Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_12983929_1 (total_power VARCHAR, construction_start VARCHAR, commercial_operation VARCHAR)

### Question ###
How many different values of total power are there for the unit whose construction started on 01.03.1977 and whose commercial operation started on 01.02.1984?

### Accurate SQL ###

SELECT COUNT(total_power) FROM table_12983929_1 WHERE construction_start = "01.03.1977" AND commercial_operation = "01.02.1984"