Combined Stochastic Optimization of Frequency Control and Self-Consumption With a Battery

Abstract

Optimally combining frequency control with selfconsumption can increase revenues from battery storage systems installed behind-the-meter. This work presents an optimized control strategy that allows a battery to be used simultaneously for self-consumption and primary frequency control. Therein, it addresses two stochastic problems: the delivery of primary frequency control with a battery and the use of the battery for self-consumption.We propose a linear recharging policy to regulate the state of charge of the battery while providing primary frequency control. Formulating this as a chance-constrained problem, we can ensure that the risk of battery constraint violations stays below a predefined probability. We use robust optimization as a safe approximation to the chance-constraints, which allows to make the risk of constraint violation arbitrarily low, while keeping the problem tractable and offering maximum reserve capacity. Simulations with real frequency measurements prove the effectiveness of the designed recharging strategy.We adopt a rule-based policy for self-consumption, which is optimized using stochastic programming. This policy allows to reserve more energy and power of the battery on moments when expected consumption or production is higher, while using other moments for recharging from primary frequency control. We show that optimally combining the two services increases value from batteries significantly.

Techno-economic analysis and optimal control of battery storage for frequency control services, applied to the German market

“…which is limited by the maximum power |P grid t | ≤ P BESS max of the BESS. This controller can be seen as an extension of the rule-based controllers proposed in [4], [5], [6], [13], [38] and [39], and as a special case of the ones in [40], [41] and [42]. Figure 7 shows an example of the grid power P grid t of a battery delivering r = 1 MW of FCR capacity, according to (7).…”

Optimal Combination of Frequency Control and Peak Shaving With Battery Storage Systems

“…In our previous work [21], we showed that this approximation does not lead to violations of the constraints when η c , η d < 1.…”

“…This work fills this gap by presenting an operational control framework that enables a BESS to successfully combine peak shaving with frequency control services. The presented method extends our previous work on frequency control with BESSs [21], by adding the peak shaving objective using dynamic programming and a customised stochastic optimisation objective. The main contributions of this paper are:…”

“…, with the maximum taken element-wise and W T W = Σ −1 ∆f the Cholensky decomposition of the inverse of the covariance matrix Σ ∆f of ∆f . We refer to our previous work [21] for the details on the derivation of (7). With these reformulations, (2) becomes a tractable second-order cone problem, which can be readily solved by various commercial and non-commercial solvers.…”

Decentralized and discretized control for storage systems offering primary frequency control

“…In the Regional Group Nordic area, the implementation of this service is called Frequency-Normal Operation Reserve (FNR). Various studies have shown the profitability of such services for battery systems and EVs, as well as the power system [1,2,3].…”