/// <summary>
/// Precomputes the cost of each possible set of generator states at
/// every time step.
/// </summary>
/// <param name="m">Microgrid input data.</param>
/// <param name="genCount">Number of generators.</param>
/// <param name="stepCount">The number of time steps.</param>
/// <param name="stepSize">The size of each time step.</param>
/// <param name="p_target">The amount of power the system needs to supply at a given time step.</param>
/// <returns>A dictionary mapping a generator state and time step pair
/// to the cost of purchasing the amount of power necessary to fulfill
/// remaining demand for that specific pair.</returns>
public static Dictionary <StateStep, float> ConstructCostDictionary(
MGInput m,
int stepCount,
int stepSize,
float penalty,
float[] p_target)
{
// It's expensive to compute the cost of the amount of power the
// microgrid needs to purchase inside the main loop. There are only
// 2^n * stepCount combinations possible which end up being
// redundantly recalculated a lot if done in the main loop.
// So we compute all of them ahead of time and store them in a
// dictionary.
// t1 and t2 define the interval of time this step occupies.
var stepInterval = new Tuple <int, int> [stepCount];
for (int iStep = 0; iStep < stepCount; iStep++)
{
stepInterval[iStep] = new Tuple <int, int>(
iStep * stepSize,
(iStep + 1) * stepSize - 1);
}
int nSqr = 1 << m.genCount; //Bitwise squaring.
int nPurchaseCombs = nSqr * stepCount;
var purchaseCostDict = new Dictionary <StateStep, float>(nPurchaseCombs);
var indexToCost = new Dictionary <int, float>(m.genCount);
float[] p_thr = new float[m.genCount];
for (int i = 0; i < m.genCount; i++)
{
// EUR for 1 hour of functioning
float cost = ThermalGenerator.GetCost(
m.p_thr_max[i],
m.thr_c_a[i],
m.thr_c_b[i],
m.thr_c_c[i]);
// EUR/MWh
float alpha = cost / m.p_thr_max[i];
indexToCost.Add(i, alpha);
}
float[] e_thr_remaining = new float[stepSize];
float[] p_remaining = new float[stepSize];
var orderedByCost = indexToCost.OrderBy(x => x.Value).ToDictionary(x => x.Key, y => y.Value);
for (int iState = 0; iState < nSqr; iState++)
{
for (int iStep = 0; iStep < stepCount; iStep++)
{
float c_total = 0.0f;
int t1 = stepInterval[iStep].Item1;
int t2 = stepInterval[iStep].Item2;
for (int t = t1; t < t2; t++)
{
e_thr_remaining[t - t1] = p_target[t] / 60.0f;
p_remaining[t - t1] = p_target[t];
foreach (KeyValuePair <int, float> kvp in orderedByCost)
{
int iGen = kvp.Key;
float alpha = kvp.Value;
var bitValue = iState & (1 << m.genCount - iGen - 1);
var state = ((bitValue | (~bitValue + 1)) >> 31) & 1;
if (state == 1)
{
if (alpha < m.price[t])
{
if (m.canSell)
{
// Since we can sell and our generator
// makes cheaper energy than the market price,
// just produce at max power.
p_thr[iGen] = m.p_thr_max[iGen];
}
else
{
// Since we can't sell but our generator
// makes cheaper energy than market price,
// we'll produce enough to cover local demand.
p_thr[iGen] = Mathf.Clamp(m.p_thr_max[iGen], 0.0f, p_remaining[t - t1]);
}
}
else
{
if (m.canBuy)
{
// Since we can buy and our generator
// makes more expensive energy than
// the market price, produce no power
// and buy.
p_thr[iGen] = 0.0f;
}
else
{
// Since we can't buy, produce enough
// power to cover local demand, regardless
// of market price.
p_thr[iGen] = Mathf.Clamp(m.p_thr_max[iGen], 0.0f, p_remaining[t - t1]);
}
}
c_total += ThermalGenerator.GetCost(
p_thr[iGen],
m.thr_c_a[iGen],
m.thr_c_b[iGen],
m.thr_c_c[iGen]) / 60.0f;
p_remaining[t - t1] -= p_thr[iGen];
e_thr_remaining[t - t1] -= p_thr[iGen] / 60.0f;
}
else
{
p_thr[iGen] = 0.0f;
}
}
if (e_thr_remaining[t - t1] < 0.0f)
{
if (m.canSell)
{
c_total += e_thr_remaining[t - t1] * m.price[t];
}
}
else
{
if (m.canBuy)
{
c_total += e_thr_remaining[t - t1] * m.price[t];
}
else
{
c_total += e_thr_remaining[t - t1] * penalty;
}
}
}
var id = new StateStep(iState, iStep);
#if UNITY_EDITOR || DEVELOPMENT_BUILD
if (purchaseCostDict.ContainsKey(id) &&
purchaseCostDict[id] != c_total)
{
throw new InvalidProgramException(
$@"IDs and purchase costs need to have a 1 to 1
mapping. There can't be an ID with a different
purchase cost. If that happens, the code is wrong
somewhere.
UID: {id}.
Existing Value: {purchaseCostDict[id]}.
New Value: {c_total}.");
}
#endif
purchaseCostDict[id] = c_total;
}
}
return(purchaseCostDict);
}
