Distributed Battery Energy Storage Systems Research Articles

Privacy-preserving finite-time average consensus and its application to power allocation of battery energy storage systems

In this paper, the privacy-preserving problem of finite-time discrete-time average consensus is studied by adding random numbers. The privacy leakage conditions are given for systems with curious but not malicious nodes and eavesdroppers, respectively. By introducing the random numbers and node decomposition mechanism, the privacy information of the nodes cannot be estimated by the adversaries. The proposed algorithm is applied to the power allocation problem of distributed battery energy storage systems. Based on the previous proposed multi-rate sampling method, the privacy-preserving finite-time discrete-time average consensus is utilized to estimate the accurate average value within finite steps. The accurate power allocation based on the same relative SoC variation rate can be achieved with the privacy preservation of the transmission information. Finally, based on a networked battery energy storage system, simulation studies are presented to verify the effectiveness of the proposed method.

Voltage regulation in low voltage distribution networks with unbalanced penetrations of photovoltaics and battery storage systems

AbstractGrid integration constraints are limiting the deployment potential of renewable energy sources in Malta. Large penetrations of photovoltaics in the low voltage (LV) distribution network pose a significant risk to grid stability due to their inherent intermittency and are known to cause overvoltages and reverse power flows. The authors evaluate how self‐consumption strategies with distributed battery energy storage systems can contribute to the voltage regulation in LV networks and the reduction of reverse power flows. The batteries are controlled to absorb the reverse power flow at the dwellings' point of common coupling, before this is injected into the LV network. Simulations show that uncoordinated strategies are not suitable to address the distribution network challenges during reverse power flows and evening peak demands. On the other hand, self‐consumption coordinated by a time‐varying feed‐in tariff (FiT) can provide higher profitability to the prosumers while providing added benefits to the utility. The net‐billing profitability for the prosumers in a self‐consumption scenario with time‐varying FiT is transformed from the downward trend of the uncoordinated scenario to an upward trend against the increasing values of storage capacity.

Fuzzy high order differentiator observer based resilient control for distributed battery energy storage systems against unbounded FDI attacks

AbstractThis paper addresses the issue of frequency recovery in distributed battery energy storage systems (BESSs) and the balancing of the state of charge (SOC) after secondary control inputs have been subjected to false data injection attacks (FDI). A fuzzy high order differentiator (FHOD) observer based distributed resilient control is introduced with the aim of achieving frequency restoration and power adaptive allocation. In order to mitigate the performance degradation caused by the chattering of traditional sliding mode observers, a high order differentiator (HOD) is employed as an observer. By introducing fuzzy control logic to optimize the coefficients of the differentiator, the coefficient of the proposed differentiator is adjusted based on the tracking error, thereby reducing the transient overshoot of the observer when the attack signal changes, which approach effectively balances the response speed and observation accuracy. The simulation outcomes demonstrate that the suggested control strategy is able to mitigate the effects caused by complex and unbounded FDI attacks on the BESSs and exhibits superior transient performance compared to traditional HOD observer in response to changes in attack signal.

A Coordinated Consensus Control Strategy for Distributed Battery Energy Storages Considering Different Frequency Control Demands

With the increasing penetration of renewable energy sources (RESs), ensuring frequency stability is becoming urgent for the power system. The distributed battery energy storage systems (DBESs) is one of the promising solutions to this problem. In this paper, a consensus control-based strategy is proposed for coordinating the DBESs to participate in the frequency regulation. Firstly, the system frequency response (SFR) model with the DBESs is introduced, and different frequency control demands are analyzed in detail, based on which the designing principles of the strategy are elaborated. Then, a revised dead band of frequency response is proposed to improve the frequency control performance under severer and more frequent RESs power fluctuation, reduce the possibility of frequency variation crossing the thresholds, and fully utilizes the DBESs' frequency regulation capability. Further, a developed consensus strategy derived from droop control is proposed, which enables the DBESs to participate in different frequency control demands simultaneously. The proposed strategy can prolong the service time when DBESs involved in frequency control as an aggregator, avoid unexpected energy exhaustion during frequency regulation, and reduce the frequency variation. The performance of the proposed control strategy is validated by the simulation cases with different operating scenarios.

