EAC4028 | Transmission System | Load Regulation Experiments

the system back to the alternating voltage. Also, this system is capable of transmitting energy in both directions while the second converter station in the HVDC plays a vital role in regulating the power in the system. Thus, the diagram below shows a setup experiment which can be used to conduct an HVDC analysis and illustration is marked as figure 1

Figure 1: HVDC Experimental Set-Up

HVDC Technologies

This technology uses two converters at the two terminal stations where one station is marked as U1 and the other station as U2. The U1 represents a rectifier while the U2, on the other hand, represents an inverter provided that the power is being transmitted from the grid to another.  Furthermore, the two transformers are often used in the system, and their presence demarcates the possibility of having variable voltage ratings in the network (Geddada et al., 2016, December p. 16). The central facility core is the conductor with DC, and this can be designed in a manner that it is either a sub-surface cable or an overhead line. However, the rectified current can exhibits ripples mostly on the chokes and in the induction cable.  There are two key technologies which often used in the recent days in line with the HVDC transmission, and these technologies are the classic HVDC which involve the use of line-commutated converter (LCC) and the modern HVDC also known as a voltage-source converter (VSC). The figure below shows the illustration for the HVDC technologies and its advanced application in the electric power transmission

Figure 2: HVDC Transmission Converter

Experimental Methods and Results

The diagram below shows the set up which was used to conduct the experiment

Load Regulation Experiments

This experiment aims at examining the energy management in line with the reduced peak loading. Before the commencement of this experiment it is essential to evaluate and take note of these aspects:

1. First, study the analysis of the experimental set up by checking the load regulation as well as configuring the settings described in it.
2. Also, take note of the SCADA section by checking the interface along with its standard setting
3. Thirdly, click the SCADA interface and run it using the Start-Stop and the Switch-on resistive load located at the left power switch.
4. Enter the values displayed on the SCADA interface as per the table 1 below

Entering the  values as per the depiction in the SCADA interface:
∑P	= 202_ W	Unfortunately
I	= 0.30 A	your answer is
		wrong

Table 1: shows the Values displayed on the SCADA Interface

Subsequently, a diagram with a load regulation or without a load regulation should be recorded, and in doing so it is important to proceed as per the outlined sets:

1. First, the data logger is opened from the overall drop-down menu, and this is marked as "Instruments" → "Logger."
2. Second, click on logger in order to start the SCADA interface and record the values
3. Also, start the makeable load manually by clicking the SCADA interface load switch
4. After that, activate pertinent dynamic load ramp and switch it on as well
5. Once, the first cycle is completed, turn on the DMS and then repeat this process and record the measurement as shown below

What peak values are reached with and without DSM?
∑Pohne DSM	= 976_ W	Correct
∑Pmit DSM	= 748_ W

Table 2: Peak Values reached in line with or without DSM

Time taken for the switch off is given as shown in the table

How long is the switch off period for the static load if it is held for 5 s?
t = 15__ s	Comment: Unfortunately the answer given is wrong

Table 3: Switch off Period

Also, the experiment requires that the dynamic load must be reduced. Hence, the torque changes from M-max-to-1 Nm and M-min-to-0.5Nm.

What do you observe?
The static load still turns off at ∑Pmax.
∑Pmax is not reached.	Correct

Which of the following statements are true?
	A. DSM now functions just as it did before.
	B. The hysteresis of the DSM system is 0.
	C. The static load is continually turned on and off ("it flutters").	Correct
	D. DSM still does not affect.
	E. ∑Pmin = 500 W

Use the ∑Pmin setting and change ΔP to 100 W.

How does the hysteresis affect the load regulation?
The hysteresis does not affect, and the static load switch is still
"fluttering."
The control system disconnects the load at 500 W and turns	Correct
it back on at 400 W.

