Son,
The EVM that you mentioned is only partial and not the whole project. Always remember that if the contractor did not met the deadline or the productivity is lower than expected there is a possibilities of cost losses. The longer it takes the higher cost will be incurred on other associated cost like overhead, office rentals, equipment hire, facilities, utilities, etc… if the client is providing all those items. You should be reporting all other associated cost and not only contractor cost. If you have multiple contractors and their productivity is lower than expected then it needs to highlight so the management can push the contractor and possible LD or EOT will be avoided which normally leads to dispute.

You should be able to illustrate using tabular reports and S-Curve highlighting the issues that will reflect the correct EVM and effect of current trend. All areas should be reported and not concentrating on a partial EVM only.

Son Le,
BCWP (EV) = Performance % complete x BAC
ACWP (AV) = Actual cost incurred
It is possible that the two is the same if you are paying per unit rate but you can analyze if the schedule is delay and the productivity output will tell you if the Budget cost is attainable or how long it will take to complete the project.

San Le,
ACWP is the actual cost. If you are applying EVM only on contractors program and not on overall program which doesn’t include other cost like overhead then yes you can use interim payment claim from contractor.