Control Strategy of Distributed Battery Energy Storage System with Harmonic Compensation

Based on the distributed battery energy storage system (BESS), a grid-connection strategy considering harmonic restraint is investigated. It can compensate the harmonic current to the grid by measuring the grid harmonics, then harmonic compensation is implemented to reduce the total harmonic distortion (THD) of the grid current. In this paper, the method of measuring harmonics in the grid and the control principle of providing power supply and harmonic compensation based on BESS are described. On this basis, the control flow is designed. Firstly, the energy storage grid-connected system is built in MATLAB/Simulink and the uncontrolled rectifier with inductive and resistance load is used for testing. The simulation results show that the grid current contains many harmonics, and the grid current THD decreases significantly by controlling BESS for harmonic compensation, which validates that the control method proposed in this paper is accurate and feasible.

Distributed Multirate Control of Battery Energy Storage Systems for Power Allocation

With the increasing integration of intermittent energy sources into the smart grid, distributed battery energy storage systems (DBESSs) are employed to balance power generation and demand. Power allocation among DBESSs plays an important role in maintaining the stability of energy systems. So far, the control of DBESSs has focused on either continuous-time control for continuous-time battery dynamics or discrete-time control for discretized battery dynamics. However, in realistic industrial applications, DBESSs have continuous-time dynamics in nature, and their control is implemented on digital controllers. To tackle this issue, a distributed multirate control system is designed in this article for continuous-time DBESSs. It allocates power by keeping the same relative State-of-Charge (SoC) variation rate for all DBESSs. For the accurate computation of the output/input power without global information, the control strategy consists of distributed multirate estimators each for a DBESS. The operating rate of the estimation algorithm is designed multiple times higher than the sampling rate of the measurement of battery and the sampling rate of the battery controller. With the proposed multirate estimator, a smaller estimation error is achieved. The same relative SoC variation rate and the stability of closed-loop system can be guaranteed. Simulation studies are given to demonstrate the effectiveness of the proposed control strategy.

Hierarchical cooperative control strategy of distributed hybrid energy storage system in an island direct current microgrid

This paper presents a distributed hybrid energy storage system (HESS) for an island DC microgrid (MG) with a central superconducting magnetic energy storage (SMES) system and multiple distributed battery energy storage systems (BESS). A hierarchical cooperative control scheme is proposed to realize coordinate power sharing among distributed HESS and uninterrupted operation of SMES. The control scheme adopts filtration control to decouple imbalance power into high frequency component and low frequency component, which will be compensated by SMES and distributed BESSs. The proposed mode switch control (MSC) enables SMES to have higher transient large power regulation capability than filtration control. When the DC microgrid suffers from 400 kW power drops and power surges, the maximum DC bus voltage overshoot is 5.6 % and 5.3 % under MSC control, while the overshoot increases to 26.9 % and 8.2 % under the filtration control. Meanwhile, an autonomous state-of-charge (SOC) recovery control is designed for SMES to regulate its SOC within a set range (0.64, 0.725), which enables uninterrupted operation of SMES without performance trade off. A design scheme is proposed to make sure the desired transient power sharing dynamics and SOC recovery with negligible interactions. Additionally, the proposed distributed HESS structure and cooperative control method allows acceptable communication failure and physical faults. Cases verification conducted in PSCAD/EMTDC demonstrates the feasibility and superiority of the proposed system and control scheme against various kinds of power fluctuations.

A unified control strategy for voltage regulation and congestion management in active distribution networks

The advent of distributed renewable energy sources (DRESs) has led to a series of technical issues affecting the secure and reliable operation of active distribution networks. Among them, under-/overvoltages, current overload, and voltage unbalance can be considered as the most important problems limiting the increase of DRES penetration. In this paper, a new control architecture is proposed to overcome these issues using the reactive power of DRESs and the active/reactive power of distributed battery energy storage systems (DBESSs). Its distinct feature is the implementation in the symmetrical components domain, allowing the efficient decoupling between under-/overvoltage and voltage unbalance mitigation techniques. Furthermore, a central controller is introduced to improve the system performance in terms of reduced network losses and effective DBESS utilization by coordinating the response of DRESs and DBESSs. The validity of the proposed control strategy is evaluated by performing time-domain and time-series simulations on the IEEE European LV test feeder. • Unified control strategy for unbalanced low voltage distribution grids. • Voltage regulation, voltage unbalance mitigation and congestion management control. • Distributed generation and energy storage are used as the main control units. • Implementation of the control schemes in the symmetrical components domain. • Performance evaluation by conducting time-domain and quasi-static simulations.

