Danny Pudjianto

Taking an active approach

The United Kingdom is leading Europe in its power market reforms and is currently engaged in addressing issues of DG integration through development of innovative approaches to network planning, operation, regulation, and pricing. This article draws on these recent advances to explore active management technologies, developing regulatory arrangements for network operation, and new commercial opportunities emerging from the low-carbon climate change agenda. It explores the changing role of the distribution system operator (DSO) in response to increasing penetration of DG and identifies the transitions currently taking place in the United Kingdom toward integration of DG that has wider implications for extrapolation across Europe.

Whole-Systems Assessment of the Value of Energy Storage in Low-Carbon Electricity Systems

Energy storage represents one of the key enabling technologies to facilitate an efficient system integration of intermittent renewable generation and electrified transport and heating demand. This paper presents a novel whole-systems approach to valuing the contribution of grid-scale electricity storage. This approach simultaneously optimizes investment into new generation, network and storage capacity, while minimising system operation cost, and also considering reserve and security requirements. Case studies on the system of Great Britain (GB) with high share of renewable generation demonstrate that energy storage can simultaneously bring benefits to several sectors, including generation, transmission and distribution, while supporting real-time system balancing. The analysis distinguishes between bulk and distributed storage applications, while also considering the competition against other technologies, such as flexible generation, interconnection and demand-side response.

Microgrids and virtual power plants: Concepts to support the integration of distributed energy resources

This article presents the concepts of the microgrid and the virtual power plant (VPP) as vehicles to facilitate cost-efficient integration of distributed energy resources (DERs) into the existing power system. These concepts were designed to enhance the system value and the controllability of DER and to provide frameworks for the development of interfaces among energy and ancillary service resources, system operators, and energy market participants. Through aggregation, DER access to energy markets is facilitated, and DER-based system support and ancillary services can be provided. By enabling this additional functionality, it is envisaged that system performance measured in the form of energy efficiency, power quality, security, and economic operation can be improved. In this paper, the technical and commercial functionality facilitated through the microgrid and VPP concepts is described. The paper concludes with case studies demonstrating the application of the concepts on a test system.

Investigation of regulatory, commercial, economic and environmental issues in microgrids

Concepts of microgrids are proposed to address primarily various issues related to integration of small scale renewables and increased demand of reliable electricity supply. With an active management control approach and ability to operate in islanding mode, a cluster of micro generators, electricity storage and electrical loads can be operated within the microgrids framework to provide higher supply reliability to highly value customers. Solutions are required not only to make these concepts technologically feasible and safe to operate but also to be commercially viable and attractive, economically efficient and supported by electricity regulations. This paper summarises the results of investigations on various economic, regulatory and commercial issues faced by the development of microgrids in MICROGRIDS project. The potential economic benefits and contributions to environment from applications of microgrid technologies are also presented and described in this paper

Transmission Network Investment With Probabilistic Security and Corrective Control

Summary form only given. This paper demonstrates that the growth in application of corrective actions to enhance network utilization will require a probabilistic treatment of network security for determining efficient levels of investment in network reinforcement. A Benders decomposition based two-stage probabilistic optimization model for the operational and investment problems is proposed. For selecting relevant contingencies (beyond N-1 criteria), a novel filtering technique for efficient elimination of redundant outages is presented and successfully tested. In 2 numerical examples we compare efficiency of network reinforcement propositions under both deterministic and probabilistic frameworks, while optimizing available preventive and corrective control actions, and in particular focusing on the application of generation reserve in combination with Special Protection Schemes (SPS) for network congestion management purposes. We highlight the inadequacies of the deterministic approach with respect to its inherent inability to optimize accurately the portfolio of pre-fault post-fault actions since the impacts of corrective actions (in the form of SPS, demand response) and occurrence of “non-credible” events require explicit consideration of the likelihood of various outages. We concluded that deterministic approach drives less efficient and potentially more risky system operation that ultimately leads to inefficient network investment.

