SMX-0309-0105 Mekorot Executes Plans Successfully With EQ-ST

MEKOROT ISRAEL NATIONAL WATER CO EXECUTES SUCCESSFUL PLANS WITH ELSPEC

TECHNOLOGY Water Supply Co, Mekorot Israel: successfully installs EQUALIZER-ST real-time compensation innovation after extensive planning on a new pumping facility. Mekorot found that the EQUALIZER-ST (EQ-ST) to be the most feasible motor startup solution that will secure the startup of 4 Motors that causes current overloads estimated to be 6-7 times the nominal currents. Read More…

FACING VOLTAGE CHALLENGES

AT NEWLY PLANNED PUMPING

FACILITY

MEKOROT STIPULATES UNIQUE

REQUIREMENTS Apart from the voltage problems, engineers at the company identified further challenges & set out their own unique requirements:

Voltage Drop: The voltage drop should not exceed the specifications below, at the following locations: ▫ Utility Sub-Station Bus Bar - 2.5%; ▫ Pumping Facility, 22kV Point of Common

Coupling (PCC) - 5%; Motor Current Overload: Reduce the Current of

the Motors during startup by 40%; Startup Period: Significantly reduce the startup

period to the required level; Feasibility: The solutions’ cost effectiveness

will be determined by: ▫ Whether or not the capacitor will require 4

Individual Soft Starters (1 per Motor); ▫ Whether or not simple & easy to operate;

Mekorot, Israel’s National water supply company & renowned leader in water resource management, commissioned Elspec to propose an alternative motor startup solution for one of their new planned installations. The proposed solution will secure the successful startup of 4 x 3500HP (11kV @ 162.9A) motors. The pumping facility is fed by the utility with 22kV, & each motor pair is fed by a 6300 kVA (22/11.5kV) transformer. The motors are running at an efficiency of 96.5%, & presents a Power Factor (PF) of 0.17% during startup.

The challenges facing the company were numerous. The first challenge to overcome were the high levels of reactive power (kVAr) demand during the start of the large motors, which can have a severe impact on the stability of the voltage supply. In addition, the motor startup current was 6-7 times that of the nominal current. The motors were to be started in a serial order, in quick succession of one another.

CONVENTIONAL SOLUTIONS

AVAILABLE TODAY

VSD Using Synchronous Transfer: On the surface this method proved to be the best motor startup solution. Results however showed it to be a complex & expensive exercise in order to only start the motor.

Soft Starter: Although this may seem to be another alternative, the starter increases the THD (V/I) to unnecessary high levels. In some cases the voltage drop didn’t improve to the required level. It also proved to be an expensive technology. This is due to the fact that individual compensation systems were required for each motor.

SIMULATION PROVES EQ-ST’S PERFORMANCE DELIVER

REQUIRED RESULTS

The system was fitted with Elspec’s Power Quality Analyzer, which continuously records all the electrical waveforms, with no gaps in the data. Data may be analyzed over any network, at any remote location.

Prior to each EQ-ST commissioning, Elspec runs a full simulation of the network behavior during the motor startup. The simulation includes EQ-ST real-time dynamic reactive compensation systems in different sizes, that will effectively address all the outlined requirements at different levels. The simulation therefore ensures that the EQ-ST will optimize the network power quality, meet all the necessary criteria & guarantee a full return on investment prior to installation. Table 1 outlines the different results for different simulations. As the table outlines, at the Substation Measurement Point the voltage drop would be reduced to 2.5% when using a 7 MVAr EQ-ST system, thereby fully complying with the utility’s requirement.

The actual installation as described in the attached diagram (Fig. 3) consisted of 7 MVAr EQ-ST formed by 5 x 1.4 MVAr groups to compensate the motor start.

The EQ-ST proved most satisfactory & met additional criteria:

Voltage Drop: The actual voltage drop at the 22kV PCC, was reduced to 5% during startup, instead of the 10% without compensation - an improvement of 50%.

Active Power: Active power during startup became 3.5MW instead of 3MW in DOL (due to the increase in voltage).

Cost Effective: The EQ-ST is a centralized real-time motor startup solution. One system serves any number of motors, assuming that two motors are not started simultaneously. In this case, the necessity to use individual motor soft starters is eliminated.

Startup Current: The startup current was significantly reduced from 340 Amp to below 200 Amp – a reduction of 41%.

Startup Time: The length of the startup period is reduced in 24% from 4 to 3.04 seconds.

ELSPEC’S G4K POWER QUALITY ANALYZER CONTINUOUS WAVEFORM RECORDING RESULTS

Parameter Without Simulated Compensation With 7 MVAr

Simulated Improvement With 7 MVAr

Simulated Compensation With 9 MVAr

Simulated Improvement With 9 MVAr

Actual Compensation With 7 MVAr

Actual Improvement

Values at Substation

5% 2.5% 50% 1.8% 64% — —

Total Voltage Drop During Startup at 22 kV ΔU %

10% 4.9% 51% 3.2% 68% 5% 50%

Total Current During Startup

340 Amp 195 Amp 42% 135 Amp 60% 200 Amp 41%

Duration 4 sec. 3 sec. 25% 2.45 sec. 38% 3.04 sec. 24%

Table 1: EQ-ST Reactive Compensation Results

NOTE: Mekorot’s main objective for the project was to limit the voltage drop by 2.5% at the utility’s sub-station bus bar, & by 5% at the 22 kV PCC. In reality, with the actual 7 MVAr EQ-ST compensation this objective was easily achieved. However, as the simulation demonstrates by using a 9 MVAr EQ-ST compensation system the voltage drop would have been reduced to 1.8% at the sub-station bus bar & to 3.2% at the PCC respectively. In addition Mekorot’s original current overloads that were 6-7 times the nominal currents during the start of the 4 Motors. Once again actual results demonstrated that the current overloads were reduced by 41% & would have potentially reduced by 68% with the deployment of a 9 MVAr EQ-ST compensation system.

Photographic installations at the site can be viewed in Figures 1a & b. The actual measurement results without & with EQ-ST reactive power compensation can be viewed in Figures 3 – 4.

Figure 1a: Mekorot Water Pump Facility

Figure 1b: EQ-ST Compensation System

Figure 2: Electrical Diagram

Figure 3a: Motor Startup, RMS Data Without Compensation

Figure 3b: Motor Startup, RMS Data With EQ-ST Compensation

Network Voltage

Network Current

Active Power - Motor

23 kV

ΔU = 10%

20.7 kV

340 A

Reactive Power – Motor EQ-ST

T = 4 Sec.

Network Voltage

Network Current


ΔU = 5%

T = 3.04 Sec.

200 A


Figure 4a: Motor Startup, Waveform Data Without Compensation

Figure 4b: Motor Startup, Waveform Data With EQ-ST Compensation

Network Voltage


Network Current Waveforms

EQ-ST Current Waveforms

Network Voltage Waveforms


Network Voltage






Figure 5a: Motor Startup, Waveform Data With EQ-ST Compensation – Zoom In Motor Startup Initiation

Figure 5b: Motor Startup, Waveform Data With EQ-ST Compensation – Zoom In Motor Startup Termination

Network Voltage






20 mSec.

Network Voltage






Documents

SMX-0309-0105 Mekorot Executes Plans Successfully With EQ-ST