Strategy optimization of distributed battery energy storage systems for improving dynamic performances of VRB in active distribution networks

Strategy optimization of distributed battery energy storage systems for improving dynamic performances of <scp>VRB</scp> in active distribution networks

Coordinated control scheme for provision of frequency regulation service by virtual power plants

This paper proposes a coordinated control strategy for a Virtual Power Plant (VPP) contribution to load frequency control. The considered VPP comprises distributed Battery Energy Storage Systems (BESSs) and Heat Pump Water Heaters (HPWHs). The frequency regulation signal is distributed between thermal generator and the VPP based on distribution coefficients which are calculated through conducting a multi-objective optimization problem. The optimization framework incorporates the dynamic regulation performance as well as the total regulation cost. A fuzzy strategy is adopted to obtain the final solution according to user-defined conditions. The regulation signal of VPP is dispatched based on the speed and the available power capacity of VPP components. The performance of the proposed coordination scheme is compared to the scheme without coordination and that with no involvement of VPP in frequency regulation. The regulation performance is also evaluated for varying time delays expected in the communication channels. An approach based on brain emotional learning is developed to coordinate the VPP and conventional generation unit to avoid large frequency deviations caused by the communication delays. Case studies are conducted on a multi-area power system in MATLAB/Simulink environment, and the results are verified by the OPAL-RT real-time simulator.

Fast hierarchical coordinated controller for distributed battery energy storage systems to mitigate voltage and frequency deviations

This paper proposes a novel hierarchical optimal control framework to support frequency and voltage in multi-area transmission systems, integrating battery energy storage systems (BESSs). The design is based on the coordinated active and reactive power injection from the BESSs over conventional synchronous generator-based control for fast and timely mitigation of voltage and frequency deviations. The principle of this new idea is to use two hierarchical schemes, one physical and one logical. The objective of the first scheme prioritises the power injection from the BESSs installed in the area where a contingency occurs, consequently reducing the disturbance of the dynamics in the neighbouring areas. In the second scheme, operational rules for aggregated BESSs in each are incorporated, increasing the safety of the asset. The proposed approach exploits the advantages of time-synchronised measurements, the eigensystem realisation algorithm (ERA) identification technique, the optimal linear quadratic Gaussian (LQG) controllers and a new aggregating agent that coordinates the power injection of BESSs in a hierarchical and scalable scheme to precisely regulate frequency and voltage of modern transmission grids, increasing their reliability and stability. The feasibility and robustness of the proposal is demonstrated using simulated scenarios with significant load changes and three-phase, three-cycle faults on a modified Kundur-system with four interconnected areas, mitigating frequency and voltage contingencies in less than 450 ms.

Shapley Value Method and Stochastic Dantzig–Wolfe Decomposition for Decentralized Scheduling of Multimicrogrid

The decentralized economic scheduling of multimicrogrid is an important aspect in the operational planning of microgrids (MGs). This article proposes an approach to maximize economic benefit among MGs through cooperative scheduling. The cooperative scheduling is achieved via price signals so that MGs are encouraged to share power among themselves for economic benefit. An MG operator generates a time-variable tariff based on energy trading status so that the parking lot operator and distributed battery energy storage system aggregator participate with flexibility in the MG’s energy management. The Shapley value method is used for generating fair price signals. The stochastic Dantzig–Wolfe decomposition is used to solve the resulting optimization problem in a decentralized manner. The uncertainties related to load demand and renewable energy sources are captured using scenario-based methods, whereas the uncertainty associated with plug-in hybrid electric vehicles is modeled using copula theory based estimation. The simulation studies and comparison with the existing methods establish that the proposed approach effectively reduces the total energy cost in a decentralized manner with the minimum amount of information exchange.

