PrimeNg p-dropdown Does not Display Array Values

Try adding your dropdown values in label and values

portNames =[
{label:'Port 01', value:'Port 01'},
{label:'Port 02', value:'Port 02'},
{label:'Port 03', value:'Port 03'},
];

portNames should be an array of objects composed of a label and a value (not an array of strings) :

portNames = [
        {label:'Port 01', value:'p01'},
        {label:'Port 02', value:'p02'},
        {label:'Port 03', value:'p03'}
        ];

See Plunker