A Power Flow Analysis Method for DC Transmission Sending-End Islanding System

Abstract

The invention discloses a load flow analysis method of a direct current transmission feed end islanding system. The method includes the following steps that (1) an alternating current system and a direct current system are divided; (2) the load flow of the islanding alternating current system is solved; (3) out-of-limit judgment is conducted on the reactive power exchange capacity of the alternating current system and the direct current system, if reactive power exchange exceeds a normal operation set value, the amplitude of a commutation busbar voltage is adjusted, the step (2) is executed again to continue, and otherwise the step (4) is executed; (4) the number of reactive power compensation groups is determined; (5) the reactive power consumption of a direct current convertor station is determined; (6) converter firing angle amplitude limiting inspection is carried out, if the amplitude is within a normal operation range limiting value, the step (7) is executed, otherwise the number of the reactive power compensation groups is added, and the step (5) is executed again; (7) a commutation tap is determined; (8) load flow convergence is judged; (9) the direct current frequency limiting value function is set. By means of the load flow analysis method of the direct current transmission feed end islanding system, the practical situation of the direct current transmission islanding system can be reflected more accurately, and planning and operating of the direct current transmission islanding system can be guided more efficiently.

Description

technical field [0001] The invention relates to a power flow analysis method for an isolated island system at the sending end of direct current transmission, in particular to a method for analyzing the power flow of an isolated island system at the sending end of direct current transmission, which is suitable for the island operation at the sending end of a direct current transmission system and considers DC frequency limit control, and belongs to the power system security Technical field of stability analysis. technical background [0002] China's energy resources such as coal and hydropower are mainly distributed in the western region, while the power load is mainly concentrated in the economically developed eastern coastal areas, and energy resources and power loads present a reverse distribution characteristic. In order to effectively develop and utilize the abundant energy resources in the west and meet the demand for electricity for economic and social development, Chi...

AI Technical Summary

Problems solved by technology

Therefore, the conventional AC / DC power flow analysis methods all assume that the frequency limit function of DC transmission is not enabled, and the power flow calculation considers that the transmission power of the DC transmission system remains unchanged, and the generator is used as the balance node of the system

[0010] However, the unit, line or transformer failure in the island operation system at the sending end of DC transmission may cause active power disturbances, cause system frequency changes, and may activate the frequency limitation function of DC transmission, and may change the transmission power of the DC transmission system. These power flow characteristics Cannot be accurately simulated by conventional AC / DC power grid power flow analysis methods

[0011] 2) Conventional AC / DC power grid power flow analysis methods cannot accurately simulate the reactive power control function and converter transformer tap adjustment function of the DC transmission system

If the total amount of reactive power compensation input by the user is unreasonable, it may happen that the converter transformer tap exceeds its gear range or the trigger angle of the converter exceeds the normal operating range, etc., and the reactive power group of the DC transmission system cannot be simulated. Automatic switching, automatic adjustment function of flow transformer tap

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