Pressure Oscillations Occurring in a Centrifugal Compressor System With and Without Passive and Active Surge Control

Abstract

A study of pressure oscillations occurring in small centrifugal compressor systems without a plenum is presented. Active and passive surge control were investigated theoretically and experimentally for systems with various inlet and discharge piping configurations. The determination of static and dynamic stability criteria was based on Greitzer’s (1981) lumped parameter model modified to accommodate capacitance of the piping. Experimentally, passive control using globe valves closely coupled to the compressor prevented the occurrence of surge even with the flow reduced to zero. Active control with a sleeve valve located at the compressor was effective but involved a significant component of passive throttling which reduced the compressor efficiency. With an oscillator connected to a short side branch at the compressor, effective active control was achieved without throttling. Both methods of active control reduced the flow rate at surge onset by about 30 percent. In general, the experiments qualitatively confirmed the derived stability criteria.

Centrifugal compressor surge and speed control

“…Of many possible actuation schemes, closed coupled valve (CCV) control is considered one of the most promising [6], [18], [21], [25], [27]. Experimental results of CCV control is reported in [6] and [21]. Surge in a compression system can be explained by the throttle line crossing the compressor characteristic in an area of positive compressor characteristic slope.…”

“…A close coupled valve is placed immediately downstream of the compressor (hence close coupled), and active control of the valve pressure drop is utilized to make the slope of the equivalent compressor (compressor in series with the valve) negative and thereby stabilizing the system. This approach was used in [21], [25], and [27] for surge control of the model of [17]. Linear stability analysis was used in designing control laws resulting in local stability results.…”

A high-speed valve for surge control in a centrifugal compression system

“…Successful surge control experiments with control valve actuation, both with close-coupled and plenum bleed valves, are reported in [13][14][15][16]. Control valves are standard equipment in industry (e.g.…”

Two results on compressor surge control with disturbance rejection

“…(12) where (8) is used. Let the virtual control be chosen as = d (13) and the estimate d be updated as …”