A DC power modulation method for power over-limit control of compound AC section

Abstract

The invention provides a DC power modulation method for the control of the power over-limit of the compound AC section, which comprises the following steps: calculating the DC power modulation amount Pmod through the power Pac of the AC tie line to realize the power fluctuation control of the AC section; judging the AC power through the power Pac of the AC tie line Check whether the section power exceeds the limit, if it exceeds the limit, go to step 3; calculate the DC power emergency control value Pemg, and complete the control of the AC section power exceeding the limit. The invention combines the DC power emergency control function with the conventional DC power modulation function, without adding an additional monitoring device, that is, it can suppress the power fluctuation of the AC tie line of the cross-regional power grid, and make up for the power shortage of the regional power grid through emergency power control. , to keep the static stability limit of the AC tie line from being destroyed, thereby simultaneously improving the transient and dynamic stability characteristics of the regional interconnected grid under complex operation modes and conditions.

Description

technical field [0001] The invention relates to a modulation method, in particular to a direct current power modulation method for compound alternating current section power over-limit control. Background technique [0002] For the AC-DC hybrid grid, the application of DC power modulation technology can suppress the power / voltage / frequency fluctuations of the AC grid. The DC power modulation technology calculates the modulation quantity by collecting the electrical quantity of the AC system and designing a letter, and sends the calculation result to the controlled DC to modulate the DC transmission power, so as to suppress the system oscillation. [0003] The commonly used DC power modulation technology damps the system oscillation by continuously changing the DC transmission power. When the system oscillation is suppressed, the DC transmission system will gradually recover to the transmission power before the fault. However, if the system oscillation is caused by some unce...

AI Technical Summary

Problems solved by technology

However, if the system oscillation is caused by some uncertain fault that leads to a power shortage in the regional power grid (such as shutdown, DC blocking, etc.), when the system oscillation gradually subsides, the AC grid may still be in an unsafe state, such as The frequency of the regional power grid is suspended, and the transmission power of the cross-region tie line is close to or exceeds the limit of temporary stability / static stability. At this time, the DC modulation function no longer operates, which may cause the system to lose stability.

[0004] For the power shortage of the regional power grid caused by the above-mentioned uncertain faults, the power grid is usually regulated through low-cycle load shedding, AGC (automatic generation control) or frequency modulation of the direct current transmission system, but these methods usually have a shorter action period. Long time and slow response, it is difficult to meet the requirements for stability control of cross-regional power grids

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