Study on the Power Quality of LED Street Luminaires

Abstract

The paper analyses the power-quality effects of connecting LED luminaires to street lighting installations. The power quality impact of LED luminaires and the implementation of smart control systems are discussed. Several power-quality measurements have been performed to determine the effect of connecting multiple LED luminaires to the electrical power network. Three LED street lighting systems were selected, each equipped only with LED luminaires of different power ratings and numbers, produced by different manufacturers. The measurements were performed at the lighting connection box, and the results are presented and discussed for each case.

1. Introduction

Street lighting is one of the biggest electrical energy consumers in a city, accounting for approximately 40% of the city’s overall electricity costs [1]. The costs of electrical energy, together with the environmental factors, encourage municipalities to implement solutions to reduce energy consumption [2].

The development of lighting that uses LED (light-emitting diode) technology has enabled the replacement of high-pressure luminaires with luminaires that consume significantly less energy [3,4]. The advantages are [5,6,7]: high luminous efficacy, long life, instant start-up, dimming possibility, lower environmental impact, and decreased investment and maintenance costs. Energy savings between 31% and 60% are estimated [8] by using quality LED street luminaires as a replacement for quality high-pressure sodium luminaires while applying multi-stage dimming scenarios. With the development of LED technology, LED street luminaires are strongly recommended to be used in road lighting in terms of environmental performance. Lower environmental impacts per lit kilometer of up to 41% are estimated for LED street luminaires (when they will reach a luminous efficacy greater than 200 lm/W) compared to high-pressure sodium luminaires. [7] A study that considered 125 countries estimated that 264 million LED street luminaires will be added over the next ten years, reaching a penetration rate of 89% by 2027 [9].

There are also drawbacks regarding the introduction of LED luminaires, mainly related to the impact on the power quality. The major issue is the problem of capacitive reactive power consumption and the distortion of the current consumed by the LED luminaires [10,11]. The power of an individual luminaire is controlled by electronic drivers supplying individual chains of LEDs. Because the single-phase ac represents the primary power supply for the LED street luminaires, the ac–dc LED drivers are required to ensure good performance and compliance with regulations (efficiency, rated lifetime hours, harmonic injection, dimming performance, and flicker-free operation). Because the power factor correction stage is mandatory, different topologies exist for the ac-dc drivers (two-stage and three-stage). The first stage is in charge of performing the power factor correction, and the second stage is in charge of regulating the current driven by LEDs. Sometimes the two-stage solution for ac–dc LED drivers is unable to ensure proper control of the forward current of each LED in complex LED arrangements. In this case, the two-stage solution becomes the three-stage solution for ac–dc LED drivers employing a post-regulator per string [12,13]. Measurements performed on LED lamps with a nominal power of less than 25 W show that the lamps operating with LED technology introduce strong distortions of the electrical current and generate reactive capacitive power, representing possible power quality problems if used in high numbers [14]. High-power LED luminaires (with nominal power ranging between 180 W to 210 W) analysis concludes that the main power quality distortion elements are the odd harmonic current generated by the luminaires and the inrush power-on electrical currents [15]. The power-on transient currents are generated by the capacitors used to perform the power factor correction. [16] The dependence of the electrical parameters of four LED luminaires (with nominal powers between 32 W and 104 W) on the power quality of the supply voltage is examined in [17]. The change in the RMS value of the supply voltage has the greatest impact on the reactive power value, affecting the value of the power factor. For the tested LED luminaires, the harmonic deformation on the supply voltage, with higher values but still within the standard limits, will cause an increase in the current harmonic distortion generated by the LED luminaires. Different studies [18,19,20] have addressed the possibility of retrofitting existing luminaires with LEDs with the purpose of reducing waste materials and reusing different components of the existing luminaires. It was concluded that the selection of the proper lighting gear is crucial during the retrofit design phase, not only for satisfying the requirements imposed by regulations on average illuminance and uniformity but also for their energy performance and power quality [20].

