摘要:

The paper discusses a new methodology for applying the pattern recognition method developed by the author in the two related areas of security-economy preventive control and reactive control. The work here has taken advantage of the fact that each application of the above controls would, in one way or another, vary the amount of active and/or reactive (P-Q) power injected into the network busbars, and the network would then respond by readjusting its busbar voltages and flows accordingly. Using the amount of P-Q busbar injections for evaluating the relative merits of one control measure against the others, a ‘raise’ and a ‘lower’ priority list may be formed for correcting overload on each transmission line and for correcting undervoltage at each busbar. These priority lists provide the operators with a fast, easy to use computational tool for searching the best available control measures after each contingency, and for enabling the consequence of each chosen control measures to be predicted. The paper also describes the development and results of an algorithm formulated using the linear programming technique to shift busbar P-Q injections for relieving the overloaded transmission lines, and for minimising the busbar P-Q injection change during shifting.

DOI:10.1049/ip-c.1991.0001

出版商:IEE    

年代:1991

数据来源: IET

摘要:

A new modal technique to analyse the effects of a signal to be fed back by stabilisers in a plant with identical units is proposed. The contribution of a mode on an output signal is used as a measure of the coupling input-mode-output to verify the effectiveness of the signal. The effects of stabilisers on oscillation modes are then analysed. Attention is then paid to selective control of modes. It was concluded that not only a sum of speeds, but many other signals may be used for cancellation of the contribution of intraplant modes on system response. With this cancellation, stabilisers may be applied on a plant without deteriorating the damping of these modes.

DOI:10.1049/ip-c.1991.0002

出版商:IEE    

年代:1991

数据来源: IET

摘要:

The paper presents a generalised numerical method for calculating the risk of failure of power transmission lines due to switching overvoltages. Contrary to other known methods, the method incorporates the influence of overvoltage profile and differences in breakdown properties of insulation along the line on the risk of failure, irrespective of their probability distribution laws. Using a special program, developed on the basis of this method, the risk is calculated for several overvoltage probability distribution laws and line insulation levels. The influence of the overvoltage distribution along the line, i.e. overvoltage profile, on the risk of failure is considered for overvoltages obtained by calculations, as well as for overvoltages obtained by measurements on a specific transmission line. If the breakdown properties of insulation are given as a function of the wave front duration, it is possible by this method to incorporate into the calculations the influence of the wave front duration along the line on the risk of failure.

DOI:10.1049/ip-c.1991.0003

出版商:IEE    

年代:1991

数据来源: IET

摘要:

An efficient method for minimising real power losses and improving the voltage profile of large scale power systems is presented. The problem is solved through optimal adjustments of reactive power generation in the system by changing generator voltages, shunt capacitors, and tap setting of tap changing transformers. It is formulated in a linearised form suitable for the linear programming technique and decomposition methods. The power system planning and corresponding problems with the addition of new reactive power sources have been integrated with the operational characteristic of the system, and results have been presented. The proposed method does not require the inversion of the Jacobian matrix, and its superiority lies in the reduction of the computation time and memory space, as well as a fast convergence for the solution of large scale systems.

DOI:10.1049/ip-c.1991.0004

出版商:IEE    

年代:1991

数据来源: IET

摘要:

The economic dispatch problem is important in both power system planning and operation. Although there have been major advances in defining and solving more complete optimal power flow (OPF) problems, there exists a need for constrained economic dispatch (CED) techniques which, though not as rigorous or as exact as an OPF, are fast enough to be used on desktop computers. The authors present a CED formulation that is based upon generalised network flow programming (GNFP). The methodology for applying GNFP to the CED problem is developed and illustrated in this paper using four examples: 5, 39, 264, and 515-bus systems. Starting with a solved loadflow case, execution times for the CED are shown to be about the same as for a Newton-Raphson loadflow, and memory requirements are approximately 75% of the loadflow. Salient features of the CED-GNFP method include the ability to minimise generation cost while meeting constraints on line flows and area interchange. Network location of loads and generators is automatically considered without need of penalty factors, and transmission line flow limits do not affect solution times significantly. The authors believe that, owing to its simplicity of application, robustness, and ease of implementation on desktop computers, the CED-GNFP procedure is an important adjunct to the group of techniques and algorithms currently available for solving the overall economic dispatch/OPF problem.

DOI:10.1049/ip-c.1991.0005

出版商:IEE    

年代:1991

数据来源: IET

摘要:

Asynchronous operation of synchronous generators is considered during power system disturbances. Particular emphasis is given to the shaft stresses which develop during such operation. Reduction in the working life of the generators due to shaft fatigue is evaluated and the advantages and disadvantages of this type of operation are investigated.

DOI:10.1049/ip-c.1991.0006

出版商:IEE    

年代:1991

数据来源: IET

摘要:

A technique known as DC ripple reinjection, which has already been shown capable of operating a six-pulse rectifier effectively as a twelve-pulse convertor, is extended in the paper to convert the standard twelve-pulse HVDC convertor group into a 24-pulse configuration. Theoretical and experimental results are provided to demonstrate that the modified convertor configuration eliminates the 12-pulse related harmonics on both sides of the convertor.

DOI:10.1049/ip-c.1991.0007

出版商:IEE    

年代:1991

数据来源: IET

摘要:

The paper represents a novel approach to studying the automatic contingency selection (ACS). The total curtailment of the reactive loads is used as the performance index to evaluate the severity of contingencies. The minimum cost network flow model is proposed to determine the optimal curtailment in the line outage case. The objective of the model is the determination of the sum of branch voltage drops in terms of the line reactive flows. The optimisation model is solved by the ‘out-of-kilter algorithm’. The numerical results for several IEEE sample systems show that the proposed technique is feasible and effective.

DOI:10.1049/ip-c.1991.0008

出版商:IEE    

年代:1991

数据来源: IET

摘要:

The interactive system, NETOPT, may be used to design subtransmission networks, principally at the 33 kV level, adopting an interconnected design philosophy advocated by MANWEB. All secure networks that are designed are stored and can, at any time, be displayed graphically and analysed by a load flow program. A relatively inexpensive, deterministic design process based on Lagrangean relaxation is employed. The cost structure used is completely new. The problem of security specification is overcome by the use of: an existing, statistically derived, security function; a ‘constraint generation’ scheme which adds missing constraints to the problem formulation when required; a collection of other new security assessing procedures. A series of cost cutting features have been added to the reformulated problem to minimise the solution time. Larger problems can be solved using either an interactive or automatic branch and bound scheme.

DOI:10.1049/ip-c.1991.0009

出版商:IEE    

年代:1991

数据来源: IET

摘要:

The paper reports on a direct power flow solution technique for radial distribution networks. The special topology of distribution networks has been fully exploited to make direct solution possible. A unique branch and node numbering scheme has been proposed to achieve storage and computational economy. Composite load characteristics can be easily modelled. The method developed has been extended for meshed and unbalanced distribution networks. In both cases, modifications required are few and the advantages obtained in balanced radial networks in respect of storage and computational requirements have been preserved. The proposed method has been successfully applied to the solution of a number of practical distribution networks.

DOI:10.1049/ip-c.1991.0010

出版商:IEE    

年代:1991

数据来源: IET