A PS is one of the most important components of your application because this document, when written correctly, will offer your readers, namely the admissions committee members, a quick glance into your life story so far and which direction you plan to take. You are inviting the reader to share your experiences as you disclose who you are as an applicant. Through your PS, you are providing them a general picture of your background and qualifications, knowledge of which will allow them to evaluate your suitability for admission to their school accurately.
Remember that tension, like all techniques, is merely another tool for making your writing more vivid and interesting to read. However, if you do use it, you must make it clear to your readers that the events you are describing have some relation to your study topic. If not, they will be confused, will have to re_read to make sense of it and may end up feeling irritated enough to stop reading.