model a nd algorithm feasible andeffective. 相似文献
8.
The main means of the voltage-reactive power control of substation are adjusting the taps of load-tap-changing transformer or the reasonable capacity of parallel compensating capacitors according to the operation condition of substation.The "nine-area control strategy" is widely used to adjust voltage in the stated range and reduce the transmission capability of reactive power for power system at present.By analyzing the existent shortages of nine-area control mode for voltage-reactive power,an adjusting voltage calculation method is put forward,input data of which are the real time data of current,voltage and power of the substation.Then operation decision of voltage-reactive power control method of substation is made.By the simulating analysis,predigesting method of upper system is built,based on which an applied real time calculating model and calculating steps is given. 相似文献
9.
In dynamic reactive power optimization problem(DRPO), action number constraints of discrete variables should be considered.By integrating immune genetic algorithm(IGA) and nonlinear interior point method(NIPM), a hybrid method for DRPO is proposed.First,the original DRPO problem is converted to a continuous optimization problem by relaxing the discrete variables,and the solution is obtained by NIPM.Then,according to the feature of control variables,the original DRPO problem is decomposed into a continuous optimization sub-problem and a discrete optimization sub-problem.The discrete optimization sub-problem is solved by IGA,and the continuous one is solved by NIPM.By solving the two sub-problems alternately,the optimal solution of the DRPO can be obtained.The proposed hybrid method combines advantages of IGA and NIPM,and finds the approximate optimal solution of DRPO.Numerical simulations on the IEEE 14 bus system illustrate that the proposed hybrid method is effective. 相似文献
10.
Liu Haijun Deng Renming 《保鲜与加工》1992,(5):51-56
This paper presents a new hierarchical and coordinative control method for reactive power optimization in large-scale interconnected power systems. It combines the interconnection forecast method for hierarchical control in large-scale steady state industrial systems with the incremental linear programming method for reactive power optimization in real time. The results of applying the method to power system examples show that the method not only solves the problem of high dimension in order, but also keeps the advantages of the incremental linear programming method. The proposed method is also suitable for the security analysis of reactive power correction in large-scale interconnected power systems. 相似文献
11.
In view of the reliability and the efficiency of the remote control systems for Electric Power Equipment, a remote control system is proposed in which the control information interacts by low voltage power network communication. Low voltage power network is used as the channel for control information of Electric Power Equipment. The MSK modulation and demodulation technology that is seasoned with the channel characteristics of low voltage power network were selected, while the theory of MSK is analyzed,and the remote control system model to Electric Power Equipment based on low voltage power network communication with MSK and Programmable Logic Controller is constructed. The remote control system for Electric Power Equipment is manufactured based on the model. Theoretical analysis and experimental results show that MSK can satisfy the channel characteristics of low voltage power network, realize reliable transmission of the remote control signals, and improve the reliability of the remote control system while decrease the cost. 相似文献
12.
Environmental/Economic Power Dispatch (EED) now is one of the critical issues in power systems.Aiming at the nonlinear fuel cost function and particle emission function which take generation unit’s real power generation amount as decision variable,the generation unit is transformed into a fuzzy variable and a novel fuzzy multi objects model for EED is proposed to replace the traditional quadratic programming model.Furthermore,an improved genetic algorithm is adopted to find out the optimal solutions.Finally,the effectiveness of the method is testified by the simulations on an IEEE 3 generator test system,and the result shows the cost of power system and particle emission amount are greatly reduced. 相似文献
13.
A section algorithm of reliability evaluation for complex medium voltage Electrical Distribution Networks (EDNs) using adjacency multilist (AM) is proposed. The constructing method for AM is introduced. The AM can be used to store the structure data of EDNs and to solve the problem of space & time complexity. A new power flow algorithm of backward / forward sweep is proposed and a fast algorithm of forming sections in distribution network is put forward. The proposed algorithm makes a perfect combination of the power flow algorithm and the section algorithm of reliability evaluation, which makes efforts to decrease the work of programming and saves the computing time. Applying the proposed algorithm in RBTS-BUS6 system and actual EDNs, the reliability assessment results show that the algorithm has an advantage of saving time and possesses efficiency in engineering practicality. 相似文献
14.
