Method for controlling a compressor installation
A method for controlling a compressor system comprising a plurality of compressors, wherein the compressor system is intended to maintain a predefined excess pressure in a pressurized fluid system, wherein decisions are met at fixed or variable intervals as to switching operations for adapting the system to current conditions, wherein—in a pre-selecting step, switching alternatives are excluded from the plurality of combinatorially available switching alternatives, —in a main selecting step, remaining switching alternatives are weighed against one another while referring to one or more optimization criterion (criteria) and optimum switching alternatives are selected from among the given criteria, and—in a control step, the selected switching alternative is output for implementation in the compressor system.
1 . A method for controlling a compressor system, the method comprising:
determining in real-time during operation of the compressor system a variable switch-off pressure for the compressor system, the determining of the variable switch-off pressure comprising basing the variable switch-off pressure on a minimum value of a function that determines a total power loss of a plurality of compressors in the compressor system during one switching cycle as a function of switch-off pressure; and
adapting the compressor system to current conditions by:
identifying a plurality of switching alternatives for the plurality of compressors, each switching alternative comprising a defined change in a configuration of the compressor system;
pre-selecting a smaller number of switching alternatives from the plurality of switching alternatives;
selecting a given switching alternative from the smaller number of switching alternatives;
increasing generation of a compressed pressurized fluid by the compressor system using the given switching alternative when a prevailing pressure of the pressurized fluid in the compressor system reaches a switch-on pressure, the switch-on pressure greater than an adaptation pressure that should not be undercut by the prevailing pressure; and
reducing generation of the pressurized fluid by the compressor system using the given switching alternative when the prevailing pressure of the pressurized fluid in the compressor system reaches the determined variable switch-off pressure, the variable switch-off pressure and the adaptation pressure defining a varying pressure band, the prevailing pressure moving along a pressure profile from at least the variable switch-off pressure and a minimum pressure between the switch-on pressure and the adaptation pressure during each switching cycle between two points at which the prevailing pressure equals the switch-on pressure.
2 . The method of claim 1 , wherein the plurality of compressors comprises compressors having different designs, different performance characteristics, or different designs and different performance characteristics.
3 . The method of claim 1 , wherein the method further comprises changing the determined variable switch-off pressure as a function of at least one of a current configuration of the compressor system and a switching operation.
4 . The method of claim 3 , wherein the current configuration of the compressor system comprises a current operation of the compressors in the plurality of compressors, and the switching operation comprises a change in the operation of one of more compressors in the plurality of compressors.
5 . The method of claim 1 , wherein determining the variable shut-off pressure comprises determining the variable shut-off pressure such that a real pressure profile in the compressor system does not exceed an upper pressure limit to assure compliance with pressure resistance limits of components within the compressor system.
6 . The method of claim 1 , wherein reducing generation of the pressurized fluid comprises executing a switching operation that changes a configuration of the compressor system.
7 . The method of claim 6 , wherein executing the switching operation comprises switching a load state of one or more compressors in the plurality of compressors.
8 . The method of claim 7 , wherein switching a load state of one or more compressors comprises switching one or more compressors to a no-load running state, changing an output of one or more compressors to a lower value, stopping one or more compressors, or combinations thereof.
9 . The method of claim 6 , wherein executing the switching operation comprises executing a switching operation immediately upon determination that the prevailing pressure of the pressurized fluid in the compressor system has reached the determined variable switch-off pressure.
10 . The method of claim 1 , wherein:
reducing generation of the pressurized fluid further comprises:
identifying a plurality of switching alternatives, each switching alternative comprising an associated switching operation; and
selecting one of the switching alternatives; and
executing the switching operation associated with the selected switching alternative.
11 . The method of claim 10 , wherein selecting one of the switching alternatives comprises selecting one of the switching alternatives in real time during operation of the compressor system.
12 . The method of claim 10 , wherein selecting one of the switching alternatives comprises using current operating conditions of the compressor system to select one of the switching alternatives.
13 . The method of claim 10 , wherein:
reducing generation of the pressurized fluid further comprises removing one or more switching alternatives from the identified plurality of switching alternatives; and
selecting one of the switching alternatives comprises selecting one of the switching alternatives from switching alternatives remaining in the identified plurality of switching alternatives.
14 . The method of claim 13 , wherein removing one or more switching alternatives comprises:
determining switching alternatives in the identified plurality of switching alternatives whose implementation is not technically feasibly based on current operating conditions in the compressor system; and
removing switching alternatives determined to be not technically feasible.
15 . The method of claim 1 , wherein reducing generation of the pressurized fluid by the compressor system comprises reducing generation of the pressurized fluid immediately upon determination that the prevailing pressure of the pressurized fluid in the compressor system has reached the determined variable switch-off pressure.
16 . The method of claim 1 , wherein the defined change in the compressor system configuration comprises a given change of the compressors in the compressor system among load running status, no load running status, and stopped status.
17 . The method of claim 1 , wherein the function is based on a load-running work loss in relation to a switching cycle duration.
18 . The method of claim 17 , wherein the function is further based on a no-load running work loss in relation to the switching cycle duration.
19 . The method of claim 18 , wherein the function is further based on a switching loss energy in relation to the switching cycle duration.