A reactive power optimization method for converter stations considering the reactive power compensation device on the low-voltage side of the main transformer

Abstract

The present invention discloses a reactive power optimization method for a converter station considering the reactive power compensation device on the low-voltage side of the main transformer. Reactive power balance calculation method; optimize the reactive power exchange range between the converter station and the AC system; formulate a strategy for automatically switching reactive power compensation equipment with the Qcontrol function that takes into account low capacity and low reactance, and modify it in the DC station control system Control logic; realize the Qcontrol function to automatically switch the reactive power compensation device; if necessary, manually switch low-capacity and low-resistance for voltage regulation. The present invention utilizes the reactive power compensation capability of low-capacity, low-resistance and other reactive power compensation devices in the reactive power adjustment of the high-voltage direct current system, reduces the reactive power adjustment gradient, and at the same time adjusts the range of reactive power exchange between the converter station and the AC system, Reduce the number of input groups of AC filters, optimize resource allocation, and improve voltage control capabilities.

Description

technical field [0001] The invention relates to the field of high-voltage direct current transmission, in particular to a reactive power optimization method for a converter station taking into account a reactive power compensation device at the low-voltage side of a main transformer. Background technique [0002] HVDC transmission system is a very important energy transmission system in power system. High-voltage direct current transmission is a power transmission method that converts the alternating current generated by the power plant into direct current through the rectifier, and then transmits it to the receiving end through the direct current line, and then uses the inverter to convert the direct current into alternating current and sends it to the receiving end AC power grid. The high-voltage DC system needs to consume a lot of reactive power when it is running. Taking the thyristor converter valve as an example, the reactive power consumed by the thyristors of a singl...

AI Technical Summary

Problems solved by technology

[0004] 1. The excess reactive power leads to an increase in the voltage of the AC system

In the case of high-voltage DC system operation, in addition to providing reactive power, the AC filter must also meet the requirements of filtering harmonics and steady-state constant value. After the AC filter is used, it will generally lead to excess reactive power.

The reactive power strategy calculation method that does not consider low capacity and low reactance fails to truly reflect the reactive power exchange between the converter station and the AC system. voltage rise

[0005] 2. Lead to long-distance transmission of reactive power

The reactive power compensation capacity of a single set of AC filter is large, and the voltage adjustment gradient is too large. If too many AC filters are used, the reactive power of the AC system will be excessive, and the excess reactive power will be transmitted to the surrounding plants and stations through the transmission line, resulting in system failure. Components generate heat, generate losses, etc., and also reduce the active power transmission efficiency of the power system

[0006] 3. Unreasonable use of resources

This forces low resistance to long-term investment, accelerates low resistance to aging, and shortens service life. At the same time, equipment heating defects are prone to occur, and equipment breakdown may occur in extreme cases.

However, the low capacity has not been put into use for a long time, and the resources are idle

[0007] 4. The AC busbar voltage adjustment margin in the converter station is not high. When the voltage exceeds the upper limit, there are no more low-resistance inputs for voltage regulation. In severe cases, the DC power may be limited and the power flow distribution of the system may be affected.

[0008] 5. Low resistance to long-term investment leads to frequent occurrence of equipment heating defects

[0010] 7. Low capacity and low resistance can only be switched manually, and the operation is not intelligent

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