Decentralized Coordination of Microgrids With Flexible Demand and Energy Storage

Scalability and privacy concerns have created significant interest in decentralized coordination of distributed energy resources (DERs) within microgrids. Previously proposed approaches, however, fail to achieve feasible solutions under flexible demand (FD) and energy storage (ES) participation. After justifying and demonstrating this challenge, this paper develops a novel Lagrangian relaxation-based mechanism achieving feasible, near-optimal solutions in a decentralized fashion, considering both active and reactive power. A two-level iterative algorithm eliminates the infeasibility effect of FD and ES nonstrict convexities, and prevents the creation of new demand peaks and troughs by the concentration of their response at the same low- and high-priced periods. Tradeoffs associated with the design and operation of the mechanism are analyzed, and the value of additional information submission by the DER, in enabling the quantification of an optimality bound of the determined solutions and significant improvements in communication requirements, is assessed. These contributions are supported by case studies on an LV microgrid test system.

Integrated reliability and cost–benefit-based standards for transmission network operation

The growing interest in decarbonizing electricity systems, together with advances in communication and information technologies that may support the application of demand and generation solutions to solve network problems, has initiated reviews of traditional operational practices and security grid standards in a number of jurisdictions. The key concern is that these historical practices and standards, mostly developed in the 1950s, may be inappropriate for the new emerging system as they may pose entry barriers for both renewable generation and Smart Grid technologies. In this context, the current paper presents a probabilistic cost–benefit framework for the development of future efficient operating strategies and network security standards enabled by new technology. By optimally balancing the costs of network constraints with various operational measures composed of preventive and corrective control actions, considering potential outages of network and generation facilities, optimal network capacity that should be released to network users in real time is determined. This framework is compatible with Smart Grid concepts integrating new generation, network, and demand technology. The study demonstrates that any attempt to fix a single generic rule for operating the network, as in the present deterministic standards, will lead to potentially significant inefficiencies. It is also shown that various operational measures (such as generation and demand response) can be effectively used to release additional network capacity. The results suggest that the probabilistic approach provides the basis for the development of future network operation and design standards that would maximize the value of the transmission network to users, enhance the utilization of existing networks, foster the entrance of new technologies that may complement and provide alternative network reinforcement, and hence facilitate efficient integration of renewable generation.

Methodology for Cost Reflective Pricing of Distribution Networks with Distributed Generation

This paper discusses distribution network pricing and the critical role that it plays in the economic and technical integration of distributed generation (DG) into power systems. The central point of DG integration is first of all to quantify the extent to which different DG technologies can replace network assets as well as the extent to which DG can be said to drive investment in network capacity. It is argued that the way to realise economic and technical integration of DG into the power system in an efficient and consistent way is through network pricing. A network pricing methodology based on the concept of economically adapted networks and forward looking investment costs is proposed. The key features of the methodology are illustrated with the aid of a simple example.

Pricing of distribution networks with distributed generation

This paper discusses the objectives of distribution network pricing and presents a detailed exposition of network cost drivers. Key policy questions in the context of developing a new distribution use of system (DUoS) charging methodology for distribution networks with distributed generation are addressed in this paper. This paper proposes a methodology based on the forward looking network investment cost. The methodology is illustrated through an example and the results of evaluating the charges are discussed

Future transmission network operation and design standards to support a low carbon electricity system

Increased connections of wind power in the Great Britain (GB) transmission system had triggered the need to review the fundamental principles behind the deterministic Great Britain Supply Quality and Security Standards (SQSS) that has been used for more than 5 decades. This review analyses the necessary upgrades to improve the efficiency of transmission system operation and capacity required to accommodate the present and future generation system. This paper in particular addresses a number of issues raised from the applications of deterministic SQSS and its operation and design efficiency concerning the best usage of N-k policy type. With respect to the United Kingdom (UK) transmission system operation, deterministic standards have been used to determine secure maximum levels of power transfers across a particular boundary. Our studies indicate that the deterministic standards are too conservative. This leads to over requirement of transmission capacity in planning timescales or significant constraints to access remote wind power in operational timescales. As an alternative, the use of an integrated reliability and cost-benefit framework to optimize the level of transmission system security has been developed. A wide range of studies have been carried out to analyze the benefits of this approach in the UK. The results indicate the need to move towards this integrated approach in order to maximize the value of transmission and to speed up the connections of wind power.