 

Technical Analysis

From the SCADA interface, different standards values are often obtained in line with load regulations. These standard values are  defined as  the “demand side management or DSM," and they act as the standard reference when taking the readings. The values are mainly summarized as shown in the table below

Logger is also another vital and vital aspect to be considered in the technical analysis section. In fact, the logger plays an essential role since it helps in the observation of both the PLC system and the appliances values (Tang et al., 2017 p.20).  Some of the elements which are shown by the logger include the active power, the torque, necessary signals as well as the status of the switching power. Moreover, the logger is what is used in evaluating the available and active signals for different signal elements (Yoon et al., 2015 p.10). In essence, the trends of the two parameters are then decisively analyzed and recorded as shown in the table below

However, the values cannot typically be displayed unless limit settings are done.  Therefore, the limit settings used in presenting the values as shown in table

Limit Setting Values for Signals
	Recording Time (s)	measurement Time ( ms)	Power (VA)	Torque (Nm)
Values	120	500	0  to 1000	-2.5 to 0

Moreover, the logger starts to record the data as soon as the makeable SCADA interface is switched on and starts to run. The operation is repeated while keeping the last 50% of final values. However, as the process run, the data logger will depict configured values as shown in the above analysis (Aragüés-Peñalba et al., 2015 p.876).

Discussion

In the recent days, the transmission lines which are often used are the AC lines of high voltage. In fact, the HVDC transmission lines are considered based on the lesser losses of about 25% MW as well as, the more elevated load carrying capacities. HVDC is also flexible and also have precisely power flow which is controllable and manageable (Cavallini et al., 2016 p.3779).

Conversely, the cost of purchasing the HVDC terminal stations is expensive, and therefore, the elements are only used in the long-haul applications. Hence, the semi-conductor Devices or also known as the Flexible AC and Transmission system (UPFC) will offer the alternative which is cheaper and efficient.  In this Load regulation experiment using the SCADA interface, the hysteresis recorded in the system is zero, and this is because HVDC has fewer losses or ideal efficiency in the overall transmission (Guangfu et al., 2014 p.15).

Moreover, HVDC has the ripple control regulator, and this helps in monitoring and maintaining the overall output of the converter voltage. This is what accounts for the zero hystereses in the system. Since the control system is set at a load of about 500 W; therefore the system can only go up to that peak value and then starts to reduce slowly back to 400W.  In this experiment, the recording time is 120 seconds, measuring time 500 ms, the power is set at 0-to-1000 (VA), and the torque is -2.5-to-0 (Nm) (Chen et al., 2015 p.12).

Supervisory Control and Data Acquisition abbreviated as SCADA is an automation technique which improves the overall power flow control in line with the related system operations. In essence, the SCADA assists in eliminating all the wastages as well as helps in increasing efficiencies while at the same time lowering the economic processes in the system (Kumari et al., 2016, September p.5). The use of SCADA also helps in enhancing the power network, uninterrupted algorithms intelligent as well as maintaining reliable power supply. Therefore, in the above experiment, the SCADA plays a vital role in enhancing the effectiveness of the system. Hence, various characteristics such inductive and capacitive of the HVDC system are easily monitored in the process (Akdemir et al.,  2016 p.1011)

Also, the load of the HVDC has been monitored progressively in the process. For instance, when the load of the system is controlled by the torque changes from M-max-to-1 Nm and M-min-to-0.5Nm, then it is clear that the maximum load peak is not attainable. This is because the SCADA has the set range from which the system operates, and this has a broader application in the electric power transmission (Gupta et al., 2015 p.35).

Conclusion

HVDC also was known as the direct high-voltage current has comparably higher cost in line with the insulation materials and the wires used than other techniques, however; HVDC helps in the transmission of higher power compared to the overall three-phase systems. In essence, the HVDC lack the dielectric materials which often accounts for the no heat losses as compared to the three-phase system. Additionally, the HVDC has different control network frequencies which can be interconnected and also a closing coupling can be used in the system as compared to other systems like three phases. Furthermore, from the experimental analysis, it is clear that the operation of the HVDC in line with the load regulation. Thus, from this analysis, it is important to conclude that the load regulation in the HVDC must be based on specific standard values for overall efficiency and maximum electric power to be transmitted. For instance, in this case, some of the values to be considered include minimum and maximum peak values of 500 and 760W as well as torque range of 0- to-2 Nm. Furthermore, it is essential to consider the Step-per-second of 0.1 Nm, and holding time of 5 seconds. Finally, it is evident that the when the ∑Pmax reduced to 500 W, then the hysteresis recorded on the DSM system is 0 and while the minimum peak value obtained at that stage is ∑Pmin = 500 W.

Bibliography

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