PMD Simulation Task Constraints:

1) Implement `PMDSampler` class that inherits from `SamplerBase`.
2) Implement `simulate_variance_controlled()` method with the required signature.
3) The method must return a tuple or dict with: (outages_log, weights_log, outage_prob, total_samples, actual_std, converged).
4) Use importance sampling to bias PMD evolution toward high-DGD regions.
5) The solution should estimate outage probability accurately and efficiently.

