• Energy Research
• 2016-2025close

The installed capacity of wind generation and photovoltaics (PV) in many countries is going to dominate generation fleets in a bid to meet growing renewable energy targets. Synchronous inertia has never been problematic as there was more available than needed, but it is being significantly reduced due to the increasing integration of nonsynchronous renewable generation. When the low bidding priced generation of wind and PV becomes considerably large, conventional economic dispatch algorithms can result in less online synchronous inertia and put power system security at risk. However, the compromise of power system security due to synchronous inertia shortage is not well studied in the literature. This paper develops a synchronous inertia constrained economic dispatch algorithm to satisfy the minimum required synchronous inertia of frequency control. Synchronous condensers and wind reserve are economically allocated to alleviate any shortage of synchronous inertia and frequency control ancillary services (FCAS). A Gaussian particle swarm optimization algorithm is introduced to simultaneously co-optimize the dispatch of synchronous generators and their FCAS, wind reserve, and synchronous condensers.

This paper presents an approach to deploy virtually settled peer-to-peer (P2P) energy trading in existing grid-connected networks without considering post-trading protection schemes that may be required for bus voltage regulation. To achieve this goal, this paper demonstrates to consider the maximum power export limit fixed by the network operators while modelling the P2P trading framework in the virtual layer and then to determine the traded quantity of each prosumer in the P2P market along with the associated price per unit of energy traded. The developed P2P mechanism in this paper is tested on a real low-voltage (LV) distribution network in Australia, where the maximum local power injection limit has already been defined for the prosumers. The simulation results show that both prosumers and other customers of the network can still be benefited significantly, compared to the current feed-in-tariff (FiT) and electricity retail prices respectively, even though P2P traded quantities are regulated by the network operator. It is also observed that the prosumers’ engagement in P2P trading at various time slots do not rise bus voltages beyond the prescribed limit. Thus, virtually settled P2P transactions considering the power export constraint are suitable for practical deployment.

Dynamic operating envelopes (DOEs) offer an attractive solution for maintaining network integrity amidst increasing penetration of distributed energy resources (DERs) in low-voltage (LV) networks. Currently, the focus of DOEs primarily revolves around active power exports of rooftop photovoltaic (PV) generation, often neglecting the impact of demand response (DR). This paper presents a two-stage, coordinated approach for residential DR participation in electricity markets under the DOE framework. In the first stage, the distribution network service provider (DNSP) adopts a convex hull technique to establish DOEs at each customer point-of-connection (POC). In the second stage, the demand response aggregator (DRA) utilises DOEs assigned by the DNSP to develop a hierarchical control scheme for tracking a load set-point signal without jeopardising network statutory limits. To assess the effectiveness of the proposed control scheme in a practical setting, software-in-the-loop (SIL) tests are performed in a grid simulator, considering a real residential feeder with realistic household load and generation profiles. Simulation validations suggest that the DRA can provide precise DR while honouring network statutory limits and maintaining end-user thermal comfort. Furthermore, the overall approach is compliant with the market dispatch interval and preserves end-user data privacy. submitted to IEEE Transactions on Power Systems, 10 pages

Abstract Uncertainties at end-user and aggregator levels can be highly detrimental to the practical implementation of residential load control schemes for electricity market applications. Uncertainty factors such as end-user non-compliance, comfort violations and load set-point changes associated with the demand response aggregator are unavoidable in practice. This paper proposes a novel two-stage control algorithm for robust centralised management of aggregate residential loads which guarantee precise load set-point tracking in the presence of uncertainties occurring in real-time while ensuring that end-user thermal comfort is not compromised. The approach is underpinned by optimal selection of appliances based on an emulated supply curve followed by solving a one-step-ahead optimisation problem. Using air conditioners and water heaters as the controllable loads, the paper illustrates the effectiveness of the proposed approach in load management whilst mitigating the effects of unknown uncertainties. Further, the developed control scheme is compared with an existing industry approach. The results yield that the proposed control scheme is robust to uncertainties, preserves thermal comfort and is applicable for practical implementation under existing demand response standards.

Most traditional Var compensation-based voltage regulation methods are developed following the single-phase Volt-Var response rule. These methods typically have competent voltage regulation performance with balanced photovoltaic (PV) integration. However, certain randomness of single-phase rooftop PV installation may lead to significant PV power imbalance across three phases, especially in low voltage (LV) distribution systems. In such unbalanced situations, unintended inter-phase Volt-Var response which is ignored in the single-phase Volt-Var response rule will become significant and greatly challenge the effectiveness of the traditional methods on voltage regulation. This can further cause inverter saturation and consequently makes distribution systems vulnerable to overvoltage problems. In this paper, the mathematical equations of unbalanced three-phase Volt-Var response are first derived and analyzed to identify the strong MVE (mutual Var compensation effect) and the weak MVE. This analysis provides the theoretical foundation for the development of the proposed inter-phase coordinated consensus algorithm, which can successfully overcome PV imbalance-induced voltage regulation challenges (e.g., inverter saturation and network overvoltage), while does not need exact system parameters. The effectiveness of this method has been validated by time-series simulations with a real LV distribution system and recorded data.

Dynamic operating envelopes (DOEs) are promising to cater for the strong uptake of distributed energy resources (DERs) in low-voltage (LV) distribution networks while ensuring secure network operation. Under the current framework, DOEs only specify active-reactive power set-points at households' point of connection (POC). In this regard, DOEs do not provide information on the feasible operating region (FOR) of end-users, which is helpful for an aggregator's market decisions. This article proposes a near real-time approach to determine DOEs that specify the FOR at end-users' POC in an LV distribution network. First, Latin hypercube sampling (LHS)-based load flow studies are performed to identify feasible pairs of P-Q injections at the POC that would not breach voltage limits. Secondly, the convex hull of feasible pairs is constructed to obtain household DOEs. Finally, a feeder-level time-varying envelope that represents the aggregate flexibility of downstream nodes of the network is calculated. A comprehensive analysis on a real Australian LV distribution network using realistic data suggests that the proposed approach is scalable and encourages active power exports beyond current industry practice. Moreover, the framework ensures privacy and separation between the distribution network service provider (DNSP) and the aggregator aligned with the existing policy and regulatory frameworks.

Despite extensive research in the past five years and several successfully completed and on-going pilot projects, regulators are still reluctant to implement peer-to-peer trading at a large-scale in today's electricity market. The reason could partly be attributed to the perceived disadvantage of current market participants like retailers due to their exclusion from market participation - a fundamental property of decentralised peer-to-peer trading. As a consequence, recently, there has been growing pressure from energy service providers in favour of retailers' participation in peer-to-peer trading. However, the role of retailers in the peer-to-peer market is yet to be established as no existing study has challenged this fundamental circumspection of decentralized trading. In this context, this perspective takes the first step to discuss the feasibility of retailers' involvement in the peer-to-peer market. In doing so, we identify key characteristics of retail-based and peer-to-peer electricity markets and discuss our viewpoint on how to incorporate a single retailer in a peer-to-peer market without compromising the fundamental decision-making characteristics of both markets. Finally, we give an example of a hypothetical business model to demonstrate how a retailer can be a part of a peer-to-peer market with a promise of collective benefits for the participants. 4 figures, 2 tables, accepted for publication in iScience (Cell Press)