SQL & PL/SQL

Hi,
I need to use the fixed_date init.ora parameter , in order to set the SYSDATE to futre date:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/initparams073.htm#REFRN10062

SYS@qa2> alter session set nls_date_format='RRRR-MM-DD-HH24:MI:SS'
  2  ;

Session altered.

SYS> select to_date(value,'RRRR-MM-DD-HH24:MI:SS')
  2  from   v$spparameter 
  3  where name='fixed_date';

TO_DATE(VALUE,'RRRR
-------------------
2017-12-10-00:00:00

1 row selected.

Now , i am trying to add one minute , but get the following error message:

SYS> select to_date(value+1/1440,'RRRR-MM-DD-HH24:MI:SS ') 
  2  from   v$spparameter 
  3  where name='fixed_date';
select to_date(value+1/1440,'RRRR-MM-DD-HH24:MI:SS ')
               *
ERROR at line 1:
ORA-01722: invalid number

Please advice how to add one minute to the result retun from "value"

Thanks