Assembling smart grid technologies to meet distribution optimisation goals

  The grid, described as most complex machine ever made by man was always the harbinger of smartness in industrial space. The power systems were the first to deploy digital computers within first few years of their emergence. However, the distribution layer was always seen to be straightforward in design, ownership, implementation and management. The fact that principal power consumption occurs at this level, distribution system was seen more as statistical solace which smoothened the demand curve and made ‘dispatch’ planning predictable. HVDC, FACTS, PMUs have given high level of observability and controllability in the transmission layer. However, the foregoing finds itself more in sync with a grid where the generation is deterministic.
With advent of renewables, the element of predictability in generation is no longer a valid assumption. Wind and solar comes with substantial variability in generation. Moving in to deep seas will mitigate variability largely and the connections would be at transmission level whereas solar would be integrated largely on lower tiers of the grid.The handling of variability of generation brings substantial challenges for operation of the grid and having reasonable estimates for dispatchable generation. This brings forth requirement of additional layer of forecasting models which would predict generation and handle demand management complementing the conventional decision making mechanism of arriving at plausible unit commitments and scheduling dispatches.
Smartness in distributionEven without new developments, distribution system saw new tools being used for asset management, revenue realisation, demand modelling and network planning. The advanced metering infrastructure has laid the foundation of new possibilities like (apart from the usual meter reading and integration with utilities):Giving better visibility to the utility and the consumer of pattern of usage during the dayBetter correlation between the time of use, kind of usage, availability and cost of powerInstead of plain tariff or simple Time-of-Day metering strategy, customer can participate in market linked consumption decision-making customer an empowered participant in electricity marketsData for the regulators for arriving at quality of service offered to the customers and have a dataset which can be legally taken cognisance of, permitting a superior level of regulatory oversight and customer satisfaction.
What is smartness in a grid?Upper tiers of grid have always been smart. However, the distribution ends were garden hoses with power flow unidirectional and it was in the distribution that the participation of consumer was absent (apart from being the one who just paid for the energy consumed). Distinguishing features of smartness as we now see it are- there is an element of active participation of all stake holders, connectivity of stakeholders (customers connected to each other and to the utility on bi-directional communication links) and flexibility (reconfigurability, multiple ways of interaction-a customer entering in to a transaction with another or customer trading his watts or negawatts).
However, one can’t limit smartness to just IT enabled services. Distribution systems as they undergo basic structural change need advanced control and protection also-which in turn get connected to themselves for meeting the assured service quality indices.
True Smartness: NegawattsThe ConceptNegawatts is a profound concept pioneered by the physicist Amory Lovins in 1970s. The beauty of this concept lies in its simplicity-which got translated in to the oft reported maxim –‘power saved is power generated’.
Negawatts is conceptually more generic than demand management and demand response. Adequate exposition of this concept permits handling of non-deterministic and intermittent distributed generation – a key imperative of power sector’s present and future. Negawatts can be loosely understood as avoided consumption-either by way of energy efficient equipment or by way of deliberate decision to modulate the demand by the customer.
Say a set of shopping malls participates in a demand management program in a region. When the demand of this region increases these participating malls can give up their air-conditioning loads by moving their thermostat settings to higher temperature (the thermal inertia of large spaces can easily permit this with users not feeling the change immediately). This avoided consumption is akin to generation of negative watts or negawatts, thereby easing the demand placed on generation of physical watts. Thus, in the paradigm of negawatts, power engineers can readily grasp demand management and response. This makes the new framework of planning on same footing as conventional approach towards generation being matched to demand.
Negawatts schedulingLike we conventionally schedule dispatches, weather forecast models embedded in generation forecasters is now emerging as key instrument of integrating variable, non-deterministic generation. Better observability afforded by PMUs make grids more resilient to intermittency (certain variability always existed in the grid-from the consumer end. This was smoothened statistically by serving several diverse customers together. In new paradigm, variability is now being introduced on generation end also). With distribution systems ceasing to be simple unidirectional flows, PMUs for distribution is also an emerging technology which will improve resilience, observability and controllability of distribution systems. Roof top solar is now being encouraged in cities all over the world and would need such elements with proliferation of distributed and intermittent generation.
