Optimal operation of HVDC links embedded in an AC network

Abstract

Electrical grid development is necessary, in order to ease the whole electricity market, to enhance the security of power systems and to facilitate the integration of renewable energies. HVDC technology is one possible response that is considered by many TSOs. A new challenge consists today in handling the operation of such HVDC links integrated in an already meshed AC network. This paper presents a possible solution for an optimal operation of such HVDC links in steady state. The power set point is chosen thanks to an optimization tool that coordinates all HVDC links and phase-shifter transformers (PST) in a widespread area. Then, for each HVDC link, an automatic device adapts the power set point in few minutes to solve, if any, overloads on close lines. Preventive and curative actions enabled by HVDC technology are used to improve the performance of the network.

Optimal Operation of the Western Link Embedded HVDC Connection

“…Non-Security Constrained OPF Program A is described by objective function (3) subject to constraints (4a)- (15). Note that parameters M g and P 0 g were set from the corresponding optimal values of the variables µ g and p 0 g for generator g ∈ J in E by M g := (µ g ) * and P …”

“…An alternative solution method and objective function are studied in [15]: a linearised 'DC'-type OPF is performed with an objective function to maximise the smallest current margin within AC circuits relative to their current ratings; the problem is described as a constrained mixed-integer linear program (MILP) solved using a commercial solver. Only [13] and [15] consider system security explicitly; in particular, [15] models both preventative and corrective security actions.…”

“…Only [13] and [15] consider system security explicitly; in particular, [15] models both preventative and corrective security actions. Only [13] and [14] use a selection of system generation and demand scenarios and thus provide significantly different system initial conditions; [5] and [15] do not generally consider different system generation and demand backgrounds.…”

“…In general, the methods in [5], [13]- [15] are quite specific: they make assumptions on what the 'best' objectives to minimise are, and typically impose a candidate loading strategy via constraints or objective functions. Satisfying these imposed strategies may lead to optimal solutions which are sub-optimal from the perspective of minimising system generation redispatch cost.…”

A deterministic approach to locating series flow-controllers within transmission systems to alleviate congestion

“…Modern power electronic devices (the review in [6] discusses several) offer new ways to use smart flow-controllers to unlock flexibilities within power networks [7,8]. However, published approaches to siting such power electronic devices have typically considered direct series or shunt connections to existing lines or buses.…”