In addition to the introduction of LED luminaires, the implementation of smart control systems allows further advantages in terms of increased energy efficiency, the possibility of individual luminaire control, and decreased maintenance costs [21,22,23]. The control of the public street lighting systems is, in the vast majority, based on astronomical clocks, with an annual calendar. The implementation of smart control can allow different light control scenarios. In [24], the on/off optimization of public lighting systems depending on the road class and visibility level are analyzed. The reduction in the luminous flux for the LED street luminaires so that, for a given lighting class, the road luminance corresponds to the value of mesopic luminance obtained under HPS lighting is analyzed in [25]. With the application of lighting control (the luminaire flux control of a given installation), it is also possible to change the road lighting class from M4 to M5 or even to M6 [26,27]. Such experiments are technically possible as LED luminaires can precisely control the emitted luminous flux [28] and also allow a relatively easy and immediate change in the emitted luminous flux [25]. The effects on the power quality of dimming two LED street luminaires (with nominal powers of 196 W and 198 W) are presented in [10]. The research concludes that dimming the LED luminaires can pose power quality issues, especially increasing capacitive reactive power and harmonic current distortion. The tests performed in [29] show that, in the case of LED street luminaires, the low THDI (total harmonic current distortion) values at the nominal luminous flux are also maintained at levels of dimming up to 70% of the nominal luminous flux (with increased values of THDI up to 20%). This will cause only a small negative impact on the supply grid. Higher THDI values are present when the luminaire is dimmed at a low level.

This paper analyses the power quality problems that may appear when multiple LED street luminaires are connected to the same power supply network (to the same electric feeder). Three different street lighting systems are considered, each equipped with different types of LED street luminaires of different power ratings and numbers. The studied streets are all located in the city of Cluj-Napoca, Romania.

2. Materials and Methods

The three different LED street lighting systems selected for study correspond to different street lighting classes, according to the European standard EN 13201–2:2015 [30]. The LED luminaires have different rated power and are produced by different manufacturers. For the purposes of the study, the streets were marked as Street A, Street B, and Street C. The main street lighting class design characteristics and the power rating of the LED luminaires are:

• Street A: M4 street ≥ 0.75 cd/m²; 79 W LED luminaire, 115.8 lm/W, Schreder Voltana 3 24 L;
• Street B: M2 street ≥ 1.50 cd/m²; 168.8 W LED luminaire, 103 lm/W, Schreder Ampera Midi 64 L;
• Street C: P2 Park/street alley Eh, av = 10 lux; Eh, min = 2 lux; 30.5 ÷ 55 W LED luminaires, Philips TownTune BDP 260.

2.1. Street A Lighting System

The first street selected for the study is located in a new neighborhood, the construction of the street being finalized in 2020. It is a single carriageway, two-way street, two-lane (7 m wide), and has parking lanes, bicycle lanes, and sidewalks on each side (each bicycle lane is 1.5 m wide; each sidewalk is 1.5 m wide), Figure 1. The street is about 0.5 km long and has been classified as an M4 street lighting class. It has a lighting installation consisting of 17 LED luminaires, with a 27 m distance between them, a 1.50 m luminaire overhang, a tilt angle of 15°, and is mounted at a height of 9 m.

The DIALux simulation of the street lighting system has enabled the calculation of the necessary light parameters for the street according to the EN 13201-2:2015 standard requirements, estimated traffic, and street configuration (for the analyzed case—M4 class motorized traffic lanes, C4 parking lanes, C5 cyclist lanes, and P2/P5 pedestrian lanes). The installed 79 W LED luminaires, mounted according to the luminous design requirements, provide light on the street according to the relevant standards.

The on/off switch procedure for this street lighting system is based on a light sensor that transmits a signal to an electromagnetic relay. In this way, the street lighting system is supplied with electric energy from sunset (when the electromagnetic relay is switched “on”) until sunrise (when the electromagnetic relay is switched “off”).

2.2. Street B Lighting System

The construction works for the reconfiguration of the second street selected for the study have been finalized in 2020—Figure 2.

It is a single carriageway two-way street with three-lane (9.2 m wide) and has bicycle lanes and sidewalks on each side (each bicycle lane is 1.5 m wide; each sidewalk is 1.8 m wide). The street is about 1.2 km long, and it is classified as an M2 street. The main street lighting system consists of 44 LED luminaires, with a 30 m distance between them, a 1.00 m luminaire overhang, a tilt angle of 10°, and is mounted at a height of 10 m. Supplementary luminaires have been placed for the lighting of 5 pedestrian crossings and for the lighting of a roundabout.

The 168.8 W LED luminaires provide light for the street according to the EN 13201-2:2015 standard requirements, estimated traffic, and street configuration (M2 class motorized traffic lanes, C2/C4 cyclist lanes, and P1/P3 pedestrian lanes).

