A Probabilistic Method Combining Electrical Energy Storage and Real-Time Thermal Ratings to Defer Network Reinforcement

Abstract

When a primary substation reaches its capacity limit, the standard solution is to reinforce the network with additional circuits. Under the right conditions, the required additional peak capacity can be provided by energy storage systems (ESS), real-time thermal ratings (RTTR) or a combination of the two. We present a probabilistic method for calculating the size of an electrical energy storage system for a demand peak shaving application. The impact of both power and energy capacity are considered, along with the reliability of the energy storage and the existing overhead lines. We also consider the combination of energy storage and RTTRtaking advantage of the inherent variability in power line rating as a result of changing weather conditionsfor enhancing reliability, deferring conventional reinforcement and increasing the availability of energy storage to participate in commercial service markets. The method is demonstrated in a case study on a network with an ongoing 6 MW/10 MWh ESS innovation project.

Impacts of Energy Storage System on Power System Reliability: A Systematic Review

“…In [31], an ESS is integrated to a conventional power system for demand peak-shaving. Results showed that utilization of ESS can sustain reliability level for nine years of 1% growth, thus reducing the need for transmission line upgrades.…”

“…Table 8 illustrates the impacts of ESS on distribution subsystem (HL3). [60] Solves energy dispatch problem in a smart grid consisting of renewable energy sources and ESS Adopts economic model predictive control to optimize economic costs Does not specify utilization of forced outage rate of system components [61] Proposes integration of tactical and operational management of a micro-grid Uses sample-average approximation (SAA) to optimally improve reliability and system profit Does not specify utilization of forced outage rate of system components [62] Presents a cost-benefit analysis in active distribution system Applies single PSO to identify optimal ESS siting and system net profit Does not specify how solar power is modelled [31] Integrates the use of RTTR alongside ESS to increase the availability of ESS and improve reliability Presents a probabilistic approach of a demand and operational constraints of the ESS May extend research to optimally locate RTTR and thus further improve reliability [63] Reliability evaluation of integrated renewable energy with electric vehicle (EV) operating strategy…”

Combining energy storage and real-time thermal ratings to solve distribution network problems: benefits and challenges

“…If only one technology is deployed, the reinforcement threshold will be reached again in around 9.5 years; if both are deployed, the EENS reaches 25 MWh/year after 10 years of demand growth. Details of this analysis can be found in [1].…”

“…In case (a), the ESS is installed alone and provides only peak demand reduction; in case (b), an RTTR system is also installed; in case (c), the ESS is operated alone, and provides both peak demand reduction and FR; in case (d), an RTTR system is also installed, and the ESS provides both peak demand reduction and FR. The results show that the addition of RTTR increases the value of the total system, and that participating in multiple services increases the value of the total system; the greatest lifetime value is achieved through deploying RTTR and an ESS, and providing a combination of demand reduction and FR Further details of this analysis can be found in [1].…”

“…Energy Storage Systems (ESS) and Real-Time Thermal Ratings (RTTR) are emerging technologies which can provide a variety of benefits to transmission and distribution networks. The benefits each technology can provide individually have been thoroughly explored; either technology can enhance security of supply [1,2] or relieve constraints on renewable energy [3]; ESS can also provide voltage support [4], reactive power services, and ancillary services such as frequency response [5] and operating reserve.…”