Energy metering in LV/MV substations and utilities: Dos and don’ts in installation and operation

Energy Metering in Power System

Energy meters are one of the most important components for monitoring and data acquisition in a power system network with roles in every part of the power system network, from the generation to the commercialized end-users, through multiple transmission and distribution setups. They are primarily used for measuring energy for end-user billing and energy trading purpose.

In this article, the focus will be on the mechanism and purpose of energy metering in the power system network along with some essential dos and don’ts for their installation and operation.

The article skims through the basic operating principles, types, and general introductions related to energy meters while concentrating primarily on the modern applications and operational details.

Table of contents:

1. Major Applications
2. Metering in Power Substations:
   1. Technical and Constructional Requirement
   2. Input/Output Interface
3. Metering for Utility End-Users:
   1. Metering for Small Consumers
   2. Metering for Bulk Consumers
   3. Sealing, Anti-Tempering, and Data-Safety
4. Smart Meter: The New Normal

1. Major applications

The vast application of energy meters can be categorized into four major parts of the power system network: Generation, transmission, distribution, and utilization. Based on the type of system and application, the specification and customized functions of the meter differ, though the principle of measurement remains the same.

There are myriad sources of energy used for commercial electricity production, ranging from large-scale nuclear energy to more sustainable solar PV energy.

Irrespective of the types of sources and the voltage of their production, the energy meter find their use in measuring the total energy released by the source.

In some cases like roof-top solar PV systems, the energy meter should be capable of measuring the net energy to account for both incoming and outgoing power depending upon the availability of solar radiation.

Similarly, the next major application of the energy meters is in power substations to monitor the energy consumption pattern and sometimes to bill the inter-branch energy exchanges. Then comes the end-users, the customers of utility companies, where the energy meters are employed for billing purposes.

Figure 1 shows the four-quadrant operation of energy meters. The first and fourth quadrant operation of meter measures the exported power/energy, whereas the second and third quadrant is for imported power/energy measurement (looking from the utility side).

Figure 1 – Four quadrant operation of energy meter

The trivector meters are capable of four-quadrant operation and thus can also be used for net metering or reverse energy recording purposes. This feature of the trivector meters makes them very versatile and useful over a range of applications and also places them in a much higher echelon compared to their electromechanical counterparts, which lack this sort of flexibility.

Also, most of the static single-phase meters installed for household purposes are designed for two-quadrant operations (1st and 4th) only to record exported power.

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2. Metering in power substations

Substation monitoring and data acquisition have come a long way from their initial days of analog systems. The modern static energy meters used in incoming and outgoing feeders of power substations come with various additional features.