TRANSMISSION & DISTRIBUTION TECHNOLOGY
Utilities face increased voltage volatility from distributed renewables-based power generation: new innovations enable improved voltage control
T
he power distribution grid is undergoing unprecedented levels of change. Te traditional one-way model of voltage regulation presumed
voltages dropping predictably along feeders from substation to customers. However, the proliferation of larger scale distributed energy resources (DER) along feeders is rendering traditional models and regulation techniques incapable of maintaining delivered voltages within ANSI C84.1 guidelines.
Tis is spurring new approaches in grid
measurement, monitoring and control that provide real time measurements that enable distribution management applications to better manage voltages and maintain high power quality.
VOLTAGE FLUCTUATION FROM DER Te traditional power delivery model pushes electricity from a centralised power generation plant through distribution feeders to the point of consumption. Power is consumed along the line with utilities using tap changers, voltage regulators and capacitor banks to regulate voltage to ensure delivery remains within an ANSI guideline range of +/- 5% all the way to the end of
ADVANCES IN DISTRIBUTION GRID MONITORING
the line. Historically, the key concern was ensuring voltages did not fall below or above these standards. Enter DER, electricity-producing
resources or controllable loads that are connected to a local distribution system. DER can include solar panels, wind turbines, battery storage, generators and electric vehicles. Tese points of power generation inject
power along the distribution feeder, which may increase or decrease voltage levels outside ANSI guidelines. In other words, increasing integration of renewables means variable load and generation fluctuations which work against the constant voltage profile model. In addition, solar and wind DER
are, by nature, intermittent. Managing unpredictable intermittency without measurement, monitoring and control is even more difficult and may result in oscillatory voltages in the system. Voltage rises at injection points may also create reverse systemic power flow. As a result, utilities require more
Three raw voltages and currents can be wired to the DGM
8
www.engineerlive.com
advanced power monitoring and control systems that can precisely and quickly measure voltage to enable their distribution management systems (DMS) to respond and regulate the voltage on their feeder lines. But this means DER integration needs real-time data to implement their control strategies. “Te issue goes beyond simply burnt toast in a home,” says Ray Wright at NovaTech. “What we are concerned about with unpredictable voltage delivery is the disruption of service to household, commercial and industrial customers all along the feeder, including damage to motors and equipment and interruption of service.”
MORE PRECISE MONITORING AND CONTROL
Te challenge of effectively controlling unpredictable, variable and potentially bi-directional voltage flow starts with measurement. Te only way to control this kind of variability is to have measurements along distribution feeder lines that are accurate and that can communicate data to control systems fast enough to modulate the voltage and keep it under control – essentially, in real-time. Voltage delivery monitoring and control can be the domain of DMS. Tese systems have evolved over the years with advanced DMS models now in use that use Volt/ Var optimisation (VVO) where capacitor banks, voltage regulators and solid-state systems are switched on and off to maintain acceptable levels of power factor and voltage. More recently, distributed energy resource management systems (DERMS) have emerged in response to the increasing
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
