Multi-machine grouping equivalence method for full-power inversion type new energy power supply

Abstract

The invention discloses a multi-unit grouping equivalence method for a full-power inversion type new energy power supply, and the method comprises the steps: building a multi-unit short-circuit current analysis model of the full-power inversion type power supply, and carrying out the phase conversion; dividing into two types according to whether the unit enters low-voltage-crossing control, wherein the unit does not enter the low-voltage-crossing control and equivalence is carried out by adopting a weighted average voltage method; the method comprises the following steps: firstly, carrying out equivalent modeling on two units entering low-voltage crossing control; calculating an electrical quantity boundary corresponding to a corresponding category by utilizing a relation between a relative error generated by equivalent modeling and an electrical quantity and combining a given error upper limit so as to realize grouping equivalence; meanwhile, based on the thought of equivalence of the two units, the method can also be popularized to a scene with more than two units. By adopting the method disclosed by the invention, the equivalent modeling precision of the new energy power supply can be ensured, the complexity of the equivalent model is simplified, the simulation time is shortened, and the calculation efficiency of the network short-circuit current is improved.

Description

technical field [0001] The invention relates to the technical field of equivalent modeling of power systems, in particular to a multi-machine grouping equivalent method for a full-power inverter type new energy power source. Background technique [0002] The installed capacity of wind power in my country is growing rapidly. As of April 2021, the installed capacity of power generation nationwide was 2.23 billion kilowatts, an increase of 9.5% year-on-year, of which the installed capacity of wind power was 290 million kilowatts, an increase of 34.6% year-on-year, and the growth rate far exceeded the total installed capacity of power generation. After the large-scale connection of new energy sources such as wind power and photovoltaics to the power grid, the topology structure and power flow distribution of the power grid are changed, and the fault characteristics of the power electronic devices in the system are prominent. Performance and safe operation level of the system und...

AI Technical Summary

Problems solved by technology

After wind power, photovoltaic and other new energy sources are connected to the power grid on a large scale, the topological structure and power flow distribution of the power grid have been changed. The fault characteristics of power electronic devices in the system are prominent. The controlled and distorted short-circuit current is quite different from the synchronous power supply, which affects the protection action. Performance and safe operation level of the system under grid short-circuit fault disturbance

However, the current equivalent modeling method for new energy stations often adopts the single-machine multiplication method. When performing equivalent modeling on a large number of new energy power sources with different operating states, the accuracy of the single-machine equivalent model is poor, which seriously reduces The accuracy of the fault current after a short circuit is not conducive to the analysis of the action performance of the relay protection device

[0003] With the rapid increase in the proportion of new energy sources such as wind power and photovoltaics, the traditional stand-alone equivalent model cannot meet the needs of actual production and operation

Moreover, compared with synchronous generators, new energy sources such as wind power and photovoltaics connected to the grid using power electronics technology have differences in their operating mechanism, grid-connected topology and control methods.

This leads to complex and special fault transient characteristics of the new energy power supply, which poses new challenges to the station modeling of high-density access to the new energy power supply

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