This worked for me:

DECLARE @p_filename varchar(200)

set @p_filename = 'filename.SQB'

declare @sql varchar(500) = '-SQL "RESTORE LOG [PCC-RRDB-CHG] FROM DISK = ''"\\BI01\PCCLogFiles\' + @p_filename +'" WITH STANDBY = ''G:\PCCBackupDONOTREMOVE\Undo_projects.dat'',PASSWORD...