How to read json file from powershell and extract a list of array

Use the ConvertFrom-Json cmdet to convert your text to json, then you can filter using the Where-Object cmdlet:

$json = 
@'
[
    {
        "name"           : "kernel",
        "change_flag"    : "TRUE",
        "localpath"      : "setupfiles\\controlroom\\kernel.jar",
        "unpack"         : "FALSE",
        "filename"       : ["",""]
    },
    {
        "name"           : "activemq",
        "change_flag"    : "TRUE",
        "localpath"      : "setupfiles\\controlroom\\activemq.jar",
        "unpack"         : "FALSE",
        "filename"       : ["",""]
    },
    {
        "name"           : "ignite-server",
        "change_flag"    : "FALSE",
        "localpath"      : "setupfiles\\controlroom\\ignite-server.jar",
        "unpack"         : "FALSE",
        "filename"       : []
    }
]
'@

($json | ConvertFrom-Json) | Where-Object change_flag -eq 'TRUE' | Select-Object -ExpandProperty name