The LED street lighting system is connected to a lighting connection box that also supplies energy to other street lighting systems corresponding to adjacent streets. The on/off switch procedure for the entire lighting system is based on a control module that transmits a signal to an electromagnetic relay. The on/off times are pre-set for each day for the entire year, based on the statistic values of the sunrise and the sunset for the last 5 years.

Inside the lighting connection box, there is a local communication network box installed for wireless monitoring, control, and management of the 168.8 LED street luminaires. Each LED luminaire is equipped with an individual controller that transmits and receives information from the local communication network box and, from here, using the cloud, the information is transferred to and from the central management system. Luminaires communicate together in a wireless network to offer dynamic profile dimming. The individual controller is also fitted with a light sensor that enables, if the network communication fails, the on/off switch based on the ambient light conditions.

2.3. Street C Lighting System

The third considered case is a lighting system mounted in the City’s Central Park. It is equipped with LED luminaires that provide light for the park alleys, according to EN 13201-2:2015 requirements (P2 pedestrian lane). The lighting system was modernized in 2020; the existing luminaires were replaced with 227 LED luminaires (nominal powers 30.5 W and 55 W) while maintaining the metal pillars’ positions, with a height of 4 m—Figure 3.

The on/off switch procedure for this street lighting system is based on a light sensor that transmits a signal to an electromagnetic relay. In this way, the street lighting system is supplied with electric energy from sunset (when the electromagnetic relay is switched “on”) until sunrise (when the electromagnetic relay is switched “off”).

2.4. Measurements

The electrical energy is supplied, for all three cases, directly from a medium/low voltage transformer station to a street lighting connection box (from a low voltage public street lighting connection box powered by a low/medium voltage transformer station). The equipment installed in the lighting connection box allows for the protection, monitoring, and control of the street lighting system, as well as the measurement of the consumed electrical energy. From the lighting connection box, the electrical energy is supplied using a 4 × 10 mm² NYY energy cable (TN—C single line supply diagram). Each active wire is protected in the lighting connection box for short-circuit and overload overcurrent: street A–32 A Neozed-type fuse; street B–50 A NH1-type fuse; street C–50 A 3P + N circuit breaker. At each lighting point, an interior electrical connection box is installed. From the interior connection box, the electrical energy is supplied to each LED luminaire using a 3 × 1.5 mm² NYY cable. Each active wire is protected in the interior electrical connection box for short-circuit and overload overcurrent with a 6 A Neozed-type fuse.

The measurements were performed, for each case, at the corresponding main connection box by using a Fluke 1730 Energy Analyzer connected to the main electrical panel, Figure 4. The measuring device met the IEC 62053-22 Class 0.2 S metering standard. The electrical parameters were measured each second according to IEC 61000-4-30 Class A [31], a power quality compliance monitoring was performed in accordance with the European standard EN 50160 [32].

3. Results

The results of the performed measurements are presented and analyzed in two stages: first, the electrical parameters corresponding to the quality of the supplied voltage, and second, the electrical parameters generated by the functioning of each street lighting system.

3.1. Power Quality of the Supplied Voltage

The European standard EN 50160 describes the limits within which the voltage characteristics can be expected to remain at the supply terminal in public European electricity networks. The electrical parameters recorded at each lighting connection box corresponding to the supplied voltage are the voltage frequency, voltage level, voltage variations (voltage amplitude, fast voltage variations), and THDU (total voltage harmonic distortion). The recorded values are afterward compared with the EN 50160 limits.

3.1.1. Voltage Frequency

According to EN 50160, the voltage frequency can vary for low voltage in the interval of 49.5 ÷ 50.5 Hz for 99.5% of the week and 47 ÷ 52 Hz for 100% of the week [33]. The maximum and minimum values of the voltage frequency for the measurement time interval (for each case) are presented in

Table 1. Voltage frequency.

Street Lighting System	Frequency [Hz]
	min	max
Street A	49.96	50.01
Street B	49.97	50.06
Street C	49.98	50.03

.

When analyzing the results, it can be observed that the measured values are within the limits of the allowable frequency.

3.1.2. Voltage Variations

The measured RMS voltage values are reproduced in

Table 2. RMS voltage values.

