Question about RAMP3 function

[Anonymous]

For RAMP3 function, if the positive rate limit is 10, the negative rate limit is -10, and X=-27. How does it calculate the output for t=DELT? If it will consider (-27-0)/DELT <-10, the output Y=-10*DELT+0. Or it won't do such a calculation for the first time step. I think it won't do it, but I need to confirm. By the way, how the function makes it. If the code is like:

IF (TIMEZERO) THEN
Y=X
ELSEIF ((X(t)-X(t-DELT))/DELT>10) THEN
X(t)=X(t-DELT)+10*DELT
ELSEIF ...
ENDIF

Thanks.

[John Nordstrom]

The RAMP3 function output at time t = 0.0 (or TIMEZERO) is always the input X.

On subsequent timesteps (ie. t = nDELT), the output is calculated according to:

If DELTX < 0 && abs(DELTX) <= Maximum negative rate, then RAMP3 = X
If DELTX < 0 && abs(DELTX) > Maximum negative rate, then RAMP3 = X - Maximum negative rate
If DELTX > 0 && DELTX <= Maximum positive rate, then RAMP3 = X
If DELTX > 0 && DELTX > Maximum positive rate, then RAMP3 = X + Maximum positive rate

where,

DELTX = change in input since last time step
Maximum positive rate = RATE1*DELT
Maximum negative rate = RATE2*DELT

Regards,

John E. Nordstrom, P.Eng.
Software Applications Engineer
Manitoba HVDC Research Centre Inc.