With interconnecting and developing of power system, the problem of power flow computation on dispersed data resource need to be solved. A new distributed computation method of power flow based on Ward equivalent is presented. According to master-slaver splitting principle, multi-area interconnected power system is divided into master-slaver areas. Boundary buses in different areas are defined as different bus-types. Neighborhood areas are equivalent by Ward equivalent principle, and the equivalent injection power and equivalent impedance are worked out. Power flows from master area to slaver areas are solved by Newton method, and the equivalent injection power and equivalent impedance on the boundary are modified by their solutions. The process above repeats until to convergence. The proposed distributed power flow method takes full advantage of the information of power, voltage, network configuration in neighborhood areas, so it is better on convergence and quality of solution. The proposed algorithm is testified by IEEE 14-bus system and a practical 181-bus system. 相似文献
15.
The synthetic quantified evaluation for power quality is one of the gist to weigh excellent or inferior of the power quality, and this is propitious to realize the electricity-purchase principle of discussing the price according to quality and high quality high price, thereby serve as to build the equitable electric power market. This paper proposes to use the method of matter-element for power quality evaluation, and then build the model based on the method of matter-element. Considering the non-compatible feature between the single recognition and evaluation results as well as the complexity of the evaluation for power quality, a model is approached for the evaluation of the power quality by using the matter-element and extension set. Case results show that use the proposed model is objective and reasonable, with a special advantage when used in power quality evaluation. 相似文献
16.
Xu Guoyu Zhu Jizhong 《保鲜与加工》1990,(2)
A new approach of the automatic contingency selection and ranking with the network flow programming (NFP) is presented in this paper. NFP is adaptable to change the network topology as the transmission or generation branches arc in single or multiple outage. Thus the fast calculation of the contingency states by NFP cm provide the urgent information in real time N- 1 security analysis. In the paper, automatic contingency selection and ranking forP- and Q-type subproblem arc solved by an unified network flow model and algorithm. It is based on the existence of weak coupling between real and reactive quantities in power systems. The performance indices to assess the severity of contingencies are defined as the total real and reactive load required to be curtailed. The proposed ACS technique including the model and its algorithm are examined with IEEE 5-, 14-, 30-, 57- and 118- bus test systems on M-340. And the encouraging results are given in the paper. 相似文献
17.
This paper discuas the controlling principle of asynchronized turbogenerators,deduces their mathematical model,and studies their regulating characteristics of real and reactive power(or voltage)by means of simulation calculation of operating characteristics for a 200MW asychronlzed turbogenerator.The conclusion is that the asychronlzed tubogenerators not only can regulate real and reactive power independently but also has an excellent dynamic performance. 相似文献
18.
Ran Li Ren Zhen Jiang Zejia 《保鲜与加工》1988,(6)
An optimal active power adjustment model is deve in this paper for hybrid AC/DC systems after outage contingencies. The objective of the model is to minimize the rejection of load when some elements are out of service, with adjustment strategy approaching practical system operation. A large number of outage contingencies are simulated when the Monte-Carlo Method is emyloyed to evaluate the system reliability, requiring fast calculation of each simulation. The model and computer method proposed in this paper satisfy such a requirment because of the application of concentric relaxation, recursive branch constraint treatment in linear programming and a direct method for B-1 matrix modification. This paper is concerned with the simplified steady state conditions of the system based on DC load-flow, which implies the reliability indices calculated are the measures about static loss of load. The results for a 14-bus hybrid AC/DC system are given. 相似文献
19.
Hou Zhencheng Lu Zhiguo Zou Yan Luo Shiguo 《保鲜与加工》1991,(6):28-31
According to the basic idea of phasar analysis and by applying a special multiplier, a new on line and real time method is derived for determining harmonic current and reactive current of an electric network. This method has a good dynamic response characteristic and solves for the first time the determining problem for the compensation system in single phase system,which is also appliable to the three-phase system. 相似文献
20.
This paper describes an application of evolutionary programming(EP) to reactive power optimization and voltage control of power systems.Some technical problems which conclude mutation sacle,fitness value and population size have been solved to make EP practical for solving the optimal power flow problems.The computational results with EP have been compared with those obtained from a conventional gradient based optimization method.The comparision shows that EP are better than conventional methods in dealing with the optimization of noncontinuous and nonsmooth funcnons.The EP show the ability to search for the global optimum in reactive optimization that has multiple optima. 相似文献