Street Lighting System	RMS Voltage [V]
	L1		L2		L3
	min	max	min	max	min	max
Street A	223.47	226.97	224.47	227.53	225.41	228.74
Street B	230.26	236.83	230.38	238.24	229.44	238.35
Street C	232.59	236.13	233.92	236.96	233.5	236.88

, where the maximum and minimum values refer to the measurement periods at particular intervals for each of the street lighting systems. According to EN 50160, the variations of voltage amplitude must be, for low voltage, in the range of 207 ÷ 253 V for 95% of the week. The fast voltage variations must be: 5% normal (218.5 ÷ 241.5 V), 10% uncommon (207 ÷ 253 V).

The displayed results correspond to the standard limits. During the measurement period, no over-voltages or voltage dips have been recorded.

3.1.3. Voltage Harmonic Distortion

The power analyzer calculates the THDU value by considering each harmonic level until the 25th order.

Table 3. Voltage THDU levels.

Street Lighting System	THDU [%]
	L1		L2		L3
	min	max	min	max	min	max
Street A	0.59	0.79	0.58	0.73	0.57	0.84
Street B	2.08	7.36	1.87	4.46	2.12	6.26
Street C	2.69	5.08	2.54	4.62	2.62	4.47

presents the maximum and minimum THDU values for each of the street lighting systems for the measured time interval.

The THDU values must be less than 8%. From the reproduced corresponding values of the electrical parameters of the distribution network, it can be concluded that the parameters of the supply voltage are within the standard limits given by EN 50160.

3.2. Power Quality of the Street Lighting Network

The following electrical parameters are analyzed: electrical current, electrical power, nonlinear PF (power factor), DPF (displacement power factor), and THDI. This analysis is made separately for each street lighting system.

The nonlinear PF, corresponding to the nonlinear equipment, considering a pure sinusoidal electrical voltage supply, is calculated with the formula:

$$PF=\frac{1}{\sqrt{\left(1+TH{D}^2\right)}}\ast DPF$$

where DPF is the cosine of the angle between the voltage and current waves for the fundamental harmonic.

3.2.1. Street A Lighting System

By switching on the electromagnetic relay, the LED street lighting system was turned on. Therefore, the electric parameters of the connected LED luminaires could be measured. The results are presented in

Table 4. Measurement results of electric parameters for street A.

Phase	Case	P	Q	S	I	U	PF	DPF	THDI	THDU
		[W]	[VAR]	[VA]	[A]	[V]	[%]	[%]	[%]	[%]
L1	1	511.75	−90.44	520.66	2.32	224.57	−0.98	−0.98	5.75	0.63
	2	501.32	−89.11	510.10	2.27	224.19	−0.98	−0.98	6.06	0.73
L2	1	437.71	−73.79	444.66	1.97	225.42	−0.98	−0.98	5.95	0.62
	2	430.11	−73.41	437.23	1.94	225.16	−0.98	−0.98	6.18	0.71
L3	1	437.94	−54.38	442.18	1.95	226.23	−0.99	−0.99	6.02	0.63
	2	427.74	−53.88	432.04	1.91	226.14	−0.99	−0.99	6.27	0.73

. Two cases are considered: 1—at the start point, and 2—at normal operation (all LED luminaires functioning, the measured values are taken—at the middle of the measurement time interval).

When analyzing the values from Table 4, it can be observed that the system is slightly unbalanced, with a few more luminaires connected to phase L1. For each phase, the increased values of the electrical current intensity can be seen at the start compared to the values taken at normal operation.

The variations in the electrical parameters—voltage, current intensity, THDU, and THDI, for the measured time interval, are presented in Figure 5.

The reactive power has negative values; therefore, the LED luminaires deliver reactive power to the system. The PF has high values for all the cases, and the THDI values are relatively constant for the entire measurement time interval, in the range of 6%.

3.2.2. Street B Lighting System

The Street B lighting system is connected to a lighting connection box that also supplies energy to the other street lighting systems, each connected to a different electrical circuit. In order to record the electric parameters of the connected LED street luminaires, the electrical circuits that correspond to other street lighting systems are disconnected. In this way, by switching on the electromagnetic relay, only the electric parameters of the connected LED street luminaires could be measured.

