In practice, it is not always possible that the theoretical pre-requisites for statistical identification be fulfilled. Consequently, the data collected are non-ideal, in the statistical sense, for identification. It ...
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In practice, it is not always possible that the theoretical pre-requisites for statistical identification be fulfilled. Consequently, the data collected are non-ideal, in the statistical sense, for identification. It is well known that the identification results from using such data may be misleading. In this paper, we discuss the practical problems involving the statistical modeling of a boiler system for an electric power plant using real plant data, and develop a methodology that yields good results in practical identification when the sample data used are non-ideal in the statistical sense. Simulation methods together with statistical tools, including a series of statistical tests, that are used to validate the model are discussed in the paper. Results of the modeling will be presented.
Standard implementations of network security functions are complex and sophisticated but inflexible. In this paper it is demonstrated, with the example of a load flow calculation, that the algorithms involved can be b...
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Standard implementations of network security functions are complex and sophisticated but inflexible. In this paper it is demonstrated, with the example of a load flow calculation, that the algorithms involved can be broken down into local and largely independent steps. The localization makes it possible to apply object-oriented programming for the implementation. Object-oriented programming is a modern programming style that makes use of software concepts such as data abstraction, information hiding, classification, inheritance and local processing. The application of these concepts results in implementations that can be easily extended and modified. The benefits of the object-oriented approach are demonstrated with an implementation of the load flow function in object-oriented programming.
Electrical Energy systems - as seen by operation - consist of objects. The objects have properties and can assume states. On the one hand the objects, by hierarchical aggregation, form larger units as bays switchyards...
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Electrical Energy systems - as seen by operation - consist of objects. The objects have properties and can assume states. On the one hand the objects, by hierarchical aggregation, form larger units as bays switchyards or substations;on the other hand, a subset of the objects is topologically linked and meshed. Starting from that view, a combined network/hierarchical-data base was developed. This data base is defined and filled using a source-language which is capable of expressing the stock of objects and its topological linkage in format free α-text. The present paper further describes a newly developed query language and the related query and state setting system, applied in simulation and software test mode. For accessing the DB-contents and convenient formulation of queries, the automatic design and production of a functional keyboard was developed.
This paper presents two types of intelligent monitoring & alarming (abbreviated as intelligent M & A) schemes. These M & A schemes are on the value added level relating to both MW & MVar stabilities. I...
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This paper presents two types of intelligent monitoring & alarming (abbreviated as intelligent M & A) schemes. These M & A schemes are on the value added level relating to both MW & MVar stabilities. In this paper, paying attention to the relationship between the auto-parametric resonance and MW stability and to the relationship between the multiple load flow solutions and MVar stability (voltage instability), a new method of M & A is proposed using two indices 'σ' (detuning parameter of auto-parametric resonance), for MW stability and 'θ' (=VIPI:Voltage Instability Proximity Index) for MVar stability. These two types of M & A of MW and Mvar instabilities to be carried out at each time point along the daily load curve are proposed as intelligent M & A.
In order to increase the numerical value of its strength, general guidelines for a measurement system design are proposed. This new concept, the absolute strength of a measurement system, is defined as the total numbe...
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In order to increase the numerical value of its strength, general guidelines for a measurement system design are proposed. This new concept, the absolute strength of a measurement system, is defined as the total number of subsets of n dimensional linearly independent measurements existing in a set of M measurements, with n ≤ M. For P-δ observability n = N-1, and for Q-V observability n = N, where N represents the number of the network nodes. The procedure to evaluate the strength of a measurement system is based on the property of the measurement to branch incidence matrix M, and the node to branch incidence matrix A of being both totally unimodular matrices. For regular, simpler networks, general formulas for the strength of their corresponding measurement systems are derived. These formulas generate new or already known integer sequences, some of the latter ones related to Fibonacci series, or to coefficients of Chebyshev polynomials.
In the new Finniston ***. courses greater emphasis is placed on innovation and design and this has led to a reappraisal of teaching methods, highlighting synthesis rather than analysis in problem solving. Although muc...
