Filtering method for direct-current side voltage of cascaded distribution static synchronous compensator

Abstract

The invention discloses a filtering method for the direct-current side voltage of a cascaded distribution static synchronous compensator. A plurality of paths of sliding average filters are provided, correspond to to-be-filtered direct-current side voltage signals one by one, and are used for filtering double power frequency fluctuation components in the direct-current side voltage; each path of sliding average filter adopts the same principle and a uniform structure, a power frequency half period is taken as a working period, and a digital signal processor is realized through a digital control method. Compared with the conventional two-order low-pass filtering method, the filtering method has a better filtering effect. Moreover, a small quantity of time resources of the digital control system are occupied in an algorithm, and the system sampling frequency is increased, thereby increasing and improving the control accuracy of digital control and the system stability. Meanwhile, the dynamic response of the sliding average filters becomes faster.

Description

technical field [0001] The invention belongs to the technical field of signal processing, and in particular relates to a method for filtering DC side voltage of a static synchronous compensator of a cascaded distribution network. Background technique [0002] Distribution Network Static Synchronous Compensator (DSTATCOM), as a new application of Static Synchronous Compensator (STATCOM) in distribution network, is to compensate load by continuously and rapidly injecting reactive power with adjustable size and nature into distribution network. It is an effective means to stabilize reactive power and harmonics, and stabilize the voltage of common connection points; compared with traditional reactive power compensators (SVC), DSTATCOM has received more and more attention and attention due to its advantages such as fast adjustment ability and wider operating range. In addition, the cascaded structure of DSTATCOM can realize high-voltage and large-capacity through the cascading of...

AI Technical Summary

Problems solved by technology

[0003] When DSTATCOM compensates the reactive load, the compensation current is exchanged between the device and the power grid, which will introduce double power frequency (100Hz) voltage fluctuations on the DC side of DSTATCOM, and the amplitude of the fluctuations increases with the aggravation of the reactive load and the DC side The value of the support capacitor increases; if the voltage fluctuation is directly sent to the DC side voltage stabilization control loop without processing, it will introduce harmonic components into the output of the voltage stabilization loop and enter the current control loop, resulting in DSTATCOM compensation current The harmonic content of the control system increases, which affects the compensation effect; at the same time, the existence of voltage fluctuations can easily cause false protection or frequent protection of the control system, which is not conducive to the stable operation of DSTATCOM

[0004] The simple way to suppress voltage fluctuation is to increase the DC side support capacitance, but it will increase the size of the device and increase the cost; in addition, H.Akagi et al. in the title Control and Performance of a Transformerless Cascade PWM STATCOM With Star Configuration (Industry Applications, IEEE Transactions on, 2007.43(4):p.1041-1049), the digital filtering method of the second-order low-pass filter (LPF) is used, which can effectively filter out voltage fluctuations and prevent them from entering the control loop; however, the second-order low-pass filter When the filter is implemented by DSP digitally, the algorithm takes up more time resources, especially the cascaded DSTATCOM has a large number of independent DC side channels. When each voltage signal corresponds to a filter, the time occupied by the second-order low-pass filter algorithm There are more resources, and even the sampling frequency of the control system can only be reduced, which will sacrifice the compensation accuracy and stability of the DSTATCOM system, which is unacceptable

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