PowerShell script for partition refresh

I am trying to create a partition refresh using the PowerShell script, when I run the script normally it’s prompting for login credentials. I entered the user id and password Manually then it is working fine but when I am trying to give the password dynamically inside the script then I am facing an error. Here it’s my script & Error.

$TenantId = "TenantID"
$AppId = # Service PRincipal ID
$Secret = " # Secret from Service Principal -
$password = ConvertTo-SecureString $Secret -AsPlainText -Force
$Creds = New-Object System.Management.Automation.PSCredential $AppId, $password

#$password = "password" | ConvertTo-SecureString -asPlainText -Force

$quote1 = '"'
# $Partition= @($Year;$Q;$quater;$Month)
$i =-2
$currentSubtractMonths = [DateTime]::Now.AddMonths($i)

# Run parameters, please specify below parameters
$WorkspaceName = "Enterprise Datasets" #Here it is the workspace name! Not the id!
$DatasetName = "Testing" #Also known as database name
# $TableName = "MyTable" #Table name in the specified dataset
$filename = "NewLog-"+ (Get-Date -Format "MM-dd-yyyy-hh-mm")
$logfile = "D:\zak\Powerbilogs\"+$filename+".log"
# Base variables
$PbiBaseConnection = "powerbi://api.powerbi.com/v1.0/myorg/"
$XmlaEndpoint = $PbiBaseConnection + $WorkspaceName

# Check whether the SQL Server module is installed. If not, it will be installed.
# Install Module (Admin permissions might be required)
$moduleName = Get-Module -ListAvailable -Verbose:$false | Where-Object { $_.Name -eq "SqlServer" } | Select-Object -ExpandProperty Name;
if ([string]::IsNullOrEmpty($moduleName)) {
Write-Host -ForegroundColor White "==============================================================================";
Write-Host -ForegroundColor White "Install module SqlServer...";
Install-Module SqlServer -RequiredVersion 21.1.18230 -Scope CurrentUser -SkipPublisherCheck -AllowClobber -Force
# Check for the latest version this documentation: https://www.powershellgallery.com/packages/SqlServer/
Write-Host -ForegroundColor White "==============================================================================";
}

for($i=-2; $i -lt 1; $i++)
{

$currentSubtractMonths = [DateTime]::Now.AddMonths($i)

$Year = Get-Date $currentSubtractMonths -format "yyyy"

$quater = [math]::Ceiling(($currentSubtractMonths).Month/3)
$Month = Get-Date $currentSubtractMonths -format "MM"
$Q = "Q"

$Partition= @($quote1;$Year;$Q;$quater;$Month;$quote1)
$partition_updated = $Partition -join ''

$partition_updated

# TMSL Script
$TmslScript =
@"
{
"refresh": {
"type": "full",
"objects": [
{
"database": "Testing",
"table": "SLA Transaction Summary Import",
"partition": $partition_updated
}
]
}
}
"@

# Execute refresh trigger on specified table
Try {
# Invoke-ASCmd -Credential $myCred
# Invoke-ASCmd -Credential $Creds -TenantId $TenantId -Query $TmslScript -Server: $XmlaEndpoint -Database $DatasetName

Invoke-ASCmd -Credential $Creds -ServicePrincipal -ApplicationId $AppId -Tenant $TenantId -Query $TmslScript -Server: $XmlaEndpoint -Database $Databasename
#Connect-PowerBIServiceAccount -Credential $Creds
Write message if succeeded

Write-Host "Table" $TableName "in dataset" $DatasetName "successfully triggered to refresh" -ForegroundColor Green
}

# try{
#$URI = "https://api.powerbi.com/v1.0/myorg/groups/" + $WorkspaceName + "/datasets/" + $DatasetName + "/refreshes"

#Connect-PowerBIServiceAccount -ServicePrincipal -Credential $Creds

#$Results = Invoke-PowerBIRestMethod -Url $URI -Method Get | Credential -$Creds
#}

Catch{
$exception = $_.Exception.Message
$Status="Dataset Refresh Failed"
Out-File -FilePath $logfile -Append -InputObject $Status
Out-File -FilePath $logfile -Append -InputObject $exception
Write-Host "Dataset has failed, Please check the log file."
}
}

Error 

Invoke-ASCmd : Unable to obtain authentication token using the credentials provided. If your Active Directory tenant administrator has configured Multi-Factor Authentication or if your account is a

Microsoft Account, please remove the user name and password from the connection string, and then retry. You should then be prompted to enter your credentials