However, when we want to leverage existing intelligence and assets, one can cleverly deploy demand avoidance by such entities which agree to forsake their demand to accommodate a demand surge elsewhere. However, negawatts of individual customers can’t be scheduled due to their small size-this opens role of a new player-the aggregator. This entity aggregates negawatts of the participant entities and make it available as a ‘unit’ which then can be scheduled. This aggregation can also factor in non-utility embedded or distributed generation (DG).
It is seen that such participation is made possible by developments in resilient networks and advanced IT tools. Development of capability to handle high velocity and high volume of data makes advanced analytics applicable in such possibilities.
The WattsHaving discussed the avoided watts, let’s take a look at the real watts that flow.
DisruptionDisruption in basic defining feature of distribution network has occurred due to integration of distributed generation in the distribution. This makes power flows bidirectional in circuits, which are designed, operated and protected for unidirectional power flows. Another interesting characteristic being-this generation is likely to be on single phase and that it would be behind (downstream) the meter.
The ImpactEmbedding increasing levels of distributed generation has potential of impacting operation, protection, fault location, voltage quality and voltage control.
There is hence need of more aware protection schemes with relays having directional sensitivity. Fault passage indicators having directional indication would facilitate more directed information on faults. However, protection of distribution with embedded DG deserves a far more detailed treatment.
Voltage quality needs to be addressed atleast at two levels. Firstly, the single inverters need to be given ability to connect to different phases depending upon the prevailing voltage quality. Research on phase reconfiguration is work in progress which investigates the strategy for over all optimisation of the system. Also, the inverters, though usually are designed for upf, they may be called upon by the utility to source or sink reactive power, to support voltage quality. This can be possibly facilitated by suitable business model.
DC vs AC debateThere is lot of discussion on the future of distribution in terms of the kind of system that would evolve as most of the end loads are increasingly becoming DC. This issue is addressed by the Systems Evaluation Group-4 (SEG-4) of IEC. The group is in process of collecting experience of use of DC from the use cases of LVDC in distribution, in marine, aviation, road and rail. SEG-4 treats voltages less than 1500 V as LVDC. Recently, SEG-4 met in New Delhi (28-Oct-2015) following international LVDC conference on 26/27-Oct 2015 (organised by IEC-BIS) to deliberate upon the user experience, with focus of arriving at strategy for adopting LVDC for distribution. The author made following submission at the meeting:Challenges faced by the third world, electricity deficit countries are very different from those of the first world.Depth and spread of skill in handling advanced technology in distribution is not available in the third world. Thus, increase in system complexity and number of components will have adverse impact on system reliability.There is need to separate voltage levels within ambit of LVDC like it has been the practice in AC. Clearly a 5 V DC USB interface can’t be dealt on the lines of 750 V DC metro power supply. Ominous designation at this stage of evolution will create perception barriers in potential users. Also, a suitable discrimination in voltage levels would facilitate application of codes, practices and norms with greater clarity and ease.Challenge of higher currents exits at lower system voltages. Thus, a more calibrated approach which pairs energy efficient end equipment with DC distribution needs to be taken. Though, domestic heavy loads like air conditioners can be served by BLDC motors which can work at lower dc voltages, living with higher currents needs much higher upgradation effort for entire distribution ecosystem of practice and skill.Distinction between electricity system at the socket, between socket and meter, between meter-distribution point.Work has been done at creating over 700 V DC backhaul circuits for distribution essentially to contain system currents.Challenge of highly dependable switchgear which can stand the abuse of distribution systems.Lack of fault discriminants in DC systems.
ConclusionDistribution systems hence see a disruption-on account of bidirectional flow in circuits designed for unidirectional power flows and due to new possibilities of integrating end customer with markets by the instrument of negawatts and customer owned generation. The market incentives can meaningfully operate only with advanced IT infrastructure and by creating better observability and controllability of the system. Embedding DG introduces additional element of interactive control. As new technologies would be implemented in brownfield distribution systems, the challenge of protection, tools for analysing fault scenarios as DG penetration increases would require to be addressed. Increasingly one sees new IT based tools emerging and at the same time, switchgear, protection, network planning and analysis tools being upgraded by the major players in power sector.