Battery Storage at the Secondary Distribution Electricity Grid by Investigating End-Users Load Demand Measurements

Energy storage systems is expected to be utilized to cover the increased electrification of energy demands and to alleviate the electrical energy production from intermittent energy sources such as solar and wind. Aggregated and distributed battery energy storage systems may improve electricity grids operability and security by providing smart energy management options and efficient resources allocation. In this paper, battery storage at the secondary distribution level is explored. The investigation is based on the end-user energy demand behavior. As such, the electrical energy consumption patterns are measured and analyzed in a residential area. Measurements were collected and analyzed in order to record the customers’ behaviors aiming to reveal their differences and similarities. Following this, aggregated and distributed battery energy storage systems are computed based on the features of the measured electrical power consumption patterns aiming to estimate the factors that could potentially incentivize the installation of a battery system either as aggregated at the low voltage transformer side or as distributed system at the load side. The parameters that affect the economic viability of the system are qualitatively evaluated with regard to the profitability of the system.

Optimal Planning of Distributed Battery Energy Storage Systems in Unbalanced Distribution Networks

The proliferation of distributed renewable generation poses many challenges to power distribution networks (DN), such as network congestion and voltage violations. Recent advances in battery technologies have made battery energy storage systems (BESS) more economically viable than ever before, which makes them suitable for many grid-scale applications. By providing grid support, distributed BESS can serve as enablers for higher penetrations of renewables at the DN. Distributed BESS can also provide ancillary services (AS), such as frequency regulation and reserves, to the bulk power grid. This article proposes a budget-constrained planning model for optimally sizing and siting distributed BESS in a DN to provide grid support for a renewable-rich DN and provide AS to the electricity market. The proposed model, formulated as a mixed-integer linear programming problem, maximizes the total profit of participating in the AS markets while supporting the operation of an unbalanced DN. Simulation results and sensitivity analyses demonstrate the merits of the proposed planning model. The accuracy of the linearized unbalanced DN model is also validated.

Coordinated active and reactive power control for distribution networks with high penetrations of photovoltaic systems

A primary concern of the large-scale application of photovoltaic (PV) power systems in distribution networks is nodal voltage fluctuations caused by active power fluctuations of PV. Therefore, this paper proposes a novel coordinated active and reactive power optimization method for distribution networks with high penetrations of PV systems, which can reduce bus voltage fluctuations, active power curtailments of PV, operating losses of distribution networks, and adjustments of conventional voltage regulation devices such as on-load tap changers (OLTCs) and capacitor banks (CBs). The proposed method coordinates the OLTC, CBs, and PV and BESS plants in two levels. The upper level establishes a mixed integer nonlinear programming (MINP) model based on the model predictive control (MPC), which can properly plan the operation of the OLTC, CBs, and PV, and a modified NSGA-II algorithm is developed to find the best solution of the MINP model. The lower level employs the leader–follower consensus algorithm (LFCA) to coordinate the charging power and reactive power of distributed battery energy storage systems (BESSs) to control real-time bus voltage fluctuations. The LFCA based control method can make BESSs fairly participate in the real-time voltage regulation of each feeder. Case studies are conducted on a modified IEEE 33-bus distribution network system, utilizing the actual active power data of a PV plant. Simulation results indicate that the proposed method can effectively control bus voltage variations of all feeders within the pre-defined range, and the distribution network can operate with higher penetrations of PV power systems, lower losses, and better economy.

Distributed control of battery energy storage systems in distribution networks for voltage regulation at transmission–distribution network interconnection points

This paper describes a control framework that enables distributed battery energy storage systems (BESS) connected to distribution networks (DNs) to track voltage setpoints requested by the transmission system operator (TSO) at specific interconnection points in an optimal and coordinated manner. The control design is based on an optimisation problem whose objective is to minimise the real-time voltage-tracking mismatch while satisfying local physical network constraints. A novel agent-based control scheme adopting an online convex optimisation (OCO) framework is developed and solved in a distributed fashion to guarantee the solution’s scalability and the service provision within the required time. The BESS agents under the proposed control framework automatically adapt to the time-varying network conditions so as to track the required voltage setpoints whilst fulfilling the technical operating requirements of the local network. The designed OCO-based framework addresses the existing conflict between the accuracy and optimality of the solution and the communication and computational efficiency. The convergence to the optimal solution is demonstrated. Several case studies are performed to corroborate the analytical results and assess the performance of the proposed approach.

