Battery Energy Storage Systems and Voltage Regulation on Distribution Feeders

Abstract

In the backdrop of the deregulated environment with growing peak demand and constrained profit margins, distribution utilities are under increasing pressure to more effectively manage operational and capital expenditure, all without compromising reliability. The emergence of new Battery Energy Storage Systems incorporating efficient Power Electronics for energy conversion has opened up a new set of possible solutions to peak demand problems. The benefits of widely incorporating BESS in distribution networks are plenty. The usage of BESS enables Demand Side Management (DSM) options that can mitigate Peak Demand issues involving End of Line Voltage Drop, Line Thermal Limits and Transformer Rating by Peak Clipping (i.e. Load Levelling). BESS enabled DSM can also reduce stress on the Transmission Grid via Peak Clipping and may also reduce peak time whole sale electricity spot prices by decoupling generation from usage, thus reducing supply-demand issues. Increasing Energy Storage on the Power System increases stability and reliability. Some such instances are in that BESS provides backup power for critical loads and can compensate for voltage dips. In this thesis the effectiveness of Battery Energy Storage (BESS) in reducing end of line voltage issues is investigated. There is a strongly entrenched notion that voltage drop is most effectively combatted by reactive power management or control. This is based mainly on the assumption that the power system is highly inductive which is true for the most part, but not necessarily for medium voltage (MV) and low voltage (LV) portions of the distribution network. There is also the emergence of four quadrant Static Synchronous Compensators (STATCOM) that use BESS, which poses the need for an updated theory of shunt compensation. The role of Shunt VAR compensation on feeder voltage profiles and line losses is comprehensively covered in the literature but a unified approach to four-quadrant compensation and its effect on feeder voltage profile and losses is lacking. Hence, after a thorough review of Optimal Capacitor placement theory, the effect of injecting a combination of real and reactive power on a feeder is looked at. The role of real and reactive power flow to the loads is also looked at. The result have implications relevant to Four Quadrant Metering. A single phase equivalent analytical model is developed for a feeder with uniformly distributed continuous load. This model is numerically solved in MATLAB using the bvp5c Boundary Value Problem solver and is used for verifying and supplementing the aforementioned results. BESS is also highly important in the context of the drive for Green Energy. Renewable energy sources are generally quite intermittent and require integration with Energy Storage. Utilities are keen to exploit for purposes benefiting the distribution network, a possible increase in the future DG and BESS penetration by way of more domestic energy management systems on the network. In the literature there seems to be a lack of comprehensive understanding of the effect of load diversity on Aggregate Demand when Demand Side Management is implemented by way of home energy management systems implementing peak reduction schemes. An aggregate diversified load model is developed using MATLAB to illustrate the role of diversity in Demand Side Management. MATLAB algorithms are also developed for calculating Storage requirements from feeder demand data provided by Plant Information (PI) Systems. Algorithms are also developed for cleaning PI data before using them in DSM algorithms.