Embedding OLTC nonlinearities in predictive Volt Var Control for active distribution networks

- Coordination of many actuators for voltage regulation and reactive power exchange in a predictive Volt Var Control scheme for active distribution systems.
- Tap changes are explicitly considered in the cost function in order to guarantee the minimization of tap changes during all life of the On Load Tap Changer.
- The classical OLTC inner control is kept to avoid fundamental modifications of the existing control devices and operating process.
- The non-linearities of the OLTC are embedded within the predictive VVC.

This paper presents an original procedure to embed the On Load Tap Changer (OLTC) nonlinearities in a predictive real-time Volt Var Control (VVC) for distribution systems. These commonly disregarded nonlinearities are namely the OLTC time-delays, the dead-band and the discrete nature of tap change. It is shown that using a continuous approximation can lead to control failures. The proposed nonlinear controller accurately anticipates the response of the system and the costs associated with control efforts. Demonstrations are performed in a 20 kV network to assess the performance of such a procedure compared to a predictive VVC using an OLTC continuous approximation.