Grid-Following Mode Operation of Small-Scale Distributed Battery Energy Storages for Fast Frequency Regulation in a Mixed-Source Microgrid

As the share of power converter-based renewable energy sources (RESs) is high, a microgrid, in islanded mode, is more vulnerable to frequency instability due to (1) sudden power imbalance and (2) low inertia. One of the most common approaches to address this issue is to provide virtual inertia to the system by appropriately controlling the grid-side converter of the RESs. However, the primary frequency controller (PFC) presented in this paper focuses on the fast compensation of power imbalance without adding inertia to the system. The proposed method is based on estimating the real-time power imbalance caused by a disturbance and compensating it using multiple small-scale distributed battery energy storage systems (BESSs). The power imbalance is estimated by observing the initial rate of change of frequency (RoCoF) following a disturbance. Based on the estimated power imbalance and the rating of the BESSs, the reference power for the BESSs is determined. The BESSs are controlled in grid-following mode to compensate for the power imbalance. The performance of the proposed PFC is verified using a Typhoon real-time simulator for various scenarios and is compared with the conventional virtual synchronous generator (VSG) controller.

Branching Dueling Q-Network-Based Online Scheduling of a Microgrid With Distributed Energy Storage Systems

This letter investigates a Branching Dueling Q-Network (BDQ) based online operation strategy for a microgrid with distributed battery energy storage systems (BESSs) operating under uncertainties. The developed deep reinforcement learning (DRL) based microgrid online optimization strategy can achieve a linear increase in the number of neural network outputs with the number of distributed BESSs, which overcomes the curse of dimensionality caused by the charge and discharge decisions of multiple BESSs. Numerical simulations validate the effectiveness of the proposed method.

A Novel Multi-Agent Model-Free Control for State-of-Charge Balancing Between Distributed Battery Energy Storage Systems

This article proposes a novel state of charge (SoC) balancing control strategy based on multi-agent control between distributed the battery energy storage systems (BESSs) in super-UPS. The proposed control strategy has plug and play capability. Batteries with different capacities are considered in the control system. The battery capacity degradation under long term operation is further taken into account. In addition, a model-free iPI control strategy is designed for primary current control to achieve the tracking response of BESS to the reference current. Firstly, the distributed voltage and per-unit current dynamic consensus algorithm is introduced to maintain the DC bus voltage and achieve the battery current sharing. Then, a SoC balancing algorithm based on multi-agent control strategy is proposed. Furthermore, an adaptive capacity estimation algorithm is proposed considering the battery capacity degradation. The efficiency of the proposed control strategy is demonstrated in MATLAB/Simulink.

A Coordinated Control of Offshore Wind Power and BESS to Provide Power System Flexibility

The massive integration of variable renewable energy (VRE) in modern power systems is imposing several challenges; one of them is the increased need for balancing services. Coping with the high variability of the future generation mix with incredible high shares of VER, the power system requires developing and enabling sources of flexibility. This paper proposes and demonstrates a single layer control system for coordinating the steady-state operation of battery energy storage system (BESS) and wind power plants via multi-terminal high voltage direct current (HVDC). The proposed coordinated controller is a single layer controller on the top of the power converter-based technologies. Specifically, the coordinated controller uses the capabilities of the distributed battery energy storage systems (BESS) to store electricity when a logic function is fulfilled. The proposed approach has been implemented considering a control logic based on the power flow in the DC undersea cables and coordinated to charging distributed-BESS assets. The implemented coordinated controller has been tested using numerical simulations in a modified version of the classical IEEE 14-bus test system, including tree-HVDC converter stations. A 24-h (1-min resolution) quasi-dynamic simulation was used to demonstrate the suitability of the proposed coordinated control. The controller demonstrated the capacity of fulfilling the defined control logic. Finally, the instantaneous flexibility power was calculated, demonstrating the suitability of the proposed coordinated controller to provide flexibility and decreased requirements for balancing power.