During the measurements, a power-up delay was observed in the LED luminaires. As previously mentioned, a local communication network box installed inside the lighting connection box allows for the wireless monitoring, control, and management of the LED street luminaires based on the ZigBee standard. The power-up delay is assumed to be determined by the time needed for the automated configuration of the ZigBee wireless network [33,34], as the LED luminaires are not connected to the ZigBee wireless network until the electromagnetic relay is switched on. The power-up delay will be investigated further in the future as it is not represented in the scope of the current paper.

Because each LED luminaire’s individual controller is fitted with a light sensor, the LED luminaire will be turned off after a certain time.

Taking the above into consideration, four cases are considered: 1—at start point, 2—after 20 s (most of the LED luminaires are still off), 3—at normal operation (all LED luminaires functioning), and 4—after the individual light sensors are switching off the LED luminaires—Figure 6.

The measurements performed for the four different cases can be relevant in considering different possible functioning scenarios (using an electromagnetic relay to control the supply of energy to the entire lighting network or using individual controllers for each LED luminaire with a continuous energy supply for the entire lighting network).

When analyzing the values from

Table 5. Measurement results of electric parameters for street B.

Phase	Case	P	Q	S	I	U	PF	DPF	THDI	THDU
		[W]	[VAR]	[VA]	[A]	[V]	[%]	[%]	[%]	[%]
L1	1	2812.32	−774.48	2917.01	12.51	233.2	−0.96	−0.99	24.51	2.15
	2	639.61	−167.88	663.67	2.83	234.39	−0.96	−0.97	7.71	2.2
	3	2218.41	−274.32	2238.06	9.56	234.19	−0.99	−0.99	4.72	2.13
	4	458.89	−162.75	490.14	2.09	234.15	−0.94	−0.94	10.77	2.15
L2	1	6576.21	−1541.62	6754.49	28.81	234.42	−0.97	−0.99	20.93	1.93
	2	244.54	−149.89	291.04	1.24	234.66	−0.84	−0.85	16.32	2.08
	3	2245.93	−235.59	2260.61	9.71	232.91	−0.99	−0.99	4.65	1.96
	4	151.23	−147.26	215.93	0.92	234.68	N.A.	−0.72	N.A.	1.95
L3	1	5384.72	−1291.68	5537.48	23.42	236.43	−0.97	−0.99	21.85	2.22
	2	469.27	−166.69	500.57	2.12	236.04	−0.94	−0.94	9.31	2.23
	3	2178.72	−225.32	2192.83	9.26	236.84	−0.99	−0.99	4.55	2.24
	4	284.95	−164.09	332.48	1.41	235.16	−0.86	−0.87	14.03	2.21

, it can be observed that the system is balanced. At the start (case 1), increased values of the electrical current can be seen, up to 28.81 A, compared with the normal operation case. The reactive power has negative values for all the cases; thus, the LED luminaires deliver reactive power to the system. The power factor has lower values for the second and fourth cases when the luminaires are switched off from the individual lighting controller. Furthermore, the THDI values are higher for the second and fourth cases due to a lower electrical current value corresponding to the fundamental frequency.

The variations in the electrical parameters—voltage, current intensity, THDU, and THDI for the measured time interval are presented in Figure 6.

From Figure 6a, the increased values can be seen for the electrical current intensity for all three phases at the start. The high electrical current intensity values at start-up are due to three transient events: the energizing of the power supply of the luminaire, the start of the driver, and the powering of the LED module. Then the luminaire transitions to the steady-state operating condition. In the initial moments after a luminaire is energized, a significant transient current appears due to the capacitors used to perform the power factor correction, the duration of this transient current is less than 1 millisecond for each luminaire, as analyzed in [16].

3.2.3. Street C Lighting System

By switching on the electromagnetic relay, the electric parameters of the connected LED luminaires can be measured, and the results are presented in

Table 6. Measurement results of electric parameters for street C.

Phase	Case	P	Q	S	I	U	PF	DPF	THDI	THDU
		[W]	[VAR]	[VA]	[A]	[V]	[%]	[%]	[%]	[%]
L1	1	4325.65	−12,491.63	13,219.39	56.26	234.98	−0.33	−0.95	271.69	5.08
	2	3713.71	−893.99	3838.33	16.36	234.64	−0.97	−0.97	10.94	2.91
L2	1	3394.15	−7592.23	8316.38	35.23	236.07	−0.41	−0.69	138.29	3.34
	2	3648.52	−842.64	3758.95	15.95	235.65	−0.97	−0.97	9.44	2.74
L3	1	6195.80	−20,179.18	21,108.94	89.47	235.93	−0.29	−0.71	221.02	4.47
	2	4538.28	−1037.76	4675	19.83	235.72	−0.97	−0.97	11.21	2.87

. Two cases are considered: 1—at the start point, and 2—at normal operation (all LED luminaires functioning, the measured values are taken at the middle of the measurement time interval).

