Method for identifying synthetic load equal value motor by asymmetric operation and frequency offset information

Abstract

The present invention discloses an asymmetric operation and frequency offset information identification combined load equivalence motor method which belongs to load model building technology field in modern electrical power system, particularly takes three phase unsymmetrical pressure instantaneous value information of bus where the load motor group in recorded by a load characteristic wave recorder as input, takes three phase unsymmetrical electrical current consumed by user load motor group under three phase unsymmetrical pressure as output, and performs coordinate transform of three-phase voltage three-phase current instantaneous value to build model of combined load equivalence motor, optimize function of current component under rotary coordinate system, apply mixing optimizing algorithm of combined differential evolution and simplex to identify combined load equivalence motor parameter; change formerly taking pressure positive sequence phasor as input and taking positive sequence power as output; also use default electric network frequency as 50Hz to identify limitation of combined load equivalence motor, enhance accuracy and credibility of model building, precision of combined load equivalence motor identification and range of application.

Description

Technical field [0001] The invention belongs to the technical field of load modeling in modern power systems, and proposes a method for identifying a comprehensive load equivalent motor based on asymmetric operation of the power grid and frequency offset information. Background technique [0002] With the gradual expansion of the scale of the power grid, the complexity of the power system has become increasingly obvious. Moreover, electric power has become an important industry related to the national economy and people’s livelihood, and its safety and reliability have a huge impact on various industries. It is impossible to conduct a large number of disturbance tests on the actual power grid to study the real power grid; on the other hand, there are many ways to operate the power grid. The fault conditions are different, and it is impossible to traverse the possible faults of the power grid through experiments; therefore, in the planning, analysis and operation of the power syst...

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Problems solved by technology

On the other hand, the operating frequency of the power grid is not necessarily 50Hz. When the frequency of the power grid changes, the power of the load motor will also change; the three-phase instantaneous value voltage of the bus connected to the motor with a comprehensive load equivalent value is: time 0-1s , three-phase voltage with a frequency of 50Hz; three-phase voltage with a time of 1-2s and a frequency of 49Hz; a three-phase voltage with a time of 2-5s and a frequency of 50Hz; where the positive sequence phasor figure 1 As shown, positive sequence phasor method and instantaneous value method are used to identify asymmetric voltage information respectively. image 3 It is the instantaneous power simulation diagram of the load motor when the positive sequence phasor method and the instantaneous value method are used respectively when the three-phase voltage frequency of the power grid changes, image 3 It shows that the power absorbed by the integrated load equivalent motor is different when the grid voltage frequency changes, so the modeling method of the load equivalent motor ignoring the frequency offset reduces the accuracy of the established model

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