Authored by__
Sujeet MishraAdvisor (Projects)Ministry of External AffairsGovernment of India

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Assembling smart grid technologies to meet distribution optimisation goals

  The grid, described as most complex machine ever made by man was always the harbinger of smartness in industrial space. The power systems were the first to deploy digital computers within first few years of their emergence. However, the distribution layer was always seen to be straightforward in design, ownership, implementation and management. The fact that principal power consumption occurs at this level, distribution system was seen more as statistical solace which smoothened the demand curve and made ‘dispatch’ planning predictable. HVDC, FACTS, PMUs have given high level of observability and controllability in the transmission layer. However, the foregoing finds itself more in sync with a grid where the generation is deterministic.
With advent of renewables, the element of predictability in generation is no longer a valid assumption. Wind and solar comes with substantial variability in generation. Moving in to deep seas will mitigate variability largely and the connections would be at transmission level whereas solar would be integrated largely on lower tiers of the grid.The handling of variability of generation brings substantial challenges for operation of the grid and having reasonable estimates for dispatchable generation. This brings forth requirement of additional layer of forecasting models which would predict generation and handle demand management complementing the conventional decision making mechanism of arriving at plausible unit commitments and scheduling dispatches.
Smartness in distributionEven without new developments, distribution system saw new tools being used for asset management, revenue realisation, demand modelling and network planning. The advanced metering infrastructure has laid the foundation of new possibilities like (apart from the usual meter reading and integration with utilities):Giving better visibility to the utility and the consumer of pattern of usage during the dayBetter correlation between the time of use, kind of usage, availability and cost of powerInstead of plain tariff or simple Time-of-Day metering strategy, customer can participate in market linked consumption decision-making customer an empowered participant in electricity marketsData for the regulators for arriving at quality of service offered to the customers and have a dataset which can be legally taken cognisance of, permitting a superior level of regulatory oversight and customer satisfaction.
What is smartness in a grid?Upper tiers of grid have always been smart. However, the distribution ends were garden hoses with power flow unidirectional and it was in the distribution that the participation of consumer was absent (apart from being the one who just paid for the energy consumed). Distinguishing features of smartness as we now see it are- there is an element of active participation of all stake holders, connectivity of stakeholders (customers connected to each other and to the utility on bi-directional communication links) and flexibility (reconfigurability, multiple ways of interaction-a customer entering in to a transaction with another or customer trading his watts or negawatts).
However, one can’t limit smartness to just IT enabled services. Distribution systems as they undergo basic structural change need advanced control and protection also-which in turn get connected to themselves for meeting the assured service quality indices.
True Smartness: NegawattsThe ConceptNegawatts is a profound concept pioneered by the physicist Amory Lovins in 1970s. The beauty of this concept lies in its simplicity-which got translated in to the oft reported maxim –‘power saved is power generated’.
Negawatts is conceptually more generic than demand management and demand response. Adequate exposition of this concept permits handling of non-deterministic and intermittent distributed generation – a key imperative of power sector’s present and future. Negawatts can be loosely understood as avoided consumption-either by way of energy efficient equipment or by way of deliberate decision to modulate the demand by the customer.
Say a set of shopping malls participates in a demand management program in a region. When the demand of this region increases these participating malls can give up their air-conditioning loads by moving their thermostat settings to higher temperature (the thermal inertia of large spaces can easily permit this with users not feeling the change immediately). This avoided consumption is akin to generation of negative watts or negawatts, thereby easing the demand placed on generation of physical watts. Thus, in the paradigm of negawatts, power engineers can readily grasp demand management and response. This makes the new framework of planning on same footing as conventional approach towards generation being matched to demand.
Negawatts schedulingLike we conventionally schedule dispatches, weather forecast models embedded in generation forecasters is now emerging as key instrument of integrating variable, non-deterministic generation. Better observability afforded by PMUs make grids more resilient to intermittency (certain variability always existed in the grid-from the consumer end. This was smoothened statistically by serving several diverse customers together. In new paradigm, variability is now being introduced on generation end also). With distribution systems ceasing to be simple unidirectional flows, PMUs for distribution is also an emerging technology which will improve resilience, observability and controllability of distribution systems. Roof top solar is now being encouraged in cities all over the world and would need such elements with proliferation of distributed and intermittent generation.
