Method for controlling at least a part of a pump station

Abstract

A method for controlling at least a part of a pump station including a number of speed controlled pumps, the method is arranged to minimize the specific energy consumption E spec of at least a part of the pump station and includes a sub method, which in turn includes the steps of: obtaining input data, determining the mutual relative relationships between a first value A 1 of a quantity corresponding to a first pump speed V 1 and a second value A 2 of the quantity corresponding to a second pump speed V 2 , and between a first specific energy consumption E spec 1 and a second specific energy consumption E spec 2 , and determining a third value A 3 of the quantity corresponding to a third pump speed V 3.

1 . A method for controlling at least a part of a pump station comprising a number of speed controlled pumps, the method ( 7 ) being arranged to minimize a specific energy consumption E spec  of said at least a part of a pump station, wherein the method comprises a sub method that comprises the steps of:
 (a) obtaining input data in the form of a set of parameters corresponding to a fictitious or elapsed first operating period t 1  and a fictitious or elapsed second operating period t 2 ,   (b) determining, based on said set of parameters, a mutual relative relationship between
 (i) a first value A 1  of a quantity that corresponds to a first pump speed V 1  and that is derived based on said set of parameters, which first value A 1  relates to said first operating period t 1 , and a second value A 2  of said quantity that corresponds to a second pump speed V 2  and that is derived from said set of parameters, which second value A 2  relates to said second operating period t 2 , 
   and between
 (ii) a first specific energy consumption E spec   1  that is derived based on said set of parameters and that relates to said first operating period t 1 , and a second specific energy consumption E spec   2  that is derived from said set of parameters and that relates to said second operating period t 2 , 
   (c) determining, based on said determined mutual relative relationships and on parameters B 3 , B 4 , B 5 , and B 6  of said quantity, output data in the form of a third value A 3  of said quantity corresponding to a third pump speed V 3  of a third operating period t 3 , wherein
 A 3  is set equal to A 2 −B 3  if the conditions A 2 <A 1  and E spec   2 <E spec   1  are satisfied, 
 A 3  is set equal to A 2 +B 4  if the conditions A 2 >A 1  and E spec   2 <E spec   1  are satisfied, 
 A 3  is set equal to A 2 +B 5  if the conditions A 2 <A 1  and E spec   2 >E spec   1  are satisfied, and 
 A 3  is set equal to A 2 −B 6  if the conditions A 2 >A 1  and E spec   2 >E spec    1  are satisfied. 
   
     
     
         2 . The method according to  claim 1 , wherein the specific energy consumption of said at least a part of a pump station is given as a predetermined value E spec  for a fictitious operating period or is calculated according to E spec =k*E for an elapsed operating period, where E is consumed energy by at least one of said number of frequency controlled pumps during said elapsed operating period and k is a time parameter, and wherein the value A of said quantity is given as a predetermined value for the fictitious operating period or is registered for said elapsed operating period. 
     
     
         3 . The method according to  claim 1 , wherein the first value A 1  of said quantity consists of the pump speed V 1 , the second value A 2  of said quantity consists of the pump speed V 2 , and the third value A 3  of said quantity consists of the pump speed V 3 . 
     
     
         4 . The method according to  claim 1 , wherein the first value A 1  of said quantity consists of a first current feed frequency F 1 , the second value A 2  of said quantity consists of a second current feed frequency F 2 , and the third value A 3  of said quantity consists of a third current feed frequency F 3 . 
     
     
         5 . The method according to  claim 1 , wherein the first value A 1  of said quantity consists of a first supply voltage S 1 , the second value A 2  of said quantity consists of a second supply voltage S 2 , and the third value A 3  of said quantity consists of a third supply voltage S 3 . 
     
     
         6 . The method according to  claim 1 , wherein the set of parameters comprises said first value A 1  of said quantity and the associated first specific energy consumption E spec   1 , as well as said second value A 2  of said quantity and the associated second specific energy consumption E spec   2 . 
     
     
         7 . The method according to  claim 1 , wherein the parameters B 3 , B 4 , B 5 , and B 6  have predetermined values, each of which corresponds to a current feed frequency change that is greater than 0.5 Hz, and smaller than 5 Hz. 
     
     
         8 . The method according to  claim 7 , wherein each of the parameters B 3 , B 4 , B 5 , and B 6  corresponds to a current feed frequency change of 1 Hz. 
     
     
         9 . The method according to  claim 7 , wherein the parameter B 3  is equal to the parameter B 5 , and the parameter B 4  is equal to the parameter B 6 . 
     
     
         10 . The method according to  claim 2 , wherein the length of an operating period is n*24 h, where n is a positive integer, and wherein the time parameter k is calculated according to 
       
         
           
             
               k 
               = 
               
                 1 
                 
                   n 
                   * 
                   24 
                 
               
             
           
         
       
     
     
         11 . The method according to  claim 2 , wherein the length of an operating period is n*24 h, where n is a positive integer, and wherein the time parameter k is calculated according to 
       
         
           
             
               
                 k 
                 = 
                 
                   1 
                   
                     c 
                     * 
                     
                       ( 
                       
                         n 
                         * 
                         24 
                       
                       ) 
                     
                   
                 
               
               , 
             
           
         
       
       where c is an equalization parameter. 
     
     
         12 . The method according to  claim 11 , wherein the equalization parameter c is calculated according to 
       
         
           
             
               c 
               = 
               
                 
                   x 
                   
                     p 
                      
                     
                       a 
                       ∘ 
                     
                   
                 
                 
                   ∑ 
                   
                     t 
                     
                       p 
                        
                       
                         a 
                         ∘ 
                       
                     
                   
                 
               
             
           
         
       
       where x on  is a number of times a pump has been activated during an elapsed operating period, and Σt on  is a cumulative time for which the pump has been active in the elapsed operating period. 
     
     
         13 . The method according to  claim 2 , wherein the length of an operating period is s seconds, where s is a positive integer, and wherein the time parameter k is calculated according to 
       
         
           
             
               
                 k 
                 = 
                 
                   1 
                   
                     c 
                     * 
                     s 
                   
                 
               
               , 
             
           
         
       
       where c is an equalization parameter. 
     
     
         14 . The method according to  claim 13 , wherein the equalization parameter c is calculated according to
     c =(Δ h   på   +Δh   av )
   
       where Δh on  is a pump station liquid level change during an elapsed operating period, which elapsed operating period takes place in connection with an end of an active period during which one of said number of speed controlled pumps is active and which directly is followed by an inactive period during which said pump is inactive, and Δh off  is the pump station liquid level change during a following operating period, which following operating period takes place in connection with a beginning of the directly following inactive period.