Implementing protection and control of future HVDC grids

  In a grid topology using HVDC circuit breakers able to provide fast clearance of a DC fault, two main contrasting, yet complementary, solutions appear possible. One would be to apply the same protection philosophy and principles used in AC systems. The second could be the “Open Grid” concept. The principle, philosophy and scheme for […]

Electrical transient interaction between transformers and the power system

  Transformers are constantly exposed to different types of transient events during their daily operation, which often imposes high stresses on their insulation structure. Field experience has shown that even when good insulation coordination studies and well-known insulation design practices are applied, a significant number of transformers suffer dielectric failures. Such failures may be caused […]

Understanding boundary conditions for reliable electrical simulations

  Understanding partial differential equations (PDEs), which form the basic language with which physicists describe many natural phenomena, such as electric and magnetic fields, acoustics, fluid flow, and heat conduction, is useful in electrical simulations. The PDEs that describe the physics inside a spatial domain of interest – so-called bulk equations – are the key […]

Power transformer fleet condition assessment and risk management

  One of the most difficult aspects of fleet management is how to deal with the unknown. When dealing with hundreds, if not thousands, of assets, the unknown must be managed, and when possible, assessed such that it becomes known. Being proactive, and planning not just for tomorrow, but for the day after tomorrow, is […]

The emerging 400 V DC microgrid

  The smart grid has resulted in a number of new approaches to electricity distribution and reticulation, one of which is the microgrid. The extension of this concept to a microgrid based on DC, in the voltage range designated as low voltage for AC, offers an number of advantages over the use of AC and […]

Reducing SA’s electrical distribution transformer losses

  Forty-eight years after the birth of the first edition of the South African Bureau of Standards (SABS 780: 1966), little has been done in South Africa to reduce the distribution transformer losses as compared to first-world and BRICS countries, with the current edition have been released in 2009. Achieving increased energy efficiency through technological […]

Hierarchical control in a 5-terminal VSC-HVDC project

  The world’s first 5-terminal ±200 kV VSC-HVDC project was put into service on 4 July 2014. This project connects China’s mainland to five isolated islands. The project presented some significant technical challenges, especially with regards to the control and protection of the five terminals. A hierarchical control system was implemented to successfully overcome these […]

Enabling efficient network management in substations

  Creating a network management interface of devices and systems using different protocols can create risks and management issues which can compromise effectiveness and security for substation automation networks. An efficient and visually represented PRP/HSR network using power SCADA with specially designed management middleware can effectively avoid these problems. Traditional substation automation system (SAS) structure […]

Correcting capacitive power factor problems

  Eskisehir’s efficient new light rail train system, which runs on non-polluting electricity, has greatly benefited the general populace; but the system’s poor power factor has created a challenge for the power utility, as well as for the train’s system operators. This paper presents the solution employed to improve the power factor problem. Eskisehir, a city in […]

Protecting insulators from lightning damage

  Insulating joints (IJ) are used to electrically isolate pipeline systems or to isolate high-voltage-interference on pipelines into sections. Cathodically protected systems are electrically isolated until the dielectric strength of the insulating joint is breached. Surges caused by a lightning strike, into exposed parts of a pipeline system, may lead to the dielectric strength of […]