<?php

$host = '10.0.0.10';
$username = 'username';
$password = 'password';

$WbemLocator = new COM ( "WbemScripting.SWbemLocator" );
$objPwr = $WbemLocator->ConnectServer ( $host, 'root\cimv2power', $username, $password );

$PowerPlanInstanceID = '{8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c}'; //Performance
$ACDC = 'AC';
$InstansID = 'Microsoft:PowerSettingDataIndex\\'.$PowerPlanInstanceID.'\\'.$ACDC.'\\{3c0bc021-c8a8-4e07-a973-6b14cbcb2b7e}'; //Turn off display after

// Change PowerSetting for "Turn off display after" from default 800 to 600
$query = "Select * from Win32_PowerSettingDataIndex WHERE InstanceID = '$InstansID'";
$PowerPlanSetting = $objPwr->ExecQuery ( $query );
foreach ( $PowerPlanSetting as $Setting ) {
  $Setting->SettingIndexValue = '600';
}

// Activating PowerPlan
$PowerPlan = $objPwr->ExecQuery ( "Select * from Win32_PowerPlan WHERE ElementName = 'High performance'" );
foreach ( $PowerPlan as $Plan ) {
  $Plan->Activate();
}

// Check PowerSetting
foreach ( $PowerPlanSetting as $Setting ) {
  echo $Setting->InstanceID . ' '. $Setting->SettingIndexValue;
}

?>