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In the new Finniston ***. courses greater emphasis is placed on innovation and design and this has led to a reappraisal of teaching methods, highlighting synthesis rather than analysis in problem solving. Although much of the analytical material remains in the courses, computer software packages are used to free the students from repetitious and tedious mathematical work in order to concentrate on the study and design of systems that bear a closer resemblance to those that might be met in practice. CTRL-C and ACSL are sophisticated computer packages which permit the modelling of complex systems using both classical and modern techniques.
The usual procedure adopted by power system engineers to determine the source of local or inter-area oscillations is to examine the speed components of the eigenvectors associated with the mode under investigation. Th...
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The usual procedure adopted by power system engineers to determine the source of local or inter-area oscillations is to examine the speed components of the eigenvectors associated with the mode under investigation. The approach does not always lead to the correct interpretation of the origin of the mode. The Participation Matrix used in parallel with the eigenvalue/eigenvector information will in general clearly identify those states which have most influence in producing a particular mode. This paper describes a procedure utilising the participation factors and eigenvector information to analyse system modes during recent investigations involving the retuning of powers system stabilisers on four 350 MW thermal units in a 3500 MW power system. The paper shows that predictions made during small disturbance analysis match those produced by transient stability analysis. Both sets of results are confirmed by actual system tests carried out during the retuning process.
Modern controlsystems in large power plants have a decentralized structure with data acquisition and control function performed by microcomputers, which are connected by a data transmission bus. In order to realize c...
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Modern controlsystems in large power plants have a decentralized structure with data acquisition and control function performed by microcomputers, which are connected by a data transmission bus. In order to realize closed loop control via the bus, data transmission of an analog signal is to be caused, if the analog signal has changed its value more than a well defined threshold since the last data transmission. Furthermore it is wanted to cause a data transmission only beyond a well defined time stop after the last data transmission. Considering the controlled system together with the control algorithm as linear sampled data system, the threshold with time stop is an additive nonlinearity whose influence on the time response of the closed loop is to be analysed. To give a general solution to this problem the sampled data control system is written by its w-transform with the relation (T/2)W = (z-1)/(z+1). As the w-transfer function gives the relation between input and output at sinusoidal steady state, now it is the idea to give a decribing function for the nonlinearity to solve the stability problem for sampled data systems in the same way as for continuous systems. As results there are given the conditions for and characteristics of limit cycles depending on the threshold, time stop and sampling period for a considered w-transfer function of the sampled data system.
The research in robotics requires efficient and flexible software tools, which supports the user in modelling and simulating the robot dynamics. In order to design a decoupled control of any robot, the exact dynamic m...
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The research in robotics requires efficient and flexible software tools, which supports the user in modelling and simulating the robot dynamics. In order to design a decoupled control of any robot, the exact dynamic models of these robots have to be obtained. This paper presents a computer-aided method, to achieve the dynamic model of any robot. The software first evaluates the basic data of the robot kinematics and dynamics, which are fundamental for the equation of motion and for the digital simulation of the robot dynamics. Then the tasks of an industrial controller for any robots are simulated to achieve realistic input values for the evaluation of forces/torques with the equation of motion and for the digital simulation of the robot dynamics. Finally the equation of motion is generated in a numerical-symbolical form.
A planning method is proposed for determining the optimal operational policy of a gas turbine combined heat and power plant connected with distributed heat supply plants at several districts. For the purpose of effici...
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A planning method is proposed for determining the optimal operational policy of a gas turbine combined heat and power plant connected with distributed heat supply plants at several districts. For the purpose of efficient planning, a hierarchical approach is adopted. At the first level, the optimal operational policy is determined for each heat supply plant so as to minimize the required amount of input energy. At the second level, the optimal operational policy is determined for the combined heat and power plant so as to minimize its operational cost. These optimization problems are formulated respectively as a mixed-integer quadratic programming problem and a mixed-integer linear one, and they are both solved by applying the branch and bound method. Lastly, the effectiveness of the proposed method is ascertained through a case study.
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