When analyzing the values from Table 6, it can be observed that the system is unbalanced, with more LED luminaires connected in the L3 phase, resulting in a higher active power value. For the L1 and L3 phases, increased values of the electrical current intensity can be seen at the start, up to 89.47 A, compared with the values taken at normal operation. The THDI has very high values at the start for all three phases, resulting in a low nonlinear PF compared with DPF. The reactive power has negative values for all the cases. The THDU values of the voltage present lower values for the steady state operation, compared with the values at the start, but still under the standard limits. The variations in the electrical parameters for the measured time interval are presented in Figure 7.

The results presented in Table 6 and Figure 7 show that the power supply system is unbalanced, with more LED luminaires connected in the L3 phase. Increased values can be seen for the electrical current intensity at the start, as well as high THDI values.

In Figure 8, the electrical current intensity and the THDI are compared for the three LED street lighting systems at normal operation. The results differ according to the type and number of LED luminaires, but all fall below the recommended values of 20%. Comparing the Street A and Street B lighting systems, we can see that, even if in lower numbers, the LED luminaires connected on Street A generate higher THDI values. Moroever, for Street C, the high THDI values are generated by the high number of connected LED luminaires.

4. Discussion

The presented paper analyses the cumulative effect of LED street luminaires on the power quality of the power network. The LED luminaires are nonlinear receivers that generate current harmonics, which can have a negative effect on the power network if the LED luminaires are connected in high numbers.

The performed measurements have provided preliminary data regarding the cumulative effects of connecting multiple LED street luminaires to the power network. The recorded data for the three different streets with the different configurations allowed for an analysis of the effect on the power quality of the network regarding the different types, power ratings, and numbers of LED street luminaires.

In all three cases, the electrical energy is supplied directly from a medium/low voltage transformer station. The supply voltage parameters are in compliance with the standard limits provided by the European standard EN 50160.

The measurement results show that the high inrush electrical currents are generated by a high number of connected LED luminaires, especially in the case of street C. The data are recorded each second, but, as presented in [16], the duration of the transient currents is less than 1 millisecond. The equipment used for the measurements is not specifically designed to capture the peak values of a very short duration and does not provide an accurate quantitative value of the inrush currents, but it can give us a relative scale regarding the amplitude of the electrical currents present at start-up to 89.47 A for street C, phase L3. The high inrush electrical current does not present a problem for tripping the circuit breaker if, as in this case, a type C circuit breaker is used to prevent overloads and short-circuits.

Different studies [13,16] conclude that one other power quality problem can be the odd harmonic currents generated by the LED street luminaires if they are connected in high numbers. From the odd harmonic currents, the third-order-type harmonic current effects on the neutral wire are neutralized by using the TN-C single line supply diagram and TN-C-S from the pole interior connection box, as is the case for all of the three street lighting systems.

If the LED street luminaires function using individual controllers for each LED luminaire (with a continuous energy supply for the entire lighting network during daytime and nighttime), higher THDI values are generated, resulting in a low PF. Even if the electrical currents are low, having a PF value below 0.9 will generate an issue regarding the payment of reactive power to the utility company.

5. Conclusions

This paper analyses the power quality effects of street LED luminaires, focusing on the cumulative effect of multiple high-power LED luminaires connected to the same power supply.

Three different street class LED lighting systems were analyzed in terms of lighting design, implementation, and operation. For all three cases, we have performed power quality measurements in different scenarios with the purpose of encompassing the LED street lighting systems’ daily operation. Under a normal operation mode, all of the three LED street lighting systems had increased values of THDI (but were still below the recommended values), with little or no effect on the PF value. Measurements of the electrical parameters must be made after the LED luminaires are connected to assure a balanced electrical load on each phase and, if needed, optimization. Future measurements will also take into consideration the harmonic components of the electrical current and voltage waveforms, as well as an in-depth analysis of the effect on the power quality of dimming cumulative LED street luminaires.