Page 192 - AJWEP-22-6

Tsankov, et al.

height, and the shortest bracket length and lowest slope
angle, while ensuring compliance with the requirements
of the given lighting class.
For the project in Pavlikeni and Byala Cherkva, where
the spacing between poles (luminaire) is fixed, a non-
standard optimization problem must be defined to determine
the lowest luminaire power, combined with the lowest pole
height and smallest bracket tilt angle that together satisfy the
requirements of the designated lighting class.
The formulation of the optimization problem, where
the pole spacing is fixed and the luminaire power,
mounting height, and tilt angle are optimized to meet
the requirements of a given M-class according to EN
13201, is as follows:

2.2.2.1. Given (parameters)
Figure 7. Light distribution of a street light-emitting The listed parameters represent the key inputs for
diode luminaire, type 1 optimizing road lighting design: Road geometry defines
the layout of the street lighting system, the EN 13201
lighting class specifies performance requirements
(luminance, uniformity, glare, edge illumination),
and the road surface R-table, together with luminaire
photometry, provide the data required for accurate
lighting calculations.
(i) Road geometry: Pole spacing, carriageway width,
number of lanes, curbs, and medians.
(ii) Lighting class under EN 13201: M , with the
k
required limits specified in Table 2—L , U , ,
o req
req
U , , TI , and EIR .
l req
req
max
(iii) Road surface type and R-table.
(iv) Luminaire photometry (Illuminating Engineering
Society-format light distribution file).
2.2.2.2. Decision variables
Figure 8. Light distribution of a street light-emitting The decision variables are calculated based on the
diode luminaire, type 2 following equation (Equation I):

P H,)
old poles were removed and replaced with new ones, x (, (I)
together with a new electrical network. A further where:
rationale for maintaining the existing poles is that a (i) P denotes the luminaire electrical power
significant proportion of the reinforced concrete poles (equivalently, luminous flux/dimming level).
are owned by the electricity distribution company and
are also used to provide electricity to domestic and (ii) H signifies the mounting height.
small business consumers. (iii) θ represents the luminaire tilt angle.
For standard optimization tasks involving completely (iv) Domain constraints are
new lighting systems, and in accordance with the two energy P[ P , P ], H [ H , H ], [ , ]
performance indicators introduced in EN 13201—power min max min max min max
density (D [W/m ]), and annual energy consumption per 2.2.2.3. Objective function
2
P
unit area (D [kWh/m /year])—the optimal solution from To minimize installed power (or, equivalently, energy
2
E
a technical and economic perspective was sought through use per unit road length), the following equation is
a combination of the largest pole spacing, the smallest pole employed (Equation II):
Volume 22 Issue 6 (2025) 186 doi: 10.36922/AJWEP025310242