Reliability assessment for economic dispatch problem in the energy hub concept

ABSTRACT

The main objectives in the management of energy systems are to reduce the operation costs and simultaneously increase the reliability indices. The achievement of these aims is among the key challenges that network operators encounter. To overcome this challenge, the current study presents a model in which the reliability criterion is calculated in addition to the well-established technical constraints for an energy hub. In this strategy, reliability evaluations are added to the classical model as new constraints. In other words, the energy hubs can be more appropriately and realistically operated by imposing these limitations. Moreover, in addition to the costs of different energy carriers, the objective function also includes the costs of “energy not supplied” (ENS) for different loads. This approach demonstrates a mixed-integer nonlinear programming (MINLP) technique implemented using the LINDOGlobal solver in GAMS. To examine the efficiency of the proposed method, modeling is performed on a sample energy hub, and the results assessed.

KEYWORDS:

• Energy hub
• operation
• reliability
• energy not supplied
• economic dispatch

Nomenclature

$i$	=	Index for hub’s input energy carrier
$j$	=	Index for hub’s output energy carrier
$m$	=	Index for energy convertor type
$s$	=	Index for energy storage type
$n$	=	Index for number of installed elements
$t$	=	Index for time block
$el$	=	Index for total types of elements (energy convertor and storage)
$N_i$	=	Number of hub’s input energy carrier
$N_m$	=	Number of energy converters types
$N_n$	=	Number of installed elements
$N_s$	=	Number of installed energy storage
$N_{el}$	=	Number of total types of elements (energy convertor and storage)
$N_t$	=	Number of time blocks
$P_i$	=	ith input energy
$L_j$	=	jth output load
$C_{ij}$	=	Coupling matrix array
$P$	=	Input matrix
$L$	=	Output matrix
$C$	=	Coupling matrix
$v_{i,m}$	=	Factor between ith input energy and mth converter
${\eta }_{Trans}$	=	Transformer efficiency
${\eta }_{CHP}^e$	=	CHP electrical efficiency
${\eta }_{CHP}^{th}$	=	CHP thermal efficiency
${\eta }_{Fr}$	=	Furnace efficiency
${\eta }_{Exe}$	=	Heat exchanger efficiency
$TC$	=	Total energy hub operation cost
$\pi \mathrm{\_}EC$	=	Price of energy carrier
$Pin\mathrm{\_}Tot$	=	Total input of energy hub
$Pout\mathrm{\_}Tot$	=	Total output of energy hub
$Pin$	=	Input power of convertor
$Pout$	=	Output power of convertor
$Sin$	=	Input power of storage
$Sout$	=	Output power of storage
${\theta }_{\hspace{0.17em}}^{dis}$	=	Discharging rate of storage
${\theta }_{\hspace{0.17em}}^{ch}$	=	Charging rate of storage
$SE$	=	Stored energy in energy storage
$\eta$	=	Component efficiency
$Pi{n}_{\hspace{0.17em}}^{min}$	=	Minimum input power of energy converter
$Pi{n}_{\hspace{0.17em}}^{max}$	=	Maximum input power of energy converter
$Si{n}_{\hspace{0.17em}}^{min}$	=	Minimum input power of energy storage
$Si{n}_{\hspace{0.17em}}^{max}$	=	Maximum input power of energy storage
$Sou{t}_{\hspace{0.17em}}^{min}$	=	Minimum output power of energy storage
$Sou{t}_{\hspace{0.17em}}^{max}$	=	Maximum output power of energy storage
$S{E}_{\hspace{0.17em}}^{min}$	=	Minimum stored energy in energy storage
$S{E}_{\hspace{0.17em}}^{max}$	=	Maximum stored energy in energy storage
$I$	=	Installation value (binary: 1=installed, 0=not installed)
$EENS$	=	Expected energy not supplied
$ENS$	=	Energy not supplied
$EEN{S}_{max}$	=	Maximum value of EENS
$pr$	=	Probability of contingency (one element has failed and other elements are in use)
$Res$	=	Amount of reserves for each element
$Restot$	=	Total reserves in energy hub
$PSout$	=	Output power of element (for Convertor =$Pout$; for Storage = $Sout$)
$PS\mathrm{\_}ou{t}_{\hspace{0.17em}}^{max}$	=	Maximum capability output power of element (for Convertor =$\eta \times Pi{n}_{\hspace{0.17em}}^{max}$, for Storage =$\eta \times Si{n}_{\hspace{0.17em}}^{max}$)
$TH$	=	Time horizon
VOLL	=	Value of loss load
ED	=	Economic dispatch
TR	=	Transformer
CHP	=	Combined heat and power
CCHP	=	Combined cooling, heat and power
HConv	=	Heat converter
Fur	=	Furnace
EStorage	=	Electric storage
HStorage	=	Heat storage
CStorage	=	Cooling storage
$f\left(x\right),d(y),h(y)$	=	General statement of functions in MINLP
$x,y$	=	General statement of variables in MINLP
$L,U$	=	Lower and Upper bound in MINLP

Conflict of interest

The authors have declared no conflict of interest.