Modular Power Flow Control is a device that is designed from its inception to be modular in nature, combining a variable number of the units together in operation to operate as one to control the flow of power. This capability has been shown to increase the capacity on distribution lines by 100MW’s, for example a single recent UK deployment provided 95MW of additional power capacity with a saving of £8M in its first year.
At present, the commercially available modular power flow control devices are Static Synchronous Series Compensators (m-SSSC). They are part of the FACTS family, injecting a leading or lagging voltage in quadrature (aka shifted 90 degrees) with the line current, using power electronics. This reactive voltage injection makes the effective impedance of a circuit increase or decrease, which increases or decreases the loading on the circuit respectively. Modular Power Flow Controllers can inject the voltage independently of the line current. This allows the devices to provide a linear not stepped response and to modify the effective reactance of the circuit immediately whilst injecting and at any point in time up to its rated value.
Monitoring Sensors. For a correctly monitored, controlled, and regulated power grid, a balance between generation and consumption of active and reactive power is needed. According to the power equation, this means measuring voltage and current as well as frequency. Since medium and high voltage as well as current levels cannot be directly connected to measurement devices a transducer is needed. This transducer can be realized with different measurement principles.
Conventional voltage and current transformers use many resources, have heavy and bulky dimensions and are expansive. However, with a smart grid, many substations, especially on medium-voltage level, could be digitalized. As a rule of thumb for every 100 households there is one substation or ring-main unit. With over 2 billion households worldwide this results in 20 million ring-main units. To digitalize one ring-main unit, around 15 sensors or conventional products are needed.
The paper has sought to show the benefit of the application of grid optimizing technologies to the distribution network and its operators can ensure faster, lower cost, more flexible, beneficial and seamlessly integrated solutions. Digitalization of the energy system is targeted, and essential, with universally recognized potential benefits to stakeholders and network operators alike.
At present, CurrENT is advocating for a Distribution Technopedia to provide DSOs with a list of commercial ready technologies to minimize the effort in identifying and learning how to appraise (often new) alternative technologies. It can provide industry best practice with regard to the range of technologies for solutions that will be considered. A transparent national or European Technopedia simplifies a DSOs task of identifying technologies, sharing with stakeholders what they are and will consider, and sharing knowledge internally.
Technical assurance of a new technology for DSOs can be challenging due to the resource commitment it requires from technical experts that often have limited availability. However paradoxically the need for new technology is increasing to keep pace with the changing role of DSOs and the move to decarbonization.
The suppliers of the technologies in this paper have a broad range of technical assurance experience with other system operators. They have at their disposal past investigations (or selection and proof of international standards) compliance for other customers that are equivalent or often more onerous than the local conditions
All of the DSO grid optimizing technologies in the paper cannot only be applied standalone, but in combination, often in a much more powerful application. The suppliers of these technologies can offer guidance on the possible combinations to address individual cases or needs, and there are other published examples included in the references of this paper. It is expected that if the Technopedia concept that forms one of the earlier recommendations of this paper is developed either national or Europe wide, that this will also be another reference source of symbiotic technologies and their unique applications.
CurrENT has recognized and been actively supporting the need for incentives to support DSOs and their introduction of grid optimizing technologies. It has and continues to recommend that regulatory bodies and policy makers both nationally and European, put incentives in place to support the introduction of these technologies.
As mentioned in many places in this paper the introduction of new technology can be highly effective for DSOs, but initially requires time and resources to be diverted to the task. This places financial costs and short-term resource management impacts on DSOs that need to be acknowledged and supported by industry. Incentives from policy makers, regulators, EC and other sources also have a second almost equally important role in combating perceived risk from new technologies.
DSOs are often questioned on their need to use, or perceived risk in applying a new technology. Incentives show that wider industry stakeholders recognize the importance of the technologies and there is universal agreement on the risks of failure to use technology to address network needs more efficiently outweighs any perceived risks from the technology itself.
Existing technological introductory processes have been built around the prolonged timelines, high resources, and very high capital expense of a project investment. The risk of a costly stranded asset is high. This supports a slow introduction of a technology. Pilot projects followed by a period of assessment, often in less vital areas of a network are a common approach. First deployments often small then follow with another period of assessment.
If successful, further projects then follow growing in size and complexity. This whole process may take a decade or more before widespread use is considered. This process is fit for purpose for a high-cost project, that uses bespoke equipment with fixed or limited capability to be reused, and whose failure or poor performance jeopardizes security of supply. The grid optimizing technologies in this paper are none of these things.
CurrENT recommends that the existing process for the introduction of new technology be reviewed and the impact that grid-optimizing technologies actually represents is considered first, and that a much more streamlined process to trial these technologies is used.
All of the technologies have a method of application that provides potential benefits but does not jeopardize the network security, by being able to be removed from service, or failing safe, that does not impact on the continuity of the network. All of these technologies are comparatively low-cost investments, with near complete ability to be redeployed in full for a range of needs or locations across the network. The complete paper is available for download here.
Layla Sawyer is the Secretary General of current. Sawyer studied sustainable business and innovation at the University of Utrecht. In her previous roles, she led business development at smartEn, and as a Dutch national worked on broader climate issues in the Netherlands. At currENT, she helps set priorities innovative grid technologies. currENT’s membership includes 9 companies working on new solutions for DSOs and TSOs, including Dynamic Line Rating, Superconductor cables, Flexible AC Transmission System Devices, sensors, and other technologies.