However, when we want to leverage existing intelligence and assets, one can cleverly deploy demand avoidance by such entities which agree to forsake their demand to accommodate a demand surge elsewhere. However, negawatts of individual customers can’t be scheduled due to their small size-this opens role of a new player-the aggregator. This entity aggregates negawatts of the participant entities and make it available as a ‘unit’ which then can be scheduled. This aggregation can also factor in non-utility embedded or distributed generation (DG).
It is seen that such participation is made possible by developments in resilient networks and advanced IT tools. Development of capability to handle high velocity and high volume of data makes advanced analytics applicable in such possibilities.
The WattsHaving discussed the avoided watts, let’s take a look at the real watts that flow.
DisruptionDisruption in basic defining feature of distribution network has occurred due to integration of distributed generation in the distribution. This makes power flows bidirectional in circuits, which are designed, operated and protected for unidirectional power flows. Another interesting characteristic being-this generation is likely to be on single phase and that it would be behind (downstream) the meter.
The ImpactEmbedding increasing levels of distributed generation has potential of impacting operation, protection, fault location, voltage quality and voltage control.
There is hence need of more aware protection schemes with relays having directional sensitivity. Fault passage indicators having directional indication would facilitate more directed information on faults. However, protection of distribution with embedded DG deserves a far more detailed treatment.
Voltage quality needs to be addressed atleast at two levels. Firstly, the single inverters need to be given ability to connect to different phases depending upon the prevailing voltage quality. Research on phase reconfiguration is work in progress which investigates the strategy for over all optimisation of the system. Also, the inverters, though usually are designed for upf, they may be called upon by the utility to source or sink reactive power, to support voltage quality. This can be possibly facilitated by suitable business model.
DC vs AC debateThere is lot of discussion on the future of distribution in terms of the kind of system that would evolve as most of the end loads are increasingly becoming DC. This issue is addressed by the Systems Evaluation Group-4 (SEG-4) of IEC. The group is in process of collecting experience of use of DC from the use cases of LVDC in distribution, in marine, aviation, road and rail. SEG-4 treats voltages less than 1500 V as LVDC. Recently, SEG-4 met in New Delhi (28-Oct-2015) following international LVDC conference on 26/27-Oct 2015 (organised by IEC-BIS) to deliberate upon the user experience, with focus of arriving at strategy for adopting LVDC for distribution. The author made following submission at the meeting:Challenges faced by the third world, electricity deficit countries are very different from those of the first world.Depth and spread of skill in handling advanced technology in distribution is not available in the third world. Thus, increase in system complexity and number of components will have adverse impact on system reliability.There is need to separate voltage levels within ambit of LVDC like it has been the practice in AC. Clearly a 5 V DC USB interface can’t be dealt on the lines of 750 V DC metro power supply. Ominous designation at this stage of evolution will create perception barriers in potential users. Also, a suitable discrimination in voltage levels would facilitate application of codes, practices and norms with greater clarity and ease.Challenge of higher currents exits at lower system voltages. Thus, a more calibrated approach which pairs energy efficient end equipment with DC distribution needs to be taken. Though, domestic heavy loads like air conditioners can be served by BLDC motors which can work at lower dc voltages, living with higher currents needs much higher upgradation effort for entire distribution ecosystem of practice and skill.Distinction between electricity system at the socket, between socket and meter, between meter-distribution point.Work has been done at creating over 700 V DC backhaul circuits for distribution essentially to contain system currents.Challenge of highly dependable switchgear which can stand the abuse of distribution systems.Lack of fault discriminants in DC systems.
ConclusionDistribution systems hence see a disruption-on account of bidirectional flow in circuits designed for unidirectional power flows and due to new possibilities of integrating end customer with markets by the instrument of negawatts and customer owned generation. The market incentives can meaningfully operate only with advanced IT infrastructure and by creating better observability and controllability of the system. Embedding DG introduces additional element of interactive control. As new technologies would be implemented in brownfield distribution systems, the challenge of protection, tools for analysing fault scenarios as DG penetration increases would require to be addressed. Increasingly one sees new IT based tools emerging and at the same time, switchgear, protection, network planning and analysis tools being upgraded by the major players in power sector.
Authored by__
Sujeet MishraAdvisor (Projects)Ministry of External AffairsGovernment of India

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